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134
Former Interns
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Journal Publications
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Conference Presentations
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2023
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Jacqueline Anatot — Biochemistry, University of Florida
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Educational Institution: University of Florida
List of Mentors: Dr. John Wilson & Taylor Sheehy
Program: NSF REU
Research Project: Macrophage-Targeted Polymer-Drug Conjugates for STING Pathway Activation to Improve Cancer ImmunotherapyResearch Abstract: The cGAS-STING pathway plays a crucial role in the immune recognition and elimination of cancer cells, and STING agonists are being explored as next- generation cancer immunotherapeutics. Specifically, STING activation has the potential to reprogram tumor-associated macrophages (M2) into an anti-tumor phenotype (M1), further facilitating cancer clearance. STING agonists suffer from poor drug-like properties and off-target toxicities, which could be mitigated using drug delivery systems. Therefore, we aim to develop a tumor and macrophage-targeted, polymer-drug conjugate that enhances macrophage uptake of STING agonists. Due to the overexpression of the mannose receptor in M2-macrophages, mannose serves as a promising cell-targeting agent. Through Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization, we synthesized 100kDa poly(N,N-dimethylacrylamide-co-Azide ethylmethacrylate-co-Mannose) terpolymers with various mannose composition. The DMA backbone enables efficient drug solubilization and prolonged circulation, while the presence of AzEMA permits conjugation of DBCO-functionalized STING agonists. Murine macrophage cell lines were polarized to an M2-phenotype and utilized to investigate uptake of our polymers. As expected, mannose functionalized polymers demonstrated enhanced uptake in M2 macrophages. An ongoing biodistribution study aims to further validate enhanced macrophage uptake by measuring polymer accumulation within macrophage-rich organs. Future studies will incorporate a STING agonist onto the lead polymer platform and demonstrate its ability to repolarize macrophages and enhance antitumor immunity. This study contributes to the advancement of polymer-drug conjugates, unlocking unparalleled potential in the realm of drug delivery technology to revolutionize therapeutic outcomes.
Bio. Jacqueline Anatot is a rising senior pursuing a B.S. in Biochemistry with a minor in MSE at the University of Florida. She is currently working as an undergraduate research assistant in Dr. Brent S. Sumerlin's research group and recently released a publication in the JACS titled: “Degradation of Polyacrylates by One-Pot Sequential Dehydrodecarboxylation and Ozonolysis.”
Jacqueline is a recipient of the prestigious CLAS Sciences Scholars program as well as the Bristol-Myers Squibb Scholars Program. She is involved in the UF Chemistry club Outreach Initiative and intends to pursue a PhD in BME, specifically focusing on mechanisms to treat and prevent disease.
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Taylor Baugher - Biomedical Engineering, Georgia Institute of Technology
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Educational Institution: Georgia Institute of Technology
List of Mentors: Dr. William Fissell & Dr. Harold Love
Program: NSF REU
Research Project: Inducible Gene Expression to Drive Cell Differentiation in Renal Tubule Epithelial Cells In VitroResearch Abstract: The growing use of tissue and cell cultures for the development of organ replacement therapies has brought about challenges regarding the differentiation of cultured cells. Renal tubule epithelial cells are specialized to carry out vital functions in the kidney such as reabsorption and secretion. These cells express genes such as NHE3, AQP1, and N-Cadherin to aid in water and ion transport. However, in vitro renal tubule epithelial cells lack the transcriptional profile to fully differentiate, decreasing transport, polarization, and metabolic activity compared to their in vivo counterparts. This presents challenges to biomedical research as cultures are used for bio-inspired design and conceptual frameworks. Cell differentiation in intestinal epithelial cells in vitro is activated by a serine/threonine kinase encoded by a tumor suppressor gene, LKB1, with the help of an LKB1-specific adaptor protein, STRAD- (Baas et. al 2004). Using a cumate gene-switch system integrated into a piggyBac transposon, we studied how induced expression of the LKB1 and STRAD- genes would influence renal epithelial cell differentiation in vitro. Gene expression analyses proved STRAD- and LKB1-induced cells significantly expressed more proximal tubule biomarkers when compared to control renal proximal tubule epithelial cells, but this was not dependent upon transgene expression. These findings suggest a transcriptional variation between clones that could aid in isolating new cell lines with better differentiation for future biomedical research.
Bio. Taylor Baugher is a rising third-year in the B.S. Biomedical Engineering program at the Georgia Institute of Technology. In the past, Taylor has worked as a data curator for the Pathology Dynamics Lab at Georgia Tech, where she used data mining and quality control techniques to aid in the buildout of a natural language processing model for drug repurposing. Currently, Taylor serves as the secretary for Bioinformatics at GT, a club that expands the knowledge of computational biology across campus. For the upcoming year, Taylor will serve as a teaching assistant in the biomedical engineering department at Georgia Tech, guiding first-year students through the development of their skills as academics and employees. As for graduate school, she hopes to dive more into the role of bioinformatics for personalized medicine along with expanding her current knowledge of genome engineering for biomedical applications.
- Baugher was awarded Best Layout at the capstone poster session.
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Emily Buckner - Mechanical Engineering, University of Tennesee, Knoxville
Educational Institution: University of Tennesee, Knoxville
List of Mentors: Dr. Xiaoguang Dong & Boyang Xiao
Program: NSF REU
Research Project: Wirelessly Actuated Soft Miniature Robots with Integrated Microfluidic Modules for Targeted Drug DeliveryResearch Abstract: The inherent softness of soft robots offers unique advantages in medical applications where safe interaction with surrounding biological tissues is crucial. Soft robots made of smart soft materials allow for programmable functionalities by spatially patterning material properties. More recently, magnetic actuation has gained significant attention due to its ability to wirelessly control soft robots for medical operations. Despite recent advances, the development of wireless soft robots for minimally invasive medical procedures that can traverse complex terrains remains challenging. In this study, we propose an untethered soft robot actuated by magnetic fields and integrated with microfluidic channels to achieve on-demand and targeted drug delivery in complex, confined environments within the body, such as the gastrointestinal (GI) tract. The robot, constructed at the millimeter scale through laser lamination and layer-by-layer assembly, boasts optimized material properties and dimensions to facilitate multi-modal locomotion and targeted drug delivery functions. By employing a tailored magnetization profile design, the robot exhibits various modes of locomotion, including crawling and climbing. Furthermore, the integration of microfluidic channels into the robot body, along with an origami-inspired self-folding pump and flexible valve, enables precise control of drug delivery. To actuate the robot's movement, we have designed a customized electromagnet array that accurately directs and regulates the magnitude of the applied magnetic field. Finally, we experimentally validate the robot's locomotion and drug delivery capabilities in phantom structures. This novel soft robot design holds great potential to navigate complex terrains and serve therapeutic functions in biomedicine as well as on-demand and targeted drug delivery, minimizing the side effects of overdosing during medical treatments.
Bio. Emily Buckner is a rising senior at the University of Tennessee, Knoxville pursuing a degree in mechanical engineering. She became involved in undergraduate research in the Advincula Lab where she works jointly between the Institute for Advanced Materials and Manufacturing and Oak Ridge National Laboratory on the additive manufacturing of nanocomposites. For this research, she has been awarded two research grants, presented at national conferences, and co-authored the paper “Digital Light Processing (DLP): 3D printing of polymer-based graphene oxide nanocomposites—Efficient antimicrobial material for biomedical devices”. In addition to research, Emily is the President of the Tau Beta Pi Tennessee Alpha chapter, an ambassador to UT’s Engineering Professional Practice Office, and involved in the Society of Women Engineers.
- Buckner was awarded a $1K travel grant at the capstone poster session.
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Erin Burgard - Environmental Engineering, Arizona State University
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Educational Institution: Arizona State University
List of Mentors: Dr. Richard Haglund & Jackson Bentley
Program: NSF REU
Research Project: Using Machine Learning with Porous Silicon to Determine IgG Concentrations in Human SerumResearch Abstract: Conventional solar panels currently operate at a low efficiency of approximately 25%. However, Mott insulators present a promising avenue for enhancing solar energy conversion as they have shown a theoretical potential to achieve over 65% efficiency. Impaction ionization occurs in a semiconductor if the kinetic energy of the charge carrier is greater than twice the bandgap, which may then excite an additional electron-hole pair. In Mott insulators, this process occurs over one hundred times faster than a typical semiconductor (i.e. silicon), which contributes to almost doubled efficiency, and the possibility of creating multiple charge carriers per photon absorption. The Mott insulator proposed to be used in solar energy is LVO (lanthanum vanadium oxide). However, this research focuses on V2O3 because it is a strongly correlated material that is easier to work with in the preliminary investigation of the multiexciton generation process. The films were synthesized using sputtering and annealing techniques, and characterized with xray diffraction, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. Using this model Mott insulator thin film, we successfully established a reliable recipe detailing the sputtering and annealing procedures for producing quality thin V2O3 films. This investigation contributes to the advancement of solar panel technology by providing a better understanding of Mott insulator synthesis and offering a potential avenue for improving solar energy conversion efficiency by studying impact ionization in a model Mott insulator system.
Bio. Erin Burgard is an honors undergraduate senior at Arizona State University, where she majors in Environmental Engineering and minors in Spanish and Environmental Humanities. This summer, she is researching at Vanderbilt University, where she is synthesizing and characterizing Mott insulators for solar cell applications. At ASU, she researches the stress response of perovskite thin films for use in solar cells. This work was supported by her honors thesis which was defended in May 2023 and awarded the Bidstrup fellowship, Mensch prize, Jaap Sustainability scholarship, and Fulton Undergraduate Research Initiative. Erin also works with the international water treatment non-profit 33 Buckets and spent two months in the rural communities in the outskirts of Cusco, Peru conducting research surveys and assessments. Within ASU, Erin worked as a first-generation engineering student mentor for the Fulton Engineering School with the objective to increase the retention of first-generation students in engineering. She also started a small business selling hand painted cards. She will graduate in May of 2024.- Burgard was $1K in the VINSE summer image competition
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Andres Cotto - Chemical Engineering, University of South Florida
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Educational Institution: University of South Florida
List of Mentors: Dr. Sharon Weiss & Kellen Arnold
Program: NSF REU
Research Project: Design and Characterization Techniques to Advance Integrated Photonics for Space MissionsResearch Abstract: Photonic integrated circuits are hybrid circuit designs that marry the data transmission efficiency of optical signaling with the compact, powerful data processing of electrical integrated circuits on a single chip. Integrated photonics research has led to strong commercial applications in communications, biosensing, and quantum computers. There is also a strong desire to develop integrated photonics for space missions, where the size, weight, power, and performance advantages of on-chip photonic systems can improve the capabilities of scientific equipment. In the Weiss group, we innovate photonic design and characterization methods for enhancing light-matter interactions at the nanoscale to advance on-chip photonic component performance and revolutionize space industry equipment. This summer, we compared energy redistribution between different nanoscale geometries in specially-designed periodic cavities in silicon waveguides, called photonic crystals. Using electromagnetic simulations, the photonic crystal unit cell designs can be tailored to match fabrication capabilities with design specifications. As we develop these photonic crystal designs, the Weiss group also works on commercially-viable photonic crystals, which are fabricated using deep ultraviolet lithography. We developed a polishing and etching technique that removes the coatings from commercially fabricated chips to reveal the photonic structures below the surface. This procedure is useful for imaging for publications and design feedback and will also be used in the future for space environment testing with/without encapsulation and biosensing experiments.
Bio. Andres M. Cotto is a rising junior at the University of South Florida, where he is earning his Bachelor of Science in Chemical Engineering. When not in the classroom, he works as an undergraduate researcher under Dr. Ryan Toomey, where he researched materials ellipsometry and developed an interest in learning about photonics. In addition to his work in curricula and research, Andres works as the elected Events Chair for the USF chapter of the American Institute of Chemical Engineers, and as the Operations Director for the USF chapter of Society of Hispanic Professional Engineers. Andres came to VINSE out of an interest to learn more about materials engineering, where he could gain insight into the life of research from Vanderbilt’s research groups. He hopes to one day use his chemical engineering knowledge for the synthesis of materials used in cutting edge, high-efficiency electronics and clean energy solutions. The industries he is most interested in are renewable energy, solar cell technologies, and the space industry. -
Anya Frazer - Physics, University of North Carolina, Chapel Hill
Educational Institution: University of North Carolina, Chapel Hill
List of Mentors: Dr. Greg Walker & Brad Baer
Program: NSF REU
Research Project: Thermal Conductivity Across Metal/Metal Oxide InterfacesResearch Abstract: Catalytic cracking of ethane to ethylene uses a large amount of heat energy, much of which goes to waste. The National Renewable Energy Laboratory has proposed a new method to reduce heat waste, which involves inductively heating the reaction through a layered metal/metal oxide device. We demonstrate a computational method for predicting thermal conductivity across nonequilibrium metal/metal oxide systems using molecular dynamics (MD) with a two-temperature model (TTM). The TTM allows for thermal conductivity to be modeled as a combination of lattice and electronic contributions by governing the exchange of energy between the lattice and an electronic subsystem. Iron and iron oxide were chosen as the model materials to demonstrate our method. Our method predicts the thermal conductivities of bulk iron and iron oxide to the same order of magnitude as experiment. The addition of the TTM improved the prediction of thermal conductivity of iron compared to MD alone, indicating that electronic contributions are significant in the thermal conductivity of iron. Our system predicted a large temperature drop across the metal/metal oxide interface. The TTM created a more physical representation of heat traveling through iron, but was not applicable to the iron oxide due to a deficiency of conduction electrons. Our approach is transferrable to other metal/insulator systems.
Bio. Anya Frazer is a rising sophomore at UNC Chapel Hill, double majoring in physics and music. Prior research experience includes a senior capstone studying the impact of practice habits on harmonic content of middle and high school flute players’ tone, as well as participation in a large-scale literature review through NASA’s Backyard Worlds research group to catalogue known qualities of star systems within 20 parsecs. She has made the Dean’s List during both of her semesters at UNC. Anya hopes to get a diverse range of research experiences in her undergraduate career to prepare her for pursuing a PhD in physics. When she is not studying physics, you can find her playing the flute in UNC’s Wind Ensemble and in solo performances. -
Jonathan Gonzalez - Mechanical Engineering, University of Puerto Rico
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Educational Institution: University of Puerto Rico
List of Mentors: Dr. Cynthia Reinhart-King & Jenna Mosier & Emily Fabiano
Program: NSF REU
Research Project: Understanding the Role of Microtubules and Focal Adhesions in Breast Cancer Cell Migration
Research Abstract: Cancer metastasis, an advanced stage of cancer, is responsible for 90% of cancer-related deaths. In this process, cancer cells migrate from the primary tumor to different regions in the human body to form secondary sites. Cell migration is a complex stage in this process requiring the coordination of cytoskeletal components and focal adhesions. Microtubules provide structure as well as internal organization of the cell. Vinculin, a key focal adhesion protein, connects the surrounding matrix and the cell cytoskeleton. Microtubule destabilization has previously been reported to increase focal adhesion size, resulting in increased vinculin recruitment to focal contact sites. While previous research has primarily focused on the physical link between actin and focal adhesions, or the individual roles of microtubules and focal adhesions, the interplay of vinculin and microtubule dynamics in directing cancer cell behavior is still unknown. To assess this relationship, we created a vinculin-knockout cell line using CRISPR/Cas9 and visualized microtubules using a live-cell dye. Additionally, we used nocodazole, a pharmacological agent to disrupt microtubule polymerization, to understand how migration is affected by microtubule and vinculin organization. Using 500 nM nocodazole treatment, we found that microtubule front:rear distribution was significantly decreased in control, but not vinculin-knockout cells. Control cells moderately decreased velocity, while no change was observed in vinculin-knockout cells with treatment. Future work in this project will involve using representative, 3D collagen microtracks to further elucidate the role of vinculin and microtubules in a physiologically relevant environment to potentially highlight key therapeutics for treating cancer metastasis.Bio. Jonathan Gonzalez is a rising junior at the University of Puerto Rico Mayagüez studying mechanical engineering. Through his education journey, he had the opportunity to join the research team Innovating Design Decisions in Engineering and Applied Systems (IDDEAS) and optimized patient waiting time at a cardiologist’s office. Here, he collected and analyzed samples to improve patient waiting time. Furthermore, he shadowed the creation of A3B, an emergency ventilator with the aim of being the first FDA-approved ventilator in Puerto Rico. Currently he is an REU student at the Vanderbilt Institute of Nanoscale Science and Engineering (VINSE) investigating microtubule-mediated behavior of vinculin knockout breast cancer cells in confined migration. After completing his undergraduate degree, Jonathan aspires to obtain a Ph.D. in biomedical engineering to further his contributions to healthcare.
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Raey Hunde - Chemical Engineering, University of Maryland, Baltimore County
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Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Ethan Lippmann & Corinne Curry
Program: NSF REU
Research Project: Stimulating Collateral Arterial Growth Using Acellular, Growth-Factor Free Hydrogels for the Treatment of Critical Limb Ischemia
Research Abstract: Critical Limb Ischemia (CLI) is a condition that affects millions of people all over the world who may suffer from diabetes or are chronic smokers. It is a severe blockage in the arteries caused by a buildup of plaque that significantly reduces blood flow to lower extremities like the legs. The lack of blood flow causes the surrounding tissue to become necrotic, thus requiring amputation. As of now, CLI lacks a lot of robust treatment options. In the past, clinical trials have attempted to stimulate arterial growth using growth-factor encapsulated hydrogels. Unfortunately, these clinical trials have failed to appreciably improve patient outcomes. We propose an alternative method that uses acellular-growth factor-free hydrogels to stimulate arteriogenesis. This methodology is twofold: (1) to further develop and characterize a previously studied GelCad hydrogel (gelatin-based hydrogel with Cadherin peptides attached) and synthesize this GelCad hydrogel into microspheres, and (2) to implement a cell-responsive siRNA release strategy that will trigger arteriogenesis through macrophage polarization. Preliminary results suggest GelCad microspheres can be synthesized using both a 4-Arm PEG SG (negative control) and 3,3′-Dithiodipropionic acid di(N-hydroxysuccinimide ester) (positive control) crosslinkers. 3,3′-Dithiodipropionic acid di(N-hydroxysuccinimide ester) is a reactive oxygen species or ROS active and is capable of macrophage polarization.
Bio. Raey Hunde is a rising senior chemical engineering student at the University of Maryland, Baltimore County. She has researched biomedical and chemical engineering at the following institutions: FDA: CBER, Laboratory of Virology, University of Minnesota: Twin Cities, University of Maryland, Baltimore County, Purdue University, and Vanderbilt University. Raey is a Meyerhoff and U-RISE scholar at the University of Maryland, Baltimore County, and aspires to obtain her Ph.D. in chemical engineering after graduation. -
Shereena Johnson - Bioengineering, Rice University
Educational Institution: Rice University
List of Mentors: Dr. Marjan Rafat & Tian Zhu
Program: NSF REU
Research Project: Irradiated Extracellular Matrix Effects on Breast Cancer Cell InvasionResearch Abstract: Triple negative breast cancer (TNBC) has a significantly higher rate of locoregional recurrence after radiation therapy than other forms of breast cancer but has limited treatment options due to the lack of targetable hormone and protein receptors. Previous work has shown that recurrence is caused by increased recruitment of circulating breast cancer cells to the irradiated site. However, the change to the tumor microenvironment that leads to increased invasion is unknown. This project aims to determine whether the irradiated extracellular matrix (ECM) is responsible for increased TNBC cell invasion through the study of irradiated ECM hydrogels. ECM hydrogels were created using mammary fat pads (MFPs) extracted from immunocompromised Nu/Nu mice. MFPs were irradiated to a dose of 20 Gy ex vivo using a cesium source, decellularized to ECM components, and formed into hydrogels through pH-controlled restructuring of the ECM environment. Murine TNBC cell invasiveness in irradiated vs. non-irradiated control ECM hydrogels was measured via colocalization of F-actin and cortactin in 4T1 cells embedded into the hydrogels for 48 hours, staining and imaging of E-cadherin and vimentin proteins, and an invasion assay.
Using fluorescence microscopy, we determined an increase in colocalization of F-actin and cortactin in 4T1 cells as well as increased invasion when embedded into irradiated ECM hydrogels. We also observed cell morphology changes toward a more invasive phenotype and increased expression of E-cadherin and vimentin proteins in irradiated ECM hydrogels. These results suggest that the isolated effect of ECM changes contribute to increased TNBC invasion after radiation therapy. Future work will focus on analyzing altered individual protein components of the ECM and interactions between immune cells and cancer cells in the irradiated microenvironment.
Bio. Shereena Johnson is a third-year undergraduate student, studying Bioengineering at Rice University in Houston, TX. She is originally from Orlando, Florida and attends Rice as a Questbridge Scholar. During her time at Rice, she contributed to research at the Tabor Lab in the Department of Bioengineering, which focuses on the study and manipulation of bacterial gene networks for use in disease diagnosis and drug delivery. Shereena is an active contributor to the engineering community at Rice through her roles as a Writing Mentor for Introductory Engineering Design Courses, the Fundraising Senator for the National Society for Black Engineers Executive Board, and through her future role as a Teaching Assistant for Fundamentals of Bioengineering. -
Deborah Oke - Chemistry, Northeastern University
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Educational Institution: Northeastern University
List of Mentors: Dr. Janet Macdonald & Tony Peng
Program: NSF REU
Research Project: Rediscovering Lost Rock Art Painting TechniquesResearch Abstract: Hundreds of years ago, the Anishinaabe people of the northern US and Southern Canada region painted on cliff sides along lakes, which leaves their art susceptible to wear and erosion – or so one would think. How to create these long lasting works of art have been lost within the culture. Previous studies have found that the main pigment is hematite, and a substance with high amounts of silicon are found below, above, and mixed within the paint layer. Using various plants native to the region and of cultural -significance, different lyes were made from the ashes of these plants to create a natural source of silica that can be painted. The silicon content of the lye was dependent on the ashing time and the identity of the plant. Chemical analysis techniques including Inductively Coupled Plasma Optical Emission Spectroscopy and X-ray Fluorescence were used to analyze the amounts of silicon in the lyes. Lyes made from sweet grass and horsetail had the highest amounts of silicon in them relative to other plants including cedar, red osier dogwood, and tamarack bark. In regards to painting, the use of water glass to represent the silicon layer beneath and above the paint aided in the overall durability. Going forward, additional plants will be used to continue making and testing lyes, as well as industrial tests to provide quantitative analysis of the durability of the paint.
Bio. Deborah Oke is a rising second year Honors student at Northeastern University, studying chemistry. She is a member of Northeastern University's Student Affiliates of the American Chemical Society, NuSci, and serves as an Honors Ambassador. During her first year, she created a curriculum surrounding molecular structure and bonding theories to be taught at a local high school, got to volunteer with the American Chemical Society for National Chemistry Week, and has aided Northeastern’s Department of Chemistry by being a student interviewer for potential faculty members. She hopes to join a lab at her home institute this fall to continue expanding her research experience.- Oke was awarded Best Use of Graphics at the capstone poster session.
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Ellie Okonak - Biomedical Engineering, Bucknell University
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Educational Institution: Bucknell University
List of Mentors: Dr. Craig Duvall & Amelia Soltes
Program: NSF REU
Research Project: Nanoparticle Development For siRNA Delivery To Treat Osteoarthritis (OA)Research Abstract: Osteoarthritis (OA) is a degenerative joint disease that affects over 32 million US adults and currently has no cure; treatments for OA focus on alleviating symptoms and include lifestyle changes, pain-relieving medications, and joint replacements. Short interfering RNA (siRNA) has the capability to degrade protein-producing mRNA, which can be used in OA to prevent the expression of the gene that drives cartilage degradation and ultimately inhibit disease progression. However, siRNA delivery is challenging in vivo due to issues such as endosomal escape and kidney clearance. One alternative method of delivery is loading the siRNA into polymeric nanoparticles (si-NPs) that enable siRNA to be delivered into the cell. The purpose of this project was to optimize nanoparticle formulation using a confined impinging jets mixer (CIJ) for effective siRNA delivery.
Various formulations of si-NPs were made using a CIJ mixer with solvent and antisolvent streams. The si-NPs contain a core consisting of poly(dimethylaminoethyl methacrylate-co-butyl methacrylate) (DB) to enable endosomal escape and poly(lactide-co-glycolide) (PLGA) for nanoparticle stability. DSPE-PEG (lipid-PEG) was used as a surfactant for biocompatibility and to prevent si-NP aggregation. The ratio of DB to PLGA in the si-NP core was varied, as well as the ratio of amines to phosphates (N:P), in order to optimize the gene silencing activity and toxicity of the si-NPs. The si-NPs were analyzed for size, zeta potential, and siRNA delivery capability. The formulation concentrations of 3 mg/mL of DB and PLGA in the solvent stream and 1 mg/mL lipid-PEG in the antisolvent stream were found to be the most successful for nanoparticle formation using the CIJ mixer. Studies investigating the gene silencing activity of the different si-NP formulations are ongoing.
Bio. Ellie is a rising third year biomedical engineering major at Bucknell University in Lewisburg, PA. She works as a study group facilitator for Chemistry and Calculus II students on-campus, and has been a teaching assistant for various calculus classes since her freshman year. Ellie also leads tours as an ambassador for the Office of Admissions, and has served on the Biomedical Engineering Society executive board. Ellie’s involvement in a sophomore year cell culturing class sparked her interest in drug delivery research, which further led her to Professor Duvall’s Advanced Therapeutics Laboratory through the VINSE REU. Ellie plans to pursue her PhD in biomedical engineering, and is grateful for the knowledge and support she gained this summer.
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Ethan Ray - Materials Science and Engineering, Georgia Institute of Technology
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Educational Institution: Georgia Institute of Technology
List of Mentors: Dr. Josh Caldwell & Saurabh Dixit
Program: NSF REU
Research Project: Controlling and Manipulating Confined Infrared Light in MoO3 via Polaritonic DesignResearch Abstract: The Infrared (IR) spectrum of light is crucial for various applications such as thermal imaging, molecular sensing, free space communication, and many others. However, the long free-space wavelength of IR light greatly limits its applications in chip-scale devices. This problem can be circumvented using hyperbolic van der Waals materials that exhibit hyperbolic anisotropy in which the dielectric permittivities along the principal crystal directions exhibit opposite signs. Such hyperbolic materials can confine high-momentum (short wavelength) electromagnetic waves with the help of phonon polaritons — a quasi-particle made up of the hybridization of charged dipoles in a crystal and photons (an external light source). In this work, we investigate sub-wavelength wedges of a hyperbolic material known as alpha-phase molybdenum trioxide (α-MoO3) to demonstrate in-plane tight focusing of electromagnetic waves beyond the diffraction limit. We design our wedges by optimizing geometrical dimensions using 3D numerical simulations. Thereafter we fabricate such structures through mechanical exfoliation and focused-ion beam etching. Furthermore, we investigate the effect of geometrical confinement on changing the propagation direction of phonon polaritons in the forbidden direction. In addition, we explore the image polariton effect on propagation direction and tight in-plane focusing of phonon polaritons by introducing a perfect electric conductor beneath an α-MoO3 hyperbolic thin film. We observe that the confinement is greatly enhanced due to the image charge effect. These findings open avenues for chip-scale mid-IR nanophotonic devices and optical components with the ease of van der Waals integration.
Bio. Ethan Ray is a rising 3rd-year Materials Science and Engineering (MSE) major from Lexington Park, MD, studying at the Georgia Institute of Technology as a Stamps President’s Scholar. His research at GT is centered around the growth of 2D heterostructures and films for multiferroic devices. He is fascinated by device miniaturization, optimization of fabrication methods, and exploitation of novel functional material properties. Outside of research, Ethan mentors students as an MSE Ambassador and serves as President and Dance-Coordinator of the GT Filipino Student Association. His choreography has garnered over 30 million views online, displaying Filipino culture on a worldwide stage and cementing his mission to preserve and educate about the Philippine arts. Ethan plans to continue working towards materials research, education, and mentorship by pursuing a Ph.D. in MSE and becoming a professor.
- Ray was awarded a $1K travel grant at the capstone poster session.
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Laura Weinstein - Biomedical Engineering, University of Delaware
Educational Institution: University of Delaware
List of Mentors: Dr. Mike King & Dr. Jason Zhang
Program: NSF REU
Research Project: Neutrophil-Mediated Transendothelial Delivery of E-selectin Liposomes for Targeting Inflammatory Sites
Research Abstract: Nanomedicine is an expanding field that is revolutionizing translational medicine. Among the various nanoscale carriers, liposomal nanoparticles have gained significant attention due to their ideal size for robust transport within the environment of the body. Cell-mediated drug delivery harnesses the unique capability of nanoparticles to transport therapeutic cargo to specific destinations, such as tumors or inflamed tissues. To exploit this potential, our laboratory has developed a strategy for conjugating the protein E-selectin (ES) to the lipid-PEG shell of liposomes. This approach is advantageous as white blood cells possess ES ligands on their surface, enabling effective attachment of the liposomes to these cells. Subsequently, the liposomes can hitch a ride with white blood cells to target cancer cells in circulation or reach inflammatory sites, leveraging the immune system's natural response. Our investigation has focused on neutrophils as carriers for this cell-mediated delivery method, given their role as the body's first responders to infection or injury. By utilizing the protein Interleukin-8 (IL-8) as a signaling mechanism, we have successfully guided neutrophils to specific locations. Through comprehensive experimentation using TransWellTM migration chambers and identification through confocal imaging, we have demonstrated the ability of liposomes to attach to neutrophils and facilitate their migration across endothelial-like barriers via IL-8 signaling. These findings highlight the potential of liposome-neutrophil conjugates as efficient drug-carrying nanoparticle carriers, offering rapid and targeted relief in various medical conditions.
Bio. Laura Weinstein is a Eugene du Pont Scholar in the Honors College at the University of Delaware where she is studying biomedical engineering and nanoscale materials. At her home university, Laura is an undergraduate researcher in the Day Lab, where she researches polymeric nanoparticle synthesis for biomimetic cargo delivery. She presented her first poster in 2022 at the University of Delaware Summer Scholars Symposium as a part of the Center for Biomechanical Engineering Research (CBER) REU, and gave an oral presentation on her research as a Winter Research Fellow in January 2023. During her time at UD Laura has won the 2022 Ratcliffe Eco Entrepreneurship Foundation Switch Pitch and Innovation Sprint, 2022 and 2023 National Cyber Scholarship, and in 2023 was awarded the Biomedical Engineering Distinguished Sophomore Award. This summer Laura is grateful to be a part of the Vanderbilt Institute for Nanoscale Science and Engineering (VINSE) REU at the King Lab where she is researching cell-mediated drug delivery. After her graduation from UD, Laura plans to earn a PhD in bioengineering with a focus on nanomedicine and drug delivery.- Weinstein was awarded a $1K travel grant at the capstone poster session.
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2022
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Thiago Arnaud - Mechanical Engineering, Florida International University
Educational Institution: Florida International University
List of Mentors: Dr. Josh Caldwell & Guanyu Lu
Program: NSF REU
Research Project: Filterless Infrared Chemical Sensing with Narrowband Thermal EmittersResearch Abstract: A plasmon polariton is a quasiparticle made from the coupling of a photon with coherently oscillating free carriers. A TAMM plasmon mode is where a plasmon polariton is induced between a distributed Bragg reflector (DBR) and a conductive surface, which provides a significant reduction in spectral linewidth. Here, we implement a machine-learning algorithm to inversely design the structure of the aperiodic DBR and the carrier concentration of the doped CdO, an n-type semiconductor that we use as the conductive layer to support the TAMM plasmon. Due to the tunability of these structures, they can be designed for narrow absorption and thus, thermal emission peaks at arbitrary spectral position, linewidth and amplitude. This attribute allows for the design of selective infrared sources for chemical sensing, which targets the emission to match the vibrational mode of a desired molecule. Commercially, chemical sensing techniques are limited to one target molecule per device due to the dependence of a bandpass filter to eliminate other frequencies where molecules not of interest absorb. By implementing a TAMM-emitter-based sensor, we demonstrate its viability for filterless non-dispersive infrared sensing featuring an increase in discrimination for a molecule of interest. Two TAMM emitters were designed, fabricated and tested; one for CO2 and another for CO gas sensing while having a low and indiscriminate absorption of the other when present. From plotting the ratio of power decrease due to gas absorption as a function of concentration, the TAMM demonstrated a more accurate sensitivity for concentrations of CO2 than a blackbody with a bandpass filter.
Bio. Thiago Arnaud is a rising junior from Miami, Florida. He studied at Florida International University as a Mechanical Engineer with FIU’s Presidential Merit Scholarship and Florida’s Bright Futures Academic Scholar. He switched majors to Physics due to his curiosity to understand fundamental concepts. He is now enrolled at University of Florida for a Bachelor of Science in Physics. In the Summer of 2021, he participated in the VINSE REU under Dr. Joshua Caldwell on a robust method of thermal imaging. He is working again with Dr. Caldwell this summer to learn more of the skills and research concepts that will prepare him for a successful graduate student career.
- Conference Presentation
-T.S. Arnaud, M. He, J. Nordlander, J.P. Maria, and J.D. Caldwell "Multi-Spectral Thermal Imaging with Inversely Designed Optical Filters for Material Recognition" Materials Research Society (MRS) Fall Meeting, Boston, MA, November 2022. - Arnaud was awarded Best Layout at the capstone poster session.
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Roxanne Hinojosa - Chemical Engineering, University of Oklahoma
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Educational Institution: University of Oklahoma
List of Mentors: Dr. Janet Macdonald & Jeremy Espano, Lexi Koziel
Program: NSF REU
Research Project: Achieving Phase Purity in Nickel SulfidesResearch Abstract: There are seven known phases of nickel sulfide: vaesite, millerite, NiS, godleskvite, Ni7S6, polydymite, and heazlewoodite. Understanding how to obtain one phase over the other would allow for more reproducible, synthetic control as well as obtain more diverse materials for a wider range of applications such as catalysis and semiconductors. Here we aim to obtain each allotrope of nickel sulfide in its phase pure form by using various chemical tools and methods to manipulate the synthesis of these phases. By changing the ratio of precursor to nickel (II) stearate, the solvent, the substituted thiourea used in the reaction, the time of the reaction, and the injection temperature, we were able to obtain vaesite in its pure form, millerite, NiS, and polydymite. By systematically changing these aspects of the synthesis, we were able to understand how the nucleation and transformations of these phases happen, such as the transformation of vaesite to polydymite, and the co-nucleation of millerite and NiS. Using this knowledge will enable the synthesis of uncommon and rare phases of the nickel sulfide family.
Bio. Roxanne Hinojosa hails from Lewisville, Texas, and is a rising sophomore at the University of Oklahoma-Norman majoring in Chemical Engineering and minoring in Computer Science. While she attended Marcus High School in Flower Mound, Texas, she was a part of the National Honor Society, Spanish Honor Society, Science Honor Society, and was an athlete on the cheer team for all four years. Currently, she is a teaching assistant and tutor in the Diversity and Inclusion program at the University of Oklahoma where she assists in the education of culturally and socio-economically diverse freshmen. In her free time, she enjoys partaking in social events hosted by the Society of Women Engineers.
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Levi Hoogendoorn - Materials Science and Engineering, Northwestern University
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Educational Institution: Northwestern University
List of Mentors: Dr. Josh Caldwell & Mingze He
Program: NSF REU
Research Project: Controlling Light Propagation at the Nanoscale in Confined Molybdenum Trioxide (MoO3) NanobeltsResearch Abstract: Light is comprised of electromagnetic waves characterized with defined frequencies and wavelengths. The wavelength determines the length scale of the light and is dependent upon the material through which it propagates. Due to the long free-space wavelengths associated with infrared (IR) light, the realization of nanoscale optical components is challenging, with flat and sub-diffractional optical components promising advances in imaging, communications, sensing, and light sources. The nanoscale confinement of this long-wavelength IR light can be achieved through the formation of polaritons – excitations in materials that result from the interaction of light and coherently oscillating charges. Polaritons exhibit much smaller wavelengths in the materials that support them, enabling us to achieve subdiffractional control of light and overcome some of these challenges. Of the numerous types of polaritons, hyperbolic polaritons exist in highly anisotropic materials, where the dielectric permittivity tensor is opposite in sign along different crystal axes. In these materials, such as molybdenum trioxide (MoO3), the polaritons can only propagate along certain in-plane directions at any given frequency. Here, we seek to enable the propagation of polaritons along the normally “forbidden axis” within MoO3, which occurs within specific spectral bands. From electromagnetic simulations, such propagation is anticipated to become allowed within narrow MoO3 nanobelts (< 500 nm width). We aim at experimentally verifying this. We first fabricate narrow MoO3 samples with the focused ion beam, an instrument which irradiates a sample with heavy ions to mill away material. Then, we carry out scattering-type scanning near-field optical microscopy (s-SNOM) experiments to visualize the propagation of polaritons, including the wavelength and direction. Such work furthers our fundamental understanding of polaritons in complex anisotropic materials and enables us to work towards advance wave-guiding and on-chip photonics and sensing applications in IR optics.
Bio. Levi is a rising junior at Northwestern University, studying materials science and Integrated Science (an honors, interdisciplinary program that covers math, biology, chemistry, and physics). At Northwestern, she has participated in research in Professor Hersam’s nanoscale group, working within the field of 2D materials. She was awarded the McCormick Undergraduate Research Grant last summer, as well as awards for her coursework, including the Outstanding Materials Science and Engineering (MSE) Sophomore award in Materials Science, the Excellence in Mathematics by a First Year award, and numerous High Honors (4.0 GPA in the academic quarter) recognitions. Levi is also a member of Northwestern’s Division I Fencing Team. As a part of this team, she has fenced at NCAA regionals, has worked with coaches and staff as a part of their Leadership Council, and has engaged with the community by introducing fencing to a local group called Girls Play Sports. Levi plans to pursue graduate school in materials science, with a strong interest in the various applications of this field, including the areas of energy and sustainability.
- Hoogendoorn was awarded a $1K travel grant at the capstone poster session.
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Lauren Hubert - Chemical Engineering, University of Rhode Island
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Educational Institution: University of Rhode Island
List of Mentors: Dr. John Wilson & Blaise Kimmel & Payton Stone
Program: NSF REU
Research Project: Synthesis of Tunable Protein-Polymersome Conjugates for Enhanced Targeting of Cancerous TissuesResearch Abstract: Protein-polymersome conjugates have the potential to impact the field of immunoengineering leading to improved therapeutics via precise targeting and systemic monitoring. Here, we synthesized a library of diblock copolymers consisting of a first, polyethylene glycol (PEG) block, and a pH-responsive second block comprised of Dimethylaminoethyl methacrylate (DMAEMA) bound to an alkyl methacrylate chain. We subsequently utilized a rapid micro-mixing technique (flash nanoprecipitation) to generate an array of polymersomes. Polymer properties including second-block molecular weight and alkyl chain length were varied to optimize a polymeric nanocarrier capable of delivering therapeutics intracellularly. The polymer array was characterized based on size, cytotoxicity, encapsulation efficiency, potential for endosomal escape, hemolysis, and pH responsiveness to help reveal the polymer composition yielding the optimal polymersome. The tuned nanocarrier was then functionalized with an azide group on the PEG first block to enable future conjugation of immunotherapeutics.
We next synthesized a plasmid, encoding for a fusion protein containing mCherry and an antibody fragment for affinity targeting of an upregulated cancer antigen (GD2). We selectively ligated a single bicyclononyne (BCN) functional group onto the C-terminal of the fusion protein using an engineering Sortase A ligase in order to covalently link our fusion protein onto the azide-linked polymersome by strain-promoted alkyne-azide cycloaddition (SPAAC).
Our protein-polymer conjugate was confirmed via flow cytometry and fluorescence microscopy. The presence of mCherry will enable a future pilot study using In Vivo Imaging Systems (IVIS) to visualize the specific pathways taken by the protein-polymersome conjugates after systemic administration. Traditionally, polymersomes lack the ability to be systemically traced or target specific areas for intracellular delivery which limits their effectiveness as nanocarriers. Further, this study provides the basis for the future exploration of polymersomes linked to selectively ligated proteins allowing for enhanced functionality of these nanocarriers in biomedical applications.
