The world’s future energy needs will almost certainly require extensive use of renewable sources of energy. Organic photovoltaics are a particularly lucrative source of energy due to their cheap materials and ease of production compared to inorganic solar cells. However, organic photovoltaics (OPVs) currently suffer several drawbacks: they have an efficiency of, at most, around 10% and they are unstable – they may begin to degrade within five to seven years. This project aims to alleviate these defects by gaining a greater understanding of the chemical interaction between interfaces within the solar cell. This project is a comprehensive study of the interactions between phenyl-C₆₁-butyric acid methyl ester (PCBM) and calcium. PCBM is an extensively researched molecule which acts as an electron acceptor in OPV devices. PCBM is typically paired with an electron donor such as poly-(3-hexylthiophene) in a working device, and calcium has energetic properties which allow for very good electron transfer at the cathode of such a device. We use adsorption micro-calorimetry under ultra-high vacuum conditions to study the reaction at the interface between calcium and PCBM, and surface analytical techniques to determine growth modes and chemical binding of calcium and PCBM. These experiments will elucidate the mechanisms of interface formation of this understudied but important OPV system.

Carboxylic acids are ubiquitous in chemistry and used in a variety of industrial applications, ranging from polymer precursors to food preservatives. Modern routes to synthesize these compounds often involve specialized equipment, harsh conditions, and potentially toxic reagents. An alternative synthetic route is the aldehyde-water shift reaction, in which an aldehyde is oxidized by water to form a carboxylic acid and molecular hydrogen. The use of water as both solvent and reagent could potentially reduce the impact of aldehyde oxidation on the environment, especially when compared to the routes . A series of iridium-, rhodium-, and ruthenium-based complexes have been synthesized and investigated for activity in catalyzing this reaction. Using ¹H NMR (proton nuclear magnetic resonance) and GC-FID (gas chromatography) to analyze reaction products, we have observed many of the catalysts to disproportionate aldehydes to alcohols and carboxylic acids in competition with the desired dehydrogenative oxidation to carboxylic acids. Mechanistic studies and catalyst optimization for dihydrogen production are presented.

Polymeric micelles are nanoscopic structures constructed with amphiphilic diblock copolymers constructed with hydrophobic and hydrophillic portions that spontaneously form micelles in solution. Small hydrophobic molecules, such as cancer drugs taxol and doxorubicin, can be encapsulated in the micelle, which effectively serves as a nanovehicle for drug delivery. Here, we will develop a diblock copolymer integrating polyurethane-based self-immolative polymers (SIPs). SIPs are polymers that sequentially disassemble into their building blocks once the disassembly process is initiated by a triggering event at the trigger head group. By using SIPs, the polymers that make up the micelle are designed to depolymerize which we hope to increase the efficacy of payload release and remove the ability for micelle reformation. For this project, the micelle and all parts of the system will be synthesized from the bottom-up; optimizing the molecular weight of the diblock for micelle formation, investigating the kinetics of depolymerization and thermal trigger activation, and examining the stability of the micelle.

Solar power is an increasingly significant resource as we look to move from fossil fuels to a cheap and sustainable source of energy. Solar cells can be manufactured using organic semiconductors by using cheap roll-to-roll printing techniques, however, the efficiency of such organic photovoltaic (OPV) devices is currently too low for cost-effective implementation. These devices utilize a built-in electric field, resulting from the difference in potential energy between the device’s electrodes, to collect photogenerated charges at the electrodes as current. Fine-tuning of the electrode energy levels also dictates the amount of voltage that can be generated by the device. As a result, the ability to chemically alter the electrode energy levels can greatly influence the overall power output of the solar cell. Phosphonic acid self-assembled monolayers (SAMs) are molecules that can be chemically attached to a variety of electrode interfaces and have been shown to alter the energy levels of certain electrodes. I am investigating the effect that attaching SAMs to the zinc oxide surface of an OPV electrode will have on both the built-in voltage and power conversion efficiency of an OPV cell. In order to test the hypothesis that the SAMs can affect OPV performance, I have fabricated solar cells with SAMs in order to compare them with solar cells without SAMs. Experiments that measure the built-in voltage of the device and investigate the lifetime of photogenerated charges will help to clarify the specific role that the SAMs play in affecting OPV device performance. If this hypothesis is correct, we have the potential to achieve higher power conversion efficiency than what is currently reported in these devices and this may lead to a greater emphasis towards understanding the role of interfaces in developing sustainable solar technology.

