Physical Sciences and Mathematics Commons^™

Evolution From The Plasmon To Exciton State In Ligand-Protected Atomically Precise Gold Nanoparticles, Meng Zhou, Chenjie Zeng, Yuxiang Chen, Shuo Zhao, Matthew Y. Sfeir, Manzhou Zhu, Rongchao Jin

Publications and Research

The evolution from the metallic (or plasmonic) to molecular state in metal nanoparticles constitutes a central question in nanoscience research because of its importance in revealing the origin of metallic bonding and offering fundamental insights into the birth of surface plasmon resonance. Previous research has not been able to probe the transition due to the unavailability of atomically precise nanoparticles in the 1-3 nm size regime. Herein, we investigate the transition by performing ultrafast spectroscopic studies on atomically precise thiolate-protected Au₂₅, Au₃₈, Au₁₄₄, Au₃₃₃, Au_∼520 and Au_∼940 nanoparticles. Our results …

Photodynamic Killing Of Human Cancer Cells With Smart Photosensitizer Materials And An Endoscopic Implement For Singlet Oxygen Delivery, Mihaela N. Minnis

Dissertations, Theses, and Capstone Projects

The thesis describes progress on probe tips for a microoptic device for the precise delivery of the components necessary for photodynamic therapy (PDT) in a highly localized and controllable fashion. The thesis also summarizes results of a photosensitized oxidation study. The work focused on i) developing a photoactive fluoropolymer surface that will release sensitizer drug molecule for use in PDT, ii) designing new probe tips surfaces for use as sensitizer support for a microoptic PDT device, iii) exploring strategies for covalent attachment of sensitizers and model compounds to Teflon/PVA surfaces with the aim of being coupled with our microoptic device, …

I. Synthesis Of Diverse Structures From Quinone Monoketal And Quinone Imine Ketal With Efficiency And Control Ii. Synthetic Study Of Phalarine, Zhiwei Yin

Dissertations, Theses, and Capstone Projects

Quinonoids are quinone derivatives that have carbonyl or carbonyl equivalent and even number of double bonds embedded in six member rings. As a result of the intrinsic α,β-unsaturated ketone or imine structures, quinonoids, such as quinone monoketals, quinols, quinol ethers and quinone imine ketals, can accommodate a wide range of reactions including 1,2-additon, 1,4-addtion, SN2’ reaction (allylic substitution) to the α-carbon of the carbonyl or imine and cycloaddition reactions (e.g. Diels-Alder reaction). Quinonoids are effective building blocks for synthesizing heterocycles, which are ubiquitous in pharmaceutically useful agents. Developing new quinonoid based methodologies is essential to expanding the boundary of synthetic …

Specific Binding Affinity Of The Non-Catalytic Domain Of Eukaryotic Like Type Ib Topoisomerase Of Vaccinia Virus, Benjamin R. Reed

Dissertations, Theses, and Capstone Projects

Topoisomerases are ubiquitous proteins that alter supercoiling in double stranded DNA (dsDNA) during transcription and replication and. vaccinia and the closely related poxvirus variola virus, at 314 amino acids in length, encode the smallest of the type I topoisomerases(TopIB). TopIB is a two domain protein that recognizes the sequence 5’-T/CCCTT, cleaves at the 3’-end and relaxes supercoiling through rotation. The C-terminal domain (CTD) alone contains the catalytic activity and specificity. Deletion of the N-terminal domain results in a greatly reduced rate of relaxation and rapid dissociation. Biochemical data suggests that the N-terminal domain (NTD) is important for pre-cleavage binding and …

Probing The Structure And Photophysics Of Porphyrinoid Systems For Functional Materials, Christopher D. Farley

Dissertations, Theses, and Capstone Projects

Porphyrins (Pors) and their many cousins, including phthalocyanines (Pcs), corroles (Cors), subphthalocyanines (SubPcs), porphyrazines (Pzs), and naphthalocyanines (NPcs), play amazingly diverse roles in biological and non-biological systems because of their unique and tunable physical and chemical properties. These compounds, collectively known as porphyrinoids, can be employed in any number of functional devices that have the potential to address the challenges of modern society. Their incorporation into such devices, however, depends on many structural factors that must be well understood and carefully controlled in order to achieve the desired behavior. Self-assembly and self-organization are key processes for developing these new technologies, …