Bio. Lauren Hubert is a rising junior, chemical engineering major on a pharmaceutical-focused track at the University of Rhode Island. She received the prestigious Thomas M. Ryan Scholarship from URI allowing her to become one of the seven members of the inaugural class of Ryan Scholars studying at the University with a full scholarship. She has completed 2 semesters of undergraduate research under Dr. Daniel Roxbury working on in vitro studies with a specific class of nanomaterials: single-walled carbon nanotubes. In that time, she has successfully applied for and obtained the (URI) 2 Undergraduate Research Grant and was published in ACS Applied Materials & Interfaces with the project titled: “Aggregation Reduces Subcellular Localization and Cytotoxicity of Single-Walled Carbon Nanotubes.” Over her two complete years at URI she has made the Dean’s List all four semesters, she was elected for an E-board position in the Sigma Gamma chapter of the professional engineering co-ed fraternity Theta Tau, and she has maintained memberships in both the American Institute of Chemical Engineers (AIChE) and the Society of Women Engineers (SWE). She hopes to continue working in the field of immunoengineering as she continues with undergraduate research and eventually pursues a PhD in chemical engineering.
- Conference Presentation
-L.A. Hubert, B.R. Kimmel, P.T. Stone, H.M. Pagendarm, and J.T. Wilson "Synthesis of Tunable Protein-Polymersome Conjugates for Enhanced Targeting of Cancerous Tissues" American Institute of Chemical Engineering, Phoenix, AZ, November 2022
*awarded first place in division - Hubert was awarded a $1K travel grant at the capstone poster session.
- Watch Lauren's vlog where she shares her experience and view of the VINSE REU program.
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Emily Martinez - Materials Science and Engineering, University of Central Florida
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Educational Institution: University of Central Florida
List of Mentors: Dr. Kane Jennings & Marc Nabhan
Program: NSF REU
Research Project: Composite Films of Photosystem I Proteins with Substituted PolyanilinesResearch Abstract: Photosynthesis is one of the most critical processes in nature, sustaining a wide array of living organisms by converting sunlight into chemical energy. The process of oxygenic photosynthesis relies heavily on four multi-subunit protein complexes, with one of these being Photosystem I (PSI). PSI proteins are photoactive, have a nearly perfect quantum yield, and bear electron-hole splitting capabilities at the P700 active site, but their lack of overall conductivity limits applications in solar conversion systems. Researchers have mixed PSI with various conducting polymers, including polypyrrole, polyaniline, and poly(ethylenedioxythiophene), to generate composite films that circumvent the challenge of poor conductivity. Still, these conducting polymers are mostly water-insoluble, are challenging to incorporate with PSI in an aqueous-based process, and have energies that may not align well with PSI’s active sites. In this work, we report the polymerization of two substituted anilines—p-anisidine and o-anisidine—in the presence of PSI in aqueous solution to form conducting polymer-protein composites. Since these are methoxyanilines, their processability in water as both monomers and polymers is greatly improved over the more common conducting polymers noted above. These composites can be easily drop-casted onto an electrode to form photactive, conductive films. Infrared spectroscopy shows that the final composite film contains both polymer and protein at a ratio that depends on the monomer-to-protein ratio in the polymerization solution. Contact angles were used to show that the composite film becomes more hydrophilic with increased ratio of polymer to protein. As ongoing work, the level of conjugation and intermolecular attraction between the protein and the resulting polymer will be examined using analytical ultracentrifugation, SDS-PAGE, and photoelectrochemical measurements of protein-polymer films. We will also examine if PSI can photooxidatively grow these polymers in a solution at neutral pH.
Bio.Emily Martinez is a rising junior at the University of Central Florida in Orlando, FL. She is majoring in Materials Science and Engineering and is also pursuing a minor in music, an area which she has been passionate about since childhood. She is a Florida Bright Futures Academic Scholar, a National Hispanic Scholarship recipient, and has been on the Principal’s List for all 4 semesters she has attended university. Outside of the lab, she demonstrates leadership in UCF’s choir ensembles, being the vice president of the chamber choir. She additionally contributes to her community as a member of the Society of women engineers (SWE) at UCF as well as being in the Burnett Honors College. At her home institution, she is a part of the NSF’s Partnerships for Research and Education in Materials (PREM) program as a research intern studying photocatalytic materials; in this program, she is gaining experience in research while also performing outreach activities to foster an appreciation for STEM and scientific research in younger students. She aims to go to graduate school to study chemical engineering and ultimately work in the renewable energy industry.
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Chiad Onyeje - Chemical Engineering, University of Maryland, Baltimore County
Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Criag Duvall & Carlisle DeJulius
Program: NSF REU
Research Project: Utilizing Microfluidics to Optimize the Formulation of Antioxidant MicroparticlesResearch Abstract: Reactive oxygen species (ROS) are a key driver of inflammation in degenerative diseases, and treatment strategies targeting ROS overabundance have shown promise in many studies. Sulfide-containing polymers (polysulfides) can scavenge ROS and can be formulated into drug-loaded microparticles for disease treatment. The classical method for particle formulation utilizes a bulk oil-in-water emulsion technique, with the polymer being introduced dropwise with the oil phase into the water phase. However, this technique is difficult to control and typically results in particles with large size variability. Thus, the introduction of microfluidic devices as a formulation process aims to provide a new method of polysulfide microparticle generation that can quickly and effectively produce batches at a controllably consistent size.
We have developed an in-house fabrication method utilizing customizable etched channels on a glass slide base. We flow the oil and water phases while harnessing droplet microfluidics to produce microparticles. This project focused on optimizing the flow rate and pressure in the device for particle production. We also tested various oil phase solvents (dichloromethane, chloroform, and ethyl acetate) for compatibility with the device. Finally, we compared the reactivity of microparticles formulated from two polysulfide derivatives in the presence of ROS via an overdosage of hydrogen peroxide (a common reactive oxygen species), demonstrating that the composition of the microparticle directly affects the rate of scavenging.
Bio. Chiad Onyeje is a biochemical engineering student at the University of Maryland, Baltimore County (UMBC). He currently attends the school as a member of the prestigious Meyerhoff Scholars program in its 31st cohort. Throughout his college career, Chiad has been delving deep into the research of the biological & chemical sciences. His projects have included a microscopy study on the brain tissue of ferrets performed before entered college, a concurrently running study on the development of nanoparticles to seal traumatic internal bleeding, and the currently presented development of microfluidic devices for microparticle formulation. His desire to seek out new horizons and understand the quickly growing field of nanotechnology has even led to a review paper’s publication early last year. Performing research at his home university of UMBC, The Johns Hopkins University, and now Vanderbilt University are testaments to his dedication towards seeking out answers in a field where questions begin. He is currently seeking new avenues to explore the biochemical and biomedical applications of engineering research, such as graduate school Ph.D. programs.
- Conference Presentation
-C. Onyeje, B. Hanan, C. DeJulius, and C. Duvall "Utilizing Microfluidics to Optimize the Formation of Antioxidant Microparticles" Annual Biomedical Research Conference for Minoritized Citizens (ABRCMS), Anaheim, CA, November 2022 - Onyeje was awarded Best Use of Graphics at the capstone poster session.
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Gianna Paier - Biomedical Engineering, SUNY Binghamton University
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Educational Institution: SUNY Binghamton University
List of Mentors: Dr. Sharon Weiss & Simon Ward
Program: NSF REU
Research Project: Using Machine Learning with Porous Silicon to Determine IgG Concentrations in Human SerumResearch Abstract: The importance of accurate, robust, and cheap disease diagnostics has proven to be essential in modern society. However, many diagnostic techniques are only available in a clinical setting with trained personnel and expensive, bulky instruments, including the quantification of different protein levels in human serum. Elevated levels of certain serum proteins can indicate a variety of diseases. In this work, we investigate a new approach using a porous silicon material, optical reflectance measurements, and machine learning analysis, which could enable point-of-care serum protein testing. Porous silicon (PSi), fabricated by electrochemically etching nanoscale pores into silicon wafers, is a promising material to form the basis for small, cheap, and robust diagnostic tests. Physical properties of PSi pores, such as size and shape, can be tuned by changing the etching current density and duration. This determines how different molecules selectively enter and adsorb in the pores, which can be quantified by measuring shifts in optical reflectance spectra. Here, we explore which pore sizes most effectively separate Immunoglobulin G (IgG), one of the most abundant serum proteins, spiked in a healthy human serum control. We found that a current density of 80 mA/cm2 best discriminated IgG from other serum proteins, both in terms of optical response magnitude and kinetics. At the highest etching current density investigated (100 mA/cm2), which gives the largest pores, sensor response to IgG spiked serum was no different to the control, likely due to surface saturation. At the lowest studied current density (60 mA/cm2), which gives the smallest pores, there was negligible difference in response, since IgG is too large to enter the majority of the pores. To further refine the initial design of our sensor, we will study other characteristics that effect pore selectivity such as solvent pH and hydrophobicity. Data from the optimized PSi sensor will be fed into a machine learning algorithm to quantify IgG in serum. This approach can provide a convenient solution to many medical diagnostic challenges in the doctor’s office, or even at home.
Bio. Gianna Paier is a rising senior studying biomedical engineering with a concentration in biomedical devices at Binghamton University. Gianna spent her summer in the Weiss lab at Vanderbilt researching the development of point-of-care medical devices using porous silicon. In fall 2021, Gianna was inducted into Alpha Eta Mu Beta, the biomedical engineering honors society, and Tau Beta Pi, the engineering honors society. She will be acting as the secretary for Tau Beta Pi in the coming academic year. She was the Vice President of the Biomedical Engineering Society (BMES) for the past 2 years and was elected to be President for next year. Gianna is also an active member of Alpha Omega Epsilon, having been their historian, outreach, sisterhood, and professional chair. Gianna has also been a peer tutor through the Educational Opportunity Program (EOP) for the last year. She was a physics lab teaching assistant during the fall 2020 and spring 2021 semesters, where she led the class by performing scientific demonstrations and answering questions to cultivate students’ interest in the field. She is also excited to be a course assistant for the biomedical instruments and devices lab this coming semester under the guidance of Ammar Abdo. Gianna plans to pursue her PhD in biomedical engineering after she finishes her undergraduate education. She is grateful for her experience, and the people she met this summer for the support that guided her towards this decision.
- Conference Presentation
-G. Paier, S.J. Ward, and S.M. Weiss "Using Machine Learning with Porous Silicon to Determine IgG Concentrations in Human Serum" Biomedical Engineering Society 2022 Annual Meeting, San Antonio, TX, October, 2022
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Nicholas Pugh - Mechanical Engineering, University of Maryland, Baltimore County
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Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Deyu Li & Zhiliang Pan
Program: NSF REU
Research Project: Heat Transfer by Surface Phonon Polaritons in Silicon Carbide NanowiresResearch Abstract: Understanding thermal transport at the nanoscale level is crucial for maintaining the safe operation of modern electronic devices. It is well-established that electrons and phonons are the major energy carriers for thermal transport in metals and semiconductors/insulators, respectively. Recently, it has been suggested that surface phonon polaritons (SPhPs) could contribute to thermal transport in polar thin films and nanowires. SPhPs are energy carriers resulting from optical phonons coupling with surface electromagnetic waves. In this study, to evaluate the contribution of SPhPs to thermal transport, measurements of the thermal conductivity of a silicon carbide (SiC) nanowire were performed using a microthermal bridge method. Measurements of the thermal conductivity of the same sample with different suspended lengths, 22 µm 11 µm respectively, were first carried out. The overlapping thermal conductivity indicated negligible contact thermal resistance. Then, we introduce SPhPs into the SiC nanowires with the electron-beam induced deposition of platinum to probe the effect of SPhPs on thermal transport. A thermal conductivity enhancement of ~2% was obtained at room temperature. The enhancement becomes larger at low temperatures and eventually reached ~12% at 30 K. The temperature dependent behavior may originate from the stronger loss in SPhP propagation at elevated temperatures. This study provides experimental evidence of SPhP contribution to thermal transport in polar nanowires and inspires a revisit of the effect of EBID treatment on thermal transport in polar materials.
Bio. Nicholas Pugh is a rising sophomore attending the University of Maryland, Baltimore County (UMBC) as a mechanical engineering major. At UMBC, Nicholas is a member of the 33rd cohort for the Meyerhoff Scholars Program and a member of the Honors College. He has been placed on the Dean’s list for the Fall 2021 and Spring 2022 semesters at UMBC for academic achievements. Nicholas is also a member of the American Society for Mechanical Engineers (ASME) and the National Society of Black Engineers (NSBE). This summer Nicholas is participating in a ten-week research experience at Vanderbilt University in Dr. Deyu Li’s Lab studying nanoscale thermal transport. He is excited to continue his research career in the upcoming years and prepare a path toward obtaining his Ph.D.
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Sarah Shibuya - Biomedical Engineering, Rose-Hulman Institute of Technology
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Educational Institution: Rose-Hulman Institute of Technology
List of Mentors: Dr. Mike King & Jenna Dombroski
Program: NSF REU
Research Project: Selective Functionalization of Leukocyte Subpopulations with E-Selectin LiposomesResearch Abstract: Metastasis occurs when cells break off a primary tumor and enter the blood stream. This process can create secondary tumors at distant sites. To combat metastasis, an antimetastatic therapy uses the protein TNF-related apoptosis inducing ligand (TRAIL) to initiate apoptosis in circulating tumor cells (CTCs) in the blood stream. Liposomes with the protein E-Selectin (ES) attach to leukocytes in the bloodstream and are used as vessels to transport TRAIL to CTCs. Here, we investigate the influence that ES has on the binding of liposomes to subpopulations of leukocytes, specifically monocytes and granulocytes. Through flow cytometry analysis of monocytes and granulocytes from healthy patient blood, the concentrations of fluorescent ES-liposomes bound to the surface of these cells were investigated. It was found that as the average number of ES per liposome increases, the greater occurrence that liposomes are bound to granulocytes. The number of ES yields no correlation on the effect of liposome-monocyte binding. The influence of the liposome component DSE-PEG was also investigated. When DSPE-PEG was removed from the liposome fabrication process, a specific subpopulation of higher fluorescence in flow cytometry measurements indicated more efficient binding to granulocytes. Imaging using fluorescence microscopy visually confirmed the binding of liposomes without DSE-PEG to leukocytes using a DiI lipid dye and DAPI nuclei dye. A population of granulocytes did not bind to these liposomes, while most were bound to them in abundance, indicating there may be selective binding to specific types of granulocytes. There was little to no binding to monocytes with 0 ES, but with ES present, binding was found to occur to select monocytes. High binding to platelets was found in both leukocyte populations. The investigation of this topic can yield better results in the utilization of liposomes as a delivery system for TRAIL in antimetastatic therapies.
Bio. Sarah Shibuya is a rising sophomore at Rose-Hulman Institute of Technology from Portland, Oregon. She is majoring in biomedical engineering with a focus in biochemistry and molecular biology. Sarah is a Commitment Scholar and a part of the Noblitt Scholars Program. She belongs to the Biomedical Engineering Society, the Society of Women Engineers, and is a player on the Rose-Hulman Women’s Soccer Team. She earned her Silver Award through Girl Scouts and continues to be a part of scouting through the Alpha Phi Omega service fraternity. In her free time, she loves to crochet, read, and enjoy nature. Looking into the future, Sarah plans to attend graduate school to study biology or biomedical engineering.
- Conference Presentation
-S.A. Shibuya, Z. Zhang, J.A. Dombroski, and M.R. King "Selective Functionalization of Leukocyte Subpopulations with E-Selectin Liposomes" Biomedical Engineering Society 2022 Annual Meeting, San Antonio, TX, October, 2022 - Shibuya was awarded a $1K travel grant and NCUR nomination at the capstone poster session.
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Trey Theobald - Biochemistry, Ohio Wesleyan University
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Educational Institution: Vanderbilt University
List of Mentors: Dr. Ethan Lippmann & Andrew Kjar
Program: NSF REU
Research Project: Identifying Early Developmental Neurotoxicity Modeled in a Cerebral Organoid SystemResearch Abstract: Pregnant individuals are typically excluded from traditional clinical trials due to ethical and safety concerns for the fetus. This lack of data leads to challenges in managing the health concerns of the expectant patient while also protecting the developing fetus from neurologically damaging medications. To be able to effectively understand how certain medications impact fetal neurodevelopment, alternative screening methods for neurotoxicity are essential. Here, we provide a scalable, human specific model for neurological drug toxicity screening using human induced pluripotent stem cell derived cerebral organoids that model the growth and layering of the developing fetal brain. In control organoids, neural progenitors (SOX2+/PAX6+) comprised the center of the tissue while mature neurons (ßIIIT+/TBR1+) formed the outer surface. We tested gabapentin for neurotoxicity using folic acid and valproic acid as controls to verify the sensitivity of our system. Size and shape characterization over 30 days revealed that folic acid and gabapentin drug concentration did not affect the growth kinetics of organoids while organoids dosed with valproic acid exhibited a decreased growth rate at a concentration of 10 mM. Secondary cell titer assays revealed decreased viability in organoids with high concentrations of valproic acid, confirming the size characterization. Preliminary spinning disc confocal imaging indicated that organoids dosed with 10mM valproic acid exhibited few ßIIIT+ cells. Future development of our high throughput screening organoid model will provide an ethical and efficient method of evaluating neurotoxicity for early developmental and fetal populations.
Bio. Trey Theobald is a sophomore in the Honors Program at Ohio Wesleyan University majoring in biochemistry. Trey is a sprinter and thrower on the track team and was named Ohio Wesleyan's 2022 Most Outstanding Freshman. He is active in the health science community on campus and serves as the treasurer of the Ohio Wesleyan Health Sciences Club. This summer Trey is working in Dr. Ethan Lippmann’s lab with his graduate student mentor Andrew Kjar to develop an early developmental neurotoxicity screening technique using cerebral organoids. Trey would like to thank Andrew, Dr. Lippmann, and the rest of his research team for their guidance and direction throughout the summer. The collaborative nature of the VINSE program has inspired Trey to pursue the possibility of future research. Finally, Trey is grateful for the experience he has had this summer with the VINSE staff as well as the rest of his cohort both within and outside of the laboratory.
- Conference Presentation
-T. Theobald, A. Kjar, and E. Lippmann "Identifying Early Developmental Neurotoxicity Modeled in a Cerebral Organoid System" Biomedical Engineering Society 2022 Annual Meeting, San Antonio, TX, October, 2022
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Andrea Valero - Chemical Engineering, University of Texas, San Antonio
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Educational Institution: University of Texas, San Antonio
List of Mentors: Dr. Cynthia Reinhart-King & Jenna Mosier
Program: NSF REU
Research Project: Using a Microtrack Platform to Determine the Effect of Reactive Oxygen Species on Confined MigrationResearch Abstract: Tumor heterogeneity remains a clinical challenge in cancer treatment as it drives differential responses of cancer cells subpopulations to various environmental cues. Both mechanical cues, such as confinement, and metabolic cues, such as levels of metabolic intermediates like reactive oxygen species (ROS), have been shown to promote cell invasion and migration. To understand the role of heterogeneity in breast cancer cell behavior, we previously sorted MDA-MB-231 triple negative breast cancer cells (MDA) into highly (MDA+) and weakly (MDA-) migratory subtypes and assessed their differential response to metabolic cues. We found that treatment with high doses of the ROS activator, tertbutylhydroperoxide (TBHP), significantly decreased speed in both subtypes, in contrast with previous reports. Here, we aim to better understand how ROS production contributes to breast cancer cell migration. To investigate the effect of ROS, collagen microtracks were formed using polydimethylsiloxane (PDMS) stamps to mold collagen into tunnels that mimic the tumor matrix. Parental MDA-MB-231 cells seeded into the microtracks and cells were treated with 25 μM, 50 μM, and 75 μM concentrations of TBHP and migration speed was assessed. We observed that when treated with 25 μM TBHP, a fraction of the parental cells slightly increased migration velocity, suggesting that ROS may have differential effects on different cell subtypes at low doses. Metabolic dysregulation is a primary driver of metastasis and understanding the contribution and influence of ROS on breast cancer cell migration is pivotal to understanding how to target metastasis.
Bio. Andrea Valero is a rising sophomore studying chemical engineering at the University of Texas at San Antonio. She has research experience in neurodegenerative diseases, wind energy optimization, drug delivery systems, and cancer cell migration. Her passion for research have earned her a position in the ESTEEMED, a NIH/Federally-funded program that helps freshman and sophomore-level trainees develop as scholars and scientists. During her freshman year, she became an undergraduate researcher under the supervision of Dr. Gabriela Romero, where she works independently in the experimentation and data analysis of polymers for drug delivery. At her home institution, she exerts a leadership role as the Senator for the College of Engineering and as part of the Presidential Student Advisory Council. Additionally, she is part of Society of Women Engineers and the UTSA SACNAS Chapter. Due to her academic achievement, she has earned her a place on the Dean’s List and as a Klesse Scholar. This summer, she is working under the supervision of Jenna Mosier and Dr. Reinhart-King to understand the behavior of breast cancer cells and the effect of reactive oxygen species on confined migration. Her professional aspirations are to obtain a PhD and become a biomedical innovator.
- Conference Presentation
-A. Valero, Q. Xing, R. Padmanabhan, J.A. Mosier, C. Reinhart-King "Using a Microtrack Platform to Determine the Effect of Reactive Oxygen Species on Confined Migration" SACNAS National Diversity in STEM Conference, San Juan, Puerto Rico, October, 2022
*awarded outstanding poster
- Conference Presentation
![VINSE Photos - Short List (73) VINSE Photos - Short List (73)](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/31155008/VINSE-Photos-Short-List-73-1.jpg)
2021
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Thiago Arnaud - Mechanical Engineering, Florida International University
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Educational Institution: Florida International University
List of Mentors: Dr. Josh Caldwell & Minghe He
Program: NSF REU
Research Project: Multi-spectral Thermal Imaging with Inversely Designed Optical Filters for Material Recognition
Poster: NSF REU Thiago Arnaud Poster
Research Abstract: Thermal radiation describes the emission of electromagnetic waves from an object whose temperature is above absolute zero. Thermal emission for objects near or just above room temperature are typically peaked at wavelengths within the long-wave-infrared (7 μm-14 μm wavelengths). This allows for the possibility of thermal imaging, the visualization of the thermally emitted infrared light from objects. A blackbody is one that thermally emits a broadband of infrared and potentially visible and ultraviolet light that is mathematically defined by Planck’s Blackbody Radiation Law. A graybody is an object that still follows this same mathematical function but is scaled to a lower emitted power by the object’s emissivity characteristic. Thus, by assuming objects within a thermal image are graybodies, this concept can be used to approximate the temperature of the objects by correlating it to the emitted power using a thermal imaging camera (TIC). However, this approximation falls short for objects where the emission is not well-described by this law and for those that are highly reflective in the spectral range of interest. Thus, we have employed inversely designed, aperiodic, Distributed Bragg Reflectors (DBRs) as optical filters that serve to only transmit a defined spectral range, allowing us to directly image thermal emission, more accurately determine materials and their actual temperature. These selective spectral filters are comparable to the Red-Green-Blue (RGB) filters used in cameras for visible light. Those RGB filters have allowed for more complicated imaging and so the same is now being applied for thermal imaging.- Arnaud was awarded a $1K travel grant at the capstone poster session.
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Mina Aziz - Biochemistry and Neuroscience, Vanderbilt University
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Educational Institution: Vanderbilt University
List of Mentors: Dr. John Wilson & Jessalyn Baljon, Hayden Pagendarm, Payton Stone
Program: NSF REU
Research Project: Polymersome formation via flash nanoprecipitation induces immunological activity to improve cancer immunotherapy
Poster: NSF REU Mina Aziz Poster.pdf
Research Abstract: Cancer immunotherapies, such as immune checkpoint blockade (ICB), have improved the efficacy of cancer treatments compared to conventional antitumor therapies in a subset of patients; however, there is a demonstrated limited efficacy in many patients. Utilizing innate immune agonists, such as cyclic dinucleotide (CDN) agonists for activation of stimulator of interferon genes (STING), has been demonstrated to increase antitumoral immunological response by activating and recruiting antitumor killer T-cells to the tumor site. Unfortunately, due to barriers in drug delivery – limited access to cytosolically located STING, rapid clearance, and limited cell-specific targeting – free CDN efficacy is limited. Recently, pH-responsive, polymeric nanoparticle mediated drug delivery approaches have been developed to circumvent these concerns. However, production techniques for these nanoparticles are relatively low throughput and variable, inhibiting clinical translation. Here, we utilize a high throughput flash nanoprecipitation (FNP) polymersome formulation platform to reproducibly formulate large quantities of polymeric nanoparticles. Utilizing a confined impingement jet (CIJ) mixer to facilitate nanoparticle self-assembly, we substantiate that the FNP platform results in an improvement in batch-to-batch variability, scalability, and particle size distribution, thus overcoming the previous inadequacies in polymersome formation and accelerating their clinical use.- Aziz was awarded Fan Favorite at the capstone poster session.
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Amber Cui - Chemical Engineering, Vanderbilt University
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Educational Institution: Vanderbilt University
List of Mentors: Dr. Ethan Lippmann & Alex Sorets
Program: NSF REU
Research Project: Isolation of Rodent Microglia to assess Gene Silencing and Drug Targeting
Poster: NSF REU Amber Cui Poster.pdf
Research Abstract: Aging is the strongest risk factor for neurodegeneration, with a majority ofthe elderly population experiencing cognitive decline. While many factors drive disease progression, impaired microglial dysfunction has recently emerged as a common hallmark of many age-associated neurodegenerative disorders. As the resident immune cell of the central nervous system (CNS), microglia serve important functions including monitoring the CNS for pathogens and apoptotic signals. However, in disease states, chronic overactivation of microglia contributes to neurotoxicity and promotes disease progression, particularly in the context of Alzheimer’s Disease. The potential to explore microglia immunomodulation in culture is an invaluable tool to help mitigate age-associated neurodegenerative disease. We established a protocol to isolate microglia from the rodent CNS and maintain them in culture. This efficient method involves dissociating mouse brains into single cells with high viability, followed by magnetic sorting using beads coated with the antibody cd11b, a microglia-specific marker. Microglial identity was confirmed by flow cytometry for cd11b and immunostaining for iba1. Microglia were maintained in culture for up to a week and retained high viability and cellular identity. Furthermore, the magnetically sorted microglia were highly abundant with over 6,000 cells and enriched in microglia-specific markers compared to the remainder of the dissociated cell population. To demonstrate the versatility of the protocol, microglia were similarly isolated from rat brains and successfully cultured. For future work, observing phenotypic changes in microglia after siRNA-mediated gene silencing and applying therapeutics to diseased murine microglia will be explored in hopes of improving our understanding of treatments for neurodegenerative disease.- Conference Presentation
-A. Cui, A. Sorets, and E. Lippmann "Isolation of Rodent Microglia to Assess Gene Silencing and Drug Targeting" Vanderbilt Undergradaute Research Fair, Nashville, TN, September 2021.
-A. Cui, A. Sorets, and E. Lippmann "Isolation of Rodent Microglia to Assess Gene Silencing and Drug Targeting" AIChE National Annual Conference, Boston, MA, November, 2021. - Cui was awarded Best Layout at the capstone poster session.
- Conference Presentation
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Brooke DeMarco - Biomedical Engineering, Vanderbilt University
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Educational Institution: Vanderbilt University
List of Mentors: Dr. Sandra Rosenthal & Ruben Torres
Program: NSF REU
Research Project: Tracking Individual Endogenous Dopamine Transporters Using Antagonist-Conjugated Quantum Dots
Poster: NSF REU Brooke DeMarco Poster.pdf
Research Abstract: The dopamine transporter (DAT) is a presynaptic transmembrane protein that drives dopamine reuptake. Abnormalities in DAT function and localization have been linked to various neuropsychiatric disorders including attention-deficit/hyperactivity disorder (ADHD), bipolar disorder (BD), and schizophrenia. Prior studies carried out in transiently transfected monolayer cell culture suggest that abnormal DAT diffusion contributes to the aforementioned disease states. Still unknown is the degree to which DAT surface diffusion is physiologically relevant in natively expressing cellular systems. Rat pheochromocytoma (PC-12) cells naturally express DAT, and upon nerve growth factor (NGF) differentiation, upregulate DAT at neurite terminals. Here, we implement a fluorescent monoamine transporter reporter, 4-(4-(dimethylamino)phenyl)-1-methylpyridinium (IDT307), to assay the presence of endogenous DAT. A significant loss in cell fluorescence using DAT and other transporter inhibitors indicates DAT presence. Using fluorescence microscopy, we apply our DAT-specific 2-β-carbomethoxy-3-β-(4 fluorophenyl)tropane (β-CFT) antagonist conjugated quantum dot (QD) probe system to track DAT in PC-12. Dynamic imaging revealed a mobile population of QD’s with an average diffusion coefficient (mean ± SEM: 0.018 ± 0.002 μm2/s) comparable to previously reported values. Our results suggest the presence of endogenously expressing DAT in PC-12 and demonstrate the utility of our antagonist-conjugated QD probe to specifically label unperturbed DAT in increasingly complex cellular environments. Insight gained from this study can be advantageous in drawing conclusions on the normal and dysfunctional diffusional behavior of DAT in native cellular architectures.- Demarco was awarded Best Use of Graphics at the capstone session.
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Santiago Lopez - Biomedical Engineering, Virginia Commonwealth University
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Educational Institution: Virginia Commonwealth University
List of Mentors: Dr. Cynthia Reinhart-King & Jenna Mosier
Program: NSF REU
Research Project: Heritability of Bioenergetic Traits in Migratory Breast Cancer Cells
Poster: NSF REU Santiago Lopez Poster
Research Abstract: Metabolic heterogeneity plays a crucial role in cancer tumor expansion. Characteristics of the tumor microenvironment, like oxygen and glucose availability, contribute to the genetic diversity of the cancer cells as they have stem-like qualities. The genetic diversity in cancer cells makes the cells more likely to preferentially utilize different metabolic pathways from normal cell populations. Abnormal metabolic processes can then drive cancer cells to metastasize throughout the body. While it’s known that metabolic heterogeneity is important in metastasis, it is unknown whether this heterogeneity is passed down during cell division. ImageJ analysis and the ratiometric PercevalHR probe transduced in MDA-MB-231 breast cancer cells were used to quantify ATP:ADP ratios before and after cell division. Here, we show that there is no significant difference between the ATP:ADP ratios between the parent and daughter cells before and after cell division. Thus, bioenergetic heterogeneity is a heritable trait during cell division, providing a foundation to determine the feasibility of sorting cells based on ATP:ADP ratios. Overall, this work gives a better understanding of the bioenergetics at play in tumor migration and may point to targeted metabolic therapies for metastasis. -
Akanke Mason-Hogans - Chemical Engineering, North Carolina A&T State University
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Educational Institution: North Carolina A&T State UniversityUniversity
List of Mentors: Dr. Clare McCabe & Co Quach, Justin Gilmer
Program: NSF REU
Research Project: Designing Monolayer Films for Nanoscale Lubrication Using Machine Learning
Poster: NSF REU Akanke Mason-Hogans Poster.pdf
Research Abstract: Micro- and nano-scale mechanical systems often have lubrication issues that prevent them from operating at full potential. Coating device surfaces with monolayer films to lubricate them shows promise in reducing friction and wear. This project aims to more efficiently identify monolayer films that exhibit low coefficients of friction (COF) and adhesive forces (F0) and can be used to improve the lubrication of both micro- and nano-scale systems. Current evaluation methods that examine systems either by experimentation or computer simulation are impractical because of the vast design space. Our goal is to develop a large-scale screening method that performs a rapid estimation of the tribological properties of candidate monolayer coatings that differ in their terminal group chemistry and allows the examination of more potential coatings. To achieve this, using simulation data performed on a small subset of systems, we are constructing machine learning (ML) models using the random forest regressor algorithm. ML is a method of data analysis where a machine identifies patterns from a training set of data, and then uses the model developed to make predictions for unknown systems. Here, we are considering molecules retrieved from an online library of small molecules that results in ~300,000 dissimilar monolayer systems to be evaluated. After iterating through all these systems and obtaining predicted COF and F0 values, we will identify the top ~20 systems that provide the most favorable tribological properties. These candidate systems will then be simulated using molecular dynamics and traditional experimentation to confirm their properties and utility as lubricants for micro- and nano-devices.- Co-authored Journal Publications
C.D. Quach, J.B. Gilmer, D. Pert, A. Mason-Hogans, C.R. Iaovella, P.T. Cummings, and C. McCabe "High-throughput screening of tribological properties of monolayer films using molecular dynamics and machine learning" The Journal of Chemical Physics, 156, 154902 (2022).
- Co-authored Journal Publications
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Avery Nguyen - Chemical Engineering, Massachusetts Institute of Technology
Educational Institution: Massachusetts Institute of Technology
List of Mentors: Dr. Greg Walker & Brad Baer
Program: NSF REU
Research Project: Predicting Raman Spectra of Group III Nitride Superlattices with Density Functional Theory
Poster: NSF REU Avery Nguyen Poster.pdf
Research Abstract: In order to understand the transport of vibrational energy in these materials, we use information from Raman spectroscopy. Utilizing density functional theory (DFT), we first calculate the Raman spectra of AlN and GaN, demonstrating the ability of simulations to accurately calculate phonon frequencies and locate Raman peaks. We then compute the Raman spectrum for the superlattice consisting of alternating unit cells of AlN and GaN. For this structure, we predict several additional Raman-active frequencies that are unique to the superlattice, indicating possible interface modes. These calculations represent new insight into the physical behavior of superlattice structures at the atomic scale. -
Addison White - Biomedical Engineering, Vanderbilt University
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Educational Institution: Vanderbilt University
List of Mentors: Dr. Cynthia Reinhart-King & Jenna Mosier
Program: NSF REU
Research Project: Long-Term Effect of Confinement on Cell Speed and Bioenergetics of Migratory Breast Cancer Cells
Poster: NSF REU Addison White Poster
Research Abstract: Of the yearly 9.6 million cancer-related deaths around the world, an estimated 90% are due to metastasis, or the stage at which cancer spreads from its primary location to form secondary colonies. From the primary tumor, metastatic breast cancer cells invade the surrounding extracellular matrix to reach the bloodstream. Physical properties such as stiffness, porosity, and density of the primary tumor microenvironment have previously been shown to influence both the migratory ability and internal metabolic pathways of cells confined within it. The long-term effect of cell confinement on cancer cell metabolism is largely unknown. To investigate the existence of this “metabolic memory”, collagen microtracks were formed using polydimethylsiloxane stamps to mold collagen into desired track geometries. MDA-MB-231 cells expressing the PercevalHR probe were seeded into these microtracks and the energy utilization of cells was quantified as ATP:ADP ratios as the cells migrated from confined (7 µm wide) to unconfined (15 µm wide) regions of the microtracks. ATP:ADP ratios were found to increase as cells traveled through confined regions, and ATP machinery relocalized towards the leading edge of the cell. High ATP:ADP ratios were temporarily maintained once the cells left confinement, suggesting metabolic memory may play a role in cell migration. Furthermore, the duration of this memory is directly dependent on the distance traveled in confinement, indicating that cells are conditioned by confinement. By further understanding cancer cell metabolism and its relationship to migration, specific therapeutic targets can be identified in preventing metastatic spread. -
Alessia Williams - Chemical Engineering, Prairie View A&M University
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Educational Institution: Prairie View A&M University
List of Mentors: Dr. Kane Jennings & Josh Passantino
Program: NSF REU
Research Project: Photoelectrochemical Polymerization of Pyrrole by Photosystem I
Poster: NSF REU Alessia Williams Poster.pdf
Research Abstract: Photosynthesis, the conversion of light energy to chemical energy, is the foundation for the sustainability of all life on Earth. One of the proteins responsible for this energy conversion is Photosystem I (PSI). Its robust reduction/oxidation capability makes it a primary candidate for enhancing solar cells with the more efficient nanotechnology found in nature. The Photosystem I protein has unique structures, namely the P700 site, that can accept electrons from a wide range of donors and the FB site that has one of the most negative reducing potentials found in nature (-0.6V vs SHE). Gel and liquid mediators have allowed electrons access to the P700 site buried within the protein through diffusion. However, we have grown a conducting polymer from the P700 site to allow for direct electron transfer. This polymer growth was accomplished by utilizing the redox capabilities of the Photosystem I protein to oxidize the pyrrole monomer to form polypyrrole. The sunlight powers the reaction, and the P700 site oxidizes the monomer, allowing it to grow and form a protein-polymer conjugate. A solution of dialyzed PSI protein, pyrrole monomer and a dopant/surfactant is exposed to sunlight to produce a protein-polymer conjugate. The characteristics of which are analyzed using gel electrophoresis, IR spectroscopy, qualitative measurements, as well as UV-Vis spectroscopy. This research aims to test multiple dopants and analyze their effect on the characteristics of the Photosystem I protein-polypyrrole conjugate.- Williams was awarded a $1K travel grant at the capstone session.
![REU2019 REU2019](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/30150229/REU2019.jpg)
2019
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Hayat Abdurahman - Engineering, Community College of Baltimore County
Educational Institution: Community College of Baltimore County
List of Mentors: Dr. Sharon Weiss & Rabeb Layouni
Program: NSF REU
Research Project: Porous Silicon based Optical Sensing in Complex Media: Antifouling Coating
Poster: NSF REU Hayat Abdurahman Poster.pdfResearch Abstract: The development of optical biosensors for use in complex media, such as blood or serum, is essential to further advance medical diagnostics especially for point of care applications. However, the majority of studies on emerging biosensor materials, such as porous silicon (PSi), are done in purified solutions. This project investigates a new approach to design a more reliable PSi-based biosensing platform in serum. PSi offers many advantages due to its ease of fabrication, large surface area, and convenient surface chemistry. In order to reduce the non-specific binding of proteins and contaminants from complex media, an antifouling coating consisting of a polyethylene glycol silane (PEG-SL) monolayer was applied to the PSi surface. The antifouling coating helps prevent protein adsorption by creating a hydration layer and exhibiting a steric hindrance effect. Contact angle (CA) measurements for PSi, PEG-SL on PSi, and PEG-SL on oxidized porous silicon (OPSi) confirmed that the surface gained hydrophilicity after the addition of the PEG-SL layer, suggesting an ability to reduce biofouling (, , ). Corrosion tests in PBS buffer () showed that OPSi is a more stable substrate compared to PSi. When exposed to serum, PEG-SL on OPSi exhibited an 80% reduction in non-specific binding compared to uncoated OPSi. This demonstrates that the antifouling capability of the added PEG-SL monolayer improves the specificity of PSi-based biosensors. The next step is to test this surface with a biotin-streptavidin assay in serum to further validate the antifouling layer efficiency.
- Conference Presentations
-H. Abdurahman, R. Layouni, B.A. Baker, T. Cao, P.E. Laibinis and S.M. Weiss “Porous Silicon based Optical Sensing in Complex Media: Antifouling Coating” 2019 IEEE MIT Undergraduate Research Technology Conference, Cambridge, MA, October 2019.
-H. Abdurahman, R. Layouni, B.A. Baker, T. Cao, P.E. Laibinis and S.M. Weiss “Porous Silicon based Optical Sensing in Complex Media: Antifouling Coating” USM LSAMP Fall 2019 Symposium University of Maryland, College Park, MD, December 2019. - Hayat was awarded Best Use of Graphics at the capstone poster session.