Tuberculosis is the second-leading cause of death due to a single pathogen, Mycobacterium tuberculosis (Mtb), with an estimated two billion people currently infected. Drug-resistant strains have emerged that are unmanageable even with combination drug therapies. Therefore, the development of novel drugs aimed at previously untargeted biochemical pathways in Mtb is of utmost importance. Among potential candidates is a newly identified proteasomal degradation pathway termed pupylation. In this system, proteins in Mtb damaged by the reactive oxygen and nitrogen species of the host’s immune response are tagged with the small prokaryotic ubiquitin-like protein (Pup) and shuttled to the 20S proteasome for degradation. Pup-mediated degradation allows Mtb to recycle key cellular components and remain virulent. Our interest is to study the two key enzymes required for pupylation: the proteasome accessory factor A (PafA) and the deamidase of Pup (Dop), which is also involved in the reverse pathway known as depupylation where Pup is removed from the substrate. Our interest is to characterize the mechanisms and substrate scopes of both Dop and PafA to facilitate the design of novel inhibitors. We synthesized and employed a model fluorescent probe that mimics the site of pupylation on a target protein to study the rates of the pupylation and depupylation enzymatic reactions. Since the Pup-probe conjugate is a substrate for Dop we also studied depupylation. We anticipated Dop to be the faster enzyme since it had fewer substrates to bind than PafA and our studies have revealed that Dop is much faster. Though the purpose of depupylation is currently unclear, our investigation has determined the relative kinetics of these opposing enzymatic pathways. The quicker kinetics of depupylation indicates pupylation of proteins also serves as a post-translational regulator rather than existing exclusively for degradative purposes.

In spite of rapid advances in detection and treatment, cancer remains one of the most deadly diseases, killing over 1500 Americans each day. The ability of cancer cells to metastasize is the driving force behind the high mortality. For this reason, early detection and improved treatment technologies are crucial to enhance the survival rate of patients. The progression of cancer pathology begins with the accumulation of DNA mutation that transforms a normal cell into a proliferating tumor cell. This unregulated cell growth is governed by disruption in reactive oxygen species, iron homeostasis, and up-regulation of ribonucelotide reductase. Studies show chelators have significant antiproliferative properties reducing tumor growth through iron chelation. Unfortunately, they also bind to iron in normal cells, therefore, there is a great need to develop chelators that bind specifically to iron in cancer cells to prevent cell proliferation. Our study focuses on the design of a new class of site-directed iron chelators using gold nanoparticles (AuNPs) as targeted molecular carriers. These AuNPs are capped with thiolate ligands that are modified using EDC/NHS coupling chemistry for attachment of chelators and targeting moieties that recognize cancer cell surfaces. We will present the synthesis strategy and characterization methods used for confirming the presence of chelators on the AuNP surface. These methods include ultraviolet-visible, fluorescence, infrared, and dynamic light scattering spectroscopies. Metal binding studies demonstrating iron uptake will also be presented.

Proton-coupled electron transfer (PCET) occurs in a variety of oxidation/reduction reactions. This thermodynamically-coupled transfer of an electron (e–) and a proton (H⁺) is important for many reactions, including catalysis and energy generation, and may occur through different mechanisms. Zinc oxide (ZnO) nanoparticles are useful for studying factors that influence the rates of PCET reactions in at metal-oxide surfaces. The ZnO nanoparticles used in this research have been well characterized and, as a colloidal solution, can be treated as molecule-like reactants in experiments. The ZnO nanoparticles described in these experiments are capped with dodecylamine (DDA), and then dispersed into air-free toluene, an aprotic solvent. The use of an aprotic solvent is important to ensure that the e–/H⁺ are transferred from the nanoparticle. When these nanoparticle solutions are irradiated with above-bandgap radiation, an electron is excited into the conduction band. This leaves a hole in the valence band that, from previously demonstrated research, is immediately quenched by EtOH left over from synthesis; EtOH provides both an electron and a proton, keeping the nanoparticle neutral. When the reduced and protonated ZnO nanoparticles are reacted with 2,4,6-tri-tert-butylphenoxyl (^tBu₃ArO·), an electron and a proton are transferred from the reduced ZnO nanoparticle to the ^tBu₃ArO·, yielding the corresponding phenol, ^tBu₃ArOH. The kinetics of this reaction are monitored using laser flash photolysis. The rates of PCET are affected by the reduction potentials and the pKa of the reactants. The reduction potentials of the nanoparticles may be tuned by changing the particle size. Initial results also show the concentration of the capping group affects the rate of PCET. We are investigating how these factors, reduction potential and capping group concentration, influence the rate of PCET from reduced and protonated ZnO nanoparticles.

