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2015

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)
Poster: NSF REU Christopher Banks Poster.pdf
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, k_app,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
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
Poster: NSF REU Ben Burdette.pdf
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
Thomas Campbell - Engineering Physics, Murray State University

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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
Poster: NSF REU Thomas Campbell Poster.pdf
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
Poster: NSF REU Alyssa Cartwright Poster.pdf
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
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
Poster: NSF REU Dion Casey Poster.pdf
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.
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
Poster: NSF REU Corey Combs Poster.pdf
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.
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
Poster: NSF REU Marc Cunningham Poster.pdf
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:VO₂Plasmon Nanomodulators
Poster: NSF REU Autumn Douthitt Poster.pdf
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.
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
Poster: NSF REU Dennis Ejorh Poster.pdf
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-g_sulfur ^-1 (at a ~.1A/g current loading) upon initial charge/discharge cycling and subsequent cycle capacities of ~1000 mAh-g_sulfur ^-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.
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
Poster: NSF REU Jane Jiang Poster.pdf
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.
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
Poster:
NSF REU Jack Lewis Poster.pdf
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 2^nd 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.
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
Poster: NSF REU Sharon Lin Poster.pdf
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 53^oC.

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 42^oC. 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
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
Poster: NSF REU Poster Jennifer Lomaki.pdf
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
Poster: NSF REU Naomi Mburu Poster.pdf
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
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
Poster: NSF REU Chris McDonald Poster.pdf
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.
  *2^nd place in Engineering and Engineering Technology
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
Poster: NSF REU Ryan Nolen Poster.pdf
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.
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
Poster: NSF REU Uc Obiako Poster .pdf
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.