- Conference Presentations
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Matthew Castanon - Biochemistry, Kennesaw State University
Educational Institution: Kennesaw State University
List of Mentors: Dr. Craig Duvall & Ella Hoggenboezem
Program: NSF REU
Research Project: Optimizing Gene Silencing Using siRNA-Loaded Porous Silicon Nanoparticles
Poster: NSF REU Matthew Castanon Poster.pdfResearch Abstract: The main premise of the project is to measure the optimal loading efficiency of siRNA into porous silicon nanoparticles for the utilizing of siRNA-loaded, Luciferase gene-suppressed PSNPS. In addition, the PSNPs will be coated with PEGDB to disrupt acidic vesicles and trigger the release of siRNA into the cytoplasm once intracellularly. The PSNPs will also have a Calcium Silicate shell allowing the electrostatic linkage between the negative surface charge of the PSNPs, the divalent cationic nature of Calcium, and the negatively charged siRNA molecules. The results from the PSiNP-siRNA gene knockdown assay demonstrate that there does not appear to be significant differences in knockdown between targeted and scrambled siRNA delivered by the porous silicon nanoparticles. Gel electrophoresis of siRNA remaining in the supernatant demonstrates that the groups without salt show the same siRNA content as those with calcium, even though the brightness is dimmer and spread out over a vast area. Interestingly, the lowest content is demonstrated in the samples without PSiNPs, potentially signaling at calcium-siRNA sequestration. From our luciferase assay results, greater luminescence and lower knockdown was shown by siRNA loaded into porous silicon nanocomposites compared to PEG-DB. We theorize that too little porous silicon and too much salt is being utilized. On a nanoscale, porous silicon is encapsulating enough siRNA but the calcium concentration is too high, causing the calcium to more compete with the porous silicon to bind siRNA. Future work will include reevaluation of concentrations used in the protocol to achieve optimal loading.
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Elyssa Ferguson - Mechanical Engineering, University of Maryland, Baltimore County
Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Cary Pint & Janna Eaves
Program: NSF REU
Research Project: Exploring New Cathode Materials to Enable High Energy Magnesium Batteries
Poster: NSF REU Elyssa Ferguson Poster.pdfResearch Abstract: Modern smartphones, electric vehicles, drones, and other evolving technologies demand improvement of Li-ion batteries into more energy-dense power sources. Magnesium (Mg) batteries are a promising alternative because the Mg2+ ion shuttles twice as many electrons as Li+, thereby doubling the theoretical volumetric energy density. Here, we investigate the storage capacity and Mg-ion hosting mechanisms of tungsten diselenide (WSe2) as a cathode material for these cutting-edge battery systems. Using a three-electrode electrochemical setup, we measured a high specific capacity of 120 mAh/g and subsequently characterized the material at 0%, 50%, 75%, and 100% discharge via X-ray diffraction and Raman. The results show that WSe2 stores Mg through a reversible intercalation mechanism, dispelling concerns that the layered material might undergo inefficient chemical conversion reactions, as it is known to experience in lithium- and sodium-ion batteries. This work opens a door to energy-dense multivalent ion batteries that surpass current lithium-ion technologies in cost, safety, and size.
- Conference Presentation
E. Ferguson, J. Eaves, and C. Pint, “Exploring New Cathode Materials to Enable High Energy Magnesium Batteries” Council on Undergraduate Research Research Symposium for Undergraduates, Alexandria, VA, October 2019. - Elyssa was awarded a $1K travel grant at the capstone poster session.
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Alyssa Livingood - Computer and Electrical Engineering, University of Kentucky
Educational Institution: University of Kentucky
List of Mentors: Dr. Josh Caldwell & Ryan Nolen
Program: NSF REU
Research Project: Non-dispersive Infrared (NDIR) Sensing of CO2 Using CdO Films
Poster: NSF REU Alyssa Livingood Poster.pdfResearch Abstract: The potential for realizing portable, light-weight devices reliant on narrowband, mid-infrared light is hindered by the low wall-to-plug efficiencies and large footprints of gas-phase lasers and quantum cascade lasers. There exists a demand for efficient, cost-effective, narrowband sources that could improve mid-infrared spectroscopy and sensing. Recent work has shown that narrowband thermal emission is feasible by using subwavelength films of n-doped cadmium oxide. These films are highly efficient thermal emitters due to the fact that cadmium oxide is a plasmonic material which supports epsilon-near-zero (ENZ) modes. ENZ modes are excited at the zero crossing of the real part of the permittivity and can couple to free space without any nanostructuring to create ENZ polaritons. Along with supporting ENZ polaritons, cadmium oxide exhibits low optical losses and has a highly tunable plasma frequency throughout the mid-infrared. While these films are a significant step towards practical, tunable narrowband mid-infrared sources, their peak emission occurs at an angle highly off normal, limiting their applicability. To increase the viability of these novel emission sources, it is necessary to achieve high narrowband emission at normal incidence. Here, we have shown that by growing n-doped cadmium oxide films on a patterned sapphire substrate, high emission is achievable at normal incidence. We conducted thermal emission measurements to confirm that our films were accurately tuned to emit at 2500 cm-1. Angle dependent thermal emission measurements were also performed and have shown that the n-doped cadmium oxide films on a patterned substrate emit omnidirectionally. It was also observed that at high angles Fano interference occurred between the ENZ mode and a propagating surface mode. This caused the bandwidth of the thermal emission to become extremely narrowed, reaching Q factors of 14. These results are promising and can guide further optimization of n-doped cadmium oxide films on patterned substrates for narrowband thermal emission. With the tunability and high emissivity at normal incidence, these films could be used for applications such as nondispersive infrared sensing of gas molecules.
- Livingood 1st Author ACS Photonics Journal Publication
A. Livingood, J.R. Nolen, T.G. Folland, L. Potechin, G. Lu, S. Criswell, J.P. Maria, C. Shelton, E. Sachet, J.D. Caldwell, “Filterless Non-dispersive Infrared Sensing using Narrowband Infrared Emitting Metamaterials”, ACS Photonics 8, 2, 472-480 (2021). - Conference Presentation
A.K. Livingood, J.R. Nolen, T.G. Folland, and J.D. Caldwell, “Non-dispersive Infrared (NDIR) Sensing of CO2Using CdOFilms” Southeast Regional Meeting of the American Chemical Society (SERMACS), Savannah, GA, October 2019. - Alyssa was awarded a $1K travel grant at the capstone poster session.
- Livingood 1st Author ACS Photonics Journal Publication
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Catherine Ludolph - Chemical Engineering, University of Texas, Austin
Educational Institution: University of Texas, Austin
List of Mentors: Dr. Cynthia Reinhart-King & Jenna Mosier
Program: NSF REU
Research Project: Alternating confinement in collagen microtracks in vitro influences cancer cell migration
Poster: NSF REU Catherine Ludolph Poster.pdfResearch Abstract: Metastasis, or the spread of cancer, accounts for 90% of cancer related deaths. During metastasis, tumor cells migrate away from the primary tumor through a collagen rich environment known as the extracellular matrix (ECM). Previously, it has been shown that cells in confinement move significantly faster than cells that are unconfined. Because cells are able to sense these spatial restrictions as they migrate through the ECM, it is thought that they can be conditioned to more readily navigate more challenging environments such as repeated confinement and employ a “mechanical memory” to inform future migration decisions. To model this environment, collagen microtracks of width alternating between 7 and 15 μm were fabricated by etching a silicon wafer, making polydimethylsiloxane (PDMS) stamps from the wafer, and stamping the PDMS into collagen to mold the microtracks. Highly metastatic MDA-MB-231 breast cancer epithelial cells were seeded into the collagen microtracks and allowed to migrate freely while their positions were tracked for at least 12 hours. The narrow 7 μm width sections fully confined the cells, such that the cells touched all four surrounding walls, while the wide 15 μm sections partially confined the cells, such that the cells touched three or fewer walls. Microtracks of 7 μm and 15 μm uniform width were used as controls. Cells in alternating width tracks reached a higher final velocity than cells in either of the uniform width tracks. However, cells in the alternating width tracks did not travel as far as those in the narrow 7 μm tracks, suggesting that repeated confinement may not induce more efficient migration. Future work will focus on further examining cell behavior in challenging microenvironments to determine how alternating confinement influences cell migration.
- Conference Presentations
-J.A. Mosier, C.M. Ludolph, M.R. Zanotelli, C.A. Reinhart-King “Short-Term and Long-Term Effects of Confinement on Cancer Cell Migration”. Virtual BMES 2020 Annual Meeting. Asynchronous Oral Presentation. October 2020.
-J.A. Mosier, C.M. Ludolph, M.R. Zanotelli, C.A. Reinhart-King “Modeling Mechanical and Metabolic Memory of Confined Cancer Cells using Collagen Microtracks”. Virtual VINSE NanoDay Symposium, October 2020. *won first place
- Conference Presentations
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Inaya Molina - Physics & Spanish, Hendrix College
Educational Institution: Hendrix College
List of Mentors: Dr. Kane Jennings & Josh Passantino
Program: NSF REU
Research Project: Polymerization of Aniline by Photosystem I Proteins
Poster: NSF REU Inaya Molina Poster.pdfResearch Abstract: Photosynthesis is a process in plants which converts solar energy into chemical energy and has become a basis for biohybrid solar cells. Solar panels today are growing in demand yet their price and the energy waste they create in production are still prominent problems. Photosystem I (PSI) is a protein vital for photosynthesis in oxidizing and reducing native redox species to produce NADPH. The two sites responsible for oxidation and reduction are the P700 and FB sites, respectively. Polyaniline (pAni) is a conductive polymer that has been shown to work well in biohybrid solar cells. If PSI can electropolymerize aniline monomer to form polyaniline, a robust protein-polymer conjugate can be produced that may result in direct electrical wiring of the key active site of the protein. pAni is formed though an oxidative polymerization, which we hypothesize is possible with PSI. By combining aniline and PSI in solution, we hypothesize that aniline can polymerize at the P700 site, forming pAni attached to the protein. We show through cyclic voltammetry and FTIR that the P700 site of PSI does polymerize pAni in solution. pAni formation was investigated at multiple pH’s with PSI to find the optimal pH for pAni growth without damaging the protein. pH 4 was determined to be the best pH for pAni growth with PSI. Our results suggest that we have produced the non-conductive leucoemeraldine form of polyaniline that can be doped in order to create more conductive forms.
- Conference Presentation
I. Molina, J. Passantino, G.K. Jennings “Polymerization of Aniline by Photosystem I Proteins”
Conferences for Undergraduate Women in Physics, Norman, OK, January 2020 *won best presentation - Inaya was awarded Best Layout at the capstone poster session.
- Conference Presentation
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Nicholas Riley - Mechanical Engineering Systems, Arizona State University
Educational Institution: Arizona State University
List of Mentors: Dr. Jason Valentine & Hanyu Zheng
Program: NSF REU
Research Project: Fabrication of Multilayered Metasurfaces
Poster: NSF REU Nicholas Riley Poster.pdfResearch Abstract: Metasurfaces are thin sheets of metamaterials, which are nanostructured surfaces that can manipulate the wave front of light. By engineering the nanostructures of a material, we can change the way that material interacts with light. Multiwavelength operation is achieved by using multiple layers of metasurfaces. Creating a multilayered metasurfaces involves fabricating separate layers with alignment marks, then using a transfer system to align and bond the layers. Previous systems utilized a transfer stage for alignment and PDMS for bonding. Our objective is to achieve a higher level of horizontal and vertical alignment of metasurfaces layers by developing more effective transfer methods to decrease fabrication errors and create better metasurfaces doublets. This project developed a transfer stage with precise translation, rotation, and tilt capabilities that allowed for testing of alignment methods. Cross and grating alignment marks were fabricated for horizontal alignment. A Fabry-Pérot cavity was used to characterize relative distance between layers as a function of beam intensity. In future work, we will explore the effectiveness of these methods on one sample, as well as optimizing the stability of the system.
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Pamela Joy Tabaquin - Chemistry, Queensborough Community College
Educational Institution: Queensborough Community College
List of Mentors: Dr. David Cliffel & Chris Stachurski & Kody Wolfe
Program: NSF REU
Research Project: Entrapment of Photosystem I within a Polyaniline Matrix on Carbon Paper for Photocurrent Generation
Poster: NSF REU Pamela Joy Tabaquin Poster.pdfResearch Abstract: Photosystem I (PSI) is a membrane bound protein complex found in plants which helps drive photosynthesis. Due to its abundance in nature and high quantum efficiency, PSI is a prime candidate for use in biohybrid solar cells. To date, several PSI bioelectrodes have been successfully fabricated using a variety of different electrode materials and host matrices, such as conductive polymers like polyaniline (pAni). pAni has been polymerized on metallic electrodes in the past; however, carbon paper (CP) substrates have also been utilized for pAni polymerization. Electrochemically polymerizing aniline in the presence of PSI onto low cost, high surface area CP, enabled the production of PSI-pAni-CP electrodes which showed enhanced photocurrent generation. The hydrophobic CP was first pretreated then characterized using contact angle and cyclic voltammetry. Using the pretreated carbon electrodes, PSI-containing pAni composites were electrochemically produced and tested in photoelectrochemical cells. It was found that devices prepared in the presence of PSI enhanced the observed photocurrent by a factor of 2 over non-PSI containing devices. By investigating different mediator systems or optimizing deposition conditions, photocurrent generation can be further improved using carbon paper-based biohybrid electrodes.
- Conference Presentations
-P.J. Tabaquin, D. Dervishogullari, C. Stachurski, K. Wolfe, G. K. Jennings, D.E. Cliffel “Entrapment of Photosystem I within a Polyaniline Matrix on Carbon Paper for Photocurrent Generation” National American Chemical Society Meeting, Philadelphia, PA, March 2020. (Canceled COVID-19)
-P.J. Tabaquin, D. Dervishogullari, C. Stachurski, K. Wolfe, G. K. Jennings, D.E. Cliffel “Entrapment of Photosystem I within a Polyaniline Matrix on Carbon Paper for Photocurrent Generation” 68th Annual Undergraduate Research Symposium, Brooklyn, NY, May 2020. (Canceled COVID-19)
-P.J. Tabaquin, D. Dervishogullari, C. Stachurski, K. Wolfe, G. K. Jennings, D.E. Cliffel “Entrapment of Photosystem I within a Polyaniline Matrix on Carbon Paper for Photocurrent Generation” Middle Atlantic Regional Meeting, New York, NY, June 2020. (Canceled COVID-19) - Pamela tied for Fan Favorite at the capstone poster session.
- Conference Presentations
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Ellis Thompson - Physics, Vassar College
Educational Institution: Vassar College
List of Mentors: Dr. Richard Haglund & Nathan Spear & Samuel White
Program: NSF REU
Research Project: Growth of VO2 Single Crystals
Poster: NSF REU Ellis Thompson Poster.pdfResearch Abstract: The phase-changing materials Vanadium dioxide (VO2) exhibits a metal-insulator transition coupled to a crystallographic transition (monoclinic to rutile) at ~68ºC, which can be harnessed in thermal, electrical, and optical devices. Large area, low-aspect-ratio VO2 microcrystals exhibit a single-domain, single-phase transition, and thus also serve as useful tools for investigations of the metal-insulator transition itself. VO2 nanowires are known to assume different morphologies based on the lattice structure and thermal expansion properties of the substrate used. However, larger single-domain and single-phase crystals are more difficult to grow, so they have not been extensively studies. Here we show how ~20-200 micron-sized VO2 crystals grown through vapor transport on different cuts of sapphire (Al2O3) and YSZ present unique morphologies and behavior. Images of the crystals show evidence of preferred orientations depending on the cut of the substrate. In addition, Raman spectroscopy indicates aluminum doping of crystals grown on sapphire and the formation of a YVO4 layer on YSZ substrates during growth. These results show that in addition to strain due to lattice mismatch, chemical reactions at the VO2-substrate interface play a more significant role in microcrystal growth than previous studies suggest. Our conclusions also shed light on the physics of crystal growth in the context of phase-change materials. Understanding how nanoscale properties of substrates affects VO2 crystals at the micro-scale will help facilitate future optical experiments and lead to novel technological applications.
- Ellis tied for Fan Favorite at the capstone poster session.
- Ellis was awarded a NSF Graduate Research Fellowship in 2022.
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Christina Trexler - Chemical Engineering & Math, University of Arkansas, Fayetteville
Educational Institution: University of Arkansas, Fayetteville
List of Mentors: Dr. Piran Kidambi & Nicole Moehring
Program: NSF REU
Research Project: Synthesis and Clean Transfer of Atomically Thin Materials
Poster: NSF REU Christina Trexler Poster.pdfResearch Abstract: When using a membrane to separate materials, the efficiency of the separation is limited by how quickly molecules pass through the membrane and by how selective the membrane is. Single atom thick 2D materials, such as graphene, hexagonal boron-nitride, and others, present new horizons for the development of novel separation processes. While pristine 2D materials realize the thinnest possible physical barrier for membrane applications, enabling ultra-high permeance, precise perforations in the material lattice can offer strict selectivity. The viability for such nanoporous atomically thin membranes (NATMs) depends on the advancement of synthesis and transfer techniques. Graphene--offering great mechanical strength, flexibility, and inherent impermeability--has been frequently synthesized using the process of chemical vapor deposition (CVD) and subsequently transferred using polymethyl methacrylate (PMMA). When growing monolayer graphene via CVD it is essentially important to create a continuous film while minimizing defects and multilayer growth. Furthermore, the large polymer particle residue generated by PMMA during the graphene transfer process is a fundamental issue that can lead to a myriad of issues during practical applications. Herein, we propose a two-step method of CVD growth in order to achieve a continuous graphene layer with minimal defects and a method of short-term liquid copper annealing that will minimize the appearance of graphene adlayers. We also demonstrate two alternative methods of transferring CVD graphene using polyvinyl alcohol and rosin. In the short term, rosin has demonstrated its superiority to PMMA for the defect free, clean transfer of graphene, whereas polyvinyl alcohol shows promise in integration with roll-to-roll graphene production. These methods also provide helpful information for the controlled growth and clean transfer of uniform monolayers of other 2D materials such as h-BN.
- Conference Presentation
C.M. Trexler, N.K. Moehring, and P.R. Kidambi, “Synthesis and Clean Transfer of Atomically Thin Materials” AIChE Mid-America Conference, Lincoln, NE, April 2020. - Christina was awarded a $1K travel grant at the capstone poster session.
- Conference Presentation
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Quinton Victor - Mechanical Engineering, University of Miami
Educational Institution: University of Miami
List of Mentors: Dr. Rizia Bardhan & Xiaona Wen
Program: NSF REU
Research Project: Portable Reusable Accurate Diagnostics with nanoAntennas (PRADA) for Multiplexed Biomarker Screening
Poster: NSF REU Quinton Victor Poster.pdfResearch Abstract: Precise detection of specific biomarkers in human fluids is compulsory for disease diagnosis, risk stratification, and treatment planning. In this work we introduce an innovative biodiagnostic sensor to circumvent the limitations of those commercially available. PRADA: portable reusable accurate diagnostics with nanoantennas, enables multiplexed biomarker detection in small volumes (~50 µL) when performed in a microfluidic platform. In this PRADA platform, magnetic microbeads capture cardiac troponin I (cTnI), a well-accepted biomarker of cardiac disorders, and neuropeptide Y (NPY), a biomarker of anxiety and stress. Gold nanostar “antennas” labeled with peptide recognition elements and Raman reporters detect the biomarkers via surface-enhanced Raman spectroscopy (SERS) in both buffer and de-identified human serum samples. The narrow characteristic peaks of SERS leveraged with the nanostar/peptide conjugates enabled multiplexed detection in both buffer and human serum with high sensitivity and specificity, with a limit of detection of 30 pg/mL of cTnI. Moreover, the magnetic beads enabled regeneration and reuse of PRADA for over 15 cycles with the same microfluidic device. In the future, PRADA will ultimately enable rapid and inexpensive assessment of multiple biomarkers in clinical samples amenable to resource-limited settings.
- Co-author Journal Publication
X. Wen., Y-C. Ou, H. F. Zarick, X. Zhang, A. B. Hmelo, Q. J. Victor, E. P. Paul, J. M. Slocik, R. R. Naik, L. M. Bellan, E. C. Lin, and R. Bardhan, "PRADA: Portable Reusable Accurate Diagnostics with nanostar Antennas for multiplexed biomarker screening", Bioengineering & Translational Medicine, e10165 (2020)
- Co-author Journal Publication
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Carlos Zuna Largo - Mechanical Engineering, New York Institute of Technology
Educational Institution: New York Institute of Technology
List of Mentors: Dr. Kelsey Hatzell & Nicholas Hortance
Program: NSF REU
Research Project: Electrochemical Ammonia Synthesis Using BZCYYb4411 Electrolyte and Ag Electrocatalyst
Poster: NSF REU Carlos Zuna Largo Poster.pdfResearch Abstract: Electrochemical ammonia synthesis is a sustainable alternative to the energy-intensive Haber Bosch process used in the commercial production of ammonia. Electrochemical production of ammonia uses a solid electrolyte and operates under ambient pressure and at intermediate temperatures of 300-600°C. This work investigates the electrochemical performance of the perovskite proton conductor [] to produce ammonia electrochemically from and . Electrolyte pellets are fabricated and sintered at 1600°C for 24hr. Pellets with a relative density of >95% are coated with a silver [Ag] catalyst to produce the finished sample. The setup of this project includes an alumina single chamber reactor in a tube furnace with gas and water steam. Current density and ionic conductivity values are measured using electrical impedance spectroscopy. Ammonia gas formed in the reaction is collected in sulfuric acid [] and is measured using UV-spectroscopy. Maximum absorption is observed at 655nm to which the highest formation rate is.
Conference Presentation
N. Hortance, C. Zuna Largo, K.B. Hatzell “Intermediate temperature ammonia production using inorganic proton conductors” Electrochemical Society Meeting, Atlanta, GA, October 2019.
![REU 2018 REU 2018](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/30150155/REU-2018.png)
2018
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Caitlin Carfano - Electrical Engineering, George Washington University
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Educational Institution: George Washington University
List of Mentors: Dr. Sharon Weiss & Tengfei Cao
Program: NSF REU
Research Project: Porous Silicon Flakes on a Flexible Substrate for Real-Time Biosensing using Smartphone TechnologyResearch Abstract:
Biosensor research is a rapidly growing field as personal diagnostics are becoming more popular. The traditional advanced medical equipment is costly and not readily available in low resource areas. The creation of a personal diagnostic biosensor that satisfies the ASSURED (Affordable, Sensitive, Specific, User-Friendly, Rapid and Robust, Equipment-Free, and Deliverable to those in need) criteria set by the World Health Organization is ideal for people in developing countries. An optical biosensor that utilizes the smartphone camera sensor to detect color changes when an analyte is present has potential to satisfy these requirements because of the ubiquitous nature of smartphones. Porous silicon (PSi) makes an ideal candidate for an optical biosensor because it has a large internal surface area, easy manufacturing process, and high sensitivity. PSi can be electrochemically etched to form various optical structures by tuning the etching current density and time. By comparing the color of the PSi before and after analyte is introduced, the concentration of the analyte can be determined. In this work, we present a flexible biosensing device consisting of PSi on a flexible substrate (PDMS and plastic) attached to paper for sample acquisition. We demonstrate that solutions such as various glucose concentrations can be detected by both an Ocean Optics Spectrometer in a scientific lab as well as an ordinary Apple iPhone camera. As a specific potential application, this device has can be used as a wearable biosensor because of its flexible nature. In future work, the smartphone camera detection will be automated by an application (app) to display the analyte concentration detected to the user consisting of a simple user-interface.- Co-author Journal Publication
T. Cao, C. Carfano, G. A. Rodriguez, M. H. Choudhury, F. O. Afzal, and S. M. Weiss, “Porous silicon sensors: From on-chip to mobile diagnostics,” Proc. SPIE 10891, 1089112 (2019). - Caitlin was awarded the Rockwell Automation Scholarship from the Society of Woman Engineers in 2019.
- Co-author Journal Publication
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Aamina Dandy - Chemical Engineering, Tuskegee University
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Educational Institution: Tuskegee University
List of Mentors: Dr. John Wilson & Jessalyn Baljon
Program: NSF REU
Research Project: Exploring the effects of pH-responsive polymeric nanoparticles on inflammasome activationResearch Abstract:
The NLRP3 inflammasome is a muli-protein oligomer that forms in cells possessing the NLRP3 gene during times of distress. During its formation, the enzyme caspase-1 activates and allows for the maturation of the pro-inflammatory cytokine interleukin-1β (IL-1β). Although much is still unknown in regards to its mechanism, various studies have been done to discover the necessary stimuli for the activation of inflammasomes. The purpose of this study was to determine if pH responsive polymeric micelles are capable of activating inflammasomes. The polymers used in this study contain a hydrophilic PEG group attached to a hydrophobic group comprised of BMA and DEMAEMA. THP-1 cells were differentiated into macrophages and dosed with polymeric micelles with various compositions of BMA. HEK-Blue IL-1β reporter cells were used to monitor the secretion of IL-1β and hemolysis, QUANTI-Blue, ELISA, and CellTiter-Glo assays were used to characterize the cells. Results show that the micelles are stable at pH 7.4 and are able to escape the endosome at endosomal pH’s. In addition, significant IL-1β secretion indicates that inflammasomes are being activated. Experiments with NLRP3 gene deficient THP-1 cells show significantly reduced IL-1β secretion, suggesting that the inflammasome is the cause of IL-1β secretion. High cytotoxicity levels indicate that the polymers themselves are cytotoxic, implying that apoptosis caused by IL-1β secretion is not the sole cause of cell death. It is possible, however, that the cytotoxicity of the polymers may contribute to inflammasome activation by causing cellular distress. Future steps for this project include studying the effects of inflammasome inhibitors on the THP-1 cells to confirm inflammasome activation as the cause for IL-1β secretion. In addition, flow cytomerty can be used to verify that lysosomal rupture is the reason for inflammasome activation.- Co-author Journal Publication
J. J. Baljon, A. Dandy, L. Wang-Bishop, M. Wehbe, M. E. Jackson and J. T. Wilson, “The efficiency of cytosolic drug Delivery using pH-responsive endosomolytic polymers does not correlate with activation of the NLRP3 inflammasome,” Biomaterials Science, 7, 1888-1897 (2019). - Aamina was awarded a $1K travel grant at the capstone poster session.
- Co-author Journal Publication
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Rebeca Gurrola - Physics and Mathematics, St. Mary’s University
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Educational Institution: St. Mary’s University
List of Mentors: Dr. Cary Pint & Janna Eaves
Program: NSF REU
Research Project: Wearable textile based energy harvester designed for human motionResearch Abstract:
While there are many different methods of generating sustainable energy, small quantities of energy otherwise wasted in the pursuit of everyday activities are often overlooked. Recently, electrochemical energy harvesters joined the ranks of piezoelectric and triboelectric harvesters to convert mechanical energy into electrical energy. Here, we exploit the diversity of materials with mechanochemical response to seamlessly integrate motion harvesting into textiles for wearable applications. This study presents a novel class of safe and non-toxic “smart” energy harvesters which can be activated via sweat, stimulated here by a solution of NaCl. The resulting textile-based energy harvester comprised of a sodium tin alloy on copper fabric is intended to exploit ambient motion at frequencies of .1 Hz. In bend tests, the harvester generates a peak power of ~36.4 μW/cm2 and energy of ~131.1μJ/cm2 with each bend. Additionally, the harvester is sensitive to changes in salt concentration, suggesting applications in hydration-monitoring. These results emphasize the exciting possibilities for a new class of wearable harvesters.- Conference Presentations
-R. M. Gurrola, J. Eaves, and C. L. Pint “Wearable textile based energy harvester designed for human motion” 2018 American Physical Society (APS) Bridge Program and National Mentoring Community Conference, Stanford, CA, November, 2018. *won 1 st place
-R. M. Gurrola, J. Eaves, and C. L. Pint “Wearable textile based energy harvester designed for human motion” 2019 American Physical Society March Meeting, Boston, MA, March, 2019. *won outstanding oral presentation
-R. M. Gurrola, J. Eaves, and C. L. Pint “Wearable textile based energy harvester designed for human motion” Spring Research Symposium, St. Mary’s University, April, 2019. *won 3rd place oral presentation - Rebeca was awarded Best use of Graphics at the capstone poster session.
- Rebeca received the Presidential Award at St. Mary's University in 2019.
- Rebeca was awarded a NSF Graduate Research Fellowship in 2020.
- Conference Presentations
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Nafisa Ibrahim - Chemistry, College of St. Scholastica
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Educational Institution: College of St. Scholastica
List of Mentors: Dr. Kelsey Hatzell & Fengyu Shen & Marm Dixit
Program: NSF REU
Research Project: Co-extruded Composite Polymer Electrolytes for Solid-State BatteriesResearch Abstract:
Composite polymer electrolytes are exciting alternatives for all solid-state batteries due to their advantages of scalability and overall better mechanical response. This work is evaluating strategies for scalable manufacturing of functionally graded composite polymer electrolytes. A custom-built setup has been made that allows fabrication of co-extruded multimaterial composite polymer electrolytes (CPEs). The project involves performing detailed material and electrochemical characterization of these co-extruded CPE films. The study evaluates two material systems: 75 wt.% LLZO-PEO (Li7La3Zr4O12 - Polyethylene Oxide) electrolyte and 25 wt.% LLZO-PEO electrolyte. The configurations include single material films and co-extruded films of both materials with features ranging from 1 mm to 23mm. Ionic conductivity measurements were carried out to evaluate initial control parameters.- Conference Presentations
-N.A. Ibrahim, M. Macdonald, M.B. Dixit, F. Shen, and K.B. Hatzell, "Co-extruded Composite Polymer Electrolytes for Solid-State Batteries," Ronald E. McNair Scholars Program and Research Opportunity Program, Albuquerque, NM, October, 2018.
-N.A. Ibrahim, M. Macdonald, M.B. Dixit, F. Shen, and K.B. Hatzell, "Co-extruded Composite Polymer Electrolytes for Solid-State Batteries," Research Experiences for Undergraduate Symposium, Council on Undergraduate Research, Alexandria, VA, October 2018. - Nafisa was awarded a $1K travel grant at the capstone poster session.
- Nafisa was awarded a NSF Graduate Research Fellowship
- Conference Presentations
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Joshua Livingston - Chemical Engineering, Prairie View A&M University
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Educational Institution: Prairie View A&M University
List of Mentors: Dr. Kane Jennings & Ricky Deng
Program: NSF REU
Research Project: pH-Responsive Copolymer FilmsResearch Abstract:
pH-Responsive films are polymer films that react to changes in pH by accepting or donating protons, which changes the properties of the film. In this report, we have prepared pH-responsive ester and carboxylic acid copolymer films by SiROMP (Surface-initiated Ring Opening Metathesis Polymerization), coupled with a quick copolymer preparation step. We successfully prepared poly(norbornene diacyl chloride) (pNBDAC) films by vapor phase SiROMP. Due to the high reactivity of acyl chloride groups, we can easily modify the pNBDAC films with other functional groups. In the copolymer preparation step, pNBDAC films are immersed into an ethanol and water mixture to form the carboxylic acid and ester copolymer. The ratio of the ethanol-water mixture determines the composition of the copolymer film the reaction yields. Electrochemical Impedance Spectroscopy was used to characterize the film impedance at different pH values. The pH-responsive behavior of the copolymer film depends on its carboxylic acid and ester content.- Co-author Journal Publication
X. Deng, J. Livingston, N.J.Spear, and G.K. Jennings "pH-Responsive Copolymer Films Prepared by Surface-Initiated Polymerization and Simple Modification", Langmuir, 36, 715−722 (2020). - Livingston was awarded Fan Favorite at the capstone poster session.
- Co-author Journal Publication
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Caylee Marshall - Chemical Engineering, University of Kentucky
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Educational Institution: University of Kentucky
List of Mentors: Dr. Craig Duvall & Prarthana Patil
Program: NSF REU
Research Project: In-vitro material characterization of ROS-responsive poly(thioketal) polymeric scaffolds for treatment of chronic woundsResearch Abstract:
Chronic wounds affect millions of Americans each year. There are currently limited and inefficient treatment regiments which augment wound healing. The use of degradable biomaterials, such as foams, is being extensively studied for the treatment of chronic wounds. These wounds are characterized by poor vasculature and elevated levels of reactive oxygen species (ROS). Our motivation is to leverage elevated ROS levels as a stimuli for the degradation of poly(thioketal) urethane (PTK-UR) scaffolds. We have previously fabricated urethane foams using two component liquid reactive molding by using trifunctional isocyanates and mercaptoethylether (MEE)PTK diol1. Nonspecific degradation of polyester urethane foams can be eliminated by using ROS degradable PTKUR chemistry to augment formation of granulation tissue and decrease fibrosis. This project has focused on making increasingly hydrophilic polymeric PTK diol components to decrease immunogenicity and increase clearance of scaffold degradation products. -
Rebecca Mendez - Electrical Engineering, Northeastern University
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Educational Institution: Northeastern University
List of Mentors: Dr. Ronald Schrimpf & Andrew Tonigan
Program: NSF REU
Research Project: Heavy Ion Strikes on Diodes: Effects of Surface Recombination on Charge CollectionResearch Abstract:
In the near-Earth regions of space, radiation from solar energetic events and the Van Allen Belts are a primary concern for space observation and exploration electronics. Radiation has the ability to flip digital logic states or destroy devices completely. As semiconductor device sizes approach the nanoscale, where material layers are at times only several atoms thick, radiation becomes a very significant concern for its effects on device and system performance. In this project, we investigate heavy ion and alpha particle strikes on insulated Silicon and Germanium diodes. In particular, we investigate how interfacial defects along the Si/SiO2 interface affect the charge collection process. Through finite element analysis simulations in Synopsis TCAD, we perform a parametric analysis of how changes in the length to width ratio, doping profile, and surface recombination velocity affect the current vs. time transient in a Si diode. Simulation results showed that long and thin diodes (width of .1um and length >1um), the Surface Recombination Velocity affected the Current vs. Time transients of the device. As SRV increased, the current collected decreased. In future work, we will look at Monte Carlo simulations of alpha particle strikes on diodes which will inform a probabilistic model to be compared with experimental results of alpha particle strikes on Ge diodes.- Rebecca was name a La Communidad Latina en Accion (LaCLA) Scholar in 2019.
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Angelo Miskalis - Biomedical Engineering, Duquesne University
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Educational Institution: Duquesne University
List of Mentors: Dr. Craig Duvall & Bryan Dollinger
Program: NSF REU
Research Project: Assessment of Antioxidant Copolymers for Superoxide ScavengingResearch Abstract:
Post Tramautic Osteoartiritis (PTOA), a form of osteoarthritis caused by the physical injury of a joint, remains one of the leading causes for mobility related diseases. PTOA is a multi-factorial disease, resulting in the inflammation and degeneration of cartilage as well as surrounding tissues within the joint. Current pharmacological treatments, such as NSAIDS, are only symptomatic. Therefore, a treatment that directly addresses the cause of PTOA is needed. Reactive oxygen species (ROS) remain a promising target for therapeutics as the overproduction of ROS, particularly superoxide anions, have been directly linked to cellular damage. TEMPO, a potential antioxidant, provides superoxide scavenging, but possesses poor retention time within joints due to insolubility and synovial clearing. To improve the bioactivity of TEMPO, random copolymers consisting of hydrophilic dimethylacrylamide (DMA) and TEMPO were synthesized as previously described. Polymer libraries consisting of various ratios of DMA:TEMPO were then formed to assess the optimum combination of ROS scavenging potential and hydrophilicity. Cellular uptake, in vitro scavenging, and in vivo scavenging assays were utilized to confirm the efficacy of each polymer. While all polymers possessed scavenging capabilities, the more hydrophilic polymers provided maximum scavenging capabilities as well as maximum cellular uptake. Results here will be utilized with continued in vivo and in vitro experiments to further confirm optimum polymer conditions for future PTOA therapies.- Co-author Journal Publication
C.R. DeJulius, B.R. Dollinger, T.E. Kavanaugh, E. Dailing, F. Yu, S. Gulati, A. Miskalis, C. Zhang, J. Uddin, S. Dikalov, C.L. Duvall. "Optimizing an antioxidant TEMPO copolymer for ROS scavenging and anti-inflammatory effects in vivo". Bioconjugate Chemistry, 32 (5), 928-941 (2021). - Conference Presentations
-A. J. Miskalis, B. R. Dollinger, C. DeJulius and C. L. Duvall “Assessment of Antioxidant Copolymers for improved ROS Scavenging in Post-Traumatic Osteoarthritis” Society for Biomaterials National Conference, Seattle, WA, April, 2019.
-A. J. Miskalis, B. R. Dollinger, C. DeJulius and C. L. Duvall “Assessment of Antioxidant Copolymers for improved ROS Scavenging in Post-Traumatic Osteoarthritis” AiChE Regenerative Engineering Conference, Pittsburgh, PA, October, 2018. - Angelo was awarded a $1K travel grant at the capstone poster session.
- Co-author Journal Publication
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Oluwalade Ogungbesan - Chemical Engineering, University of Maryland, Baltimore County
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Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Clare McCabe & Alex Yang
Program: NSF REU
Research Project: Using molecular simulation to understand the interactions between DNA-coated graphene sheets and phospholipid bilayersResearch Abstract:
Graphene has been beneficial in the area of gene and drug delivery because of its unique structural properties. Derived from its parent material, graphite, graphene is a nanocarbon composed of two-dimensional hexagonally arranged carbon atoms, which causes it to have a porous structure and contain only hydrophobic regions. Particularly, certain chemicals like DNA can be transported into lipid bilayers with the use of graphene due to the molecules both containing nonpolar regions, but more studies are needed in order to gather information on how graphene affects lipid bilayers.1 Some ways to determine these effects include controlling the graphene’s angle of insertion and force applied to pull the graphene sheet into the bilayer. These experiments are modeled by using molecular dynamic simulations, which provides a cost effective and fast way of simulating these experiments. Based on our experiments, the maximum work and force done on the graphene increased when the force constant and the angle increased, and DNA remained on the graphene sheet when using a force constant no greater than 250kJ/mol x nm2. 1. Bao, H. et al. Chitosan-functionalized graphene oxide as a nanocarrier for drug and gene delivery. Small 7, 1569–1578 (2011).- Journal Publication
-T.C. Moore, A. Yang, O Ogungbesan, R. Hartkamp, Q. Zhang and C. McCabe, “Influence of a Coating on the Interaction Between Graphene Nanoflakes and Lipid Bilayers” Journal of Physical Chemistry B, 120 (37), 9944-9958 (2019). - Conference Presentations
-O. Ogungbesan, Alexander Yang, and Clare McCabe, "Using Molecular Simulation to Understand the Interactions Between DNA-Coated Graphene Sheets and Phospholipid Bilayers," Council on Undergraduate Research's Research Experience for Undergraduates Symposium, Alexandria, VA, October, 2018. - Olu was named a Meyerhoff Scholar
- Journal Publication
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Keiann Simon - Forensics, Queensborough Community College
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Educational Institution: Queensborough Community College
List of Mentors: Dr. Kane Jennings & Josh Passantino
Program: NSF REU
Research Project: Photosystem I Proteins in Gel-State Biohybrid Solar CellsResearch Abstract:
In converting solar energy into chemical energy, photosynthesis is necessary for the sustainability of all life on Earth. This use of light energy triggers a chain of electron transfers, which when interfaced with photoactive protein complexes and conducting materials for photovoltaics, can be utilized via light induced photocurrents. The Photosystem I (PSI) super-complex demonstrates the desired properties of photochemical applications for the enhancement of green renewable energy. PSI has unique structures such as P700 and the FB site, that can accept electrons from a wide range of donors and has a reducing potential near -0.6V vs. SHE (Standard Hydrogen Electrode) respectively. A process that benefits from this phenomenon is the production of PSI-derived biohybrid solar cells. Existing research focuses on integrating PSI in liquid-based electrochemical cells; however, liquid cells tend to suffer from poor portability and solvent loss due to evaporation requiring frequent replacement. Consequently, a gel-base medium, namely agarose, was substituted to address these issues. The benefits included not only that these gel-state devices would be more portable and durable than the liquid mediums, but they would also be organic, inexpensive, and easy to process. Another advantage is that liquid-state devices require three electrodes whilst the gel-sate devices only require two. Four mediators (ferri/ferrocyanide, sodium ascorbate-DCPIP, methyl viologen, and potassium chloride) and four cathodes (copper, aluminum, gold, and p-doped silicon) were examined. This research will incorporate photo-chronoamperometric tests to find best conductive gel for the devices, thus determining which configuration is superlative for optimization into this new field of green renewable energy.- Co-author Journal Publication
J. Passantino, K. Wolfe, K. Simon, D.E. Cliffel, and G.K. Jennings “Photosystem I Enhances the Efficiency of a Natural, Gel-Based Dye-Sensitized Solar Cell”, ACS Applied BioMaterials 3, 7, 4465-4473 (2020) - Conference Presentation
K. Simon, J. Passantino, and G.K. Jennings “Photosystem I Proteins in Gel-State Biohybrid Solar Cells” Conference Presentation 27th Annual CSTEP Statewide Conference, Bolton Landing, NY, April, 2019. (Honorable Mention)
- Co-author Journal Publication
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Jade Stanley - Chemistry, Tuskegee University
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Educational Institution: Tuskegee University
List of Mentors: Dr. David Cliffel & Christopher Stachurski & Dilek Dervishogullari
Program: NSF REU
Research Project: The Modification of Photosystem I with Carbon Nanotubes for Photocurrent GenerationResearch Abstract:
Photosynthesis is the biological process by which plants use visible light to produce chemical energy. Photosystem I (PSI) is one of the two main protein complexes involved in photosynthesis. The process of light absorption excites an electron and shuttles it from the P700 site to the iron cluster, FB. Due to this spatial and energetic transition of this electron, PSI is a prime candidate for implementation in photoeletrochemical cells. Biohybrid solid state and liquid solar cell devices were utilized to generate current from the light absorbed by the protein. Carbon nanotubes (CNTs) are flexible and inexpensive allotropes of carbon that have been used as conductive additives in solar cells. The objective of the experiment was to conjugate PSI proteins to carbon nanotubes and construct a solar-state device that enhances the photocurrent generated from PSI. The use of carbon nanotubes was expected to increase the surface area available for the PSI deposition, which in turn enhances photocurrent production. Devices were prepared using lightly p-doped silicon as a substrate and were tested using photochronoamperometry to measure the produced photocurrent. Devices with PSI conjugated onto carbon nanotubes demonstrated an increase in photocurrent. However, due to inconsistences in the deposition methods, there was a large range in device performance; many devices produced measurably lower currents than others. Future directions will be geared towards improving device fabrication methods or further optimization of the conjugation process.- Conference Presentations
-J. Stanley, D. Dervishogullari, C. Stachurski, K. Wolfe, G.K. Jennings, and D.E. Cliffel “The Modification of Photosystem I with Carbon Nanotubes for Photocurrent Generation” The Southern Regional Meeting of the American Chemical Society, Augusta, GA, October 2018.