As we move our energy production and consumption economy towards a cleaner, “green” energy paradigm, it has become clear that research into solar energy harvesting is of real world significance. While fundamentally challenging, the capture and storage of solar energy into chemical bonds, such as hydrogen, can be envisioned as a large scale energy solution. In nature, the champion of solar water splitting for energy production and storage is Photosystem I and II (PS I and II). After a photon absorption event, the manganese oxygen evolving center (OEC) in PS II increases its reductive capacity enough to oxidize water into its oxygen and hydrogen constituents. Following the water oxidation reaction, the manganese oxidation state returns to the original to further oxidize additional water molecules. In practice however, it is incredibly difficult to create a regenerative OEC mimic, as high valent Mn is not usually stable. Therefore, our focus is to develop and explore materials which mimic the PS I and II solar water splitting reaction. α-Fe2O3 has shown great promise for the solar water oxidation half reaction. Upon photo-excitation, electrons are collected at the back contact leaving the surface of α-Fe2O3 in an oxidized state, providing a driving force for water oxidation. Additionally, upon introduction of certain catalysts, we can increase the oxidative capacity of α-Fe2O3, and thus improve the overall solar-to-hydrogen efficiency. So far, we’ve observed a significant enhancement in the oxidative efficiency with the use of a certain cobalt catalysts, and we are investigating the use of other metal centered catalysts including: nickel, iridium, silicon, tin, iron, niobium, and titanium. Ideally, we’d like to see these other metal centered catalysts demonstrate a greater increase in solar-to-hydrogen efficiency than our cobalt catalysts. We hope to, one day, apply this technology towards increasing the efficiency of solar powered fuel cells.

Gas chromatography - mass spectrometry (GC-MS) is a widely used analytical technique for separating and identifying volatile and semi-volatile compounds in complex mixtures. It is beneficial to research ways of increasing sample throughput (i.e. decreasing analysis time) while not losing any chemical information. This study investigates the change in volatile chemicals (odors) that are emitted from banana peels in varying stages of ripeness. The headspace of banana peels was first analyzed using Solid Phase Micro-Extraction (SPME) with a standard gas chromatograph and a quadrupole mass spectrometer (qMS). For demonstrating a viable platform for increased sample throughput, the samples were then analyzed on a LTM (Low Thermal Mass GC) coupled to a Time-of-Flight mass spectrometer. The banana peel analyses on the LTM-TOFMS decreases the run time by tenfold when compared with the traditional GC-qMS. A new data analysis program developed by the Synovec Lab is used to visualize the data and identify compounds.

Compound I is the intermediate responsible for substrate oxidation in the catalytic cycles of a variety of heme-containing metalloenzymes, such as peroxidases, oxygenases, and importantly, cytochrome P450s. Cytochrome P450s, through compound I, oxidize approximately 75% of foreign substances that enter the body, such as pharmaceuticals and chemicals from the environment, so there is an interest in the mechanism by which this reaction occurs. The goal of this project is to probe the potential reversibility of Compound I formation, a step traditionally thought to be irreversible. Due to its stability and availability, horseradish peroxidase (HRP) was used as the model enzyme. In the case of HRP, hydrogen peroxide is reduced to water at the heme cofactor, while oxidizing a variety of substrates. In the presence of an oxidant and the absence of a substrate to oxidize, hydrogen peroxide coordinates to the iron of the heme, the O-O bond is cleaved, which forms water and compound I. A key experiment reacts HRP with unlabeled H₂O₂ in ¹⁸O-labeled water, and determines whether mixed-labled H₂O₂ is formed. The presence of mixed-labeled H₂O₂ indicates that there is reversibility of the O-O bond cleavage that forms compound I. The existence of mixed-labeled H₂O₂ is ascertained by first removing HRP by filtration, leaving the H₂O₂ in the filtrate. This is followed by the addition of a water soluble phosphine. In this case, the phosphine cannot be oxidized by Compound I, but can readily react with free hydrogen peroxide in solution to give the corresponding phosphine oxide. Mass spectroscopy is used to determine whether the phosphine oxide has incorporated the ¹⁸O label. Results show that when the experiment is performed in the presence of ¹⁸OH₂, there was no observable increase in the intensity of a peak corresponding to ¹⁸O-phosphine oxide, so reversibility of Compound I formation was not confirmed.

Thin-film solar cells can address the cost barrier of solar power by virtue of less material usage and more efficient manufacturing processes like roll-to-roll printing. The thin-film material Cu/Zn/Sn/Se (CZTS) is of particular interest because it is composed of earth-abundant elements; however, the current record for CZTS device efficiency is 12.6%, which is far from the 20% efficiency that is needed to be commercially competitive. Low CZTS device efficiencies have been linked to low open-circuit voltages (Voc), which are likely due to high charge-carrier recombination. Recombination can be increased by irregularities in crystal structure and composition known as defects. In this project, different microscopies will be used to study the defects present at the interfaces of a working CZTS photovoltaic device in relation to the device's V_oc. The interfaces of concern include those between different material layers and those between CZTS crystal grains, i.e. grain boundaries. A variety of scanning probe microscopies (SPM) will be used to map local electronic properties at these interfaces, relating position on a device cross-section to current and voltage characteristics. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) will be used to correlate these electronic properties with CZTS device structure and composition. In making these correlations between SEM, EDS, and SPM data we hope to better understand the origins of Voc loss in CZTS devices and, in turn, inform more effective CZTS cell fabrication. Thus far, we have acquired SPM, SEM, and EDS images that display the distinct layers of the device cross-section. Further optimization of sample preparation is required to achieve both resolution of grain boundaries and a sample surface that is smooth enough for SPM to obtain reliable electronic data.

Ion mobility mass spectrometry is a powerful technique for analyzing proteins and protein complexes in the gas phase. Ions are generated using nanoelectrospray ionization from aqueous, buffered solutions containing the protein or protein complex of interest. The resulting ions are native-like; their structures have low, narrow charge-state distributions and resemble those in the condensed-phase. There is an interest in probing different charge states of protein and protein complexes. High charge-state distributions of proteins and protein complexes, for example, can be seen after addition of ‘supercharging’ reagents, e.g., sulfolane or m-nitrobenzyl alcohol, to the electrospray buffer. Several mechanisms have been proposed to explain the mechanism of supercharging. Here, we used ion mobility mass spectrometry to probe the charge-state distributions and collision cross sections of a large set of native-like protein and protein complex ions, with masses ranging from 6–468 kDa, generated from solutions containing 1% m-nitrobenzyl alcohol. We determined the extent of supercharging by calculating the percent increase in highest charge state observed between supercharged and non-supercharged cations. We observed a large range of percent increases in highest charge state but in general, there is evidence that small proteins (<100 kDa) exhibited a greater increase than larger proteins in these experiments. Upon comparison of these results to those for ions generated from sulfolane-containing solutions, we found that the maximum extent of supercharging observed with m-nitrobenzyl alcohol was less than that observed when sulfolane was used. The most supercharged cations generated with m-nitrobenzyl alcohol had up to a 96% increase in collision cross section compared to ions generated without supercharging agents, but the differences in collision cross sections with and without supercharging were less than 2% for large protein complexes (> 100 kDa). These results suggest that ions supercharged using m-nitrobenzyl alcohol may retain their structures better than those supercharged using sulfolane.

We describe an exo-selective cyclization of enantioenriched allenols to form cyclic ethers containing an α-tetrasubstituted stereocenter. Cyclic ethers bearing α-tetrasubstituted stereocenter are present in acetogenins, macrodiolides, ionophores, and lignans. These natural products have been found to have anti-fugal, anti-tumor, and/or antibiotic properties. However, an asymmetric catalytic synthesis of α-tertrasubstituted cyclic ethers remains a major synthetic challenge. Our method works with as little as 0.02 mol % of a gold catalyst for the exo-selective cyclization of enantioenriched allenols, and proceeds with excellent chirality transfer, and high functional group compatibility.

Composites of conjugated polymers with semiconducting nanocrystals (NCs) are of interest for low-cost, solution- processable photovoltaics. However, compared to typical polymer/fullerene composites, relatively little is known about factors influencing charge generation. Without understanding these factors, design principles for improving solar cell applications remain elusive. Previous studies of blends of the polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) with PbS nanocrystal quantum dots showed the excited NC undergoing charge transfer by hole transfer from the NCs to the polymer. To further investigate this hole transfer mechanism, quasi-steady-state PhotoInduced Absorption (PIA) was performed on blends of P3HT with PbS nanocrystal quantum dots as a function of excitation energy. As the energy exciting the PbS quantum dots was increased, the yield, per photon absorbed, of positive charge carriers on the organic host polymer increased. This occurred even at excitation wavelengths that only the NCs could absorb at. Our result provide direct evidence that holes generated on the NC retain some of the additional energy from excitation, e.g. hot holes. Further understanding of these results could provide even more insight to the mechanisms of organic/inorganic photovoltaics.

Physicochemical DNA research contributes to cutting edge medical applications such as single nucleotide polymorphism (SNP) detection and drug delivery. DNA can be modified with azobenzene moieties to form azobenzene DNA. I used UV light to induce a trans to cis isomerization reaction of the azobenzene moiety which causes double stranded azobenzene DNA (dsDNA) to split into a single stranded DNA (ssDNA). We study the effects of UV light on the azobenzene photoisomerization of perfectly matched and mismatched DNA. For the experiments, a glass substrate is functionalized with amino-silane molecules and single stranded azobenzene DNA. I hybridized the azobenzene DNA with either a perfectly matched or a mismatched strand to form double stranded DNA. I destabilize the DNA duplex by adding UV light to the hybridized DNA sample. Since the mismatched strand has a single base mismatch, it is less intrinsically stable than a perfectly matched strand due to less contributing intermolecular forces. Consequently, the melting temperature is lower for the mismatched strand. The mismatched DNA strand returns a less intense fluorescent signal in my detection. Experimental parameters such as hybridization time, UV exposure time and temperature applied to the experimental set-up are varied in order to study changes in ssDNA vs. dsDNA fluorescence. Consistent reproduction of these results is vital for a reliable DNA chip assay that can detect single nucleotide polymorphisms (SNP) in fragments of DNA.