-J. Stanley, D. Dervishogullari, C. Stachurski, K. Wolfe, G.K. Jennings, and D.E. Cliffel “The Modification of Photosystem I with Carbon Nanotubes for Photocurrent Generation” National Association of African American Honors Program Conference, Concord, NC, November 2018.
-J. Stanley, D. Dervishogullari, C. Stachurski, K. Wolfe, G.K. Jennings, and D.E. Cliffel “The Modification of Photosystem I with Carbon Nanotubes for Photocurrent Generation” Emerging Researchers National Conference, Washington, DC, March, 2019.
-J. Stanley, D. Dervishogullari, C. Stachurski, K. Wolfe, G.K. Jennings, and D.E. Cliffel “The Modification of Photosystem I with Carbon Nanotubes for Photocurrent Generation” Joint LSAMP/S-STEM Conference, Tuskegee, AL, April, 2019. - Jade was awarded Best Layout at the capstone poster session.
- Conference Presentations
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Joseph Veglak - Chemical Engineering, Rose-Hulman Institute of Technology
Educational Institution: Rose-Hulman Institute of Technology
List of Mentors: Dr. Janet Macdonald & Jordan Rhodes
Program: NSF REU
Research Project: Nickel Sulfide Nanocrystal Synthesis Using Substituted ThiophenolsResearch Abstract:
Different phases and morphologies can largely effect the catalytic abilities of nickel sulfide nanocrystals. While nickel sulfides contain an abundance of different phases, phase control of these crystals can be difficult. One proposed method of selectively isolating these phases involves manipulating the sulfur reagent used, where the electron donating ability of substituent groups influences the reactivity of the sulfur precursor. Para-substituted thiophenols were used as the sulfur for this work. We have observed a phase change in this reaction: as the electron donating abilities of the substituted group increases, the oxidation number of nickel decreases, creating a different phase whose preliminary results suggest slightly different catalytic abilities. Nickel Sulfides have shown potential as catalysts, and in the future, we look to further test and enhance the particles catalytic abilities and test to see if the ligands on the particles are surface or crystal bound.- Conference Presentation
J. Veglak, J. Rhodes, and J. Macdonald “Nickel sulfide nanocrystal synthesis using substituted thiophenols,” ACS Annual Conference, Orlando, FL, April, 2019. - Joe was awarded a $1K travel grant at the capstone poster session.
- Conference Presentation
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2017
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Bridget Anger - Chemical Engineering, University of Maryland, Baltimore County
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Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Kane Jennings & Max Robinson
Program: NSF REU
Research Project: Efficient Charge Separation in Composite Photosystem I/PEDOT Photocathodes Prepared by Vapor Phase Polymerization
Research Abstract:
Photosystem I (PSI) is a stable, abundant, and highly efficient photocatalytic protein that is found in photosynthetic organisms and has been utilized in solar cells and hydrogen fuel cells. This project incorporates an electrically conductive polymer, poly (3,4-ethylenedioxythiophene) (PEDOT), in a PSI:PEDOT composite film, developed through vapor phase polymerization. Introducing conductive PEDOT into the film facilitates highly directional electron transfer when used in a solar cell with electrolyte solution. When a PSI:PEDOT composite film on a gold electrode is paired with a methyl viologen mediator and electrolyte solution, photocurrents of 1.35μA/cm2 have been recorded. In an effort to improve charge separation and increase photocurrent, we performed tests with anion exchange of ferri/ferrocyanide ions in the composite films, but the experimental data showed that films with anion exchange produced ~0.612 μA/cm2, which was less than half of the photocurrent recorded with films that had no anion exchange. While we had initially thought that cycling in the redox ions would make a more energetically favorable path for the electrons, we now believe that the incorporation of these ions decreases the charge transfer efficiency. Moving forward, we then developed a solar device composed of a dye-sensitized mesoporous TiO2 anode and a PSI:PEDOT composite photocathode which produced anodic photocurrents around 100 μA/cm2. When this device was tested with different concentrations of PSI and a control with only PEDOT, there was a strong correlation with higher concentrations of PSI resulting in higher photocurrent.- Conference Presentation
-B. Anger, M.T. Robinson, D.E. Cliffel, and G.K. Jennings “Efficient Charge Separation in Composite Photosystem I/PEDOT Photocathodes Prepared by Vapor Phase Polymerization” NCUR (National Conference on Undergraduate Research) Annual Meeting, Edmond, OK, April, 2018.
-B. Anger, M.T. Robinson, D.E. Cliffel, and G.K. Jennings “Efficient Charge Separation in Composite Photosystem I/PEDOT Photocathodes Prepared by Vapor Phase Polymerization” UMBC Meyerhoff Selection Weekend, Baltimore, MD, February, 2018 - Bridget was awarded a $1K travel grant at the capstone poster session.
- Conference Presentation
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Mariah Arral - Chemical Engineering, University of New Hampshire
Educational Institution: University of New Hampshire
List of Mentors: Dr. Scott Guelcher & Tom Spoonmore
Program: NSF REU
Research Project: Characterization ofS. AureusGrowth and ToleranceDevelopmentin 2D and 3D in vitroModels
Research Abstract:
Staphylococcus aureus is a common bacteria that can infect fractures and cause serious bacterial infections. Chronic infections can be attributed to the presence of bacterial cell communities that are tolerant to clinically relevant treatment. These communities can be defined as biofilms and are relate to 80% of human infections. The goal of our experiments is to understand if and when tolerance develops to treatment of vancomycin and rifampin on 2D and 3D convex substrates in a novel in vitro biofilm model. Along with tolerance we will examine how S. Aureus strain UAMS-1 grows on 2D and 3D convex surfaces over time. A second goal of our project is to characterize the ability of vancomycin and rifampin to eradicate infection when delivered through polyurethane foam carriers. From our experiments, we were able to conclude that regardless of seeding density and geometry bacterial cell communities grow to similar surface densities (LOG[CFU/cm 2 ]) after 24 hr. Vancomycin and rifampin tolerance studies proved that tolerant bacterial cell communities existed on the substrate surface following 24 hours of bacterial cell growth. We believe these tolerant cell communities to be biofilms based off the tolerant phenotype when exposed to vancomycin at concentrations up to 100 μg/mL. Interestingly, bacterial growth on 3D convex surface was found to have slower kinetic development of tolerance than bacterial infection on 2D surfaces, while the surface density of cells was determined to be similar. Finally, delivery of vancomycin and rifampin through polyurethane foams proved to inhibit bacterial growth on both the 2D substrate and the scaffold surface when delivered concurrently with inoculation. However, foams loaded with vancomycin or rifampin were unable to eradicate tolerant infections at 24 hours. Foams loaded with rifampin also became a nidus for infection when delivered to tolerant bacterial communities at 24 hours. Interestingly, foams loaded with 6 wt% vancomycin were able to inhibit the bacterial infection from spreading to the scaffold at 0, 6, and 24 hours, suggesting the ability to prevent biofilm cells from spreading to the scaffold surface.- Mariah was awarded a NSF Graduate Research Fellowship in 2018
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Timothy Bernard - Mechanical Engineering, University of Maryland, Baltimore County
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Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Leon Bellan & Brian O'Grady
Program: NSF REU
Research Project: Retrofitting a Commercial 3D Printer for Bioprinting Capabilities
Research Abstract:
In order to create Lower Critical Solution Temperature (LCST) polymer frameworks with complicated 3D structures, we present a low-cost hardware and software adaptation for a commercial dual extrusion 3D printer. The modified printer uses the two existing thermoplastic extruders and adds a third pressure extruder with a blunt needle to extrude biocompatible materials. In addition, the software revises the conventional G-Code instructions for the triple-extrusion process. This allows for three separate materials (including one biomaterial) to be printed on the same layer.- Conference Presentation
T. Bernard, A. Greenberg, B. O’Grady, and L. Bellan “Retrofitting a Commercial 3D Printer for Bioprinting Capabilities” UMBC Meyerhoff Selection Weekend, Baltimore, MD, February, 2018. - Tim was named a Meyerhoff Scholar
- Conference Presentation
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Michael Davies - Physics/Mechanical Engineering, Fisk University
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Educational Institution: Fisk University
List of Mentors: Dr. Doug Adams & Cole Brubaker
Program: NSF REU
Research Project: Damage Detection In 3D Printed Parts Using Optical Properties of Gold Nanoparticles
Research Abstract:
Gold nanoparticles (AuNPs) are a nanomaterial that possess unique optical properties that can be used in many applications as a sensing material. The Adams lab has developed another application for these AuNPs in the form of defect detection for 3D printed parts. AuNPs were synthesized and incorporated within polylactic acid (PLA) which was then 3D printed into various geometries (primarily a square and rectangular shape) with a varying number of print layers. These 3D structures were then tested to identify if the varying number of print layers had an impact on the absorbance of light of the materiel. It was determined that pure PLA (PLA without the AuNPs) saw no change in the absorbance of the material in the visible range regardless of the number of print layers. However, PLA with AuNPs showed a linear trend in absorbance based on the number of print layers in the 3D printed structure. Using this trend, we were able to successfully identify and quantify the number of missing print layers and material defects in 3D printed structures based on the optical response of AuNPs alone.- Co-author Journal Publication
C.D. Brubaker, M.A. Davies, J.R. McBride, S.J. Rosenthal, G.K. Jennings, and D.E. Adams, “Nondestructive Evaluation and Detection of Defects in 3D Printed Materials Using the Optical Properties of Gold Nanoparticles”, ACS Applied Nano Materials, 1 (3), 1377-1384 (2018). - Conference Presentations
-M. Davies, C. Brubaker, and D. Adams “Damage Detection in 3D Printed Parts Using Optical Properties of Gold Nanoparticles” Vanderbilt University Summer Undergraduate Research Fair, Nashville, TN, September, 2017. *poster winner
-M. Davies, C. Brubaker, and D. Adams “Damage Detection in 3D Printed Parts Using Optical Properties of Gold Nanoparticles” VINSE Open House & Ribbon Cutting Ceremony, Nashville, TN, October, 2017.
-M. Davies, C. Brubaker, and D. Adams “Damage Detection in 3D Printed Parts Using Optical Properties of Gold Nanoparticles” 15 th Annual Tennessee Louis Stokes Alliance for Minority Participation Undergraduate Research Conference, Chattanooga, TN, February, 2018. *poster winner
-M. Davies, C. Brubaker, and D. Adams “Damage Detection in 3D Printed Parts Using Optical Properties of Gold Nanoparticles” Fisk Annual Research Symposium, Nashville, TN April, 2018. *poster winner - Davies received a Department of Defense SMART Scholarship in 2018
- Co-author Journal Publication
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Jenna Dombroski - Biomedical Engineering, SUNY College at Buffalo
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Educational Institution: SUNY College
List of Mentors: Dr. Qi Zhang & Kristina Kitko
Program: NSF REU
Research Project: Quantum dot-enabled tracking of single synaptic vesicle protein Synaptotagmin-1 in live neurons
Research Abstract:
Synaptotagmin-1 (Syt-1) is a prominent synaptic vesicle protein and one of the Ca2+ sensors that triggers neurotransmitter release. Given the heterogeneity of the synaptic vesicle population and the associated variation of Ca2+ sensors, it is informative to study the distribution and mobility of individual Syt1-containing vesicles within live neurons. Quantum dots (Qdots), a.k.a. photo-luminescent semiconductor nanocrystals, possess superior optical properties ideal for single vesicle tracking. Their high quantum efficiency leads to a large signal-to-noise ratio and their photostability enables long-term tracking. Qdots were randomly tagged to single vesicular Syt-1 in live neurons via a highly selective monoclonal antibody; stimulation-induced synaptic vesicle turnover. After labeling, continuous fluorescence imaging of single Qdots was performed while neurons were continuously stimulated to induce vesicle release. Image stacks were processed in FIJI and single Qdot tracking trajectories were generated using the TrackMate plug-in.We observed significant differences (>20%) between diffusion coefficients for stimulation vs. non-stimulation using antibody-conjugated Qdots. However, there was only a 6% difference in the mean diffusion coefficients between stimulation and another control - non-specifically uptaken Qdots. Looking further into this discrepancy, we noted that there was also a significant loss of Qdots over time during field stimulation (40%). Although the effect of activity is an important cornerstone of understanding vesicle mobility, results throughout the literature remain inconsistent. Given this information, we propose that a possible explanation for the discrepancies among the literature is that when vesicles release during field stimulation, Qdots are washed away after dissociating from the antibody in the acidic vesicular environment. Future research directions involve combining Qdot imaging with dyes to specifically label synaptic vesicles, but this information holds the potential to impact the validity of results from previous findings using field stimulation.
- Jenna was awarded a NSF Graduate Research Fellowship in 2020
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Jennifer Donohue - Mechanical Engineering, SUNY Binghamton University
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Educational Institution: SUNY Binghamton University
List of Mentors: Dr. Cary Pint & Kathleen Moyer
Program: NSF REU
Research Project: High Power alternative-ion batteries via co-intercalation
Research Abstract:
The rate-limiting de-solvation step required for graphitic intercalation of alkali ions has limited the use of modern batteries in high-power technologies like grid-energy storage and electric vehicles. The co-intercalation phenomenon observed in the presence of linear ethers allows for high-power devices through co-solvate intercalation, which effectively eliminates the rate-limiting de-solvation step. This phenomenon is observed not only with conventional lithium chemistries but also with alternative ion chemistries which promise reduced battery fabrication cost. Herein, we demonstrate high-rate potassium and sodium co-intercalation into graphite with specific capacities >100mAh/g at 5A/g. Prussian blue was also investigated as a high rate cathode and in its sodiated form showed specific capacities >100mAh/g at 10C. These results prove the viability of alternative-ion co-intercalation based batteries for use in low-cost high-power applications."- Co-author Journal Publications
-K. Moyer, J. Donohue, N. Ramanna, A. P. Cohn, N. Muralidharan, J. Eaves and C. L. Pint, "High-rate potassium ion and sodium ion batteries by co-intercalation anodes and open framework cathodes," Nanoscale, 10, 13335-13342 (2018).
-A. Cohn, T. Metke, J. Donohue, N. Muralidharan, K. Share, and C.L. Pint “Rethinking Na-Ion Anodes as Nucleation Layers for Anode-Free Sodium Batteries” Journal of Materials Chemistry A, 6, 46, 23875-23884 (2018). - Conference Presentation
J. Donohue, K. Moyer, A.P. Cohn, and C. Pint “High-power alternative-ion batteries via co-intercalation”, 2018 MRS Spring Meeting & Exhibit, Phoenix, AZ, April, 2018. - Jennifer was awarded a $1K travel grant at the capstone poster session.
- Jennifer was awarded a Department of Defense National Defense Science and Engineering Graduate Fellowship.
- Co-author Journal Publications
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Crystal Nattoo - Electrical Engineering, University of Miami
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Educational Institution: University of Miami
List of Mentors: Dr. Sharon Weiss & Tengfei Cao
Program: NSF REU
Research Project: Porous Silicon on Glass for Low-Cost Diagnostics
Research Abstract:
In the search for approaches to improve medical diagnostics around the globe, the World Health Organization created the ASSURED criteria: Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Delivered to those who need it. Smartphone based lab-on-a-chip systems have the potential to satisfy the ASSURED criteria because of the widespread availability of smartphones, even in low resource environments. In this work, we report on the fabrication and characterization of a new type of optical transducers for a smartphone based lab-on-a-chip system using porous silicon thin films (PSiTF). The performance of the PSiTF sensor is evaluated on different substrates with both smartphones and traditional spectrometers. Porous silicon was selected because it is a versatile material with large specific area, easy surface modification, high optical quality and low fabrication cost, which makes it a promising candidate for multi-analyte detection in our system. Preliminary sensing results based on detection of different concentrations of glucose showed that a glass-PSiTF-paper sandwiched structure exhibits reproducible optical performance in a flow-cell setting using both smartphone and spectrometer detection schemes. In the smartphone detection scheme, image processing is performed on pictures taken of the sample under test to determine color changes that result from the introduction of analyte. In the spectrometer detection scheme, reflectance spectra shifts track the introduction of analyte. Future work will focus on correlation of the smartphone and spectrometer results to benchmark detection sensitivity using the smartphone. The demonstrated glass-PSiTF-paper system has strong promise for enabling smartphone based lab-on-a-chip systems to achieve ASSURED criteria for a variety of diagnostic applications.- Co-author Journal Publication
T. T. Cao, Y. Zhao, C. Nattoo, M.H. Choudhury, and S.M. Weiss, “A Smartphone biosensor based on analysing structural colour of porous silicon,” Analyst,14 (13), 3942-3948 (2019). - Conference Presentation
T. Cao, Y. Zhao, C. A. Nattoo, and S. M. Weiss, “A Smartphone Biosensor based on a Colormetric Analysis of Porous Silicon Filters,” Porous Semiconductors Science and Technology, La Grande Motte, France, March, 2018. - Crystal was awarded Best Layout at the capstone poster session.
- Crystal was awarded a NSF Graduate Research Fellowship
- Co-author Journal Publication
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Alexandra Quinones Melendez - Chemical Engineering, University of Puerto Rico
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Educational Institution: University of Puerto Rico
List of Mentors: Dr. David Cliffel & Christopher Stachurski, Dilek Dervishogullari
Program: NSF REU
Research Project: Oriented Interface of PSI and PSII for Solar Driven Hydrogen Evolution
Research Abstract:
In response to a growing demand for alternative energy sources, many researchers consider hydrogen fuel as a strong contender for an emissions-free and sustainable energy source. Yet current methods for hydrogen fuel production can require expensive resources or elaborate designs to function properly. Alternatively, there are a number of naturally occurring enzymatic processes with similar outcomes which could be utilized for fuel production. Photosystem I (PSI) and Photosystem II (PSII), which are the two key proteins in photosynthesis, are capable of acting in series in order to split water into hydrogen and oxygen. Our aim is to systematically functionalize both proteins allowing for their oriented assembly on a common conductive substrate, which would allow PSI and PSII to work in tandem . This work establishes a strategy to effectively short-circuit the photosynthetic pathway to sustainably generate hydrogen from sunlight in a self-contained device.- Alexandra was awarded Best Use of Graphics at the capstone poster session.
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Sarah Ruiz - Physics, Grinnell College
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Educational Institution: Grinnell College
List of Mentors: Dr. Jason Valentine & Zack Coppens
Program: NSF REU
Research Project: Graphene Processing for tunable MetasurfacesResearch Abstract:
Metamaterials enable optical properties that cannot be found in nature. Graphene has increasingly become an important component in some metamaterials due to its two-dimensional structure and potential for tunable applications. Through the use of graphene intercalation, we seek to create a tunable perfect absorber metamaterial that can be used for low power visible displays. A design for this metasurface has been developed; however, graphene processing and characterization for the design have not been fully explored. Here, we study exfoliation techniques and etch rates of graphene for fabrication of the metasurface. We characterized the etch rate for both aluminum and graphene using atomic force microscopy (AFM) to measure the step heights of graphene flakes. We found that aluminum and graphene etch at approximately the same rate of 0.8 nm/minute because of the low surface binding energy of aluminum and graphene relative to the kinetic energy of the incoming argon ions. -
Mitchell Stokan - Chemical Engineering, University of Kentucky
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Educational Institution: University of Kentucky
List of Mentors: Dr. Craig Duvall & Dr. Meredith Jackson & Sean Bedingfield
Program: NSF REU
Research Project: Screening of Novel Hydrophobically Modified Triblock Copolymers for Improved Stabilization of siRNA Polyplexes
Research Abstract:
Our lab has shown that diblock polymer-based siRNA nano-polyplexes (si-NPs), containing zwitterionic phosphorylcholine (PMPC) as the corona and a copolymer of dimethylamino ethyl methacrylate (DMAEMA), and butyl methacrylate (BMA) as the core, function as efficient vectors for siRNA delivery. These polymers possess several desirable properties including lack of toxicity, pH dependent endosomal escape, long circulation half-lives, and high levels of tumor cell uptake and silencing activity. Here, we hypothesized that a third, hydrophobic block of polypropylene sulfide (PPS), would yield si-NPs with higher stability and biocompatibility due to added hydrophobicity and core stabilization. The polyplexes were analyzed using ribogreen, luciferase, hemolysis, and fluorescence resonance energy transfer (FRET) assays to test for siRNA encapsulation, knockdown, endosomal escape, and stability respectively. The size of the nanoparticles formed were assessed using dynamic light scattering techniques by the Malvern Zetasizer. The polyplexes were tested at different N:P ratios and with or without palmitic acid hydrophobized siRNA-conjugates. Overall, the use of the polyphenylene sulfide block helped improve the encapsulation properties of the polymers and allowed for a higher efficiency in delivering the siRNA for gene knockdown. With improved stability, the polymers could be readily used for circulation in the body with less of an effect on their performance. These factors contribute to a better gene delivery system that allows for more success in drug delivery.- Co-author Journal Publication
M. A. Jackson, S. K. Bedingfield, F. Yu, M. E. Stokan, R. E. Miles, E. J. Curvino, E. N. Hoggenboezem, R. H. Bonami, S. S. Pate, P. L. Kendall, T. D. Giorgio, and C. L. Duvall, “Dual carrier-cargo hydrophobization and charge ratio optimization improve the systemic circulation and safety of zwitterionic nano-polyplexes,” Biomaterials, 192, 245-259 (2019). - Conference Presentation
M. Stokan, M. Jackson, S. Bedingfield, T. Werfel, and C. Duvall “Screening of Novel Hydrophobically Modified Triblock Copolymers for Improved Stabilization of siRNA Polyplexes” Society for Biomaterials Symposium, Atlanta, GA, April, 2018. - Mitchell was awarded a $1K travel grant at the capstone poster session.
- Co-author Journal Publication
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Donna Xia - Chemical and Biomolecular Engineering, University of Alabama, Tuscaloosa
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Educational Institution: University of Alabama, Tuscaloosa
List of Mentors: Dr. Clare McCabe & Tim Moore
Program: NSF REU
Research Project: Self-Assembly of Stratum Corneum Lipid Bilayers Via Coarse-Grained Simulations
Research Abstract:
The skin barrier function is localized to the lipid lamellae of the stratum corneum (SC), which is composed of ceramides (CER), cholesterol (CHOL), and free fatty acids (FFA). While this lipid composition is well-known, limited experimental resolution makes it difficult to uncover the molecular-level details of its organization. In this regard, molecular dynamics simulations offer atomic-level resolution, and can be used to study the effects of lipid composition on structural properties of SC lipid lamellae. However, the slow dynamics mean that systems are heavily influenced by their initial configurations. To bypass this effect, self-assembled structures are desirable. To reduce computational cost and allow self-assembly to be simulated, simplified coarse-grained models are used instead of their more detailed atomistic counterparts. In this study, different lipid compositions were self-assembled into bilayers, and structural properties, such as area per lipid, tilt angle, nematic order parameter, and lipid density profiles across the bilayers were examined. These properties were then compared across compositions to investigate the effects of lipid composition on bilayer structural properties.- Co-author Journal Publication
T.C. Moore, D. Xia, C.R. Iacovella, and C. McCabe, “A Course-grained Model of the SPP Structure of Stratum Corneum Lipids” Journal of the Physical Chemistry B, manuscript in preparation - Conference Presentation
T. C. Moore, D. Xia, A. C. Leonhard, C. R. Iacovella, R. Hartkamp, A. L. Bunge, C. McCabe, “Self-Assembly Simulations of Stratum Corneum Lipid Mixtures,” AIChE Annual Meeting, Minneapolis, November, 2017. - Donna was awarded a 2018 Goldwater Scholarship
- Co-author Journal Publication
![REU2016VVINSE REU2016VVINSE](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/31155312/REU2016VVINSE.png)
2016
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Louis Apraku-Boadi - Chemistry, University of West Georgia
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Educational Institution: University of West Georgia
List of Mentors: Dr. Janet Macdonald & Evan Robinson
Program: NSF REU
Research Project: Cu2S Nanocrystals as Signal Amplifiers for Biomolecule Detection
Research Abstract:
The research concerning nanomaterials is a growing and interesting field of study. They have applications in targeted drug delivery, photovoltaics, and, as is the case in this study, diagnostics. A recently developed method in our lab allows the production of highly stable crystal-bound Cu2S nanocrystals. Unlike the more ubiquitous surface-bound ligands, crystal-bound ligands are integrated in high coordination number sites – greatly enhancing Cu2S nanocrystal stability. Cu2S crystals, though small, contain thousands of individual Cu atoms. Using various chromogenic copper chelators, this fact can be exploited and used in biochemical and biological assays. One such chelator is cuprizone, which forms a chromogenic bidentate complex with Cu that has an intense and characteristic absorption band. This provides an effective means of detecting Cu at M concentrations. Here we assess the stability of crystal-bound nanoparticles and the viability of the copper-cuprizone complex as a reporter. -
Clayton Blythe - Physics/Economics, Central College of Iowa
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Educational Institution: Central College of Iowa
List of Mentors: Dr. Kalman Varga & Jorge Salas
Program: NSF REU
Research Project: Simulation of High Harmonic Generation in Helium due to Bichromatic Counterrotating Circularly Polarized Laser Fields
Research Abstract:
Attoscience is an important emerging area of research in modern atomic and molecular physics. In many electron-atom systems that are excited by femtosecond lasers, the recombination of an electron from the continuum occurs on the order of attoseconds. Precision on the sub-femtosecond and sub-angstrom scale will be necessary to probe the intricacies of light-matter interactions. High Harmonic Generation (HHG) is a technique that is growing in popularity for exploring these interactions. Harmonics with much higher frequencies and energies can be produced with various ellipticities. In this work, we present 3D Time Dependent Schroedinger Equation (TDSE) simulations combined with Time Dependent Density Functional Theory (TDDFT) for HHG in Helium. In this specific application, bichromatic counterrotating circularly polarized laser fields are employed, experimenting with various intensities, wavelengths, and pulse shapes. A circularly polarized fundamental is combined with its counterrotating second harmonic. The time-dependent electric field describes a Lissajous figure with threefold spatio-temporal symmetry resembling a clover. Dipole moment, ionization, and sensitivity to rotational symmetries are calculated, as well Fourier transformations employed to examine the intensity and ellipticity of emitted harmonics. Harmonics such as these with attosecond pulse lengths have potential applications in molecular and atomic chemistry such as photo-electron circular dichroism and x-ray magnetic circular dichroism. -
Adam Boyer - Chemistry, Emporia State University
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Educational Institution: Emporia State University
List of Mentors: Dr. David Cliffel & Evan Gizzie
Program: NSF REU
Research Project: Controlling the Orientation of Photosynthetic Protein Assembly on Solid Surfaces: a Strategy for Improving Bio-derived Solar Cells
Research Abstract:
Current methods of harnessing energy have led to severe environmental impacts and necessitated the development of more conscientious methods, specifically solar cell conversion. Solar cell technology has attained efficiencies nearing 20% and is limited by high costs for processing silicon. One solution to this growing problem is implementing bio-derived solar cells with the photosynthetic protein, Photosystem I (PSI). Bio-derived solar cells provide remarkably clean energy production and utilizing Photosystem I affords a substantial supply of low cost material. Photosystem I acts as a pseudo-photodiode efficiently exciting electrons, and shuttling them unidirectionally through the protein; thus creating charge separation. However, harvesting the protein for solar cells leads to a mixed protein orientation on the solar cell surface. In order to maximize current flow, it is imperative that the orientation of PSI on a surface is controlled uniformly. In this work, Photosystem I was selectively modified with 2-iminothiolane during the extraction from spinach leaves while still thylakoid membrane bound. Following purification, modified PSI was allowed to self-assemble onto gold surfaces via high-affinity gold-thiol interactions. Once self-assembled onto the gold surface, photoelectrochemical analyses and highly resolved topography mapping techniques (i.e. Scanning Tunneling Microscopy) were utilized to investigate the photocurrent production under illumination and orientation of Photosystem I on the gold surface. Future applications of this exciting research includes considerable advances in bio-sensors and bio-technologies. -
Timera Brown - Biology, Tougaloo College
Educational Institution: Tugaloo College
List of Mentors: Dr. Eva Harth & Dian Beezer
Program: NSF REU
Research Project: Regenerative Medicine: Synthesis of Functionalized Polyglycidol Building Blocks for Diverse Network
Research Abstract:
Currently, a main focus of regenerative medicine is limited to embryonic stem cells as well as in vitro cell maturation. However, a more diverse approach using network forming materials is emerging as an innovative concept. Regenerative medicine is an interdisciplinary field of biomechanics which is geared toward the bioengineering and implementation of human cells, tissue, and/or organs in order to restore expected function. For example, currently in many knee operations where cartilage must be replaced, cartilage must be extracted and manipulated from cadavers or either grown from chondrocytes before being inserted into the patient. However, as an alternative to the delicate and time-consuming process of cartilage extraction and growth, this cartilage can be engineered through via polymeric networks. My project centers on acrylate-polyglycidol functionalization which due to the compound’s reactivity could combine with other materials and networks to lead to a robust polymer network with tunable crosslinking. This tunable amount of crosslinking could lead to the engineering of scaffolds of multiple sizes that could mimic not only cartilage tissue but potential other tissues such as dermal, bladder and liver tissues.- Conference Presentations
-T. Brown, D.B. Beezer, and E.M. Harth “Regenerative Medicine: Synthesis of Functionalized Polyglycidol Building Blocks for Diverse Networks” Kincheloe Society Symposium, Tougaloo, MS, October, 2016.
-T. Brown, D.B. Beezer, and E.M. Harth “Regenerative Medicine: Synthesis of Functionalized Polyglycidol Building Blocks for Diverse Networks” Annual Biomedical Research Conference for Minority Students, Tampa, FL, November, 2016.
- Conference Presentations
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Kaleigh Ellis - Chemistry, Saint Mary's College
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Educational Institution: Saint Mary's College
List of Mentors: Dr. Sandra Rosenthal & Kemar Reid
Program: NSF REU
Research Project: Engineering CdSSe-CdS Core/Shell Quantum Dots for Use in Single-Protein Imaging
Research Abstract:
Semiconductor nanocrystals, or quantum dots (QDs), play an important role in in vivo single-protein imaging due to their size-tunable optical properties. However, the synthesis of QDs that are ideal for biological imaging - namely that they have a narrow size distribution, retain high quantum yields (QYs), and are photostable - is difficult due to interior and surface-related defects, including the interaction of the electron-hole pair with the QD’s environment. By growing an inorganic shell onto the QD to passivate the QD the QY and photostability can be increased. The goal of this research is to optimize the QY and stability of alloyed CdSSe QDs by growing a CdS shell onto the alloyed cores and to study their photoluminescence and structural properties using fluorimetry and transmission electron microscopy (TEM), respectively. Two shell growth methods are explored: one using successive ion layer adsorption and reaction (SILAR) techniques with cadmium(II)-oleate and sulfur precursors to grow successive monolayers of CdS shell, and a second continuous infusion method in which Cd(II)-oleate and octanethiol are infused slowly over the course of the shell-growth process. Initial results indicate that the continuous infusion method is the preferred procedure, producing higher quantum yields and a narrow size distribution while also requiring less reaction time than the SILAR method. These brighter and more size-uniform CdS-shelled QDs have the potential to revolutionize the use of QDs in in vivo single-protein imaging.- Conference Presentations
-K. Ellis, K.R. Reid, and S.J. Rosenthal “Engineering CdSSe/CdS Core/Shell Quantum Dots for Use in Single-Protein Imaging” 10th Year Undergraduate Engineering Research Symposium, Notre Dame, IN, September, 2016.
-K. Ellis, K.R. Reid, and S.J. Rosenthal “Engineering CdSSe/CdS Core/Shell Quantum Dots for Use in Single-Protein Imaging” Women Chemist’s Symposium Senior Comprehensive Presentation, Notre Dame, IN, March, 2017. - Kaleigh was awarded Best Use of Graphics at the capstone poster session.
- Conference Presentations
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Yasmin Graham - Mechanical Engineering, University of Maryland, Baltimore County
Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Sharon Weiss & Yiliang Zhou
Program: NSF REU
Research Project: Low Cost Portable Biosensors Made From Porous Silicon Annular Bragg ResonatorsResearch Abstract:
Point of care testing is a form of medical diagnostic testing which takes place at a patient’s bedside or directly at an active site. Our research is aimed at creating low cost, low power, high quality, portable biosensors that enable color-based detection and can be easily integrated with mobile devices such as a smartphones. The biosensing platform explored in this work is an annular Bragg resonator (ABR) on a porous silicon (PSi) substrate. ABRs are radially symmetric structures that possess a discrete refractive index profile that creates a cavity region surrounded by highly reflecting mirrors. These structures have been traditionally used to resonantly enhance the emission of fluorescent molecules incorporated in the cavity region. PSi, a nanostructured material formed by electrochemical etching of a silicon substrate, possesses a large surface area which is highly advantageous for capturing large quantities of molecular species inside the pores. To form a colorimetric biosensor, colloidal AgInS2/ZnS quantum dots (QDs) are infiltrated into PSi ABRs; the ABR modifies the QD emission, leading to a structure with a relatively narrow and distinct fluorescence spectrum. Since the QDs only cover a portion of the internal pore surface area, the remainder of the pore surface is available to selectively capture desired target molecules when appropriately functionalized. Target molecule binding in the pores modifies the ABR resonance wavelength and consequently shifts the peak emission wavelength of the embedded QDs. Hence, molecular binding events lead to a biosensor color change. The QDs embedded in PSi ABRs were excited with a 532 nm laser and the fluorescence emission was collected with a Raman microscope equipped with a 100x objective lens. An 8-fold enhancement of the peak QD intensity was measured when the QDs were embedded in a PSi ABRs compared to a planar PSi film. A preliminary experiment to detect 5 µM of Catalase protein caused a 30nm average shift of the QD photoluminescence peak which indicates that this platform has the potential to achieve highly sensitive biosensing.- Co-author Journal Publication
Y. Zhao, G. A. Rodriguez, Y. M. Graham, T. Cao, G. Gaur, and S. M. Weiss, “Resonant photonic structure in porous silicon for biosensing,” Proc. of SPIE 10081, 100810D (2017). - Conference Presentation
Y.M. Graham, Y. Zhao, G. Gaur, and S.M. Weiss, “Low Cost Portable Biosensors Made From Porous Silicon Annular Bragg Resonators” REU Symposium 2016, Arlington, VA, October, 2016. - Yasmin was awarded a $1K travel grant at the capstone poster session.
- Co-author Journal Publication
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Marne Helbing - Engineering, University of Tennessee, Martin
Educational Institution: University of Tennessee, Martin
List of Mentors: Dr. Florence Sanchez & Yonathan Reches
Program: NSF REU
Research Project: Reactivity of Nano-Particles in Cementitious SystemsResearch Abstract:
Nano-particles (NP’s) have been studied as additives for improving the mechanical and durability properties of cement-based materials. The contributions of NP’s to the cement system have been attributed to their high surface area to volume ratio, although the specific chemical interactions between NP’s and the cementitious system have yet to be defined. The intrinsic and catalytic reactivity of NP’s in cement-based systems were studied, including the effect of cement chemistry on the agglomeration of NP’s. NP’s were reacted with real and simulated cement systems, and their reaction products were characterized chemically and microstructurally. The effects of cement on the surface charge and agglomerate size of the NP’s were simulated using salt solutions and observed by dynamic light scattering (DLS). It was demonstrated that for the nano-TiO the nano-particles agglomerated to approximately 102 NP’s/agglomerate. Agglomeration further increased due to the effects of the ions in the salt solutions.- Co-author Journal Publication
Y. Reches, K. Thomson, M. Helbing, D.S. Kosson, and F. Sanchez “Agglomeration and reactivity of nanoparticles of SiO2, TiO2, Al2O3, Fe203, and clays in cement pastes and effects on compressive strength at ambient and elevated temperatures” Construction and Building Materials, 167, 860-873, (2018).
- Co-author Journal Publication
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Eion Hindsman-Curry - Applied Physics/Mechanical Engineering, Morehouse College
Educational Institution: Morehouse College
List of Mentors: Dr. Richard Haglund & Claire Marvinney
Program: NSF REU
Research Project: Enhanced Porosity and Exciton-Phonon Coupling in Zinc Oxide NanopopcornResearch Abstract:
Semiconductor zinc oxide (ZnO) nanostructures are acclaimed as efficient optoelectronic materials and stable light emitters at room temperature. Zinc oxide features a wide bandgap (3.37 eV) and a stable exciton (Ebinding=60 meV), and nanostructured ZnO used for various applications such as gas sensors, photocatalysts, nanolasers, etc. [1] A novel ZnO nanostructure, christened “nanopopcorn”, has been fabricated by a modified vapor solid method, evaporating Zn in a chamber at a temperature of 700°C to bond with O2 gas on a GaN substrate. The free-form crystalline structure has a high porosity, among other attributes, making it ideal for biological and molecular sensing. Zinc oxide nanopopcorn displays an enhanced surface area to volume ratio compared to planar and one-dimensional nanostructures and has multiple distinct exciton binding peaks. Using image analysis on select samples, a consistent surface area to volume ratio is observed of about 0.023:1 nm-1. This ratio is enhanced over that of ZnO nanowires, a commonly used nanostructure for optoelectronics and sensing applications. The higher surface area creates more bonding sites with the surrounding material, making ZnO nanopopcorn useful for optoelectronic enhancement techniques such as exciton-phonon and exciton-plasmon interactions. The exciton-phonon coupling and the exciton-plasmon coupling create novel vibrational and optical modes, respectively. Studying these fundamental properties will help us to fully characterize the physical and electronic properties of this novel material. Given these properties, ZnO nanopopcorn may be an ideal sensor for many medical and biological applications such as cancer cell detection [3] and electrochemical glucose sensing [4].1. Wang, X., Liu, W., Liu, J., Wang, .F, Kong, J., Qiu, S., He, C. and Luan, L. “Synthesis of Nestlike ZnO Hierarchically Porous Structures and Analysis of Their Gas Sensing Properties” Applied Materials and Interfaces, 4, 817-825 (2012).
2. Politi, J., Rea, I., Dardano, P., De Stefano, L. and Gioffre, M. “Versatile synthesis of ZnO nanowires for quantitative optical sensing of molecular biorecognition” Sensors and Actuators B: Chemical, 220, 705-711 (2015).
3. Sudhagar, S., Sathya, S., Pandian, K. and Lakshmi, B. “Targeting and sensing cancer cells with ZnO nanoprobes in vitro” 33, 1891-1896 (2011).
4. Ali, S. “Fabrication and characterization of ZnO nanostructures for sensing and photonic device applications” Linköping Studies in Science and Technology Dissertation No. 1412, (2011). -
Tao Hong - Engineering Science, CUNY Queensborough Community College
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Educational Institution: CUNY Queensborough Community College
List of Mentors: Dr. Deyu Li & Lije Yang
Program: NSF REU
Research Project: A Microfluidic Device for Sorting C. elegans
Research Abstract:
Caenorhabditis (C.) elegans locomotion is a stereotyped behavior by generating waves of dorsal-ventral bends and propagating them forward along its body from head to tail. Noticeably absent from the C. elegans literature, however, are studies of evaluating the motility of nematode in waved-like channels in the microfluidic device. Major applications of immobilizing nematode are related to pressure involved process in the straight narrow-down channels. This presentation focus on studying of the spontaneity of mobility for C. elegans in wave-like channels. By utilizing this unique spontaneity, we designed and fabricated a microfluidic device which can sort and immobilize C.elegans from a colony mixed with nematodes in different larvae stage. The front part of channels in this microfluidic device is waved-like with the 30-micron diameter, so that only the fit-sized nematodes can swim in spontaneously and trapped in the body part which is straight and narrow down to 20 microns. Most medicine stimuli application of C.elegans is carried on synchronized well-fed young adults cultivated from only eggs with diameter vary from 30-35 micros. Synchronizing C.elegans by old method is labor-intensive and time-consuming. This design performs a convenience to separate nematodes within any region of diameter from an unsynchronized colony, thus enhance of the efficiency of immobilization and further biological stimuli of C. elegans.- Co-author Journal Publication
L. Yang, T. Hong, Y. Zhang, J.G. Sanchez Arriola, B.L. Nelms, R. Mu and D.Y. Li, “A microfluidic diode for sorting and immobilization of Caenorhabditis elegans” Biomedical Microdevices, 19, 38 (2017). - Tao was awarded a $1K travel grant at the capston poster session.
- Tao was awarded a 2017 Barry Goldwater Scholarship
- Tao received a Jack Kent Cooke UT Scholarship
- Tao was awarded a Bill Nye '77 Award
- Tao was awarded a NSF Graduate Research Fellowship in 2022.
- Tao was awarded a World-Class PD Soros Fellowshiop for New Americans in 2022.
- Co-author Journal Publication
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Ayisha Jackson - Engineering, Brown University
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Educational Institution: Brown University
List of Mentors: Dr. Craig Duvall & Dr. Meredith Jackson & Thomas Werfel
Program: NSF REU
Research Project: The Use of Microfluidic Mixing Devices for Minimizing Polyplex Nanoparticle Size and Increasing Tumor Penetration
Research Abstract:
Despite the use of various formulation methods for the polyplex packaging and delivery of siRNA, current polyplex formulations remain inconsistent with poor shelf life, and often particles that are too large to allow sufficient penetration of tumor tissue. To solve these formulation challenges, the Lee Visco-Jet Micro-mixer has been used to examine methods of improving siRNA polyplex formulation due to its ability to increase turbulence and particle interaction; varying flow-rate settings to determine optimal conditions. Dynamic light scattering (DLS) was used to quantify the micro-mixer’s effect on PEGylated micelles’ size and polydispersity; using multiple polymers with DMAEMA and BMA cores and varying coronas. To test particle stability, the hand-mixed and micro-mixed particles were compared after lyophilization and reconstitution. Furthermore, a Ribogreen assay was used to determine the encapsulation efficiencies of each particle formulation method.Overall, these tests have shown that the use of the micro-mixer consistently minimizes particle sizes from a hand-mixed average of around 100 nm to around 60 nm. The micro-mixer also significantly improves the encapsulation efficiency of siRNA during formulation from an average of 65% up to almost 80%. Further studies will include examining the effects of excipient additions for increased long-term stability of nanoparticles. Additionally, further studies will include in vitro testing of micro-mixed nanoparticle performance on tumor penetration using 3D matrigel-based models. These studies also show that the micro-mixed particles were more stable after freeze-drying and reconstitution than the hand-mixed counterparts. The above mentioned results indicate the ability of micro-mixer use to provide optimal complexing processes for clinical practice.- Co-author Journal Publication
M.A. Jackson, T.A. Werfel, E.J. Curvino, F. Yu, T.E. Kavanaugh, S.M. Sarett, M.D. Dockery, K.V. Kilchrist, A.N. Jackson, T.D. Giorgio, and C.L. Duvall “Zwitterionic Nanocarrier Surface Chemistry Improves siRNA Tumor Delivery and Silencing Activity Relative to Polyethylene Glycol” ACS Nano, 11 (6) 5680-5696 (2017). - Conference Presentation
A. Jackson, M.A. Jackson, T.A. Werfel, and C.L. Duvall “The Use of Microfluidic Mixing Devices for Minimizing Polyplex Nanoparticle Size and Increasing Tumor Penetration” Society for Biomaterials Annual Meeting and Exposition, Minneapolis, MN, April, 2017. - Ayisha was awarded a $1K travel grant at the capstone poster session.
- Co-author Journal Publication
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Amira Kessem - Renewable Energy Engineering, Alfred University
Educational Institution: Alfred University
List of Mentors: Dr. David Cliffel & Dr. Kane Jennings & Dr. Jeremy Beam
Program: NSF REU
Research Project: Strategies for Scaling Up Solid State Photosystem I-based Devices for Solar Energy Conversion
Research Abstract:
In order to commercialize solid state solar cell devices, it is important to show that they can be scaled up to industrially relevant sizes. Photosystem I (PSI)-based solid state devices for solar energy conversion have shown to yield an appreciable photocurrent over small surface areas. However, devices with larger surface areas have so far not been synthesized. This research project focuses on the fabrication and testing of solid state PSI-based solar cell devices of 4cm diameter and 6cm diameter. It includes two device architectures: p-Si/PSI/ZnO and TiO2/PSI-polyaniline. -
Anne Leonhard - Chemical Engineering/Computational Science, Rose-Hulman Institute of Technology
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Educational Institution: Rose-Hulman Institute of Technology
List of Mentors: Dr. Clare McCabe & Tim Moore
Program: NSF REU
Research Project: Coarse-Grained Simulations of the Self-Assembly of Skin-Relevant Lipid StructuresResearch Abstract:
The barrier properties of the skin are largely governed by the lipid lamellae of the outermost layer of skin, the stratum corneum (SC). While the composition of the SC is known, the molecular-level features of the lipid organization are not. This information would be useful for repairing an impaired skin barrier or selectively bypassing the barrier, e.g., for transdermal drug delivery. Molecular simulation allows precise control over system composition and direct visualization of the system structure, making it a useful tool for studying such systems. The slow kinetics of lamellar self-assembly make using atomistic models computationally inefficient. Thus, coarse-grained models, where groups of atoms are treated as individual interaction sites, are employed to study the self-assembly of SC lipids. Here, coarse-grained models of SC lipids, including CER NS C16, CER NS C24, cholesterol, and free fatty acids, are simulated to gain insight into the low-energy structures adopted by mixtures of these lipids. Self-assembly of both single and stacked bilayers in solution is studied by cooling systems from a high-temperature, disordered state. Structural properties, such as lipid positioning, angle between lipid tails, tilt angle of lipid tails, nematic order parameter, and bilayer lipid density are calculated. These properties are compared between simulations to determine the effects of lipid concentration on bilayer structure. This research increases understanding of the structural role of various lipids in SC organization and is an important step in the use of accurate coarse-grained models of the SC lipids.- Co-author Journal Publication
T. C. Moore, C. R. Iacovella, A. C. Leonhard, A. L. Bunge, and C. McCabe, “Molecular Dynamics Simulations of Stratum Corneum Lipid Mixtures: A Multiscale Perspective, Biochemical and Biophysical Research Communications, 498, 313-318 (2018). [Invited] - Conference Presentations
-A. Leonhard, T.C. Moore, C. McCabe “Coarse-Grained Simulations of the Self-Assembly of Skin-Relevant Lipid Structures” AICHE Student Conference, San Francisco, CA, November 2016.
-T. C. Moore, A. C. Leonhard, C. R. Iacovella, R. Hartkamp, A. L. Bunge, and C. McCabe, “Self-Assembly of Model Stratum Corneum Lipid Mixtures,” Gordon Research Conference on the Barrier Function of Mammalian Skin, Waterville Valley, NH, August, 2017.
-T. C. Moore, D. Xia, A. C. Leonhard, C. R. Iacovella, R. Hartkamp, A. L. Bunge, C. McCabe, “Self-Assembly Simulations of Stratum Corneum Lipid Mixtures,” AIChE Annual Meeting, Minneapolis, November, 2017. - Anne was awarded a NSF Graduate Research Fellowship
- Co-author Journal Publication
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Clara Simons - Physics/German, Wofford College
Educational Institution: Wofford College
List of Mentors: Dr. Kane Jennings & Max Robinson
Program: NSF REU
Research Project: Photocatalytic Photosystem I/PEDOT Composite Films Prepared by Vapor Phase PolymerizationResearch Abstract:
Photosystem I (PSI) is a globally abundant protein complex that facilitates the light reactions of photosynthesis in green plants and cyanobacteria with near-unity quantum efficiency, and has been used in solid state cells and hydrogen production. Extracted PSI can also be rapidly assembled atop conductive surfaces for photocatalytic response. We report the incorporation of PSI proteins within an electrically conductive poly(3,4-ethylenedioxythiophene) matrix using a vapor phase approach, allowing for the desired increase of impedance and conductance in our films. The inclusion of Friedel-Crafts catalyst (FeCl3) within drop cast solutions of PSI permits subsequent polymerization when in contact with an appropriate monomer, while an ideal amount of surfactant (Triton X-100) improves film smoothness and uniformity. Using these techniques, we observe optimal photocurrents of nearly 1 μA/cm2 over control films when 6μM PSI is included in the drop cast solution. PSI’s absorbance spectrum has a characteristic peak at 675nm, which is indicative of its red light absorption and photocatalysis and which contributes significantly to photocurrent outputs following the vapor phase deposition of our polymer. Due to the significant red light photoresponse contribution of composite films, we suggest their use within light-activated counter electrodes in dye-sensitized solar cells.- Co-author Journal Publication
M.T. Robinson, C.E. Simons, D.E. Cliffel, and G.K. Jennings, “Photocatalytic photosystem I/PEDOT composite films prepared by vapor-phase polymerization” Nanoscale, 9 (18), 6158-6166 (2017). - Clara was awarded Best Layout at the the capstone poster session.
- Co-author Journal Publication
![VINSEREU2015 VINSEREU2015](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/31155440/VINSEREU2015.png)
2015
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Christopher Banks - Physics, Norfolk State University
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Educational Institution: Norfolk State University
List of Mentors: Dr. Rizia Bardhan & Naiya Soetan
Program: NSF REU
Research Project: Analysis of the Catalytic Effects of Multi-branched Gold Nanostructures (MGNs) on the Kinetics of the Degradation of P-nitrophenol (PNP)
Research Abstract:
Recently, interest in metallic nanoparticles has skyrocketed. Applications using nanoparticles include photo-thermal biomedical uses, fuel cell technology, and constructing sensors based on localized surface plasmon resonance (LSPR). A type of nanoparticles known as multi-branched gold nanostructures (MGNs) are exceedingly interesting because their size and shape are tunable based on the pH and the concentration of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic Acid (HEPES) and the concentration of HAuCl4 in the solution, in which the MGNs are suspended. The customizability of the size and shape of MGNs allows for use in various applications, because they enable optical tunability and the plasmonic enhancement of materials. We investigated the effects of the morphology of the MGNs on catalytic activity by observing their catalysis of the degradation of p-nitrophenol (PNP) to p-aminophenol (PAP) in the presence of sodium borohydride (NaBH4). Previous work shows that this reaction follows the Langmuir-Hinshelwood model. We found that the degradation of PNP on the surfaces of MGNs with plasmon resonances at ~680 nm and ~800 nm follow the Langmuir-Hinshelwood model in that the apparent rate constant, kapp,decreases as the concentration of PNP increases. These results will be useful for future research in MGN surface area and morphology and other metallic nanoparticle morphology including bimetallic nanoparticles, biosynthesized nanoparticles or other types of nanoparticles made from noble metals.- Co-author Journal Publication
N. Soetan, H.F. Zarick, C. Banks, J.A. Webb, G. Libsion, A. Coppola, and R. Bardhan, "Morphology-directed Catalysis with Branched Gold Nanoantennas" Journal of Physical Chemistry C, 120 (19) 10320-10327, (2016). - Conference Presentations
-C. Banks, N. Soetan, and R. Bardhan “Analysis of the Catalytic Effects of Multi-branched Gold Nanostructures (MGNs) on the Kinetics of the Degradation of P-nitrophenol (PNP)” Annual Biomedical Research Conference for Minority Students, Seattle, WA, November, 2015.
-C. Banks, N. Soetan, and R. Bardhan “Analysis of the Catalytic Effects of Multi-branched Gold Nanostructures (MGNs) on the Kinetics of the Degradation of P-nitrophenol (PNP)” Norfolk State University Undergraduate Research Symposium, Norfolk, VA, March, 2016.
C. Banks, N. Soetan, and R. Bardhan “Analysis of the Catalytic Effects of Multi-branched Gold Nanostructures (MGNs) on the Kinetics of the Degradation of P-nitrophenol (PNP)” NSU-OSA, Norfolk, VA, April, 2016. - Chris was awarded a NSF Graduate Research Fellowship
- Co-author Journal Publication
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Ben Burdette - Chemical Engineering, University of Kentucky
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Educational Institution: University of Kentucky
List of Mentors: Dr. Craig Duvall & Brian Evans
Program: NSF REU
Research Project: Testing Fabrication Conditions to Optimize Properties of Peptide-Loaded Nanoparticles
Research Abstract:
The use of peptide-, protein-, and nucleic acid-based therapeutics has increased drastically due to the advantages they hold in terms of potency, specificity, and biocompatibility compared to commonly-utilized small molecule drugs. However, biomacromolecular therapeutics are limited by poor cellular uptake and susceptibility to proteolytic degradation, spurring the development of nanoparticle based systems that can protect biologic cargo and facilitate cellular internalization. To realize the clinical translation of these nanoparticle-based systems, the parameters affecting synthesis need to be highly controlled to consistently yield an optimized drug delivery vehicle. Here, we studied the effect of various synthesis parameters on the formation of pH-responsive, electrostatically complexed nanoparticles for the intracellular delivery of an established therapeutic MAPKAP Kinase 2 inhibitory peptide. Specifically, we studied the influence of ionic strength, solute concentration, and lyophilization/reconstitution on particle morphology and stability. Upon investigating the impact of the charge ratio [CR: the molar ratio of the number of negatively charged carboxylates (COO-) moieties on the polymer to the number of positively charged primary amines (NH2+) present in the peptide) on nanoparticle synthesis, we found that a CR of 1:3 demonstrated robust complexation without aggregation. An important question for clinical translation is whether nanoparticles can be reconstituted and remain active following long-term storage as a lyophilized powder. Results were promising, as Lyophilization of our particles appeared to result in more monodisperse, smaller particles, and the size of lyophilized particles was inversely proportional to the ionic strength of the buffer used during lyophilization. These results indicate that nanoparticle morphology, polydispersity, and stability can be controlled by modulating specific parameters utilized during nano-scale synthesis. Flow cytometric quantification of the effect of particle fabrication conditions on cell uptake is ongoing. Future work will involve investigation of the effect of formulation conditions on peptide bioactivity. We ultimately seek to provide a framework for repeatable, optimized nanoparticle synthesis for the clinical translation of biomacromolecular therapeutics such as the MAPKAP Kinase 2 inhibitory peptide showcased herein.- Co-author Journal Publication
A.J. Mukalel, B.E. Evans, K.V. Kilchrist, E.A. Daling, B. Burdette, J. Cheung-Flynn, C.M. Brophy, and C.L. Duvall “Excipients for the Lyoprotection of MAPKAP Kinase 2 Inhibitory Peptide Nano-Polyplexes” Journal of Controlled Release
- Co-author Journal Publication
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Thomas Campbell - Engineering Physics, Murray State University
Educational Institution: Murray State University
List of Mentors: Dr. Richard Haglund & Robert Marvel
Program: NSF REU
Research Project: Characterization of vanadium dioxide by scanning probe microscopy
Research Abstract:
Vanadium dioxide (VO2) experiences a phase transition from a monoclinic, semiconductor phase to a rutile, metallic phase, during which a vast change in physical, thermal, electrical, and optical properties are observed. This transition, which can easily be induced by temperature change, optical pumping, or electric field, makes VO2 an attractive material for applications in a wide range of device fabrication, from waveguide couples to passive thermal cooling devices. The implementation of VO2 thin films onto micro- or nanoscale device structures necessitates the use of more advanced phase transition characterization techniques, as simple optical reflection or transmission experiments will no longer be viable in complicated device architectures. This research project explores the feasibility of using Scanning Probe Microscopy (SPM) techniques to characterize and study the propagation of the vanadium dioxide phase transition in thin films. Specifically, Scanning Tunneling Microscopy (STM) and Scanning Thermal Microscopy (SThM) techniques are discussed, with corresponding images. -
Alyssa Cartwright - Electrical Engineering, Massachusetts Institute of Technology
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Educational Institution: Massachusetts Institute of Technology
List of Mentors: Dr. Sharon Weiss & Gilberto Rodriguez
Program: NSF REU
Research Project: Detection of Specific DNA Sequences using Porous Silicon Photonic Crystal Nanobeams
Research Abstract:
In this work, porous silicon (PSi) photonic crystal (PhC) nanobeam biosensors are computationally and experimentally demonstrated for the detection of specific DNA sequences. The structures are composed of a linear array of air holes forming mirror and cavity regions, which are lithographically etched into a PSi waveguide. The large internal surface area of the PSi substrate increases the probability of target molecule capture and increases the interaction between target molecules and light guided in the structure. The transmission spectra of the PSi nanobeams are characterized by a resonant peak within a photonic bandgap region, thus overcoming the potential limitations imposed by the free spectral range of ring resonator structures. Design studies revealed that the air hole spacing is the most critical parameter in determining the resonance wavelength. Quality (Q) factors as high as 5000 have been experimentally measured for the PSi nanobeams. When an analyte is introduced within the pores of the nanobeam structure, the effective refractive indices of the structure are increased, resulting in a measurable shift of the resonance wavelength. The magnitude of this spectral shift directly correlates to the size and quantity of analyte introduced. The label-free detection of a 16-base DNA sequence is conducted by first functionalizing oxidized PSi nanobeams with the linker molecule, 3-aminopropyltrimethoxysilane (3-APTES), and then a 16-base PNA probe that is synthesized in-situ. Complementary and non-complementary 16-mer DNA are exposed to the functionalized PSi nanobeams and selective detection is demonstrated. The PSi nanobeam demonstrates an approximate 40-fold improvement in small molecule sensitivity over standard silicon-on-insulator (SOI) nanobeam biosensors, which is in good agreement with field confinement simulations. The merging of the PSi material with the compact, high Q-factor PhC nanobeam design results in the highest reported nanobeam sensitivity to date with a reduced fabrication cost when compared to traditional SOI devices.- Co-author Journal Publication
G. A. Rodriguez, P. Markov, A. P. Cartwright, M.H. Choudhury, F. O. Afzal T. Cao, S. I. Halimi, S. T. Retterer, I. I. Kravchenko and S. M. Weiss, “Photonic crystal nanobeam biosensors based on porous silicon,” Optics Express, 27, 9536-9549 (2019). - Conference Presentation
G. A. Rodriguez, A. P. Cartwright, P. Markov, and S. M. Weiss, “Advanced porous silicon photonic structures for biosensing applications,” Porous Semiconductors – Science and Technology Conference, Tarragona, Spain, March 2016. - Alyssa was awarded a NSF Graduate Research Fellowship
- Co-author Journal Publication
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Dion Casey - Engineering Mathematics, St. Augustine's College
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Educational Institution: St. Augustine's College
List of Mentors: Dr. Yaqiong Xu & TianjiaoWang
Program: NSF REU
Research Project: Fabrication and characterization of 2D materials
Research Abstract:
Since the discovery of single layer graphene in 2004, the research field of 2-Dimensional (2D) material became very appealing. 2D material such as graphene, boron nitride (BN), and transition metal dichalcogenides (TMDCs) have unique electrical, optical, and mechanical properties that can be used in a wide range of applications. 2D material can be obtained in various methods, Chemical vapor deposition, Liquid phase exfoliation, etc. The method we used is the primary and most effective method is Mechanical exfoliation. Mechanical exfoliation is a physical process which gives the best results in purity and mobility of 2D material, rather than the other chemical processes. In this project we fabricated and characterized graphene and molybdenum disulfide based transistors/heterostructures. Graphene is single layer of carbon atoms arranged in a hexagonal lattice with a band gap of zero. Monolayer molybdenum disulfide (MoS2) has a triangular prismatic lattice and a direct band gap of 1.8eV. MoS2 and Graphene flakes were mechanically exfoliated from their bulk materials and then transfer to a degenerately doped 290 nm SiO2/Si substrate to build transistors/heterostructures . Then electrodes were fabricated using electron-beam lithography then thermal evaporation of Cr and Au. By studying the electrical and optical properties of these structures will offer a new way optimize optoelectronics devices.- Conference Presentations
-D. Casey, T. Wang, and Y. Xu “Characterization of Two Dimensional Materials and Fabrication of the Transistor and Heterostructure” 2016 St. Augustine’s Undergraduate Research Symposium, Raleigh, NC, September, 2015
-D. Casey, T. Wang, and Y. Xu “Characterization of Two Dimensional Materials and Fabrication of the Transistor and Heterostructure” Annual Biomedical Research Conference for Minority Students (ABRCMS), Tampa, FL, November, 2016.
- Conference Presentations
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Corey Combs - Materials Science, University of Tennessee, Knoxville
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Educational Institution: University of Tennessee, Knoxville
List of Mentors: Dr. Sokrates Pantelides & Xian Shen
Program: NSF TN-SCORE
Research Project: Discovery of Unusual Structural and Electronic Properties in Monolayer and Multilayer Si2Te3
Research Abstract:
Silicon telluride, a two-dimensional chalcogenide, could potentially bring unique 2d material properties to the fields of thermal and optical sensing. Determined experimentally, silicon telluride, Si2Te3, assumes a two-dimensional layered crystal structure. Not much is known of this material’s electronic properties, except that it is a p-type semiconductor with an experimentally determined indirect band gap close to 1 eV. The tellurium forms a hexagonal close packed lattice, and the silicon sits in pairs in alternating layers of the material. These silicon pairs occupy one of four possible orientations within the layers, three of which lie along the plane of the layer, and the fourth is orthogonal to the first three. This gives rise to high variability concerning the electron band structure of the material, due to a near limitless number of possible combinations of the silicon dimer orientations. Using molecular dynamics simulations, we see that the silicon dimers switch orientations without much difficulty at finite temperatures. We also see that, if the majority of silicon dimers have the same orientation, the lattice constant will expand along the direction of the dimers. Because of this, we believe strain could be used to control the orientation of the dimers. As changes in temperature have a large effect on the properties of the electron band structure, this material could be useful in both optical and thermal sensing applications.- Co-author Journal Publication
X. Shen, Y.S. Puzyrev, C. Combs and S.T. Pantelides, “Variability of Structural and Electronic Properties of Bulk and Monolayer Si2Te3” Applied Physics Letters, 109 (11), (2016). - Conference Presentation
C. Combs, X. Shen, Y. S. Puzyrev, L. Pan, and S. T. Pantelides “Discovery of Unusual Structural and Electronic Properties in Monolayer and Multilayer Si2Te3” American Physical Society, Baltimore, MD, March, 2016.
- Co-author Journal Publication
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Marc Cummingham - Chemical Engineering, University of California, Berkeley
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Educational Institution: University of California, Berkeley
List of Mentors: Dr. Peter Pintauro & Junwoo Park
Program: NSF REU
Research Project: Electrospun Nanofiber Bipolar Membranes
Research Abstract:
Bipolar membranes (BPMs) consist of cation exchange and anion exchange membranes stacked together leading to formation of a bipolar junction at the interface. In an electrochemical cell, BPMs enable water splitting into protons and hydroxide ions. Unlike in standard water electrolysis, water splitting in BPMs occurs without the evolution of hydrogen and oxygen gas. Thus water splitting can theoretically occur at 0.83V, significantly lower than 1.23V required in electrolysis. A significant amount of energy (about 60%) can be saved. The key applications of BPMs include commodity chemical production, waste recycling, and water purification. Recently, attempts to use BPMs in fuel cells have also been reported. In my work, the fabrication of bipolar membranes via electrospinning was investigated. Electrospinning allowed for careful control of the BPM composition, morphology, and thickness. BPMs were electrospun as fiber mats and densified into membranes via solvent exposure and hot pressing. The key novelty was the introduction of a 3D bipolar junction by dual-fiber cospinning of anionic and cationic nanofibers. The membranes were tested in an electrodialysis cell where current-voltage curves were recorded. The composition and thickness of the bipolar junction was varied. Preliminary testing has shown increasing junction thickness relative to the ion exchange layers decreases the water splitting potential but also reduces selectivity. The best performing bipolar membrane fabricated had a total thickness of 30 microns, a 3 micron 3D bipolar junction, and an extrapolated water splitting potential of 0.95V. In terms of future work, the introduction of catalysts at the junction could further improve electrospun bipolar membrane performance. -
Autumn Douthitt - Chemical Engineering, Tennessee Technological University
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Educational Institution: Tennessee Technological University
List of Mentors: Dr. Richard Haglund & Christina McGahan
Program: NSF TN-SCORE
Research Project: Modeling of Au:VO2 Plasmon Nanomodulators
Research Abstract:
On-chip communication is currently the principal limiting factor in computer speed. Optical modulators could replace electronic switches and interconnects on computer chips, carrying data by light pulses instead of electrical signals. This would greatly increase speed while reducing electrical resistance and heat generation. Plasmonic devices built from metal nanostructures can be used to transmit and manipulate light on a sub-wavelength scale, reducing the modulator footprint. In this research project, the goal is to improve upon signal processing using optical modulators by simulating electromagnetic waves propagating through a gold:vanadium dioxide (Au:VO₂) dimer placed on a glass substrate using a finite-difference, time-domain (FDTD) modeling software (Lumerical® Solutions). Such dimers have recently been described as efficient photon modulators.1 Normalized data after repeating the Au:VO₂ computations reproduced those results. We hypothesized that dimers comprising gold nanorods and VO2 nanodisks would produce narrower resonances than the nanodisk dimer, resulting in higher contrast and optimized signal switching. FDTD simulations assessed the ideal aspect ratios for nanorods placed on a glass substrate. The results harvested from rod and disk simulations compared favorably with experimental observations.2 Working towards combining these studies, we have found that small (4nm) gaps between VO2 disks and Au particles with higher aspect ratios affect the plasmon resonance shift as the VO2 switches, seen previously for disk dimers.1
1Appavoo, K. and Haglund, R. F., “Polarization selective phase-change nanomodulator,” Scientific Reports 4, 6771 (2014). 2. Sönnichsen C, Franzl T, Wilk T, von Plessen G, Feldmann J. “ Drastic reduction of plasmon damping in gold nanorods,” Phys Rev Lett 2002, 88:077402. *Research partially supported by the Office of Science, United States Department of Energy (DE-FG02-01ER45916)- Conference Presentation
A. Douthitt, C. McGahan, and R. Haglund “Modeling of Au:VO2 Plasmon Nanomodulators” American Chemical Society Regional Meeting, Memphis, TN, November 2015.
- Conference Presentation
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Dennis Ejorh - Mechanical Engineering, Tennessee Technological University
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Educational Institution: Tennessee Technological University
List of Mentors: Dr. Cary Pint & Rachel Carter
Program: NSF TN-SCORE
Research Project: Porous Silicon Templated Nanoporous Carbons for Tunable Li-S Battery Electrodes
Research Abstract:
Lithium-ion batteries have proven to be the universal standard for commercial battery technology. However, materials that comprise conventional lithium-ion battery electrodes are expensive and environmentally scarce (e.g. lithium, cobalt, etc.). Lithium- Sulfur batteries are currently viewed as the likeliest potential replacement for conventional lithium-ion electrodes, boasting high theoretical capacity about 6 times higher than conventional lithium-ion. In this work, we aim to promote an economically innovative means of fabricating high-performance electrode material, through the implementation of scalable processes and utilization of low-cost process materials: Silicon and Carbon. With fabrication of mesoporous carbon by means of Chemical Vapor Deposition on a highly controllable template such as nanoporous Silicon and subsequent Sulfur penetration, a high-quality cathode material is made; furthermore, the mesoporous nanostructure serves to improve cycle performance (the current focus in Li-S batteries) by preventing irreversible electrochemical reactions through encapsulation of sulfur atoms (allowing volumetric expansion of lithium-polysulfides) within the network formed by carbon meso-pores. Optimal device performance results of ~1360 mAh-gsulfur -1 (at a ~.1A/g current loading) upon initial charge/discharge cycling and subsequent cycle capacities of ~1000 mAh-gsulfur -1 have been shown; thus validating the feasibility of future industrial translation.- Co-author Journal Publication
R. Carter, D. Ejorh, K. Share, A. P. Cohn, A. Douglas, N. Muralidharan, T. W. Tovar, and C. L. Pint, “Surface Oxidized Mesoporous Carbons Derived from Porous Silicon as Dual Polysulfide Confinement and Anchoring Cathodes in Lithium Sulfur Batteries” Journal of Power Sources, 330, 70-77, (2016). - Conference Presentations
-D.C. Ejorh, R.E. Carter, K.E. Share, A.E. Douglas, A.P.Cohn, and C.L. Pint “Porous Silicon Templated Nanoporous Carbon for Tunable Li-S Battery Electrodes” National Society of Black Engineers Regional Conference, Memphis, TN, November, 2015.
* 1st place in poster and 2nd place in oral presentation
-D.C. Ejorh, R.E. Carter, K.E. Share, A.E. Douglas, A.P.Cohn, and C.L. Pint “Porous Silicon Templated Nanoporous Carbon for Tunable Li-S Battery Electrodes” The Tennessee Louis Stokes Alliance for Minority Participation Conference, Knoxville, TN, February, 2016.
-D.C. Ejorh, R.E. Carter, K.E. Share, A.E. Douglas, A.P.Cohn, and C.L. Pint “Porous Silicon Templated Nanoporous Carbon for Tunable Li-S Battery Electrodes” The National Society of Black Engineers National Convention in Boston, MA, March, 2016.
-R. Carter, D. Ejorh, K. Share, A. P. Cohn, A. Douglas, N. Muralidharan, and C. L. Pint “Controlled mesoporous carbons derived from porous silicon as dual polysulfide confinement and anchoring cathodes in lithium sulfur batteries” Gordon Research Conference – Batteries, Ventura, CA, February, 2016.
- Co-author Journal Publication
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Yi Jane Jiang - Liberal Arts & Science, Queensborough Community College
Educational Institution: Queensborough Community College
List of Mentors: Dr. Kane Jennings & Maxwell Robinson
Program: NSF REU
Research Project: Macroporous TiO2 Photoanodes for High Efficiency PSI-Based Biohybrid Photovoltaics
Research Abstract:
Photosystem I (PSI) is a protein complex residing within chloroplast of photosynthetic organisms. It is being studied as a candidate for dye-sensitized solar cell (DSSC) because it converts solar radiation to electrons with near-unity internal quantum efficiency. One of the obstacles that hinder PSI from being a more widely used dye is its large size. It is difficult to get sufficient PSI loaded throughout the photoanode of DSSC, a layer of titania (TiO2) nanoparticle coating, because the regular titania coating is mesoporous (pore size less than 50 nm).This presentation focuses on designing macroporous titania coatings with pore size as large as 1000 nm so that integration between titania coating and PSI would be enhanced. Sacrificial templating technique is employed to incorporate porosity into titania paste using oil-in-water emulsion and polystyrene latex as templating materials. The templated titania paste has been made directly from titanium dioxide powder. Then a titania coating has been produced on fluorine doped tin oxide (FTO) glass by doctor blading. The resulting coatings are uniform and crack-free. Scanning electron microscopy shows that the templated titania coatings have high porosity and interconnected meso and macro pores. They also demonstrate increased absorbance of PSI according to UV-Vis photospectroscopy. Using the macroporous titania coating as a photoanode would potentially enhance the overall efficiency of PSI-based biohybrid photovoltaics due to the high integration of PSI and titania coating. Further research will be carried to understand the effect of the added porosity on PSI and titania interface through cell performance studies.
- Conference Presentation
Y.J. Jiang, M.T. Robinson, D. E. Cliffel, and G. K. Jennings, “Macroporous TiO2 Photoanodes for High Efficiency PSI-Based Biohybrid Photovoltaics” National Council for Undergraduate Research, Asheville, NC, April, 2016. - Jane was awarded a $1K travel grant at the capstone poster session.
- Conference Presentation
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Jack Lewis - Engineering Science, Trinity University
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Educational Institution: Trinity University
List of Mentors: Dr. Cary Pint & Keith Share
Program: NSF REU
Research Project: Optimal Composition of Tungsten Diselenide (WSe2) Electrodes in Sodium Ion Batteries
Research Abstract:
This project explores for the first time the use of tungsten diselenide (WSe2) as an electrode material in sodium ion batteries. Using CMC as the binder and a mixture of EC:DEC as the electrolyte, we have achieved a 2nd discharge capacity of 225 mAh/g and retention of 69% after 25 cycles. Sodium ion batteries have recently attracted more attention as a viable energy storage method, due to the natural abundance of sodium and similarities to lithium ion technology. WSe2 is a transition metal dichalcogenide (TMD), and is comprised of a layered structure similar to graphite. Because of the large size of sodium, WSe2 is susceptible to damage caused by the insertion and removal of ions during cycling of the battery. Therefore, it is important that we select additive materials that will optimize the performance of our batteries. By determining which binders and electrolytes work well, we can drastically improve the capacity of the battery and how well it cycles. Charge/discharge tests were conducted to determine how each composition performed. This method gave us a way to measure the cell’s capacity and degradation, which we could use to compare different cells. For the future, we want to create nanostructured WSe2 to further improve the performance.- Co-author Journal Publication
K. Share, J. Lewis, L. Oakes, R. Carter, AP. Cohn, and C.L. Pint, “Tungsten diselenide (WSe2) as a high capacity, low overpotential conversion electrode for sodium ion batteries” RSC Advances, 5, 123 (2015). - Jack reecived a NASA Space Technology Research Fellowship award in 2019.
- Co-author Journal Publication
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Sharon Lin - Chemical Engineering, University at Buffalo
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Educational Institution: University at Buffalo
List of Mentors: Dr. Rizia Bardhan & May Ou
Program: NSF REU
Research Project: IR Laser Triggered Chemo-photothermal Treatment of Doxorubicin Resistant Breast Cancer Cells
Research Abstract:
Multibranched gold nanoantennas (MGNs), which are gold nanoparticles with multiple sharp protrusions, have been hailed as a potential agent for cancer treatment due to their ability to convert light to heat efficiently for photothermal therapy. We synthesize MGNs using HEPES, a biological buffer that acts as a capping and reducing agent. When MGNs are exposed to light at a characteristic wavelength, its surface plasmon resonance (SPR) is achieved, which leads to an enhanced light absorption, allowing for effective light-to-heat conversion. A concentration of 170 ug of MGNs per ml that is exposed to a laser, at 4 W/cm2 in the near-infrared (IR) region, can produce a temperature increase of up to approximately 53oC.We utilize the photothermal characteristics of MGNs to exploit the drug delivery capabilities of liposomes. We use thermo-sensitive liposomes, which will disassemble when it reaches its transition temperature, which is 42oC. At this temperature, about 90% of the drug that is encapsulated will be released within the first ten minutes. The cell line that we use in this project, MDA-MB-231, is normally Doxorubicin-resistant, but once these cells reach the hyperthermia temperature, which is also the transition temperature of the liposomes, they become more susceptible to Doxorubicin. Because the photothermal characteristics of MGNs can allow liposomes to reach their transition temperature, this combination can be effective in photothermal therapy of breast cancer cells.
- Sharon Lin was named a Barry Goldwater Scholar
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Jennifer Lomaki - Physics, State University of New York, Geneseo
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Educational Institution: State University of New York, Geneseo
List of Mentors: Dr. David Cliffel & Aaron Daniel
Program: NSF TN-SCORE
Research Project: Electrochemical TNT Detection Utilizing VO2 Particle Films
Research Abstract:
Due to its toxic nature, rapid and sensitive detection of TNT is important for groundwater testing, especially near military bases or areas that have been exposed to large quantities of explosive materials. Previous research has shown that vanadium dioxide (VO2) thin films have the ability to electrochemically detect 2,4,6-trinitrotoluene (TNT) in solution. VO2 is an interesting material that undergoes a phase transition at 68°C from a semiconducting monoclinic phase (M) to a metallic rutile phase (R). Limitations of the VO2 thin films include expensive reagents, expensive equipment and low yield. The hydrothermal synthesis utilized in this project generates a larger yield using inexpensive precursors. Additionally, doping the material with W6+ allowed for access to the VO2(R) phase at room temperature. Both VO2(M) and VO2(R) particles were then cast onto a glassy carbon electrode and tested for the ability to detect TNT. Various polar organic solvents were used to wash the particles and revealed that certain solvents either blocked or enhanced the particles’ ability to detect TNT. -
Naomi Mburu - Chemical Engineering, University of Maryland, Baltimore County
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Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Leon Bellan & Bradly Baer
Program: NSF REU
Research Project: Using 3D Printing to Model Disturbed Flow Through Arteries
Research Abstract:
To develop artery-shaped fluidic channels that exhibit both laminar and disturbed fluid flow patterns expected in mouse arteries, we use a 3D printing strategy combined with relevant sacrificial materials. Our goal is to reproduce flow patterns found in mouse arteries in order to increase research speed while reducing cost and the need for animal testing.Models of arteries are designed using CAD software and printed on a modified MendelMax2 3D printer using water-soluble polyvinyl alcohol (PVA) filament. The sacrificial templates are then embedded in polydimethylsiloxane (PDMS), and after the PDMS has cured the devices are placed in a water bath to dissolve the PVA, thus leaving hollow channels in the PDMS. We use fluorescent imaging beads to track particle flow through the channels and particle tracking algorithms to analyze flow patterns through these devices. The velocity profiles are used to illustrate areas of laminar and disturbed flow by modeling the devices as tubes and comparing the experimental velocity profiles with expected Newtonian flow patterns. The next step will be to reduce the channel sizes to better emulate the size of an artery in a mouse. After the scaled-down channels have been fully characterized, endothelial cells will be grown on the channel walls of the device to mimic the inside of the artery. Eventually, these devices will be used to test the delivery of drugs targeted to sites of the artery that are prone to plaque buildup due to disturbed flow. The use of such 3D printed vessel models may eventually reduce the need to perform initial experiments on animal models, thus making research on vascular diseases like atherosclerosis more ethical and efficient.
- Conference Presentaiton
N. Mburu, M. Richardson, and L. Bellan, “Using 3D Printing to Model Disturbed Flow Thorugh Arteries” American Chemical Society, San Diego, CA, March, 2016. - Naomi was awarded a $1K travel grant at the capstone poster session.