We investigate which structural features of sterols most strongly influence miscibility of lipids in membranes. Lipid membranes serve as simple models of cell membranes. Within cell membranes, discrete domains in which lipids, sterols, and proteins are non-uniformly distributed are thought to be essential to cellular function. Sterols including cholesterol in mammals and ergosterol in yeast are often discussed as being evolutionarily optimized to interact with membranes. Here we examine the miscibility phase behavior of membranes that contain either a plant sterol or a yeast sterol with the eventual goal of comparing the interactions between lipids and plant sterols, or lipids and yeast sterols, with the interactions between cholesterol, and lipids. To do so, we map miscibility phase diagrams of vesicle membranes containing a sterol (stigmasterol, beta-sitosterol, or ergosterol), a lipid with a low melting temperature (DOPC), a lipid with a high melting temperature (DPPC), and a small amount of a fluorescently labeled lipid that preferentially partitions into one of the two membrane phases. We compare our resulting phase diagram to a well-studied system, specifically membranes composed of DOPC/DPPC/cholesterol. The method that we use to generate giant unilamellar vesicles is electroformation, and we observe phase separation via fluorescence microscopy. Our results suggest that minor structural changes in the sterol have large effects on membrane miscibility.

Solar technology is a potential way to help meet the growing demand for clean, renewable energy. Hybrid composites of inorganic quantum dots, with organic semiconducting polymers, offer a potential means of producing low-cost, solution-processable photovoltaics. Photovoltaics can convert sunlight directly into electricity to capture solar energy. The synthesis of quantum dots typically involves the use of large surfactant molecules to facilitate particle growth and solubility. These native ligands act as electrical insulators that impede charge transport in photovoltaic devices. Therefore, it is necessary to exchange these large ligands with small molecules to achieve efficient charge carrier photogeneration and transport. In this research, we examine bulk heterojunction blends of low band gap PbS quantum dots with the conjugated polymer poly((4,8-bis(octyloxy)benzo(1,2-b:4,5-b')dithiophene-2,6-diyl)(2-((dodecyloxy)carbonyl)thieno(3,4-b)thiophenediyl)) (PTB1) treated with different ligands including halide ions and organic crosslinkers. By using photoinduced absorption and transient photovoltage techniques, we study the long-lived charge generation dynamics and recombination kinetics of our devices. We find that the ligand treatments exhibiting higher device performance correlate to longer carrier recombination lifetimes in both spectroscopic and photovoltaic device measurements.

Localized surface plasmon resonances (LSPRs) can be described as oscillations of large electron densities. Traditionally observed in metals, LSPRs have recently been observed in semiconductors, and have gained more attention because of their tunability over a wide range of energies. Additionally, semiconductor LSPRs could offer a cheaper alternative to plasmonic applications. Here, we aim to observe the effect of band-gap engineering on LSPRs in zinc oxide semiconductor nanocrystals by incorporating Cd^{2 +} and Mg^{2 +} ions into zinc oxide host lattices. Cd^{2 +} -and Mg^{2 +} -doped zinc oxides of different molar dopant ratios are synthesized via base-initiated hydrolysis and air-free hot injection synthesis. The size and structure of the nanocrystals are characterized via transmission electron microscope (TEM), absorption and photoluminescence. The molar dopant ratios of the samples are determined analytically via inductively coupled plasma atomic emission spectroscopy. In order to observe LSPRs in semiconductors, conduction-band electrons are added to the semiconductor nanocrystals via photochemical reduction to give them metallic-like properties. The number of electrons accumulated can be measured by titrating the samples with mild oxidants such as decamethylferrocenium. The LSPRs in the zinc oxide nanocrystals are studied by electron paramagnetic resonance spectroscopy (EPR) and infrared (IR) spectroscopies. In combination with absorption and photoluminescence, EPR is used to measure the conduction-band, valence-band and overall band-gap energies. Using IR spectroscopy, we study how these energies influence the LSPR energies.

As scientific studies have been focusing on generating alternative renewable energy sources, attention has been drawn to the need to store energy from the sun. One strategy is to develop catalysts capable of producing the energy-dense molecule hydrogen from the reduction of water. This kind of solar fuels system would allow for on-demand release of the energy that is stored in the chemical bonds of hydrogen through environmentally benign, carbon-free combustion. We are interested in the potential of catalyzing proton reduction with cobalt in a diimine-dioximato ligand framework. Previous studies on cobalt diglyoxime complexes have demonstrated the viability of such catalysts for proton reduction. Our research is focused on synthesizing bimetallic complexes using the same framework and studying the effect of another metal center on catalytic activity. Our entry into this chemistry relies on the initial synthesis of a doubly-deprotonated diimine dioximate complex of cobalt as a starting material, which can be considered as a “metalloligand”. The physical and electronic properties of this cobalt metalloligand and its multimetallic derivatives are studied by X-ray crystallography, 1H- and 13C-NMR, UV-visible spectroscopy, and cyclic voltammetry.

Luminescent solar concentrators (LSCs) are solar energy harvesting devices that promise to revolutionize the next generation of solar energy by separating the task of sunlight absorption from power generation. These devices use phosphors that absorb sunlight and wave-guide reemitted light to photovoltaics (PVs) to generate electricity. One promising class of phosphors is that of doped semiconducting nanocrystals (known as quantum dots) due to their intense absorption and minimal reabsorption of dopant-emitted light. In these materials the semiconductor quantum dot absorbs sunlight and transfers the energy to an emissive dopant to prevent efficiency loss by reabsorption. CdSe quantum dots are well known for their intense absorption across the visible spectrum, and doping with Ytterbium would enable their emission to be used in LSCs. Moreover, the Yb³⁺ ions emit at an energy that is nearly perfectly matched with the bandgap of a silicon PV cell, boosting its efficiency. The focus of my research is the synthesis of Yb³⁺-doped CdSe. Ytterbium is incompatible with the tetrahedral CdSe lattice with respect to its larger oxidation state and coordination preference, and introducing it as a dopant is a challenge that has yet to be solved by the chemistry field. While employing air-free Schlenck techniques, I am modifying the doping methods that have proven successful in the synthesis of other Gamelin Group materials, including a process we recently developed called nanocrystal diffusion doping. Success can be measured by detecting quantum dot sensitized ytterbium luminescence. The goal is that this approach will lead to a repeatable procedure by which to synthesize stable Yb³⁺-doped CdSe for novel characterizations as well as for eventual application in a new generation of solar devices.

Binary chromophore systems contribute to more favorable intermolecular interactions and can significantly enhance electro-optic (EO) activity of EO materials, which have potential applications for telecommunications. Optimization of EO activity of binary chromophore systems consisting of dendrimer host (i.e. PSLD-33) and guest chromophore (i.e. FTC) will be achieved by determining the ideal host to guest concentration ratio. Synthetic schemes for known dendritic systems were proposed and synthesis is currently underway. Linear optical properties, including max absorbance (λmax) and molar absorptivity (ε), of materials in solutions with chloroform will be characterized using UV-vis spectroscopy. These properties have implications in chromophore packing density, which up to a thresh hold can improve EO activity. Additional steps include making films of the materials. EO activity of the materials will be characterized using the Teng-Man method, which has proven to be a convenient way to determine the EO coefficient (r33) in the Dalton lab over the past ten years.

An efficient and environmentally benign means of creating semiconducting polymers is necessary for the commercialization of organic electronics. Furthermore, it is crucial that as much control as possible be exerted over the polymerization process. To these ends, two polymerization methods are useful – C-H activation and living polymerization. First, C-H activation is a collection of synthetic techniques where C-H bonds undergo direct catalytic alteration to yield new homo- or heteroatom linkages. Whereas organometallic reagents were traditionally used to achieve these results, C-H activation allows for shorter syntheses utilizing less-hazardous reagents and broader functional group compatibility. Living polymerization is a form of addition polymerization and in our case, the number of chains is constant during the reaction and dependent on the catalyst-to-monomer ratio. This allows for much narrower mass distributions of the desired polymer and more consistent growth. To achieve this, benzoxazole-based monomers containing a C-O electrophile are to be reacted in the presence of a zero-valent nickel species with electron-rich phosphine ligands. By increasing the electron density on the metal center, we aim to facilitate a “ring-walking” mechanism at higher temperatures than previously thought possible. Monomer synthesis and polymerization results are detailed.