- Naomi was named a MARC U*STAR Scholar
- Naomi was awarded a Barry Goldwater Scholarship in 2016
- Naomi was named a Rhodes Scholar
- Conference Presentaiton
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Christopher McDonald - Physics, Austin Peay State University
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Educational Institution: Austin Peay State University
List of Mentors: Dr. Rizia Bardhan & Eric Talbert
Program: NSF TN-SCORE
Research Project: Perovskite Layer Optimization of Planar Solar Cells
Research Abstract:
Perovskite Solar Cells (PSC’s) are an extremely hot topic in research due to both how new the field is and the amazing growth in efficiency it has shown. This research was to discover an easily repeatable way of creating planar PSC devices that eliminated many of the issues that have currently plagued fabrication such as pin holes and excessive roughness. Our methodology included varying spin coating speeds, anneal temperature and time, and perovskite weight percentage to control layer thickness. To control roughness of the planar layers, which is a function of the crystallization speed, we tested the addition of toluene during spin coating, varied toluene deposition rates and times, and experimented with varying substrate temperature prior to deposition of the perovskite layer. Using profilometer measurements we discovered that the biggest contributing factors for perovskite smoothness were the addition of toluene via a slow drip method during the ramp phase while spin coating at 4000 rpm’s for 60 seconds, and using a 40 wt% solution of perovskite in dimethyl sulfoxide and y-butyrolactone. We then tested our devices using electrochemical impedance spectroscopy to quantify the improvements in efficiency, fill factor, and short circuit and open circuit voltage as a function of perovskite smoothness. This knowledge will help speed along the ability for others to produce reliable and consistent solar cell devices and allow more time and funding to be directed toward improving efficiency and stability.- Co-author Journal Publication
E.M. Talbert, H.F. Zarick, N.J. Orfield, W. Li, W.R. Erwin, Z.R. DeBra, C.P. McDonald, K.R. Reid, J. Valentine, S.J. Rosenthal, and R. Bardhan, "Interplay of Structural and Compositional Effects on Carrier Recombination in mixed-Halide Perovskites” RSC Advances, 6 (90), 86947-86954, (2016). - Conference Presentation
C. McDonald, E. Talbert, and R. Bardhan “Perovskite Layer Optimization of Planar Solar Cells” Tennessee Academy of Sciences, Murfreesboro, TN, November, 2015.
*2nd place in Engineering and Engineering Technology
- Co-author Journal Publication
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Joshua Ryan Nolen - Physics, Lipscomb University
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Educational Institution: Lipscomb University
List of Mentors: Dr. Richard Haglund & Daniel Mayo
Program: NSF TN-SCORE
Research Project: ZnO nanowire radiation detectors with high spatiotemporal resolution
Research Abstract:
Zinc oxide nanowires are potentially useful photoluminescent (PL) radiation detectors, because both the ultraviolet (near band-edge) and visible (donor-acceptor pair defect) emission are altered by ionizing radiation. Zinc oxide in thin film and nanopowder form has been studied for use as a scintillator, but the omnidirectional optical response is relatively weak for finite detector solid angles. However, zinc oxide nanowires can be grown to emit in a single direction through waveguiding effects, therefore making PL detection highly efficient. We have measured the PL response of zinc oxide nanowires to gamma rays (662 keV) and quantified the effects of nanowire surfaces and interfaces on the PL response. By studying the PL kinetics as a function of time following irradiation, we infer the relaxation rates of specific radiation-induced defects, including oxygen vacancies.- Conference Presentation
R. Nolen, D. Mayo, C. Marvinney, A. Cook, R. Mu, and R. Haglund, “ZnO Nanowire Radiation Detectors with High Spatiotemporal Resolution” The Minerals, Metals and Materials Society Annual Meeting, Nashville, TN, February, 2016.
- Conference Presentation
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Uchechukwu Uc Obiako - Chemical Engineering, Cleveland State University
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Educational Institution: Cleveland State University
List of Mentors: Dr. David Cliffel & Evan Gizzie
Program: NSF REU
Research Project: Enhancement of Solar Energy Conversion in Bio-derived Cells via Side Selective Modification of Photosystem I
Research Abstract:
Deleterious effects of some methods used to harness energy from the environment today have garnered the exploration of safer and more reliable options, specifically solar energy conversion. Current solar cell technology has yielded quantum efficiencies commonly in the range of 10-20% but is limited by extensive processing methods, high cost, and need for rare materials. However, bio-derived solar cells containing Photosystem I (PSI) address these problems as PSI is highly abundant, very efficient, and low-cost. PSI acts as a biomolecular photodiode through rapid photoexcited charge separation, making it very promising for use as an integral element in solar cells. To further improve the efficiency of bio-derived cells, controlling the orientation of PSI films on gold substrates was explored. This was achieved by side-selectively modifying PSI to introduce terminal thiol groups to the protein complex thereby providing a vector of self-assembly onto the gold surface. Spinach thylakoid membranes containing PSI were extracted and chemically modified using the ligands: sulfo-N-succinimidyl S-acetylthioacetate and 2-iminothiolane. As a result, the functionalized PSI underwent direct surface coupling on gold electrodes in an inverted orientation. Fluorescence tagging was used to quantify ligand attachment to PSI. Additionally, photoelectrochemical analysis revealed an enhancement in photocurrent produced by the modified biohybrid electrodes.
![VINSEREU2014 VINSEREU2014](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/31155941/VINSEREU2014.png)
2014
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Nastasia Allred - Chemical Engineering, Tennessee Technological University
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Educational Institution: Tennessee Technological University
List of Mentors: Dr. Rizia Bardhan & Will Erwin
Program: NSF TN-SCORE
Research Project: Plasmon Enhanced Tandem Dye-Sensitized Solar Cells
Research Abstract:
Our current energy economy faces environmental concerns, as well as concerns of lacking availability of fossil fuels. In 2013, roughly 80% of energy consumption in the U.S. was achieved through fossil fuels, while only 0.3% of the energy consumed was produced by solar resources.1 Dye sensitized solar cells (DSSCs) show promise because they are less expensive and made of more easily recyclable, less hazardous materials than silicon photovoltaics (Si-PVs); however, one of the major problems with DSSCs is that they do not reach high enough efficiencies to compare to Si-PVs. In this work, two approaches to enhancing DSSC efficiency are complementary to each other; i) making a tandem DSSC with two types of sensitizing dye and ii) by incorporating tunable plasmonic particles into the devices. Each DSSC has a mesoporous TiO2 layer onto which an organic dye is adsorbed. In this study, the tandem DSSCs consist of cells using N719 (red) and N749 (black) dyes. The cells are arranged such that the light source strikes the cell containing the N719 dye first. This is such that the light not absorbed by the red dye now has the chance to be absorbed by the black dye, thus increasing the cell’s light harvesting capabilities. Plasmon enhancement is accomplished by incorporating broad resonance Au@Ag bimetallic nanoparticles into the mesoporous semiconductor layer, thereby increasing the scattered light and overall photocurrent of the device. -
Efrem Beraki - Electrical Engineering, Georgia Institute of Technology
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Educational Institution: Georgia Institute of Technology
List of Mentors: Dr. Sharon Weiss & Yiliang Zhao
Program: NSF REU
Research Project: Kinetic Analysis of Porous Silicon Biosensors
Research Abstract:
This research investigates the molecular binding kinetics and detection sensitivity differences between mesoporous optical biosensors of closed-end porous films and open-ended, flow-through membranes. A porous silicon material system is employed due to its many advantages for biosensing applications, including a large active sensor surface area and tunable porosity and pore size, as well as it amenability to standard silicon lithographic processing techniques. Size-selective sensing and relatively high detection sensitivities have already been demonstrated in closed-end porous silicon biosensors. Here, we describe the fabrication process to realize porous silicon membrane sensors, which is based on photolithographic patterning and reactive ion etching of a silicon wafer followed by selective electrochemical etching to form the porous silicon regions. We then seek to characterize and compare the performance of closed-end and membrane style porous silicon sensors. The binding kinetics of the porous silicon sensors were evaluated by flowing different molecules through a flow-cell attached to each sensor and monitoring the change in the Fabry-Perot interference pattern as a function of time and flow rate. A comparison of the detection sensitivity of closed-end and membrane sensors can be made by evaluating the rate of change of the interference pattern, as well as the saturation time for which all available binding sites are occupied. This work is expected to lead to the realization of lab-on-chip compatible porous silicon membrane sensor arrays capable of fast response, high sensitivity, and simultaneous detection of multiple analytes. -
Matthew Billingsley - Chemical Engineering, Rose-Hulman Institute of Technology
Educational Institution: Rose-Hulman Institute of Technology
List of Mentors: Dr. Peter Cummings & Andrew Summers
Program: NSF REU
Research Project: Investigating Wear Mechanisms of Alkylsilane Monolayers through Molecular Dynamics Simulation
Research Abstract:
Alkylsilane monolayers have been proposed as lubricants for microelectromechanical and nanoelectromechanical systems (MEMS and NEMS), having been shown to reduce friction and wear and protect surfaces from oxidation. However, these monolayers are known to degrade over time, whereby chains break off of the surface. In this study, we utilize molecular dynamics (MD) simulations to study the frictional properties of hexylsilane monolayers attached to silica substrates, focusing on the effects of monolayer wear. Wear is introduced in a controlled manner by randomly detaching a specified fraction of chains from each substrate. Frictional properties and free-chain mobility (i.e., broken chains) are investigated as function of induced monolayer wear. For crystalline silica substrates, we find that normal load has a negligible effect on the mobility of free chains; mobility is instead correlated with the fraction of broken chains. Amorphous systems reveal a higher degree of free-chain mobility compared to crystalline systems with identical levels of induced wear, which we correlate to the increased surface roughness of the amorphous substrates. Furthermore, systems with amorphous substrates have higher coefficients of friction (COF), suggesting an inclination toward increased wear at all conditions.- Co-author Journal Publication
A.Z. Summers, C.R. Iacovella, M.R. Billingsley, S.T. Arnold, P.T. Cummings, C. McCabe, “Influence of Surface Morphology on the Shear-Induced Wear of Alkylsilane Monolayers: Molecular Dynamics Study,” Langmuir, 32, 10 2348-2359 (2015). - Conference Presentations
-A.Z. Summers, M.R. Billingsley, C.R. Iacovella, P.T. Cummings, C. McCabe, “Investigating the Shear-Induced Wear of Alkylsilane Monolayers through Molecular Dynamics Simulation,” SERMACS 2014, Sheraton Music City Hotel, Nashville, TN, October, 2014.
-A.Z. Summers, C.R. Iacovella, M.R. Billingsley, S.T. Arnold, P.T. Cummings, C. McCabe, “Investigating the Shear-Induced Wear of Alkylsilane Monolayers through Molecular Dynamics Simulation,” Poster presented at the 15th Annual Nanoscience and Nanotechnology Forum, Vanderbilt University, Nashville, TN, November, 2014.
- Co-author Journal Publication
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Elijah Brown - Electrical Engineering, Austin Peay State University
Educational Institution: Austin Peay State University
List of Mentors: Dr. Kirill Bolotin & Alex Wynn
Program: NSF TN-SCORE
Research Project: Nano-capacitors: Investigating Electrical Fields between Different 2-Dimensional MaterialsResearch Abstract:
Graphene is one of the most diverse and exciting materials currently being investigated by researchers. Graphene is known as a 2-Dimensional material, it is called this because electrons are only moving through the material in two dimensions. 2-Dimensional materials are observed as a one to three atom thick substance typically called a mono-layer. There are many other materials available to researchers that can produce mono-layers besides Graphene, such as molybdenum disulfide, tungsten disulfide, and niobium diselenide among others. Artificially creating new materials by stacking mono-layered substances such as these is becoming commonplace. When Graphene is stacked with some materials, such as the forementioned ones, researchers have witnessed the effects of sending an electric current through them, an electrical field begins to form in the gap between them. Generally researchers have taken for granted that the electrical field building up between these layers is due to the mechanics of charge transfer. However, there have been several other plausible speculations that could possibly explain this event; such as the suggestion of a characteristic called FRET (florescence resonance energy transfer). To allow for the testing of this hypothesis measurable devices will have to be fabricated. Capacitors are a commonly used component of analog electronic circuits. Capacitors are made using two electrically conductive plates separated by a small gap, as voltage is pushed through the plates over time an electrical field will build up between them. Since the stacked mono-layers behave like capacitors, it is possible to put them through the same physics tests as capacitors, and should prove or disprove that charge transfer is responsible for the phenomenon. -
Kathryn Bumila - Chemical Engineering, Worcester Polytechnic Institute
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Educational Institution: Worcester Polytechnic Institute
List of Mentors: Dr. John Wilson & Max Jacobson
Program: NSF REU
Research Project: Developing New Amphiphilic Diblock Co-Polymers for Delivery of Cytosolicly Active Immunostimulants
Research Abstract:
A major barrier to synthetic vaccine development is inefficient delivery of immunostimulatory adjuvant molecules to the cytosol of antigen presenting cells. In order to overcome this challenge, we are developing pH-responsive diblock copolymers that can be utilized as nano-carriers for these adjuvants. A successful nano-carrier must form stable micelles under physiological conditions as well as have endosomal escape capabilities to promote delivery to cytosolic pathogen recognition receptors. A library of amphiphilic diblock copolymers was synthesized in order to compare the effect of the hydrophobic group on nanoparticle properties and drug delivery qualities. The hydrophobic groups compared were butyl methacrylate (BMA) and hexyl methacrylate (HMA), as components of [poly(ethylene glycol)]-block-[2-dimethylaminoethyl methacrylate-co-BMA] and [poly(ethylene glycol)]-block-2-[dimethylaminoethyl methacrylate-co-HMA] polymers, respectively. The second blocks were designed to have compositions of 20%, 30%, and 40% BMA or HMA. To determine the polymer’s ability to form micelles, dynamic light scattering was performed over a range of pH 5.8-7.4. This experiment showed that the polymer containing 30% HMA, 40% HMA, and 40% BMA successfully formed 13-18 nm diameter micelles at pH 7.4 and transitioned to unimeric polymer chains with decreasing pH. Next, a hemolysis assay was performed across the same pH range. The results showed that 40% BMA displayed the greatest membrane disruptive characteristics at pH 5.8 and pH 6.2, however, at most pH values 20% HMA and 30% HMA were significantly more hemolytic than their BMA counterpart. Lastly, a cell viability assay was carried out to determine if any of the polymers were harmful to cells. The results showed an average of 80% or higher cell viability at concentrations ranging from 0.01-10 μg/ml, with the 40% HMA polymer appearing the least cytotoxic. In conclusion, initial results suggest that PEG-bl-DMAEMA-co-BMA and PEG-bl-DMAEMA-co-HMA are promising cytosolically active nano-carriers. However, the novel HMA containing polymers could prove to be even more efficacious for this application because of the increased membrane destabilizing activity and particle stability associated with longer hydrophobic chains.- Conference Presentation
K. Bumila, M. Jacobson, S. Sevimli, and J. T. Wilson, “Developing New Amphiphilic Diblock Copolymers for Delivery of Cytosolically Active Imunostimulants” 2014 AIChE Annual Meeting, Atlanta, GA, November, 2014. - Katie was awarded a $1K travel grant at the capstone poster session.
- Conference Presentation
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Ashton Davis - Mathematics, LyMoyne-Owen College
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Educational Institution: LeMoyne-Owen College
List of Mentors: Dr. Cary Pint & Andrew Westover
Program: NSF TN-SCORE
Research Project: Remote Charging for Light Integrated Energy Storage Systems via Lasers
Research Abstract:
As we move into the future, finding new methods of obtaining energy has become a priority of research. Solar Panels have proven to be an efficient means of converting energy from sunlight to electricity and super capacitors have proven to be one of the most efficient energy storage systems for our future. This project is focused on combining both of these technologies in order to have an energy storage device that can obtain a charge remotely with a supercapacitor integrated on the back of the solar cell. One potential method of remotely charging these integrated energy storage devices is through the use of LASERS. LASERS give a form of transmissible energy that can be used at any time. One of the great advantages of lasers is their high wall plug efficiency allowing for efficient energy in addition to its remote capabilities Not only do lasers have great energy efficiencies, but they can be used distances farther than kilometers away and being paired with a supercapacitor, the device can be charged rapidly. This technology will allow for high efficiency remote charging of a variety of energy storage devices ranging from UAVs, household electronics, robotics etc. The research and findings of this project are promising to greatly improving everyday energy usage. -
Elizabeth Delesky - Materials Science & Engineering, University of Florida
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Educational Institution: University of Florida
List of Mentors: Dr. Eva Harth & Kelly Gilmore
Program: NSF REU
Research Project: Biodegradable Polyester Hydrogels for Sustained Drug Delivery
Research Abstract:
Hydrogels have recently emerged as promising materials for drug delivery applications for both synthetic and biological cargo. However, many of the current systems are limited due to the non-degradable nature of the gels. Polyester hydrogels synthesized using oxime click chemistry are an attractive option as drug delivery vehicles due to their biocompatibility and degradability. In this study, we have utilized a copolymer comprised of δ-valerolactone and 2-oxepane-1,5-dione as well as an amino-oxy functionalized polyglycidol to synthesize these gels. Hydrogels were synthesized using three different ratios of the two reactants in order to tune the swelling and degradation profiles. The swelling profiles revealed that maximum swelling occurs within the first few hours. Swelling was observed after degradation began as the ester linkages were hydrolyzed, which allowed water to infiltrate the gels and increase the mass as the gels degraded. Both the swelling and degradation profiles revealed that increasing the amount of cross-linker prevents rapid degradation of the hydrogel. The free drug release rate of these hydrogels was also studied, using brimonidine as a model drug, as well as release rates incorporating the drug into an additional complex, such as β-cyclodextrin. β-cyclodextrin can be homogeneously dispersed through the hydrogel to provide an ancillary boundary for the drug and prolong the release.- Elle was awarded a NSF Graduate Research Fellowship in 2017.
- Elle was awarded a ACI Presidents' Fellowship from the American Concrete Institute in 2017.
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Amadou Fall - Chemistry, Tennessee State University
Educational Institution: Tennessee State University
List of Mentors: Dr. Janet Macdonald & Andrew LaCroix
Program: NSF TN-SCORE
Research Project: Investigating the electronic coupling of quantum dot-ligand interaction
Research Abstract:
Photocatalysis and the use of solar cells are having an ever increasing importance in our search for renewable energies. Quantum dots, which are nanoscale particles of semiconductors (in our case Cadmium selenide), are a driving force in this endeavor. Reasons for this include that they are inexpensive to make, have a strong molar absorptivity, and are easily tunable to the desired size. The synthetic methods used to obtain monodisperse samples of different sizes require charge transfer inhibiting organic ligands. The Macdonald group has discovered a crystal-bound ligand system that can increase nanoparticle stability and charge transfer efficiency. We optimized the synthesis of CdSe@ZnS core-shell nanoparticles to increase the quantum yield. Hydrolysis of the ester group in dodecyl-3-mercaptopropionate-capped CdSe@ZnS core-shell nanoparticles results in a red shift in absorbance and fluorescence, which could be due to energetic overlap of the carboxylate ligand and the CdSe@ZnS core-shell nanoparticle. In this project we plan to compare the results of our seed, shelling, and hydrolysis with the Brus quantum confinement equation to determine if the observed electronic interaction is with the valence or conduction band. We can use the results of the data to design better and more efficient photocatalytic and photovoltaic devices.- Co-author Journal Publication
M.J. Turo, X. Shen, N.K. Brandon, S. Castillo, A.M. Fall, S.T. Pantelides, and J.E. Macdonald “Dual-Mode Crystal-Bound and X-type Passivation of Quantum Dots” Chemistry Communications, 52 (82) 12214-12217, (2016). - Conference Presentations
-A. Fall, S. Castillo, N. Brandon, A. La Croix, and J. Macdonald, “Investigating the electronic coupling of quantum dot-ligand interaction” 2014 ACS Southeast Regional Meeting, Nashville, TN, October, 2014.
-A. Fall, S. Castillo, N. Brandon, A. La Croix, and J. Macdonald, “Investigating the electronic coupling of quantum dot-ligand interaction” 2014 Annual Biomedical Research Conference for Minority Students, San Antonio, TX, November, 2014.
-A. Fall, S. Castillo, N. Brandon, A. La Croix, and J. Macdonald, “Investigating the electronic coupling of quantum dot-ligand interaction” 249th Annual American Chemical Society National Meeting and Exposition, Denver, CO, March, 2015. - Amadou was awarded a $1K travel grant at the capstone poster session.
- Co-author Journal Publication
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Nicholas Morgan - Chemical Engineering, University of Oklahoma
Educational Institution: University of Oklahoma
List of Mentors: Dr. Peter Pintauro & Devon Powers
Program: NSF REU
Research Project: Optimizing the Fabrication of Solution-Cast Membranes
Research Abstract:
As the current fossil fuel-based economy continues to present environmental challenges and issues of sustainability, the fuel cell shows promise to be a highly efficient source of clean energy in the near future. Integral to the operation of a fuel cell is the membrane, which separates the cathode and the anode and provides pathways for proton transport. For efficient operation, the membrane must exhibit high proton conductivity, robust mechanical strength, and low fuel crossover. The most common proton transport material used is perfluorosulfonic acid (PFSA) polymer, sold by DuPont under the name Nafion. This material exhibits high conductivities but also relatively high crossover rates for many fuel and oxidants used in fuel cells such as methanol or bromine species, leading to the degradation of catalysts at the electrodes. Additionally, Nafion’s poor mechanical strength poses a problem due to excessive swelling during each on/off cycle. To make up for these deficiencies, Nafion can be mixed with an inert reinforcing polymer such as polyvinylidene fluoride (PVdF), resulting in a favorable reduction in swelling and fuel crossover but also a loss of conductivity. In the present study, Nafion-PVdF membranes were fabricated by solvent casting, where a solution containing the two polymers is spread on a glass plate to form a film that is dried in an oven, producing a 50-100 μm-thick membrane. We investigate the effect of using N,N-dimethylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone as casting solvents and the effect of varying annealing times and temperatures on the conductivity, water uptake, and swelling properties of these blended membranes. We also vary the Nafion-to-PVdF ratio for each solvent to map the ranges over which the most successful solvent-annealing combination can be applied. Results indicate that the annealing condition that yields the highest conductivity is not solely a function of solvent but of both solvent and proportion of Nafion, with membranes containing the highest and lowest proportions of Nafion showing sensitivity to higher annealing temperatures and subsequent losses in conductivity. Phase separation is observed to consistently lead to a loss in conductivity as well. Water uptake and swelling properties appear to be constant and largely independent of solvent and annealing conditions. Future work will include testing additional combinations of solvents, annealing conditions, and Nafion proportions in order to draw further conclusions about the interactions of these parameters, as well as examining fuel crossover and tensile strength. -
David Needell - Math & Physics, Bowdoin College
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Educational Institution: Bowdoin College
List of Mentors: Dr. David Cliffel & Gabriel LeBlanc
Program: NSF REU
Research Project: Biohybrid Solid State Solar Cells
Research Abstract:
While traditional p-n junction photovoltaic panels continue to be the most popular solar cell currently available, the cost of processing and constructing these cells have limited their dissemination into the energy market. For this, alternative solar cells constructed from organic and easier to obtain materials aim to be one solution to this problem. Photosystem I (PSI) is an essential part of the photosynthetic process present in green plant cells and cyanobacteria – a protein responsible for exciting a free electron given an incident photon. PSI’s abundance in nature and nearly perfect quantum efficiency make PSI a prime candidate for use in solar cells.The ultimate aim of this research is to determine if a biohybrid, solid-state solar cell – constructed from inexpensive conductive substrates – can generate electrical power. Conductive and transparent Reduced Graphene Oxide (rGO) and Poly(3,4-ethylenedioxythiophene) Polystyrene sulfonate (PEDOT:PSS) served as the counter and working electrode in the solid-state cell, respectively. Current-voltage analyses and photochronoamperometry tests show that both rGO and PEDOT:PSS can be successfully incorporated into a fully functional, solid-state biohybrid cell with a doped semiconducting substrate. This information gives strong support to the construction of a working, metal free, and biohybrid solid-state solar cell with rGO, PSI, and PEDOT:PSS. Future work includes refining the technique of constructing this metal free, flexible solar cell and improving the orientation alignment of the multilayered PSI film.
- Co-author Journal Publication
J.C. Beam, G. LeBlanc, E.A. Gizzie, B.L. Ivanov, D.R. Needell, M.J. Shearer, G.K. Jennings, C.M. Lukehart, and D.E. Cliffel, “Construction of a Semiconductor Biological Interface for Solar Energy Conversion: p-Doped Silicon/Photosystem I/Zinc Oxide,” Langmuir, 31, 10002-10007 (2015). - David was named a National Science Foundation I-Corps Fellow in 2019.
- David was named a CalSEED Concept Award Recipient in 2019.
- Co-author Journal Publication
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Jason Ray Alfaro - Physics, Juanita College
Educational Institution: Juanita College
List of Mentors: Dr. Qi Zhang & Kristina Kitko
Program: NSF REU
Research Project: Effects of Cholesterol Enhancement on Cell Properties in the Presence of Graphene
Research Abstract:
Graphene is a two-dimensional carbon crystal with remarkable mechanical strength and a singular electrical conductivity, a combination that has led to surging interest in its biomedical applications. However, this demands a clear understanding of graphene’s interaction with cell surface molecules and its impact on cell function. Here, based upon the observed increase of synaptic surface cholesterol in cells directly growing on bare graphene, we propose that graphene interacts with cholesterol. This increase changes the amount, the release probability, the turnover mode and the reuse rate of synaptic vesicles, which results in a presynaptic potentiation of neurotransmission. Further spectral analysis of fluorophore interaction with graphene reveals a time-dependent fluorescence decay that is unique from that of the fluorophore, consistent with the interaction involving energy transfer. Assaying for the cholesterol concentration of culture media in the presence of graphene may provide direct insight into this interaction. These data may be further supported by an increase in the membrane resistance in the presence of graphene, although additional verification is necessary. Our findings highlight a molecular mechanism underlying graphene's effect on the lipid membrane and cell signaling, which infers caution as well as opportunity in basic research and translational implementation of graphene. -
Jesús Sosa-Rivera - Biotechnology, Universidad del Este
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Educational Institution: Universidad del Este
List of Mentors: Dr. Craig Duvall
Program: NSF REU
Research Project: Localized Delivery of a Chemotherapeutic from Cell-Degradable Polymeric Films
Research Abstract:
Cancer is the second leading cause of death worldwide. In gastric cancer, most patients are treated by tumor resection in the early progression stages. However, recurrence of cancer at the margin of resection can occur in 50% of cases. Secondary, more systemic treatments like chemotherapy and external radiation are the current gold-standard treatments for inhibiting cancer recurrence but produce systematic totoxicities that can severely limit the long term survival of the patient. To limit these systemic toxicities, we hypothesize that prolonged, localized drug delivery at the tumor resection margins will prevent cancer cells proliferation and tumor recurrence. Here, we propose to incorporate a hydrophobic, anti-neoplasmic drug into a hydrophobic, acidically-inert, polymeric film to achieve prolonged drug release and sustained inhibition of cancer cell proliferation in the harsh environment of the stomach. These films were made with poly(thioketal) (PTK) polymers, which are both stable across a wide range of pH values and are specifically degraded by cell-produced reactive oxygen species (ROS). The PTK polymers, synthesized from biocompatible mercaptoethyl ether (MEE) monomers, were rigorously characterized and then incorporated into films by solvent casting with a non-degradable hexamethylene diisocyante trimer (HDIt). The PTK-UR films were loaded with either Nile Red (fluorescent hydrophobic model drug) or the strong anti-tumor hydrophobic drug 10-hydroxycamptothecin (HCPT), which has seen limited clinical use due to its poor aqueous solubility but has great potential as a locally delivered chemotherapeutic (Wolinsky, JB. et al 2010). In preliminary studies, Nile Red-loaded PTK-UR films demonstrate gradual, sustained levels of drug release when incubated in an ROS-producing medium, while demonstrating minimal drug release when incubated in saline. Ongoing studies are evaluating the cytotoxic activity of released HCPT and drug release under stomach-mimicking acidic conditions, while futures studies will evaluate the sustained cytotoxic effect of released HCPT both in vitro and in vivo.- Conference Presentation
J.Rivera-Sosa, J.R. Martin, C. L. Duvall, “Long term delivery of a chemotherapeutic from cell degradable polymeric films” Annual Biomedical Research Conference for Minority Students (ABRCMS) San Antonio, TX, November, 2014.
*Poster award in engineering, physics and mathematics category
- Conference Presentation
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Lucas Thal - Biochemistry, University of Tennessee, Knoxville
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Educational Institution: University of Tennessee, Knoxville
List of Mentors: Dr. David Cliffel & Gabriel LeBlanc
Program: NSF TN-SCORE
Research Project: A New Method for Improving Solar Energy Conversion: Side Selective Modification of Photosystem I
Research Abstract:
Adverse environmental impacts caused by traditional methods for harnessing energy have prompted the search for clean renewable energy. Recently, solar power has been at the forefront of researchers’ investigations for viable new, sustainable sources of energy. Solar cell devices on the market convert solar radiation to electricity at around 10-20% efficiency. They are constructed with inorganic materials (e.g. silicon, indium, and tellurium) that are resource- and cost-limiting. Alternatively, biohybrid cells produce photocurrent when integrated with the plant protein Photosystem I (PSI)—a sterically stable transmembrane redox protein found in light-dependent photosynthesis. This approach offers extremely efficient solar conversion (approaching 100% at specific wavelengths) without resource depletion. Given that the charge separation that occurs in is unidirectional with regard to PSI’s molecular orientation, the protein must be oriented on electrodes such that the P700 chlorophylls are aligned away from the electrode. Visual inspection of the crystal structure of the protein extracted from spinach (PDB ID: 2WSF), reveals that the hydrophilic areas are similar in both basic and acidic acid compositions. This similarity allows for the protein to bind to electrodes in both upright (P700 distal from the electrode) and inverted orientations. Previous research has shown that increasing the fraction of upright oriented proteins on electrode in turn increases photocurrent produced [1]. We can accomplish this by modifying the chemical properties of the hydrophilic regions to promote surface asymmetry so that the stromal/luminal sides of the protein have different affinities for the underlying electrode. Side-selective functionalization of extracted PSI was performed by pre-extraction EDC/Sulfo-NHS coupling to glutamic and aspartic acids with thiol terminated adducts on the stromal side of the thylakoid. We have shown that the functionalization was successful by performing - UV-vis and fluorescence spectroscopic analysis. We have also developed a chromatographic purification procedure that would potentially remove the unmodified proteins from the bulk sample. Currently, we are performing electrochemical analysis on the effectiveness of the functionalized samples. Further optimization of this method will create a new library of ligands to adjoin allowing for many new biomolecular applications.- Conference Presentations
-L. Thal, E. Gizzie, G. LeBlanc, G.K. Jennings, and D. E. Cliffel, “A New Method for Improving Solar Cell Conversion: Side Selective Modification of Photosystem I” 2014 ACS Southeast Regional Meeting, Nashville, TN, October, 2014.
-L. Thal, E. Gizzie, G. LeBlanc, G.K. Jennings, and D. E. Cliffel, “A New Method for Improving Solar Cell Conversion: Side Selective Modification of Photosystem I” 249th Annual American Chemical Society National Meeting and Exposition, Denver, CO, March, 2015. - Louie was awarded a Vanderbilt Chemistry-Biology Interface Training Grant
- Conference Presentations
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Holly Thomas - Mechanical Engineering, St. Ambrose University
Educational Institution: St. Ambrose University
List of Mentors: Dr. Melissa Skala & Jason Swartz-Tucker
Program: NSF REU
Research Project: Metabolic Imaging of Human Breast Carcinoma Treatments
Research Abstract:
Human breast carcinoma is known to dramatically alter cellular metabolism. Rather than generating ATP through oxidative phosphorylation, cancerous cells utilize aerobic glycolysis, which requires an increase in glucose consumption. Current autofluorescence imaging techniques, particularly two-photon microscopy, are capable of detecting changes in cellular metabolism by quantifying biological markers of cellular metabolic rate. These markers include the autofluorescent metabolic co-enzymes NADH and FAD, and two-photon microscopy is used to measure their fluorescence lifetimes and relative intensities (redox ratio). These measurements reflect enzyme activity and relative rates of cellular glycolysis, respectively. However, redox ratio and lifetime analysis neglects the possible effects of glucose uptake and mild hyperthermia in breast cancer cells. To measure glucose uptake in breast cancer cells, cells were incubated with the fluorescent glucose molecule 2-NBDG and imaged at the NADH and 2-NBDG emission wavelengths using two-photon microscopy. Additionally, cells were treated with the anticancer drugs trastuzumab, paclitaxel, and XL147 to investigate their effects on 2-NBDG uptake. The findings demonstrated a significant (p<0.05) decrease in 2-NBDG fluorescence in cells treated with anticancer drugs from those that were left untreated. Furthermore, treated and untreated breast cancer cells were incubated with iron oxide-coated gold nanorods and imaged at the NADH, FAD, and nanoparticle emission wavelengths to determine whether the presence of gold nanorods altered cellular metabolism. Controlled photothermal heating of nanorods in distilled water verified that the nanorods are capable of being heated, yet two-photon imaging indicated that the nanorods were not functionalized properly for in vitro applications. Further work must be done to properly functionalize the nanorods and image them in vitro to measure variations in cellular metabolism. 2-NBDG fluorescence imaging will likely be expanded to measure glucose uptake in three-dimensional organoids with the goal of implementing these measurements to determine the most beneficial treatment for breast cancer patients on an individual basis. -
Vincent Viola - Physics, Rhodes College
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Educational Institution: Rhodes College
List of Mentors: Dr. Peter Pintauro & Jun Woo Park
Program: NSF TN-SCORE
Research Project: Solvent Effects on Single-Fiber Electrospinning and Membrane Properties
Research Abstract:
Fuel cells utilize redox chemistry to convert chemical energy of various fuels, for example hydrogen, into electrical energy. They provide environmentally friendly alternative to conventional energy conversion devices, like internal combustion engines, that use fossil fuels. However, currently available fuel cells still require optimization to improve their performance and lifetime. The key areas of interest are more durable and cheaper catalysts and better membranes. This study focuses on novel proton conducting membranes fabricated using single-fiber electrospinning of Nafion-PVDF (polyvinylidene fluoride) blends. Here, a solution of Nafion and PVDF mixture is electrospun onto a rotating and oscillating aluminum target forming a porous mat of thickness 120-200 μm. The mat is then annealed at elevated temperture (150-210oC) and hotpressed at 182oC and 24000lb, to close the pores and create dense, defect free proton conducting membrane. Finally, the membrane is preconditioned in boiling 1M H2SO4 and then boiling water. The goal of this study is to understand the effect of electrospinning solvent, composition and post-processing conditions on the membrane proton conductivity, water uptake and swelling. The conductivity was measured using four-electrode Bekktech cell. Water uptake was measured gravimetrically and areal swelling was determined by comparing membrane’s dry and wet dimensions. The most desired characteristics were obtained for membranes electrospun from 80% Nafion and 20% PVDF, pre-compacted and annealed at 150oC for 1.5 hours under vacuum. The obtained conductivity was in the range 0.066-0.070 S/cm, the gravimetric swelling was in the range 12.91-13.74% mg/mg, and the areal swelling was in the range 15.59159681-17.98638329% mm2/mm2. Selected membranes will later be tested in hydrogen, direct methanol and hydrogen-bromine fuel cells. -
Patrick Wellborn - Chemistry & Engineering, Washington & Lee University
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Educational Institution: Washington and Lee University
List of Mentors: Dr. Kane Jennings & Max Robinson
Program: NSF REU
Research Project: Bridging the Gap: Photosystem I Initiated Polymer Growth for Solid-State Solar Cell Applications
Research Abstract:
Photosystem I (PSI) is a photocatalytic membrane protein contained within the thylakoid membranes of plants. Boasting ~1 V light-induced charge-separation and near-unity quantum yield, PSI has garnered interest as a photoactive species in next generation biohybrid solar cell devices. Order-of-magnitude improvements in generated photocurrents have been observed for PSI-integrated systems utilizing a liquid electrolyte mediator to transport photoexcited electrons from PSI to the anode. However, practical devices of this sort introduce problems of degradation and expense. Solid-state devices eliminate the need for liquid mediation, shuttling photoexcited electrons directly using solid conductive materials, creating a more durable device.This study explores a PSI-initiated polymerization technique, providing a route to more efficient PSI-PSI electron transport within the active layer of solid-state devices. Incident amino acid residues from PSI are used as initiators for Surface-Initiated Ring-Opening Metathesis Polymerization (SI-ROMP). A fluoro-alkyl substituted norbornene monomer—characterized by fast growth kinetics and a unique spectroscopic signature—was chosen for preliminary studies. Polarization-Modulation Infrared Reflection Absorption Spectroscopy (PMIRAS) and three-electrode photochronoamperometry were used to establish retained secondary structure and photoactivity during each step of the polymerization process.
Two methods of polymer attachment were utilized on PSI monolayers and multilayers: lysine-based attachment using amine termini and glutamic and aspartic acid-based attachment using carboxylic acid termini. Both methods proved successful for polymer growth, achieving ~10nm of growth on monolayers and hundreds of nanometers of growth on PSI multilayers. Results of polymer growth were characterized using goniometry, ellipsometry, profilometry, and IR. With no previous literature indicating polymer growth on proteins via SI-ROMP, this study acts as a proof-of-concept with promising results. Future work entails the synthesis of an anchored polythiophene (PT) monomer to a norbornene backbone, providing for a covalently-wired and highly conjugated polymer matrix for efficient PSI-PSI charge mediation.
- Patrick was awarded a NSF Graduate Research Fellowship in 2016.
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Anna Yanchenko - Physics & Math, University of Virginia
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Educational Institution: University of Virginia
List of Mentors: Dr. Richard Haglund & Rod Davidson
Program: NSF REU
Research Project: Electric-Field-Induced Second-Harmonic Generation in Asymmetric Nanogaps
Research Abstract:
Asymmetric plasmonic nanoparticles can be used to generate and control the spatial distribution of electric fields at the nanoscale in order to efficiently generate second-harmonic light and control its polarization response. Electric-field-induced second-harmonic generation (EFISH) allows for the optical modulation of second-harmonic light using an external, applied electric field. Previous work has shown modulation of EFISH signals using DC electric fields in plasmonic grating geometries. (Brongersma, Science 2011) The governing mechanism in second-harmonic generation is a second order, nonlinear process controlled by a tensor, χ(2), which vanishes under central symmetry. In our experiments, we fabricated novel asymmetric gold nanogaps and demonstrated that they produced second-harmonic light with a conversion efficiency on the order of 10-11. Three plasmonic geometries were fabricated to create unique electric field gradients on a length scale of the order of 100nm. Finite-difference time-domain (FDTD) simulations and experimental extinction spectra of the nanogaps were performed, and the nanogaps were found to have broad plasmonic resonances at 800 nm. The plasmons were excited with a horizontally polarized ultrafast Ti:Sapphire laser at 800nm and a spatial light modulator was used to compress these pulses to ~20fs. The SHG efficiency resulting from this plasmon excitation was measured as a function of power. PMMA was then deposited into the nanogaps, and we found that the PMMA red-shifted the plasmon resonance and reduced the SHG conversion efficiency due to absorption by the PMMA. Future experiments are planned with additional centrosymmetric materials, such as Si, Si3N4, and SiO2, non-centrosymmetric materials, like GaAs, and ferroelectric materials, such as BaTiO3. Additionally, the relation between the polarization of the incoming pulse and the produced SHG will be explored and further experiments are planned to pump the gold nanogaps with a different frequency of light (1053 nm), with potential applications for optical switching.- Co-author Journal Publication
R.B. Davidson, II, A. Yanchenko, J. Ziegler, S. Avanesyan, B. Lawrie, and R.F. Haglund, Jr., “Ultrafast Plasmonic Control of Second Harmonic Generation,” ACS Photonics, 3 (8), 1477-1481, (2016). - Conference Presentation
A. Yanchenko, R. Davidson, J. Ziegler, R. Marvel, S. Avanesyan, R. Haglund, “Electric-Field-Induced Second-Harmonic Generation in Serrated Nanogap Arrays” Southeastern Section of the American Physical Society” Columbia, SC, November 2014.