The genomic RNA packing enhancer (GRPE) is an RNA element found in the HIV-1 genome that is implicated in the packing of HIV-1 genomic RNA (gRNA). This 140 base-pair sequence is found within the p1-p6 region of gag and is believed to fold into a structure that interacts with viral components to enhance packing, most likely by recruiting the nucleocapsid protein. Understanding this RNA structure would provide molecular understanding of the GRPE’s function in gRNA packing, which would in turn shed light on how HIV-1 assembles. Ultimately, it could also facilitate the design of new anti-HIV therapeutics. The goal of this study is to determine the structure of GRPE using nuclear magnetic resonance (NMR) spectroscopy. Using previously published chemical mapping data, I designed an optimal sequence to study and cloned the resulting 140 base-pair DNA sequence corresponding to the GRPE RNA into a high copy number plasmid for the purpose of generating sufficient amounts of DNA template for transcription. The transcription of GRPE was optimized, and I am in the process of synthesizing and purifying sufficient amounts of GRPE to conduct NMR spectroscopy studies using large scale gel electrophoresis and flash chromatography. Once this is done, I will use NMR spectroscopy to elucidate the GRPE structure.

Micro RNAs (miRNAs) control translation of certain proteins through degradation of the messenger RNA which code for these proteins. These non coding RNAs are often up-regulated in many forms of cancer and can inhibit the expression of tumor suppressor proteins. The goal of this project is to engineer a protein which can bind to and inhibit the biogenesis of a miRNA-21, which is overexpressed in many cancers. Previous reports have shown that the RNA recognition domain (RRM) of human splicing factor Fox-1 protein has high affinity and specificity for the UGCAUG sequence. We are engineering this RRM to target the stem-loop sequence of precursor miRNA-21. Amino acid site changes were introduced into Fox-1 to generate a protein which will inhibit production of the oncogenic miRNA-21 in cancer cells. This project involves the application of various methods in biochemistry, including PCR site-directed mutagenesis, cell transfection, DNA cloning, protein expression and purification, RNA transcription and purification as well as gel electrophoresis assays and 3-Dimensional structural analyses of protein and RNA through nuclear magnetic resonance studies. Currently, a stable protein has been expressed and the precursor species of miRNA-21 is being prepared to characterize its interaction with the engineered protein biochemically, biophysically and structurally.

Currently there is extensive interest in the health of honeybee colonies, both in the United States, and worldwide. A healthy and functioning agricultural system requires honeybees, and bees in turn, require nutritious, diverse forage that includes both nectar and pollen. This study involved analyzing the pollen collected by honeybee colonies maintained on the campus of Edmonds Community College, and matching that with pollen collected directly from local plants. We isolated pollen from honey collected and stored by the bees and also collected pollen directly from cells in the hive. In order to identify the different pollen species, the pollen was chemically extracted and acetolyzed to remove sugars and waxes. The treated pollen was then stained, slide-mounted and viewed by light microscopy. These pollen samples were compared to samples of pollen that were collected directly from local plants as well as to existing pollen databases. Preliminary analysis revealed the presence of pollen from brassica, salvia, and trifolium. We were unable to identify some of the extracted pollen species. During the coming foraging season we will expand our database of locally-collected pollen and will generate a local pollen identification key. This will allow us to conclusively identify all of the pollen found in the hives. Results of this study will help us track what the bees are eating and will inform decisions about what best to plant to insure healthy colonies.

The amino acid tryptophan can participate in biological reactions as a reducing agent, in which it as converted to a radical. Tryptophan radicals embedded in proteins can participate in electron transfer chemistry, such as in DNA photolyase and cryptochrome enzymes, or catalytic chemistry, such as in peroxidases enzymes. The properties of tryptophan radicals are heavily dependent on the microenvironment within the protein. The objective of my research is to study how the protein environment can control the properties of tryptophan radicals. For this, I utilize the beta hairpin peptide as a model protein. This system allows for controlled changes to be made near the tryptophan, altering its microenvironment. The effect of these changes are monitored using electron paramagnetic resonance (EPR), a spectroscopy that is sensitive to electron radicals and can help elucidate the specific effects that the protein microenvironment has on the radical.

Cyanide-bridged transition metal complexes serve as model systems to study photoinduced charge transfer reactions. These complexes are important to understand because they play a major role in processes such as photosynthesis and the conversion of light to electronic energy in solar cells. Using RuCl₃•XH₂O salt, 2,2':6',2"-terpyridine (tpy), 2,2'-bipyridine (bpy) and KCN we synthesized [Ru(tpy)(bpy)CN]²⁺, [(tpy)(bpy)Ru-{CNRu(tpy)(bpy)]³⁺ and [(bpy)₂Ru-{CNRu(tpy)(bpy)]⁴⁺. These multistep syntheses were monitored using FTIR, UV-vis and ¹H NMR in order to verify that the compounds of interest were made. These compounds are interesting because of their metal-to-ligand charge transfer and metal-to-metal charge transfer processes when excited with visible light.  In the future these complexes will be studied using nonlinear spectroscopies in the visible and infrared regions of the spectrum in order to investigate their charge transfer capabilities.

Malaria, due to parasitic infection by Plasmodium protozoa, is a severe global disease with 300 million annual cases leading to 1-2 million deaths. While a few anti-malarial treatments continue to work, the continual emergence of new drug resistant parasites is an urgent public health concern. Previous studies in the Rathod laboratory suggest that chemical tools can be used to distinguish variations in evolutionary capabilities of different malaria parasite strains. Some strains such as Dd2 display the Accelerated Resistance to Multiple Drugs (ARMD) phenotype, whereas the HB3 strain displays the non-ARMD phenotype. In previous studies, Dd2 strain acquires resistance to several antimalarials at a significantly higher frequency than the HB3 strain. In this experiment, a cyclopropyl carboxamide (GSK2645947), a novel class of antimalarial agent, was used to select for resistant parasites from Dd2 and HB3 with the aim of comparing their relative frequencies of resistance to GSK2645947. A series of selection experiments were carried out utilizing different concentrations of GSK2645947 and different numbers of starting parasites. The parasites acquired resistance to GSK2645947 at similar frequencies in Dd2 and HB3 cells. The extent of resistance to GSK2645947, measured using EC50 assays, was similar in Dd2 and HB3 resistant clones; resistant parasites from neither lines showed cross-resistance to other antimalarial drugs. The present results point to a novel mechanism for rapidly acquiring resistance to GSK2645947, a mechanism that is equally prevalent in Dd2 and HB3 strains of P. falciparum parasites.

Balance control, or stability, is the ability to maintain the body’s center of mass over a base of support. Measurements of stability have a wide range of applications in both clinical and research settings. Many methods have been developed for measuring stability, including functional balance tests, force plate analysis, and video analysis. The preferred method to evaluate standing stability employs the use of a triaxial accelerometer (TA) due to ease of use, portability, cost, and reliability. The aim of this study was to develop an accelerometry-based system for measuring inverted stance (handstand) stability. Using a TA, we collected accelerometry data from a group of acrobats and gymnasts who performed handstands over a period of 30 seconds in four different test conditions: eyes open/firm surface, eyes closed/firm surface, eyes open/compliant surface, and eyes closed/compliant surface. We calculated a set of performance parameters, including medial/lateral displacement, anterior/posterior displacement, and mean speed for each condition from the TA data. Our statistical analysis showed that the TA reliably distinguishes between test conditions for handstands. This suggests that accelerometry can be expanded from regular stance analysis to the evaluation of inverted stance stability. Future applications of accelerometry may include evaluating an acrobat’s handstand stability, comparing the relative stability of differing handstand techniques, or as an additional tool for those investigating the balance control mechanisms of the inverted stance.

Graphite Oxide combined with selective laser scribing were used to create laser scribed graphene based electrochemical electrodes. Combining multiple electrodes with varying types of gelatinous and aqueous electrolyte a highly conductive, flexible, and robust capacitor was produced. The primary goal of this research was to discover an optimal combination between variables including graphite oxide density, substrate type, laser scribing patterns, and electrolyte porperties. A range of possible combinations were selected to be tested based on prior resaerch and their probability to produce an increase in energy density. To insure consistency, isolation of a single variable insured each capacitor was constructed with the same methods and regiment. In order to isolate a single variable and maintain uniformity within the test capacitor, a single sheet of laser scribed graphene electrodes were used to construct capacitors of a similar size and shape while simultaneousy adjusting a single parameter at any one time. Initial research was used to select starting values for variables, which were then individually adjusted, with a new capacitor constructed for each test run. Further research with seek to discover the feasibility of maintaining the combinations discovered through current work.

 Organic thin-film solar cells have received considerable attention on account of their flexibility, ease of production, and light weight. Recently, modifications of these solar cells’ nanoscale structures has yielded efficiencies higher than 10%. To further improve device efficiency and durability, detailed understanding of the pathways of charge generation and loss (through recombination of opposing charges) is essential. Electron paramagnetic resonance (EPR) spectroscopy, which directly observes radicals and unpaired electrons, including the charge carriers in these solar cells, is a useful tool for the characterization of these pathways. EPR analysis of relevant materials such as P3HT:PCBM blends indicate aspects of charge carrier lifetime and recombination rate that are temperature-dependent. Also, analysis of the variation of EPR spectra with modulation frequency allows us to directly determine the lifetime of excited charge carriers. Combination of this data alongside theoretical modeling of charge generation and recombination allows us to determine parameters such as charge recombination rates. For this purpose, a new method for simulation of an EPR spectrum that allows for computationally-efficient incorporation of radical life times, relaxation times and saturation has been created.