- Co-author Journal Publication
![VINSEREU2013 VINSEREU2013](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/30153556/VINSEREU2013.png)
2013
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Christopher Armenia - Chemistry, Villanova University
Educational Institution: Villanova University
List of Mentors: Dr. Eva Harth & Dan Beezer
Program: NSF REU
Research Project: Derivatization of Polyglycidol and the Synthesis of Hydrogels by Oxime Click ChemistryResearch Abstract:
A hydrogel is a network of hydrophilic polymers that has the ability to absorb water. These gels have similar properties to human organs and tissues, and thus have many medical applications, such as drug transport and gene therapy. These hydrogels can act as a matrix to which biomedical nanoparticles can be attached and allow drugs to be more effectively delivered throughout the human body. This project focused on the synthesis of polyglycidol hydrogels by functionalizing polyglycidol polymers and reacting these various derivatives with each other. Three different polyglycidols were synthesized: amino-oxy polyglycidol, 3-mercaptopropanoyl polyglycidol, and 4-pentenoyl polyglycidol. In order to characterize the properties of the derivatives that were synthesized, model reactions were conducted using 3-ethoxy-1,2-propanediol because it has similar functional groups to polyglycidol. Using click reactions, three hydrogels were synthesized: the first was composed of 3-mercaptopropanoyl polyglycidol and 4-pentenoyl polyglycidol, the second was composed of 4-pentenoyl polyglycidol and 3,6-dioxa-1,8-octanedithiol which acted as a linker between the polymers, and the third was composed of the amino-oxy polyglycidol and a previously synthesized polymer of o-phenylenediamine and valerolactone. These gels are further characterized of their functionalities and physical properties. -
Megan Burcham - Engineering, University of Tennessee, Martin
Educational Institution: University of Tennessee, Martin
List of Mentors: Dr. Peter Pintauro & Ethan Self
Program: NSF TN-SCORE
Research Project: Influence of Polymer Binder Properties on the Performance of Si-Based Anodes for Li-ion BatteriesResearch Abstract:
Since their 1990 market debut by Sony, Li-ion batteries (LIBs) have become a popular energy storage platform for portable electronic devices. Electric vehicles powered by LIBs have also experienced recent successes, but they are currently limited to short range commutes due to the low capacity of electrode materials. Silicon is a promising candidate for next generation LIB anodes due to its high theoretical capacity (3,576 mAh/g), which is an order of magnitude greater than that of graphite (372 mAh/g) used today in commercial battery anodes. Industrial adaptation of Si anodes, however, has been hindered by complications arising from Si volumetric changes (~400%) during battery charging and discharging. These volumetric swings ultimately lead to poor capacity retention resulting from Si electronic isolation and an unstable solid-electrolyte interface. In this study, a number of polymers —poly(acrylic acid), carboxymethyl cellulose, poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), and poly(vinylidene fluoride)—were investigated as potential binders to accommodate Si swelling without compromising the overall electrode integrity. The selected polymers contained different functional groups to better understand the effects of Si-binder and binder-electrolyte interactions on anode stability. Thermally induced polymer crosslinking was also examined as a way to house Si volume changes without disrupting the electronic conductivity network. Composite anodes containing Si nanoparticles and conductive carbon powder embedded in a polymeric binder were characterized in Li-ion half-cells where anode performance was evaluated by means of cyclic charge/discharge experiments. These composite anodes exhibited outstanding initial capacities, exceeding 1,000 mAh/g. Moderately stable anodes were obtained using binders that (i) participated in hydrogen bonding with the Si-O surface layer on the Si nanoparticles and (ii) exhibited low swelling in the battery electrolyte. Crosslinking the polymeric binders did not further enhance capacity retention. These findings will be used as reference data for future studies that will focus on silane surface modified Si nanoparticles. -
Emily Darby - Chemistry, Pomona College
Educational Institution: Pomona College
List of Mentors: Dr. David Cliffel & Gabriel Leblanc
Program: NSF REU
Research Project: Transparent Reduced Graphene Oxide Electrodes with Photosytem I for PhotoconversionResearch Abstract:
Photosystem I (PSI) is a photoreactive electron transport protein found in plants that participates in the process of photosynthesis. Because of PSI’s abundance in nature and its efficiency with charge transfer and separation, we are interested in applying the protein to photovoltaic devices. Past research has shown increased photocurrents by integrating PSI with graphene electrodes. Here, we developed a transparent, conductive electrode using reduced graphene oxide (RGO) on which PSI could be deposited. The electrodes were characterized using Raman spectroscopy, UV-Vis spectroscopy, and electrochemical techniques; and we determined the photocurrent density in varying concentrations of several mediator solutions.The use of transparent RGO electrodes is an attractive alternative to graphene because it affords facile and inexpensive production through chemical processes. Furthermore, the transparency of the RGO electrode gives us the ability to utilize an opaque mediator solution, such as dichloroindophenol. The resulting photoelectrode demonstrated current densities comparable to a gold electrode modified with PSI and significantly higher than a graphene electrode modified with PSI. The relatively large photocurrents produced by integrating PSI with RGO and using an organic mediator can be applied to the production of more economic, easily produced, and completely organic solar cells.
- Darby 1st author on Langmuir Journal Publication
E. Darby, G. LeBlanc, E.A. Gizzie, G.K. Jennings, and D.E. Cliffel, “Photoactive Films of Photosystem I on Transparent Reduced Graphene Oxide Electrodes,” Langmuir, 30 (29), 8990-8994 (2014). - Conference Presentations
-E. Darby, G. LeBlanc, G. K. Jennings, and D. E. Cliffel “Transparent Reduced Graphene Oxide with Photosystem I for Photoconversion,” Pacific Conference on Spectroscopy and Dynamics, Pacific Grove, CA, January, 2014.
-E. Darby, G. LeBlanc, G. K. Jennings, and D. E. Cliffel “Transparent Reduced Graphene Oxide with Photosystem I for Photoconversion,” Southern California Undergraduate Research Conference in Chemistry and Biochemistry, Irvine, CA, April, 2014. (oral presentation) - Emily was awarded 2014 Goldwater Scholarship.
- Emily was awarded a NSF Graduate Research Fellowship in 2015.
- Darby 1st author on Langmuir Journal Publication
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Domenic DiGiovanni - Physics/Economics, Hillsdale College
Educational Institution: Hillsdale College
List of Mentors: Dr. Yaqiong Xu & Roel Flores
Program: NSF TN-SCORE
Research Project: Chemical Treatment Effects on the Photoluminescence and Raman Spectra of Atomically-Thin Molybdenum DisulfideResearch Abstract:
Monolayers of the transition-metal dichalcogenide molybdenum disulfide exhibit properties that could make the material ideal for future nano-scale optoelectronic applications. The monolayers’ direct bandgap property and photocurrent-generating ability makes single-layer MoS2 a promising material for use in nano-scale devices such as high-sensitivty photodetectors. This study focuses on the changes of MoS2 monolayers’ photoluminescence (PL) and Raman spectra due to chemical treatments. Samples of few-layer and single-layer MoS2 obtained using mechanical exfoliation and transferred to SiO2 substrates were treated with ozone or oxygen plasma. The flakes were identified using optical microscopy and analysis of Raman spectra; their PL and Raman spectra were measured before and at various stages during the plasma treatment. Synthesis of MoS2 monolayers using a vapor-solid method for the purpose of comparative study was also attempted and is discussed. This study demonstrates that the photoluminescence of the monolayers increases by up to a factor of four with the plasma treatments, perhaps due to the adsorption of oxygen. In the future, we plan to improve our synthesis methods and to investigate how optoelectronic properties of MoS2 phototransistors’ can be altered by chemical and x-ray treatments. -
Jon Paul Elizondo - Mechanical Engineering, Texas A&M University
Educational Institution: Texas A&M University
List of Mentors: Dr. Cary Pint & Dr. Rizia Bardhan & Landon Oakes
Program: NSF REU
Research Project: Electrophoretic Deposition of Nanomaterials for Plasmonically Enhanced PhotodetectorsResearch Abstract:
Nanocarbon materials coupled with plasmonically active nanoparticles show great promise in ultrafast, tunable photodetection. However, current methods for producing such devices are costly and non-scalable, making them impractical for manufacturing. In this study, we propose electrophoretic deposition (EPD) as an alternative means for fabricating structures necessary for plasmonically enhanced photodetectors. EPD is a scalable, cost-effective assembly method that utilizes coulombic interactions to deposit materials onto a substrate. Typical substrates used in the EPD process are conductors; however, through the application of novel EPD techniques we have deposited films of Au nanoparticles and graphene onto dielectrics, creating morphologies suited for plasmonic photodetection. Tests of these devices indicate slight plasmonic activity (~1% difference), and we believe that future optimization of the EPD process will significantly improve these results. -
Timothy Haley - Physics, University of Tennessee, Chattanooga
Educational Institution: University of Tennessee, Chattanooga
List of Mentors: Dr. Kirill Bolotin & Hiram Conley
Program: NSF TN-SCORE
Research Project: Chemical Vapor Deposition of Atomically Thin Films of MoS2 for Electro-Optical DevicesResearch Abstract:
After graphene was developed and the scientific community began to understand its properties and limitations, it became prudent to explore other two-dimensional materials. Molybdenum Disulfide is a dry lubricant with similar properties to graphite. Likewise, we may confine it to a single layer, where it becomes an atomically thick, 2D material. Unlike graphene, monolayer Molybdenum Disulfide is a direct band gap semiconductor. This property allows monolayer MoS2 to be useful in the field of optics and will allow monolayer MoS2 to be integrated into modern electronic devices like resonators and transistors. As of now, the majority of monolayer MoS2 is obtained by using exfoliation methods. These methods produce quality monolayers but have limited flake size. Here, we explore chemical synthesis processes for creating millimeter-sized atomically thin films of MoS2. We then intend to use this material to fabricate tunable electro-optical devices. In these devices, a film of MoS2 suspended over a hole can be controllably strained using a gate electrode. Since it has been shown that the band gap of monolayer MoS2 is inversely proportional to strain, the band gap of these membranes -- and hence their optical absorption and photoluminescence -- would be tunable by controlling their deflection. These devices could have the potential to create more efficient photovoltaic devices, tunable lasers, and excitonic concentrators. -
Jeffrey Holzgrafe - Engineering & Physics, Olin College
Educational Institution: Olin College
List of Mentors: Dr. Cary Pint & Landon Oakes
Program: NSF REU
Research Project: Electrophoretic Deposition for Inexpensive Carbon Nano-Composite Lithium Air Battery CathodesResearch Abstract:
Lithium air batteries take advantage of a reversible oxidation reaction of lithium with O2 to create a rechargeable energy source with energy densities that could approach that of gasoline. We demonstrate that the relatively inexpensive and easily scaled process of electrophoretic deposition can be used to create carbon nanotube-nanohorn composite air electrodes for Li-air batteries. Preliminary results suggest that these composite materials improve the specific capacity of Li-air batteries over that of nanotube only materials. While significant work is still required to control and optimize these composites, the results suggest that electrophoretic deposition is a viable high-throughput process for manufacturing improved Li-air battery cathodes.- Co-author Journal Publication
R. Carter, L. Oakes, J. Holzgrafe, H. Zarick, S. Chatterjee, R. Bardhan, and C. Pint, “Solution assembled single walled carbon nanotube foams; Superior performance in supercapacitors, lithium ion, and lithium air batteries,” Journal of Physical Chemistry, 118 (35), 20137-20151 (2014). - Holzgrafe named 1st Marshall Scholar at Olin College
- Holzgrafe awarded 2014 Goldwater Scholarship
- Co-author Journal Publication
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Olivia Hurd - Engineering, Vanderbilt University
Educational Institution: Vanderbilt University
List of Mentors: Dr. Rizia Bardhan & Holly Zarick
Program: NSF TN-SCORE
Research Project: Au@SiO2 Core-Shell Nanocubes for Plasmon-Enhancement of Dye-Sensitized Solar CellsResearch Abstract:
As the need for renewable sources of energy has become a more pressing topic, a number of solutions have been presented and remain in the running as promising sources of energy, solar cells included. In order for any energy source to remain competitive, devices must constantly make advances in terms of cost and efficiency. In the field of photovoltaics, dye-sensitized solar cells (DSSCs) were introduced as an economical alternative to the traditional silicon-based solar cells, but modifications can still be made to improve the efficiencies of these DSSCs and make them more comparable to the traditional solar cells. This project focuses on improving the photo conversion efficiencies of these cells through plasmon-enhancement. Brown et al. [Plasmonic Dye-Sensitized Solar Cells Using Core-Shell Metal-Insulator Nanoparticles. Nano Lett. 2010, 11, 438-445] showed efficiency improvements through plasmon-enhancement achieved with core-shell Au@SiO2 nanospheres. Similarly, this project focuses on the integration of Au@SiO2 nanocubes. These nanocubes, as opposed to nanospheres, show near-field enhancement at their corners and edges due to localized surface plasmons, which prompts greater efficiencies in the completed cells. The DSSCs are enhanced and tested using two different incorporation geometries of the nanocubes, top layer and imbedding. Top layer geometry is achieved by airbrushing the nanocubes over the layer of titania on the anode of the cell, so that they remain mostly on top of the titania. Cells with the imbedded geometry are made by mixing the nanocubes directly into titania paste before it is added as a layer onto the cell. The efficiencies of these enhanced cells and those of reference cells lacking nanoparticles are tested using a solar simulator and a potentiostat, and the photo conversion efficiencies of DSSCs with incorporated nanocubes are found to be greater. Future work will continue to compare the efficiencies of reference cells with those of Au@Ag@SiO2 nanocube-enhanced DSSCs.- Co-author Journal Publication
-H.F. Zarick, O. Hurd, J.A. Webb, Chanse Hungerford, and Rizia Bardhan, “Enhanced Efficiency in Dye-Sensitized Solar Cells with Shape-Controlled Plasmonic Nanostructures,” ACS Photonics, 1 (9), 806-811 (2014).
-H. F. Zarick, W. R. Erwin, A. Boulesbaa, O. Hurd, J. A. Webb, A. Puretzky, D. Geohegan, R Bardhan*, "Improving Light Harvesting in Dye Sensitized Solar Cells using Hybrid Bimetallic Nanostructures", ACS Photonics, 3, 385–394 (2016).
- Co-author Journal Publication
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Jacob Jordan - Engineering, Tennessee Tech University
Educational Institution: Tennessee Tech University
List of Mentors: Dr. David Cliffel & Gabriel LeBlanc
Program: NSF TN-SCORE
Research Project: Synthesis of Polyviologens as Mediators for Photosystem I-Based AssembliesResearch Abstract:
Photosystem I (PSI) is a well-studied integral membrane protein that is found in algae, bacteria, and plants that mediates electron photo-excitation. When an electron within PSI is excited by light, it is transported across the protein through a series of electron accepting steps in the electron transport chain and is finally carried to the Fb site, an iron-sulfur complex that acts as a final electron acceptor. This project centers around removing electrons from the Fb site to a counter electrode in order to complete the circuit. Viologens have been an interesting mediator type to study as they have a formal potential very similar to that of the Fb site and thus can accept the electron from PSI with relatively little energy loss. Polyviologens are of specific interest as the polymer network allows increased electron transfer, reduces orientation effects, stabilizing PSI, and allowing a three-dimensional network. Electrochemical tests involving various electrode setups allowed us to generate photo-response data for polyviologens when used in conjunction with PSI. The polyviologens were synthesized using the Menshutkin reaction and characterized with 1H NMR and electrochemistry. Two different PSI-polymer electrode setups were assembled in order to test the photo-response: a gold macro-electrode system that was alternately layered with a polymer and PSI; and a heavily-P-doped silicon electrode system that used the polymers as aqueous mediators. -
Helena Keller - Chemical Engineering, Michigan Tech University
Educational Institution: Michigan Tech University
List of Mentors: Dr. Kane Jennings & Leo Yang
Program: NSF REU
Research Project: Organic Monolayers on p-Doped Silicon Affect Photocurrents of Photosystem I FilmsResearch Abstract:
Biohybrid solar cells convert light energy to electricity through the use of Photosystem I (PSI), a protein complex that drives photosynthesis in green plants. The near-one-hundred percent quantum efficiency of PSI, in addition to its vast abundance in nature, gives this technology enormous potential as a sustainable source of energy. Prior work from our group has shown that PSI films on p-doped silicon yield photocurrents that approach 1 mA/cm2, far exceeding those for PSI on metals or for unmodified silicon. In this project, we have investigated the use of organic monolayers deposited between the p-doped silicon semiconductor and the PSI layer to facilitate electron transfer and increase the stability of the PSI film. These monolayers were prepared by exposing silicon to solutions containing -terminated alkynes to produce an alkenyl attachment of the monolayer to silicon and create a surface of the -terminated functionality for interaction with PSI. Of the monolayer surface groups tested, including alcohols, amines, carboxylic acids, and covalently reactive groups, the carboxylic acid terminus most consistently achieved the highest photocurrents, suggesting favorable electrostatic attraction between the negative surface of the monolayer and positive patches on PSI. Carboxylic acids of varying carbon chain lengths—specifically three, five, six, and seven carbons—were then tested using photochronoamperometry in order to observe the effect of monolayer thickness on photocurrent as well as the stability of the photocurrent over time.- Conference Presentation
H. Keller, S. Yang, G. LeBlanc, D. E. Cliffel and G. K. Jennings. “Organic Monolayers on p-Doped Silicon Affect Photocurrent of Photosystem I Films,” 2013 AIChE Annual Meeting: Global Challenges for Engineering a Sustainable Future, San Francisco, CA, November, 2013. - Helena was awarded a $1K travel grant at the capstone poster session.
- Helena was awarded a NSF Graduate Research Fellowship
- Conference Presentation
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John Lonai - Physics & Engineering, Northwest Nazarene University
Educational Institution: Northwest Nazarene University
List of Mentors: Dr. Sharon Weiss & Gilbert Rodriquez
Program: NSF REU
Research Project: Optimized porous silicon Bloch surface and sub-surface wave structure for simultaneous detection of small and large moleculesResearch Abstract:
A Porous silicon (PSi) Bloch surface and sub-surface wave (BSW/BSSW) biosensor is optimized and demonstrated for the size selective detection of both small and large molecules. PSi biosensors have been previously shown to offer enhanced label-free sensing of small biological and chemical molecules that can infiltrate the pores due to a large internal surface area and tunable optical properties. The PSi BSW/BSSW biosensor offers the possibility to sensitively detect both small molecules that infiltrate the pores and large molecules attached on the sensor surface. The BSW/BSSW structure consists of a periodic stack of high and low refractive index layers, known as a Bragg mirror, with a reduced optical thickness surface layer. The truncated surface layer gives rise to a BSW with an evanescent tail that extends above the surface and enables the detection of large surface-attached molecules that cannot penetrate the porous matrix. Implementation of a step or gradient refractive index profile within the Bragg mirror generates a large electric field intensity spatially localized to a desired region of the mirror, known as the BSSW. The BSSW mode is entirely confined within the multilayer Bragg mirror and can detect small molecules attached within the pores with an enhanced sensitivity compared to other PSi biosensor designs. The design and experimental realization of optimized step and gradient refractive index profiles necessary to realize the BSSW is presented here for the first time. The PSi BSW/BSSW biosensor is designed using rigorous coupled wave analysis and transfer matrix theory simulations. Size-selective molecular detection is demonstrated using a prototypical small chemical molecule, 3-Aminopropyltrimethoxysilane (3-APTES; size of 0.8 nm) and large, 60 nm carboxyl latex nanospheres. Attachment and quantification of the small and large species are performed by monitoring the angle-resolved reflectance spectrum of the PSi BSW/BSSW structure. The BSW and BSSW modes are each manifested as a distinct resonance peak in the spectrum, and the angular shift of each peak can be used to quantify the number of molecules or nanospheres attached to the sensor. Detection and quantification of the 3-APTES attachment and nanosphere binding is separately performed with the BSSW mode and BSW mode, respectively. Good agreement between theoretical simulations and experimental measurements is found for both the PSi step and gradient BSW/BSSW biosensors. The size-selective detection of both small and large molecules using the same sensor platform is expected to be a significant advantage for future multi-analyte detection schemes using a microfluidics approach.- Co-author Journal Publication
G. Rodriguez, J.D. Lonai, R.L. Mernaugh, and S.M. Weiss, “Porous silicon Bloch surface and sub-surface wave structure for simultaneous detection of small and large molecules,” Nanoscale Research Letters, 9 (1), 383 (2014). - Conference Presentation
G. A. Rodriguez, J. D. Lonai, and S. M. Weiss, “Porous silicon Bloch surface and sub-surface wave structure for simultaneous detection of small and large molecules,” Porous Semiconductors – Science and Technology Conference, Benidorm, Alicante, Spain, March, 2014. [selected as invited talk by peer review]
- Co-author Journal Publication
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Katina Mattingly - Engineering & Physics, Murray State University
Educational Institution: Murray State University
List of Mentors: Dr. Jason Valentine & Wei Li
Program: NSF REU
Research Project: Development of nanophosphor films for use in thermometry of nanoscale thermoplasmonic antennaeResearch Abstract:
With a variety of applications in optics, semiconductors, and drug delivery; thermoplasmonic nanoantennae, which act as nanoscale heat sources, have a growing need for optimization and characterization. Current thermometry techniques that implement phosphors involve a high temperature annealing step. This step, used after deposition of the phosphor film, limits the device design and allowable substrates. In this project, an improved thermometry technique based on nanophosphors is investigated in an effort to improve current thermal characterization ability. To achieve maximum detector coverage, a nanoparticle phosphor film has been developed. Cerium doped yttrium aluminum garnet phosphor powder was first created via combustion synthesis and then transformed into nanoparticles via laser ablation. The nanoparticles are distributed onto nanoscale plasmonic devices in a uniform film that is utilized to detect the local temperature through the temperature dependent photoluminescence lifetime of the phosphor. The proposed thermometry technique removes the necessity of an annealing process, allowing for greater flexibility in device design and material. This research will help optimize thermometry of thermoplasmonic antennae and remove limitations on design parameters. -
Marc Panu - Chemical Engineering, Vanderbilt University
Educational Institution: Vanderbilt University
List of Mentors: Dr. Bridget Rogers & Courtney Mitchell
Program: NSF TN-SCORE
Research Project: Fabrication of Gadolinium Aluminum Garnet Phosphor by Combustion SynthesisResearch Abstract:
Cerium-doped gadolinium aluminum garnet (GAG:Ce) can be used to improve the efficiency of white-light LEDs (light emitting diodes). The Rogers group has gained expertise in combustion synthesis of yttrium aluminum garnet doped with Ce and/or Eu, however the process procedure does not produce good quality, pure phase GAG. This project focused on developing a gel-combustion synthesis of GAG:Ce. Photoluminescence (PL) spectroscopy, powder x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were used to characterize the effects of processing conditions on the resulting materials’ properties. Fuel type, combustion temperature, annealing temperature and annealing time were investigated. XRD showed that nearly pure phase GAG was formed by using citric acid as the fuel, a combustion temperature of 500°C, and a 4.5 hour, 1100 °C anneal. The trends observed in our results are consistent with phase diagrams that indicate pure-phase GAG should be formed at 1200 °C and above. Material combusted at 400 °C and annealed for 14 hours at 1100 °C had the most intense PL emission but did not contain the most garnet phase of the materials produced. This observation indicates PL emission intensity depends on factors in addition to crystal phase. We investigated the effects of host doping on GAG PL intensity. Yttrium was substituted for gadolinium, and gallium was substituted for aluminum in the GAG lattice. XRD and XPS analyses were used to interpret the trends in PL emission of these host-doped materials.- Conference Presentations
-M. Panu, C. A. Mitchell, S.L. Gollub, B.R. Rogers, and G. Walker, “Optical Property Tuning of Cerium-Activated Gadolinium Aluminum Garnet Phospor Powders,” GEM 2013: Expanding Our Horizons, San Juan, Puerto Rico, August, 2013.
-M. Panu, C. A. Mitchell, S.L. Gollub, B.R. Rogers, and G. Walker, “Combustion Synthesis of Gadolinium Aluminum Garnet (GAG) Phosphor,” AICHE conference, San Francisco, CA, November, 2013.
-M. Panu, C. A. Mitchell, S.L. Gollub, B.R. Rogers, and G. Walker, “Optical Property Tuning of Cerium-Activated Gadolinium Aluminum Garnet Phospor Powders,” National Society of Black Engineers -Region 3, Lexington, KY, November, 2013. *won first place able to present at National NSBE conference
-M. Panu, C. A. Mitchell, S.L. Gollub, B.R. Rogers, and G. Walker, “Optical Property Tuning of Cerium-Activated Gadolinium Aluminum Garnet Phospor Powders,” National Society of Black Engineers -National Meeting, Nashville, TN, March, 2014.
- Conference Presentations
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Michael Reynolds - Physics, Columbia State Community College
Educational Institution: Columbia State Community College
List of Mentors: Dr. Richard Haglund & Jed Ziegler
Program: NSF REU
Research Project: Good Vibrations: Plasmon-Exciton Coupling in Gold/Molybdenum Disulphide Hybrid SystemsResearch Abstract:
Monolayer Molybdenum Disulphide (MoS2), a two dimensional transition metal dichalcogenide, has interesting optical and electronic characteristics, specifically a direct optical band gap of 1.85 eV that is tunable by stress, applied voltage, as well as optical excitation source intensity. This band gap along with a large (0.5 eV) exciton binding energy makes MoS2 an attractive candidate for applications in two dimensional photoelectronics. In this study, we intend to couple the excitons from MoS2 to a second species of bound state generated in gold nanoparticles, the local surface plasmon, which is the oscillation created by electron cloud and photon wave coupling as light passes through metallic particles. We fabricate gold nanorods of varying lengths on top of MoS2 flakes separated by a spacer layer to promote direct coupling between the two bound states, excitons and plasmons. Photoluminescence measurements are taken using excitation energies at 532 nm and 633 nm, to probe the exciton-plasmon binding behavior of the hybrid system. This system presents in two configurations, which are observable in the photoluminesce and extinction spectra: off resonant enhancement or on resonant binding. Off resonant enhancement occurs when the resonant energy of the plasmon occurs at a higher energy than the energy of the exciton, resulting in an increase in exciton emission intensity. On resonant binding occurs when the resonant energy of the plasmon is equal to the exciton energy and results in a significant blue shift and enhancement of the MoS2 excitonic photoluminescent peaks. This typically signifies strong, coherent coupling between the exciton and plasmon, a bound state termed plexcitons. The plexciton could be used to modulate and enhance the excitonic properties of MoS2 and thereby introduce further versatility to MoS2-based two dimensional transistors. -
Ryan Rhoades - Physics & Applied Math, Florida State University
Educational Institution: Florida State University
List of Mentors: Dr. Richard Haglund & Rod Davidson
Program: NSF REU
Research Project: Mapping Plasmonic Response of Nanostructures via Multiphoton Absorption in Poly (methyl methacrylate)Research Abstract:
The near-field plasmon response of nanoparticles has previously been mapped by complex techniques such as electron energy-loss spectroscopy (EELS) and scanning near-field optical microscopy (SNOM). However, recent research has shown that four-photon absorption in poly(methyl methacrylate) (PMMA) is a more efficient way to map and characterize localized surface-plasmon resonance modes. In this work, the use of PMMA development as an optical means to characterize plasmonic responses in the near-field is verified with simple nanoparticles and then applied to more complex structures with resonance modes that have been only computationally observed. Nanoparticles were spin-coated with PMMA, exposed to an Ti:sapphire laser to induce areas of intense electric fields that cause polymer scission. Once the polymer is developed, it is characterized by scanning-electron microscopy to create an electric near-field intensity profile that corresponds with areas where the strong localized surface-plasmon resonance has generated the largest electric field. This process then will be used to experimentally map multiple plasmonic modes in gold Archimedean nanospirals. Future studies will refine and optimize this characterization technique and apply it to additional complex resonance modes in nanospirals and other asymmetric nanoparticles. -
John Shannon - Biochemistry, Colorado State University
Educational Institution: Colorado State University
List of Mentors: Dr. James Crowe
Program: NSF REU
Research Project: Exploring Respiratory Syncytial Virus Fusion and Matrix Protein Interactions in Membranes Using Recombinant Proteins and NanodiscsResearch Abstract:
Respiratory syncytial virus (RSV) belongs to the Paramyxoviridae family and is the leading cause of severe viral respiratory disease in young children, the elderly and immunocompromised individuals. Currently, there is no effective vaccine available and each year there are over 64 million reported cases of RSV resulting in ~160,000 deaths worldwide. RSV infects predominately epithelial cells of the upper respiratory tract, and little is known about how the virus mediates viral assembly and release in the host. In cell culture systems, it has been shown that RSV infects at, and is released from, the apical surface of polarized cells and exhibits distinct and dynamic filamentous structures in non-polarized cells. Our laboratory has previously shown that RSV viral filament formation requires interaction of the viral nucleoprotein (N), matrix (M) protein, and phosphoprotein (P) through a terminal phenylalanine (Phe) residue of the fusion protein cytoplasmic tail (F CT). We hypothesized that RSV M and RSV F have a transient interaction that mediates assembly of the viral proteins into filamentous structures prior to budding and release from epithelial cells. Data provided here using site-directed mutagenesis and confocal microscopy show attenuated filament formation in RSV M mutants, as compared to those that possess the wild-type sequence of M protein. Given the transient nature between RSV M and F, it has been difficult to detect the interaction through commonly used molecular and cell biology techniques. We sought to develop an innovative method to examine the transient interaction between these viral proteins utilizing nanodiscs and Förster resonance energy transfer (FRET). We generated a RSV F CT wild-type recombinant soluble protein and a F CT (F22A) mutant protein to be assembled and displayed in a nanodisc platform, and we used these constructs in interaction assays using FRET-based technologies. This approach will provide a practical method for examining transient protein-protein interactions that occur only in the context of lipid bilayer membranes. Data obtained through these various assays provides insight into the mechanism controlling RSV viral egress, leading towards the development of novel disease interventions- Conference Presentation
J.P. Shannon, J.A. Pickens, J.E. Crowe, “Exploring Respiratory Syncytial Virus Fusion and Matrix Protein Interactions in Membranes Using Recombinant Proteins and Nanodiscs,” Keystone Symposia: Pathogenesis of Respiratory Viruses, Keystone Colorado, January, 2014. - John was awarded a $1K travel grant at the capstone poster session.
- John was a 2016-2017 and 2017-2018 NIH IRTA fellow
- John was awarded an NIH Oxford-Cambidge Scholarship in 2018
- Conference Presentation
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Corban Swain - Biomedical Engineering, Washington University, St. Louis
Educational Institution: Washington University, St. Louis
List of Mentors: Dr. Craig Duvall & Chris Nelson
Program: NSF REU
Research Project: Controlled Release of siRNA from Hydrolytically Degradable Nanomicelles for Potent Gene KnockdownResearch Abstract:
RNA interference—an endogenous system in eukaryotic cells by which double-stranded RNAs lead to the degradation of complementary mRNA—can be exploited by small interfering RNAs (siRNAs) to silence almost any gene in the human body.[1] This premise allows siRNA to be utilized as a targeted therapeutic agent against disease. However, siRNA alone is prone to degradation by enzymes and marked by limited transfection into cells; moreover, delivery is the primary barrier to the use of siRNA as a therapeutic. Our previous work has shown safe and effective delivery of siRNA and gene silencing in cells with the use of PEG-shielded#, pH-responsive, endosomolytic, micellar nano-polyplexes (NPs) formed from diblock copolymers[2] (poly(EG-b-[BMA-co-DMAEMA]))*.Intracellular release of siRNA from NPs once they have been internalized is a limiting step in siRNA bioavailability and bioactivity. In this study, working under the motivation to have greater siRNA release post endosomal escape, we employ a new set of polymers (poly(EG-b-[BMA-co-DMAEA]))** capable of self-catalyzed hydrolysis. In aqueous solution, poly(DMAEA) will degrade to poly(acrylic acid) and a benign alcohol; by this process the positive charge on the BMA-co-DMAEA polymer block will undergo charge reversal over time, leading to decomplexation and release of negatively charged siRNA. Förster resonance energy transfer (FRET) studies showed our hydrolytically degradable (HDG) NPs to have significantly greater release (with tunability) of labeled DNA over time when compared to non-HDG NPs. Flow cytometry measurements showed comparable cellular uptake for HDG NPs vs. non-HDG NPs at multiple dosages, proving that cellular uptake is not significantly reduced despite the different polymer chemistry of our HDG NPs. These data suggest that HDG NPs are a novel platform to improve siRNA gene silencing through enhanced intracellular bioavailability. Ongoing work will confirm improved intracellular release and bioactivity of HDG NPs relative to our established non-HDG NP system.
- Co-author Journal Publication
T.A. Werfel, C. Swain, C.E. Nelson, K.V. Kilchrist, B.C. Evans, M. Miteva,C.L. Duvall, “Hydrolytic Charge-reversal of PEGylated Polyplexes Enhances Intracellular Un-packaging and Activity of siRNA” Journal of Biomedical Materials Research: Part A., 104 (4), 917-27, (2016). - Conference Presentations
-C.N. Swain, C.E. Nelson, C.L. Duvall, “Charge Reversing, Endosomolytic Nanoparticles to Enhance Intracellular Bioavailability of siRNA,” Annual Meeting of the Biomedical Engineering Society, Seattle, WA, September 2013. (Oral)
-C.N. Swain, C.E. Nelson, C.L. Duvall, “Charge Reversing, Endosomolytic Nanoparticles to Enhance Intracellular Bioavailability of siRNA,” Washington University in St. Louis Chapter of BMES, St. Lous, MO, November, 2013.
-C.N. Swain, C.E. Nelson, C.L. Duvall, “Charge Reversing, Endosomolytic Nanoparticles to Enhance Intracellular Bioavailability of siRNA,” Washington University in St. Louis Journal Club for Undergraduates in Biological Engineering and Sciences, St. Louis, MO, February, 2014.
-C.N. Swain, C.E. Nelson, C.L. Duvall, “Charge Reversing, Endosomolytic Nanoparticles to Enhance Intracellular Bioavailability of siRNA,” Washington University in St. Louis Spring 2014 Undergraduate Research Symposium, St. Louis, MO, April, 2014. - Corban was awarded a Department of Defense SMART Scholarship
- Corban was awarded a NSF Graduate Research Fellowship
- Co-author Journal Publication
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Miranda Trentle - Chemistry, University of Tennessee, Chattanooga
Educational Institution: University of Tennessee, Chattanooga
List of Mentors: Dr. Rizia Bardhan & Will Erwin
Program: NSF TN-SCORE
Research Project: Large Area Nanoplasmonic Architectures for Solar Applications”Research Abstract:
Solar energy represents a transformational energy resource for future sustainability. Everyday ~0.56x1022 J of energy is incident on Earth from sunlight. By efficiently harvesting only 7 % of this incident light in one day, the global energy needs (0.41x1021 J) for one year can be effectively fulfilled. Solar energy driven dye-based and polymer-based organic solar cells offer a promising and inexpensive alternative to crystalline Si solar cells; however, the efficiencies of these organic solar cells remain <10%. Recent advances have demonstrated that plasmon resonances in metal nanostructures can be engineered to enhance carrier collection in adjacent molecules and semiconductors resulting in significant optical enhancements and better performance. However, the integration of plasmonic nanostructures for enhanced photon concentration in organic solar cells remains in its infancy due to the lack of conceptual understanding of plasmonic engineering. Therefore in this project I have designed large area plasmonic architectures with various geometries and dimensions, and unique optical resonances enabling the capture of broadband solar radiation. These wafer scale nanoplasmonic architectures have ideal surface characteristics to directly integrate with organic and inorganic media for solar device fabrication.The plasmonic architectures (nanoholes, Fischer patterns, and nanocups) were designed by nanosphere lithography (NL). In NL a close-pack monolayer of polystyrene or silica nanospheres are formed on a substrate by self-assembly, followed by metal deposition to generate an array of plasmonic architectures. Unlike electron beam lithography which is reproducible but is a slow, expensive process, NL has low precision, but is relatively fast and cost effective. In our approach we casted a closed-packed layer of nanospheres on the surface of water and then transferred the free-floating nanosphere mask on a solid substrate. Long range ordering (~ 1 cm x 1 cm) with very few defects were observed using this method of NL. By using nanospheres of different sizes, and combing Cr/Au deposition by electron beam and reactive ion etching, we generated plasmonic Fischer patterns and nanoholes of variable diameters and pitch length. The plasmon resonances of these large area architectures are highly tunable by simply altering the nanosphere size. Our experimental absorption properties demonstrate a broadband absorption across the visible and near-field overlapping with the solar spectrum. We are currently designing routes to integrate these with standard dye-sensitized solar cells to achieve higher efficiency by plasmonic enhancement.
![2012 REU 2012 REU](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/30153307/2012-REU.png)
2012
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Keisha Carr - Chemical Engineering, University of Maryland
Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. David Piston and Dr. Tara Schwetz
Program: NSF REU
Research Project: α-cell Response to Low GlucoseResearch Abstract:
Pancreatic α-cells play an important role in regulating glucose homeostasis by secreting glucagon during hypoglycemia. To date, it has been poorly understood how intact α-cells respond to very low levels of glucose (less than 1mM). To elucidate α-cell behavior within the islet, mouse islets were loaded with Fluo4-AM, a calcium (Ca2+) indicator dye, to detect changes in intracellular Ca2+. The islets were exposed to glucose concentrations between 0.1 and 5 mM and the changes in α-cell parameters were determined by confocal microscopy. Further, two-photon excitation microscopy was used to measure the combined autofluorescence of NADH and NADPH (NAD(P)H, collectively), which serves as a cellular redox state indicator and provides information on the cell's metabolic activity. NAD(P)H autofluorescence was measured as a function of glucose (between 0.1 and 5 mM). As glucose concentration increases, both Ca2+and NAD(P)H activity also increase. However, there is minimal activity at 0.1 mM glucose in the α-cells. These data show that intact α-cells exhibit a reponse to glucose even at very low concentrations. Thus, it is postulated that α-cell activity as a function of glucose may be left-ward shifted compared to the β-cell, which is active at higher glucose levels. -
William Crosby - Chemistry, University of Tennessee - Martin
Educational Institution: University of Tennessee, Martin
List of Mentors: Dr. David Cliffel and Gabriel LeBlanc
Program: NSF TN-SCORE
Research Project: Photoreduction of Graphene Oxide with Photosystem IResearch Abstract:
Photosystem I (PSI) is a protein in green plants that carries out the processes of photosynthesis. Graphene has shown potential and popularity in electronics research due to its high conductivity and optical transparency. Graphene can be produced through the oxidation of graphite, producing graphene oxide (GO) followed by thermochemical reduction to reduced graphene oxide (rGO). Here we aimed to combine PSI and rGO in order to produce an efficient, photoactive electrode with many applications. We prepared the biohybrid composite by photoreducing GO to rGO using PSI as a photoactive reducing agent. This alternative reduction method lowers the risk of denaturing PSI, which is likely with the high heat and harsh chemicals used in traditional reduction methods of GO. The resulting biohybrid composite demonstrated decreased solubility in water after exposure to light, which we attributed to the partial reduction of the GO. This insolubility greatly benefits the composite deposition on electrodes for use in aqueous experiments as it promotes good contact with the electrode surface and thus faster electron transfer. The new PSI-rGO composite material was characterized using UV-Vis spectrophotometry, Raman spectroscopy, and various electrochemical techniques. It has been shown that PSI-rGO biohybrid composites can be prepared and deposited on many electrode materials while still maintaining photoactivity.- Co-author Journal Publication
G. LeBlanc, K.M. Winter, W.B. Crosby, G.K. Jennings and D.E. Cliffel, “Integration of Photosystem I with Graphene Oxide for Photocurrent Enhancement” Advanced Energy Materials, 4 (9) (2014).
- Co-author Journal Publication
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Karla Dumeng - Chemical Engineering, University of Puerto Rico at Mayaguez
Educational Institution: University of Puerto Rico at Mayaguez
List of Mentors: Dr. Kane Jennings and Darlene Gunther
Program: NSF REU
Research Project: The Improvement of Photosystem I Deposition Using a Spin-coating MethodResearch Abstract:
Photosystem I (PSI) is a photocatalytic protein complex that drives photosynthesis in green plants and cyanobacteria. PSI extracted from plants and deposited onto a surface can covert solar energy to electrical energy. Previous methods, such as vacuum-assisted assembly, face challenges when depositing PSI onto an active electrode, including lengthy deposition time and controlling the coverage and uniformity of the PSI film. Here we deposit PSI, which is extracted from the spinach leaf, onto a gold substrate by spin-coating for the first time in order to optimize the coverage of the PSI layer. The spin-coating method consists of adding an aqueous solution of PSI onto a gold substrate and then rotating it to remove the water from the system, obtaining a thick film of PSI that can be rinsed down to a dense monolayer. Electrochemical experiments using a 3-electrode cell show that photocurrents of ~50-100 nA/cm2 are obtained for samples with thicknesses of ~40-80 Å. The spin-coating method provides improved uniform deposition of PSI, is an order of magnitude faster than vacuum-assisted assembly, and creates a consistent light-induced current. For future work, we will deposit thicker films of PSI with the aim of increasing the photocatalytic response of the system.- Conference Presentations
-K. Dumeng, D. Gunther, D. Cliffel and G.K. Jennings “Investigation of a Spin-Coating Method to Deposit Photosystem I Films,” Ana G. Mendez University System Research Symposium, San Juan, PR, September, 2012.
-K. Dumeng, D. Gunther, D. Cliffel and G.K. Jennings “Investigation of a Spin-Coating Method to Deposit Photosystem I Films,” American Institute of Chemical Engineers Annual Meeting, Pittsburgh, PA, October, 2012. - Dumeng was awarded a $1K travel grant at the capstone poster session.
- Conference Presentations
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Adam Edwards - Chemical Engineering, Tennessee Technological University
Educational Institution: Tennessee Technological University
List of Mentors: Dr. Peter Pintauro and Matt Brodt
Program: NSF TN-SCORE
Research Project: Nanofiber Composite Membranes for Formic Acid Fuel CellsResearch Abstract:
Direct formic acid fuel cells (DFAFCs) have great potential for portable power applications. DFAFCs have the advantages of high efficiency and reasonable power densities (156 mW/cm2) at low temperatures. While DFAFCs have been proven to be less susceptible to fuel crossover than direct methanol fuel cells, crossover still occurs and is a function of concentration and temperature. Unreacted fuel that permeates from the anode to the cathode can create a mixed potential, flood the cathode, and decrease the efficiency of oxygen reduction. This research project is focused on making low formic acid crossover membranes. A dual-nanofiber electrospinning approach was employed where composite membranes composed of Nafion and poly (phenyl sulfone) were prepared. The performance of the composite membranes in direct formic acid fuel cells was measured and compared with commercial Nafion 212 film at 40oC. The resistance to water swelling of composite membranes should reduce the permeability of fuel crossover in formic acid fuel cells, thus providing an alternative polymer electrolyte membrane for future DFAFC applications. -
Robert Fuller - Physics, Villanova University
Educational Institution: Villanova University
List of Mentors: Dr. Sharon Weiss, Jeremy Mares, Gilbert Rodriguez
Program: NSF REU
Research Project: Real-Time Biomolecular Sensing with Porous Silicon Microcavity FilmsResearch Abstract:
Porous silicon has become a very promising material for biological sensing due to its large internal surface area, tunable optical properties, and rapid fabrication. Present transducers have limited porous silicon devices to the confines of a lab; however, with the integration of a microfluidic channel, real-time sensing is achievable with applications in medical, food, environmental, and military monitoring. In this work, we report on the demonstration of real-time sensing in porous silicon microcavities integrated with microfluidic channels and the evaluation of molecular diffusion speeds and size-dependent molecular sensing in the pores. Electrochemical etching is used to create the porous films on silicon wafers. The etching parameters are adjusted to produce films with multiple layers of various thicknesses and porosities, allowing the optical properties of the film to be carefully tuned. The porous silicon microcavity structure used in this study consists of a pair of multilayer Bragg mirrors separated by a cavity or “sensing” layer deep within the structure. The reflectance spectrum of the microcavity is characterized by a sharp resonant dip. Introduction of an analyte into the film changes the effective refractive indices of the porous layers, causing a shift in the cavity’s resonant wavelength. The magnitude of the shift quantifies the amount of analyte in the cavity. Porous silicon microcavities were exposed to two different lengths of DNA molecules. Unlike prior work that suggest long diffusion times for molecules to reach the active sensing region of the microcavities, real-time sensing experiments performed in this study show that small molecule infiltration times are comparable to thinner porous sensing structures. However, due to the buried active sensing region, size-dependent sensitivity of molecular detection was observed. Detection of short, 8-mer DNA at concentrations as low as 18uM was demonstrated, while 40-mer DNA was found to not have a resolvable spectral shift, likely due to the inability of the larger molecule to penetrate deep inside the porous film to the active sensing region of the microcavity. In summary, porous silicon microcavity sensors integrated with microfluidic channels are promising for the real-time detection of small molecules and have the ability to size-selectively filter out larger molecules.- Co-author Journal Publication
G. Rodriguez, J. Ryckman, Y. Jiao, R.L. Fuller, and S.M. Weiss, “Real-time detection of small and large molecules using a porous silicon grating-coupled Bloch surface wave label-free biosensor,” Proceedings of SPIE, 8570 (2013). - Conference Presentation
G. Rodriguez, J. Ryckman, Y. Jiao, R.L. Fuller, and S.M. Weiss, “Detection of small and large molecules using a porous silicon grating-coupled Bloch surface wave label-free biosensor,” Proceedings of SPIE, 8570, 857004 Photonics West, San Francisco, CA, February, 2013. - Robert was awarded a NASA Graduate Student Fellowship
- Co-author Journal Publication
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Walter Harrington - Biochemistry, University of Tennessee, Chattanooga
Educational Institution: University of Tennessee, Chattanooga
List of Mentors: Dr. Jim Davidson and Hank Paxton
Program: NSF TN-SCORE
Research Project: Diamonds are a Sun’s Best Friend: A study to improve TEC efficiency using solar energyResearch Abstract:
Thermionic Energy Conversion (TEC) is a means by which thermal energy can be directly converted into electrical energy, bypassing the conventional need to go through the medium of mechanical energy via a generator. When a material is heated, electrons with sufficient energy will be emitted through a process known as thermionic emission. A current can be established using this principle by engineering a “hot emitter” nanometers away from a “cooler emitter,” thus capitalizing on the flow of electrons from hot to cold surfaces. Diamond is one of the most efficient electron emitting materials known; this study examined the photoconductivity of a boron doped diamond film deposited on a molybdenum substrate as a means to create a more efficient TEC device capable of using solar energy as both the thermal and photonic source. The results obtained imply that a thermionic device using diamond as the electron emitter could be enhanced though solar photons. Thermal tests were similarly run on the diamond film to characterize its behavior in relation to temperature. A conceptual study was also performed which shows the use of preexisting solar concentrators would be sufficient to reach the temperature needed for a diamond TEC device to operate. By using solar energy to heat the diamond, the TEC device could benefit from the diamond’s inherent photoconductivity along with its high rate of thermionic emission from heating alone. -
Albert Hinman - Biological Sciences, Virginia Polytechnic Institute and State University
Educational Institution: Virginia Polytechnic Institute and State University
List of Mentors: Dr. Scott Guelcher and Jon Page
Program: NSF REU
Research Project: The Synthesis, Optimization, and Characterization of Polyurethane FoamsResearch Abstract:
NSF There is a need for regenerative therapies for soft tissue applications that have lower costs, less invasive procedures, and can deliver biologics more effectively. Injectable polyurethane foams have been shown to be applicable for these purposes, primarily for soft tissue repair applications. For this study, novel diisocyanates were utilized to develop injectable polyurethane foams for soft tissue repair. Two unique, fully degradable diisocyanates, para-amino benzoic acid-lactide-diethylene glycol (PLD) and para-amino benzoic acid-glycolide-diethylene glycol (PGD),were compared along with two common urethane blowing catalysts, triethylene diamine (TEDA) and dimethyl aminoethyoxyethanol (DMAEE) for maximal foam efficiency. The foams were composed of a degradable isocyanate, water, sucrose bead fillers, and a degradable, trifunctional polyester (polyol). Each formulation was analyzed for utilization as an injectable graft. The diisocyanates used in the study allowed for microphase separation through unique hard segment symmetry. The hydrogen bonded microdomains allow for greater mechanical properties when dry. However, the foams weaken in aqueous environments due to water breaking the hydrogen bonding. Glass transition temperatures were determined with dynamic scanning calorimetry. PLD foams had a Tg -4oC, while PGD foams had a Tg 24oC.. Formulations were tested for porosity both gravimetrically and via electron microscopy with each catalyst and isocyanate. A peak porosity value around 86% was attained for each formulation. Additional porosity was created by the addition of the sucrose filler. The sucrose can be quickly leached out for an additional 5-7% porosity. This increases interconnectivity and can allow for better cellular infiltration in vivo. Cytotoxicity analysis showed that DMAEE is lethal to cells while TEDA is nontoxic. TEDA was utilized for the remainder of the experiments. PLD and PGD foams had an elastic modulus ranging from 50-90 kPa. Degradation testing has shown that the foams remain stable in vitro up to 21 days. Further work in this study can demonstrate the effectiveness of the polyurethane diisocyanate networks effects within synthetic regenerative medicine.- Albert was awarded a Mason Case Graduate Fellowship in 2015.
- Albert was named a Stanford School f Medicine Blavatnik Fellow in 2019.
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Erik Jewell - Chemistry, Austin Peay State University
Educational Institution: Austin Peay State University
List of Mentors: Dr. Janet Macdonald and Emil Hernandez
Program: NSF TN-SCORE
Research Project: Photodegradation study of Copper (I) Oxide nanoparticles synthesized with different geometriesResearch Abstract:
Copper (I) Oxide (Cu2O) has been widely researched as a photocathode for overall water splitting due to its high absorption in the visible range, with a band gap of 2.2 eV. In addition, it is made of abundant, inexpensive, and non-toxic elements, making it suitable for large scale production. However, this material photodegrades under conditions required for practical photoelectrochemical cells (PECs), which hinders its application. In order to develop preventative techniques, fundamental studies of the degradation process are desired. A major question is how does this degradation vary for Cu2O with different exposed crystal facets. To this end we have synthesized cubic, truncated octahedral, and bipyrimidal Cu2O nanoparticles. Structural characterization was carried out by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). The particles were then used as photocathodes in a PEC, and their photodegradation was studied employing cyclic voltammetry under dark and illuminated conditions.- Conference Presentation
E. Jewell, E. Hernandez, and J. Macdonald, “Photodegradation study of Copper (I) Oxide nanoparticles synthesized with different geometries,” American Chemical Society, New Orleans, LA, April, 2013.
- Conference Presentation
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James Kintzing - Chemistry, Grove City College
Educational Institution: Grove City College
List of Mentors: Dr. Craig Duvall and Chris Nelson
Program: NSF REU
Research Project: PEG-Cloaked, pH-Responsive Nanomicelles for Effective andResearch Abstract:
Small interfering RNA (siRNA) is a potent mediator of cellular expression and can be used to assert precise control over cell behavior. Harnessing the power of gene therapy through siRNA is emerging as powerful approach to disease treatment. This auspicious technique hinges on the development of a safe and effective delivery mechanism. A variety of polymer formulations have been proposed as a method for carrying genetic material into cells, but many existing schemes have been hindered by barriers to successful delivery. An efficacious carrier must overcome the hurdles of enzymatic degradation, cytotoxicity, and endosomal escape to make treatment feasible. In this study, a novel pH-responsive diblock polymer (polyethylene glycol–[block]–2–(dimethylamino)ethyl methacrylate–[co]–butyl methacrylate) is used to form nanomicelles that encapsulate siRNA, forming nanomicelle polyplexes (NMPs). The micelle corona is composed of a polyethylene glycol (PEG) shell, which cloaks the surface charge and improves biocompatibility. NMPs are characterized using dynamic light scattering and transmission electron microscopy and have a hydrated diameter of ~100nm. NMPs have a measured zeta potential of 0mV, which confirms the ability of PEG to cloak the internal charge. NMPs are both stable and nontoxic over time and remain inert and intact when incubated in human whole blood. Cell uptake, measure by flow cytometry, shows slow internalization compared to commercial standards, yet gene knockdown assays demonstrate that slight uptake of NMPs is enough to maintain acute gene silencing activity. Treated cells experience up to 75% reduction in gene expression after 48 hours. These results indicate that NMPs escape endosomal trafficking and deliver siRNA with exceptional release efficiency. The development of an innocuous siRNA carrier with maintained delivery capacity and whole blood stability provides strong support for the plausibility of intravenous micelle injection. The findings of this study suggest that NMPs are a useful platform for siRNA delivery and can be effective in-vivo via IV injection.- Co-author Journal Publication
C.E. Nelson*, J.R. Kintzing*, A. Hanna, J.M .Shannon, M.K. Gupta, C.L. Duvall, “Balancing Cationic and Hydrophobic Content of PEGylated siRNA Polyplexes Enhances Endosome Escape, Stability, Blood Circulation Time, and Bioactivity in Vivo,” ACS Nano, 7 (10), pp 8870–8880 (2013).
*equally contributing authors - Conference Presentation
-J. Kintzing, C. Nelson, J. Shannon, M. Gupta and C. Duvall “Testing of a Novel RAFT-Synthesized Polymer Library for Efficient, Hemocompatible siRNA Delivery,” Biomedical Engineering Society 2012 Annual Meeting, Atlanta, GA, October, 2012.
-C.E. Nelson, J.R. Kintzing, J.M. Shannon, M.K. Gupta, C.L. Duvall, “Hemocompatible pH-responsive polymeric nanoparticle for intravenous siRNA Delivery,” Society for Biomaterials 2013 Annual Meeting, Boston, MA, April,2013. - Kintzing was awarded a $1K travel grant at the capstone poster session.
- Kintzing awarded NSF Graduate Research Fellowship in 2014.
- Co-author Journal Publication
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Laura Lanier - Polymer & Fiber Engineering, Georgia Institute of Technology
Educational Institution: Georgia Institute of Technology
List of Mentors: Dr. Eva Harth
Program: NSF REU
Research Project: Controlled Branching of Glycidol Polymers and Subsequent Formation of Bioconjugates with Improved BiocompatibilityResearch Abstract:
Glycidol, an analog of ethylene glycol, provides a promising polymer system for medical applications of nanomaterials. Due to their hydroxyl functionality, glycidol polymers are inherently hydrophilic, an important property for applications inside the body, such as nanoparticles for drug delivery and solubilization for biomolecular transport. Polymerization of glycidol proceeds through a ring-opening polymerization of the epoxide ring, and as the epoxide ring can open in two ways, these systems are generally hyperbranched. Linear systems are possible, but the process is more complicated and oxygen sensitive. However, it has been recently determined that the amount of branching in the system can be kinetically controlled. Being able to control the amount of branching easily is very desirable, as it allows polyglycidol to be tuned for specific applications, including biomaterials, nanoparticles, and biomolecular transport. Part of this study focused on incorporation of a second monomer with allyl functionality into the system. The desired monomer has epoxide functionality for ring-opening polymerization, allyl functionality for post-modification, and an ester group to impart degradability on the system. However, incorporation of this mixed length glycidyl ester allyl (MLGEA) monomer into the glydicol polymer is difficult as the polymerization of the MLGEA proceeds much more slowly than that of the glycidol. This problem was addressed through the use of an analog of glycidol with a protected hydroxyl group. The second part of this study focused on grafting polyglycidol to proteins to increase solubilization and biostability of the biomolecule. Maleimide alcohol was attached to the free thiols of bovine serum albumin (BSA), and glycidol polymers were grown directly from these alcohols on the protein. The bioactivity of these conjugates will be studied using a bioactivity assay. Future work will study the effect of branching on the bioactivity of the protein.- Co-author Journal Publication
B.R. Spears, J. Waksal, C. McQuade, L. Lanier and E. Harth, “Controlled branching of polyglycidol and formation of protein-glycidol bioconjugates via a graft-from approach with “PEG-like” arms,” Chemical Communications, 49, 2394-2396 (2013).
- Co-author Journal Publication
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Marc-Andre LeBlanc - Chemistry & Physics, Lyon College
Educational Institution: Lyon College
List of Mentors: Dr. Eva Harth
Program: NSF REU
Research Project: Synthesis and Characterization of Polyester Nanosponges for Drug DeliveryResearch Abstract:
Poor water solubility is one of the most significant and fundamental barriers limiting drug delivery. Not surprisingly, many promising chemotherapeutics, antibiotics, and peptide therapeutics have failed clinically due to solubility issues. A recent approach with the potential to fix the issue of solubility uses nanoparticles to encapsulate the potential therapeutic. By using biodegradable nanoparticles, or nanosponges, it is possible to increase the solubility of the therapeutic without altering the drug itself. These nanoparticles are formed by covalently cross-linking linear, functionalized polyesters. The functional groups included in the polyesters allow us to add targeting ligands or imaging agents after nanoparticle formation, enabling targeted drug delivery and imaging. Our current research focuses on optimizing the synthesis of both the polyesters and the nanoparticles. In the synthesis of the polyesters, by increasing the amount of catalyst and using precipitation in place of dialysis we have reduced the previous three day synthesis to six hours. Additionally we have started optimizing the cross linking process, running a kinetics study to ensure optimal reaction time. After completing optimization, we will move on to test the drug encapsulation ability of the particles using thiostrepton, a powerful breast cancer drug that is completely water-insoluble. Finally we will utilize imaging dyes to monitor biodistribution of our tumor-targeted nanoparticles in vivo.- Co-author Journal Publication
D.M. Stevens, M.A. LeBlanc, H. Watson, R. Wang, W.S. Bauer, J. Chou and E. Harth, “Metal catalysed ring-opening polymerizations of functionalized lactones and carbonates with Sn (OTf)2: Practical synthesis and endgroup removal,” Polymer Chemistry, 4, 2470-2474 (2013). - LeBlanc awarded NIH Graduate Student Fellowship
- Co-author Journal Publication
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Ruben Medina-Perez - Physics, California State University
Educational Institution: California State University, Dominguez Hills
List of Mentors: Dr. Kalman Varga and Dr. Sergiy Bubin
Program: NSF REU
Research Project: Investigation of electron and ion dynamics in small hydrocarbons subjected to short intense laser pulsesResearch Abstract:
With advances in lasers, the last two decades have seen a growing interest in studying the interaction of matter with strong electric fields. In particular, there have been recent experiments with small hydrocarbon molecules subjected to short intense laser pulses. While a lot of interesting features can be determined through the experimental measurements of fragments formed in the process of the light-matter interaction, the internal electron and ion dynamics often remains vague. In this work, we study the ion dynamics in methane and ethylene subjected to 17 fs (FWHM) pulses of intensities of 8, 16, and 24 * 1014 W/cm2. These molecules represent a simple, yet nformative, case when the details of the dynamics taking place during the Coulomb explosion can be studied. In the framework of time-dependent density functional theory (TDDFT) complemented with the Ehrenfest molecular dynamics, we have performed numerical simulations which provide an insight into the mechanism of Coulomb explosion in small molecules. In particular, we have shown that the ejection of protons occur simultaneously, thereby confirming the all-at-once scenario proposed by Roither et al. [Phys. Rev. Lett. 106, 163001 (2011)]. We have found that for higher intensity pulses the kinetic energies of the protons ejected in each explosion are very similar in magnitude. We have also studied the orientational dependence of the fragmentation process by repeating the calculations for several representative configurations. -
Barclay Randall - Physics, Middle Tennessee State University
Educational Institution: Middle Tennessee State University
List of Mentors: Dr. Sandra Rosenthal and Toshia Wrenn
Program: NSF TN-SCORE
Research Project: Electrochemically Assisted Deposition of Indium Tin Oxide for Use inResearch Abstract:
Indium tin oxide (ITO) was used as a hole conductor for quantum dot sensitized solar cells (QDSSC) and optimization of the deposition of ITO was investigated. To determine optimal voltage for electrochemically assisted deposition (EAD) of ITO, linear sweep voltammetry was employed. The results showed a cathodic voltage of 0.8V is an optimal voltage for the reactions needed to facilitate ITO deposition. To determine an optimal time for deposition of ITO, EAD of ITO was performed on multiple titanium foils for various times. The optimal time was determined to be around 300 seconds as determined by using scanning electron microscopy (SEM) to look at the morphology of the film deposited. QDSSCs were created by anodization of titanium to produce titanium dioxide nanotubes, nanotubes were sensitized by chemical-linking of cadmium selenide quantum dots, and EAD of ITO. Devices were subjected to EAD of ITO for 60s, 120s, and 300s. EDX of this device showed that there was significantly more indium and tin throughout the device area than either the 60 second or 120 second film, indicating that the 300s device has the largest active area. In agreement with the EDX findings, photovoltaic efficiency of these devices showed that the device that underwent EAD for 300s had the highest efficiency. -
Sarah Robb - Biomedical Engineering, Robert Morris University
Educational Institution: Robert Morris University
List of Mentors: Dr. Bridget Rogers, Dr. Greg Walker, and Bobby Harl
Program: NSF REU
Research Project: Mixed Fuel Combustion Synthesis of Yttrium Aluminum Garnet (YAG)Research Abstract:
Yttrium aluminum garnet (YAG) doped with cerium (Ce) fluoresces when irradiated by photons. Combustion synthesis is a common route to making YAG. Typically, a single fuel is used to produce YAG via combustion synthesis. Recently, optimization of combustion processes through using fuel mixtures has been studied. This project focuses on characterizing the properties of YAG:Ce1% combusted using a mixture of citric acid and urea in different fuel ratios.Citric acid is a chelating agent, which creates a well-distributed dopant solution during dehydration, and thus in the final product. Urea produces a high flame temperature during combustion, which crystallizes the YAG:Ce1% upon formation. We hope that by using a mixture of fuels, the combustion synthesis will produce crystalline YAG:Ce1% with a uniform dopant distribution.
Photoluminescent spectroscopy (PL) and x-ray diffraction (XRD) were conducted on the resulting materials to determine the effect of synthesis conditions on the properties of the product. The PL compared the intensity of the fluorescence and XRD compared the crystal structure of the synthesized YAG:Ce1%. We have shown that mixing the fuels produces YAG:Ce1% with an overall lower PL signal than either pure fuel. We have also studied the effect of post-synthesis heat treatment on the PL intensity and crystal structure. Materials produced with pure urea have the highest PL intensities for all heat treatments studied. Urea also produces YAG:Ce1% with the best initial crystal structure. Combustion synthesis using fuel mixtures with increasing percentages of citric acid produces materials with decreasing crystallinity.
- Conference Presentations
S.M. Robb, R.R. Harl, and B.R. Rogers “Mixed Fuel Combustion Synthesis of Yttrium Aluminum Garnet (YAG),” American Institute of Chemical Engineering Annual Student Symposium, Pittsburg, PA, October, 2012. - Sarah awarded NSF Graduate Research Fellowship in 2014
- Conference Presentations
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Andrew Santos - Chemical Engineering, North Carolina State University
Educational Institution: North Carolina State University
List of Mentors: Dr. Peter Cummings and Will French
Program: NSF REU
Research Project: Impact of Metal Type on the Deformation and Conductivity of Ultrathin NanowiresResearch Abstract:
Metallic nanowires have shown potential to meet the demand of the miniaturization of electronics due to their promising structural and electrical properties. These properties can be classified in specific metals by straining nanowires. In this study, gold, platinum, silver, copper and aluminum nanowires were elongated with a constant applied tensile strain rate at 10 K and 298 K. Elongation was simulated using molecular dynamics with the second moment approximation of the tight binding potential. Different deformation modes, characterized by necking and slip planes, were exhibited in each metal. The different deformation modes were identified by an analysis of the stress-strain relationship, changes in the minimum cross-sectional area and visual inspection. For smaller nanowires, the conductance was shown to be strongly dependent on structural changes and impurities. Decreases in conductance up to 28% of the initial crystalline structure were caused by slip planes and twin boundaries; drastic changes of the structure were correlated with sudden changes of the conductance.- Co-author Journal Publication
W.R. French, A. Pervaje, A. Santos, C.R. Iacovella, and P.T. Cummings, “Probing the Statistical Validity of the Ductile-to-Brittle Transition in Metallic Nanowires Using GPU Computing,” Journal of Chemical Theory and Computation, 9 (12), 5558-5566 (2013). - Conference Presentation
A. Santos, W.R. French, C.R. Iacovella and P.T. Cummings, “GPU-Enabled Simulations of Size Effects on the Elongation and Rupture of Metallic Nanowires Using Many-Body Potentials," American Institute of Chemical Engineers Annual Meeting, Pittsburg, PA, October, 2012. - Santos awarded NSF Graduate Research Fellowship in 2014
- Co-author Journal Publication
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James Taylor - Chemistry, University of Maryland, Baltimore County
Educational Institution: University of Maryland, Baltimore County
List of Mentors: Dr. Hak-Joon Sung and Tim Boire
Program: NSF REU
Research Project: Synthesis and Characterization of a New Class of Shape Memory Polymers for Development of “Smart” Vascular ConstructsResearch Abstract:
Current vascular stents, grafts, and patches for treating occluded or ruptured blood vessels associated with vascular diseases require open surgeries, which leads to cumbersome implantation and removal procedures. Through the development of a shape-memory polymers (SMPs) however, we hope to create minimally invasive ways to deliver vascular patches or stents through catheters or laparoscopes, which would make the procedure a lot more patient-friendly. Poly(ε-caprolactone) (PCL) is a thermoresponsive and biodegradable shape memory polymer that can be programmed into a specific shape at one temperature and return to its original shape at the melting point. In order to use PCL in physiological conditions, its melting point would have to be slightly less than 37 degrees C. The melting temperature should be tuned by copolymerizing with varying the molar ratio of carboxylated-PCL (cPCL). The polymer is currently being characterized by differential scanning calorimetry (DSC) for thermal properties; gel permeation chromatography (GPC) for degradation properties; dynamic mechanical analysis (DMA) for theromechanical (“Shape memory”) properties; and goniometry for surface properties. Preliminary results show promise in synthesizing this polymer with an appropriate melting point, suggesting its possible utility in creating non-invasive and biodegradable vascular therapeutics.- Conference Presentations
- J. Stewart, J. Taylor, T. Boire, M. Gupta and H.J. Sung “Development of Biodegradable, Biocompatible Shape Memory Polymers for Vascular Patch Applications,” Biomedical Engineering Society 2012 Annual Meeting, Atlanta, GA, October, 2012.
- J. Taylor, T.C. Boire, M.K. Gupta, J.M. Stewart, H.J. Sung “Synthesis and Characterization of a New Class of Shape Memory Polymers for Development of “Smart” Vascular Constructs” 2012 Annual Biomedical Research Conference for Minority Students, San Jose, CA, November, 2012.
- Conference Presentations
![VINSEREU2011 VINSEREU2011](https://cdn.vanderbilt.edu/vu-wpfsx/wp-content/uploads/sites/40/2024/08/31155621/VINSEREU2011.png)
2011
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Rebecca Cioffi - Materials Science, Rensselaer Polytechnic Institute -
Educational Institution: Rensselaer Polytechnic Institute
List of Mentors: Dr. Yaqiong Xu, Yunhao Cao, Tu Hong
Program: NSF REU Program
Research Project: Use of micromechanical exfoliation of bulk graphite and MoS2 to establish a graphene/MoS2 junctionResearch Abstract: The goal of this study is to explore the properties of a graphene/molybdenum disulfide junction using photoconductivity measurements. To begin, micromechanical exfoliation via the scotch-tape method has been used to obtain monolayer and few layer thick flakes of graphene and MoS2. Optical and Raman microscopes have been used to determine whether the flakes are one atomic layer thick. Using the same cleavage process as for cleaving bulk graphite and MoS2, graphite and MoS2 will be cleaved simultaneously, creating a junction between the two single-layer flakes. This mixture will be deposited onto the SiO2/Si substrate. This will form a Schottky barrier between the graphene, a semimetal and MoS2, a p-type doped semiconductor. Electrodes will then be deposited connecting to both materials on the silicon wafer. Analysis of the electronic transport properties and photon-electron conversion of the graphene/MoS2 junction will allow for further research into the potential usage of such a device in photovoltaics, transistors, and optoelectonic devices.
- Conference Presentation
G. Musick*, R. Cioffi, Y. Cao, T. Hong and Y. Xu, “Creating a Junction between Single layer graphene and single layer MOS2” 22nd Annual EPSCoR Conference, Coeur d’Alene, ID, October 2011.
- Conference Presentation
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Jonathan Clinger - Physics, Lipscomb University
Educational Institution: Lipscomb University
List of Mentors: Dr. Kirill Bolotin, Hiram Conley
Program: NSF TN-SCORE Program
Research Project: Creating controllable strain in grapheneResearch Abstract: It has been predicted that a controlled distribution of strain in graphene can create a band gap in its density of states, which could potentially lead to multiple device applications of graphene in electronics. We developed two novel methods to induce strain in large-scale graphene grown by chemical vapor deposition. We demonstrated creation of uniaxial strain up to 0.5% by fabricating a device where a sheet of graphene is suspended between two gold supports and then controllably pulling the graphene down onto a third support. In a different approach, we induced a strain of 0.2% in graphene by depositing it onto a polymer that was then strained. The graphene can then be transferred onto an arbitrary substrate to enable greater flexibility in device design. We expect that the devices fabricated using these methods will allow us to investigate the influence of strain on electronic transport in graphene.
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Justin Colar - Civil Engineering, Alabama A&M University
Educational Institution: Alabama A&M University
List of Mentors: Dr. Greg Walker, Dr. Rachael Hansel, Sarah Gollub
Program: NSF-REU
Research Project: Investigation of the Quenching Concentration of Europium in Photo Luminescent Lanthanum ZirconateResearch Abstract: Lanthanum Zirconate, La2Zr2O7 (LAZ) is commonly used within the aeronautics industry as a protective coating on the surface of gas turbine blades. The LAZ coating is used to protect the blades from the hot corrosive gases that are produced during the operation of a gas turbine. When LAZ is doped with europium (Eu) it can become a temperature sensor. This is done by beaming a wavelength of light to excite the electrons within the LAZ:Eu lattice, and as the electrons come back to down to the ground state they will give off energy in the form of photons. The time it takes for the electrons to come back down to the ground state is known as the decay time. Decay time is temperature dependent; therefore, the time it takes for the electrons to come down to the ground state is proportionate to the temperature. However, it is currently not known at what concentration of europium in LAZ will give the brightest intensity. The goal of this summer research project is to find out at what concentration of europium in LAZ will quench. This is possible by increasing the concentration of europium and then comparing the emissions spectra at different concentrations. This research will produce a higher intensity sensor that will be able to relay better results when trying to measure temperature.
- Justin was awarded a Department of Defense SMART Scholarship.
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Megan Dunn - Chemical Engineering, University of Arkansas
Educational Institution: University of Arkansas
List of Mentors: Dr. Craig Duvall, Dr. Hongmei Li, Brian Evans
Program: NSF-REU
Research Project: Delivery of an MK2 Inhibitor Utilizing Peptide StaplingResearch Abstract: Coronary artery bypass grafting is an effective treatment for ischemic heart diseases, but long-term patency remains a significant problem. Recent studies have shown that greater than 45% of grafts experience failure in the first 18 months. Graft failure is primarily attributed to intimal hyperplasia, a pathological process in which vascular smooth muscle cells (VSMCs) migrate, proliferate, and deposit extracellular matrix into a neointima. MAPKAP kinase II (MK2) is an upstream regulator of heat shock protein 27 which has been shown to play a major role in the transition of VSMCs to the pathological, proliferative phenotype characteristic of intimal hyperplasia. Therefore, we hypothesize that successful inhibition of MK2 will prevent intimal hyperplasia and ultimately improve graft patency. A previous study has identified a peptide sequence, MK2i, which effectively inhibits MK2 at a concentration range of 8.1-134 µM. However, efficient intracellular delivery of the peptide emains a significant barrier. The overall goal of this project is to determine if peptide stapling can be utilized to enable intracellular delivery of the MK2i peptide. Peptide stapling uses a ring closing reaction to add a hydrocarbon “staple” to successive turns of an α-helix. Stapled peptides have increased helicity, potency, protease resistance and most importantly, cell permeability. The specific aim of this project was to determine if MK2i was a suitable candidate for peptide stapling and develop a protocol for the synthesis of the stapled MK2i peptide. Mk2i was synthesized using solid-phase peptide synthesis (SSPS) with Fmoc chemistry. Circular dichroism was used to assess secondary structure of MK2i in both water and trifluoroethanol which is known to induce α- helical secondary structure in peptides. The circular dichroism results showed that the peptide was 6% α-helical in water and 13% α-helical in trifluoroethanol. These findings suggest that MK2i may be a suitable candidate for peptide stapling. This hypothesis will be further tested by implementing the developed peptide stapling protocol to determine if stapled MK2i peptides showed increased potency, specificity and cell permeability for potential use as a therapeutic in coronary artery bypass grafting.
- Dunn awarded NSF Graduate Student Research Fellowship in 2014
- Dunn awarded a Ford Foundation Fellowship in 2014
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Elly Earlywine - Chemistry, Hope College
Educational Institution: Hope College
List of Mentors: Dr. Sandra Rosenthal, Emily Jones
Program: NSF REU Program
Research Project: Exploring Cytotoxicity of Silica Coated Water-Soluble CdSe NanocrystalsResearch Abstract: For this study, red-emission CdSe nanocrystals were prepared and their cytotoxicity was tested. In order for hydrophobic CdSe nanocrystals to be used in biological studies, they must be coated with a water soluble, nontoxic shell such as ligands, polymers, or silica. Using the standard pyrolysis of organometallic reagents, CdSe nanocrystals were prepared and coated with a silica shell by a reverse microemulsion method. UV-Visible absorption spectroscopy and transmission electron microscopy were used to determine the characteristics of the nanocrystals prepared. The CdSe nanocrystals were approximately 4.4nm in diameter. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) colorimetric assay was performed in HELA cells to determine the cytotoxicity of the CdSe nanocrystals. Toxicity of the CdSe nanocrystals was compared to 605 ITK amino quantum dots (Invitrogen). As the assay exhibited, the CdSe quantum dots were more cytotoxic than the 605 ITK amino quantum dots. Improvements in the silica coated nanocrystals still need to be made before their cytotoxicity can be fully tested. Some of the nanocrystals were successfully coated in silica; however, a great deal of aggregation of both the nanocrystals and silica were observed.
- Conference Presentation
E. Earlywine, E. Jones, and S.J. Rosenthal, “Exploring Cytotoxicity of Silica Coated Water-Soluble CdSe Nanocrystals,” ACS National Meeting, San Diego, CA, March, 2012.
- Conference Presentation
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Stephen Filippone - Materials Science, Johns Hopkins University
Educational Institution: Johns Hopkins University
List of Mentors: Dr. Florence Sanchez, Lesa Brown
Program: NSF REU Program
Research Project: Effect of C-S-H Coated CNFs on the Performance of Cement PasteResearch Abstract: Increasing the strength of cement can bring huge benefits to people and the environment. Research has been conducted on the incorporation of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) into cement. CNTs and CNFs have properties desirable to make strong and durable cement composites. Although effective means of dispersing fibers in solution have been found, upon adding that solution to cement, the fibers re-agglomerate leading to cement pastes that do not exhibit large enough strength increases to be good composites. The goal of this study was to devise an effective means of preventing the re-agglomeration of CNFs in cement by coating them with synthetic calcium silicate hydrate (C-S-H) to help the fibers bond better with the cement matrix. An effective way to form C-S-H on the CNFs was first studied using both calcium oxide and silicon dioxide or calcium nitrate tetrahydrate and sodium meta-silicate pentahydrate. The calcium and silica salts were easier to react and were used in the cement pastes that were tested. It was found that the sonication time of the salts in solution affected the consistency of the cement paste. Longer sonication times led to more synthetic C-S-H formed and thicker cement paste that was difficult to pour, leading to a porous material. Less porous cement pastes were made by decreasing the sonication time. SEM coupled with EDS (energy dispersive X-ray spectroscopy) was used to characterize the coating of the CNFs with C-S-H and also the dispersion of the CNFs in the cement matrix. Compression and flexural strength test were conducted on the cement pastes after 24 hours, 3 days and 7 days.
- Filippone awarded 2014 Gates Cambridge Scholarship
- Filippone awarded 2013 Goldwater Scholarship
- Filippone awarded NSF Graduate Research Fellowship Program in 2016
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Annalisa Fowler - Mechanical Engineering, University of Alabama, Huntsville
Educational Institution: University of Alabama, Huntsville
List of Mentors: Dr. Jason Valentine, Joy Garnett
Program: NSF REU Program
Research Project: Maxwell Fisheye for Use as an Optical Cross ConnectResearch Abstract: The Maxwell fisheye lens is a non-homogenous, aberration free, perfectly focusing lens. This lens focuses light from a point source on the surface of the lens to another point on the opposite side. While the fisheye has been studied in the past for its application in imaging, here we extend its use for chip based photonics. Specifically, we are developing the lens for use as a massively parallel and low-loss optical cross-connect. Our study focuses on creating this lens in a silicon-on-insulator (SOI) architecture which is commonly used in optical circuitry because of its high refractive index contrast. A correlation can be found between modal refractive index and silicon waveguide height by using effective waveguide theory. With grayscale electron beam lithography and reactive ion etching (RIE), a gradient refractive index can be fashioned in the silicon by varying its height, allowing the non homogenous lens to be produced. An important part of this project was developing a precise RIE transfer process with low roughness and accurate pattern transfer from a lithographically defined pattern. This was done by varying the chemistry, power, and pressure of the etch. Based on this work the designed lens can now be fabricated and experimentally characterized for use in on chip photonics applications.
- Conference Presentation
J. Garnett, A. Fowler, and J. Valentine, “Maxwell Fisheye Lens as a Waveguide Crossing for Integrated Photonics,” OSA Conference on Lasers and Electro-Optics/ Quantum Electronics and Laser Science, San Jose, CA, May, 2012.
- Conference Presentation
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William "Reb" Kornahrens - Chemical Engineering, North Carolina State University
Educational Institution: North Carolina State University
List of Mentors: Dr. Eva Harth, Benjamin Spears
Program: NSF-REU
Research Project: Synthesis and Characterization of Nanosponges for Drug Delivery and Brain Cancer TreatmentResearch Abstract: Degradable 3-D polyester nanoparticles, or nanosponges, have been receiving more attention for their potential biomedical applications. Conventional cancer treatments involve the use of drugs that are toxic to healthy cells as well as tumor cells. A more ideal form of treatment could be facilitated through the use of nanoparticles crosslinked with targeting units, such as peptides, that selectively recognize receptors on the surfaces of tumor cells. Unlike other delivery systems, nanosponges have the advantage of enabling a controlled, linear release of a large amount of drug over a long period of time. In addition, post modification strategies can be utilized to alter several properties of nanosponges, such as hydrophobicity, morphology, particle size, and functionality. We utilized two different linear copolymers for nanoparticle formation: one is poly( valerolactone-allylvalerolactone ) and the other is poly( valerolactone-allylvalerolactone –oxepanedione). These two linear polymers have different morphologies and will be investigated with future in vivo andin vitro drug release studies. In particular, temezolomide, a chemotherapeutic used to treat advanced brain tumors, will be encapsulated inside these nanoparticles and the rate of drug release will be measured with UV-visible spectroscopy. Furthermore, the nanoparticles will be labeled with a fluorescent dye in order to conduct biodistribution studies to determine if they are capable of crossing the blood-brain barrier.