Electrochemical Nanoprobes For Electron Transfer Kinetics And Electrocatalysis Study, Yun Yu

Dissertations, Theses, and Capstone Projects

The studies of electrochemical processes on the nanoscale have led to a significant progress in understanding of electrochemical mechanisms and characterization of nanomaterials in the fields of energy, catalysis, and biological research. Electrochemical experiments at nanoscale require the fabrication and characterization of nanometer-sized electrochemical probes. The main advantages of the nanoprobes include very fast mass-transfer rate, high signal-to-noise ratio and extremely fine spatial resolution of electrochemical imaging. In the course of my Ph.D. research, different types of electrochemical probes were developed for measuring electron-transfer kinetics, probing single catalytic nanoparticles and sampling ultra-small volume of liquids.

We developed methodologies to fabricate …

Nmr Studies Of Electrochemical Energy Storage Materials, Jing Peng

Dissertations, Theses, and Capstone Projects

Electrochemical energy storage materials constitute essential elements in the development of sustainable energy technologies. They are crucial for improving the efficiency of energy storage devices to facilitate the use of renewable resources. The increasing human demands for energy and limitation of fossil fuel stimulates the continued development of energy storage materials. Better understanding of their working mechanisms and electrochemical properties from a view of chemistry is quite necessary for improving the energy storage technology. In this work, Nuclear Magnetic Resonance (NMR) has been used as a powerful tool to characterize the solvation behavior and diffusion ability of some commonly used …

Metabolic Profiling And Polymer Formation Of Gene Silenced Potato Periderms, Qing Cai

Dissertations, Theses, and Capstone Projects

Suberin is a biopolyester constituent of specialized plant periderm tissues formed within the phellem cell walls. Suberin and waxes of the periderm layer act to prevent water diffusion, mechanical breakdown and pathogenic invasion in plants. Ferulic esters, ω-hydroxyacids and α,ω-fatty diacids are considered to be the most important linkage between aliphatic and aromatic suberin domains and also linked with cell-wall polysaccharides. The potato gene FHT (fatty ω- hydroxyacid/fatty alcohol hydroxycinnamoyl transferase) esterifies ferulic acid to suberin. Diminished levels of feruloyl transferase activity have been associated with lowered amounts of feruloyl esters of fatty acids in both suberin-associated waxes and suberin …

Metabolic Profiling Of Genetically Modified Potato Periderm Tissues, Liqing Jin

Dissertations, Theses, and Capstone Projects

Potato tubers are protected from dehydration and pathogens by a covering peel (periderm) impregnated with suberin, a complex cross-linked biopolymer that contains both polyaliphatic and lignin-like aromatic domains. Current models describing the macromolecular structure of suberin assume that ferulic acid cross-links both domains as it may form carboxyl ester bonds with aliphatic monomers and non-ester radical-coupled bonds with phenolics. Ferulic acid also links by ester bonds to glycans and acts in cross-linking polysaccharides and lignin. Fatty alcohol/ω-hydroxyacid hydroxycinnamoyl transferase (FHT) is a BADH acyltransferase responsible for the synthesis of akyl-ferulates that is necessary for suberin biosynthesis. Periderm from FHT-RNAi …

Development Of New Radiolabeling Methods And Insights On Ionizing Radiation Interactions With Nanoparticles, Travis Shaffer

Dissertations, Theses, and Capstone Projects

Nanoparticles are often combined with radionuclides for various applications, ranging from waste remediation to imaging and therapy in the medical field. The overarching aim of this body of work is two-fold. The first aim is development of new radiolabeling methods for various nanoparticles that allow stable attachment of a variety of imaging and therapeutic radionuclides. The second portion more fully describes mechanisms of interaction between ionizing radiation and nanoparticles.

The following advancements will be presented in this dissertation: i) a new radiolabeling method for silica and silica-based nanoparticles that does not require the use of specific chelators, with both radiochemical …

Sustainable Molecular Gelators: Beta-D-Glucoside Derived Structuring Agents And Their Material Application, Julian R. Silverman

Dissertations, Theses, and Capstone Projects

Though molecular gelators may by synthesized and formulated into gels following a variety of methods, it should serve that the most valued methods may utilize renewable and waste resources and follow sustainable procedures. Molecular gelators are systems capable of structuring liquids into solid-like materials and they represent a class of surfactant and amphiphilic materials which posses the capability to be not only useful in their ability to form gels, but multifunctional in the ability to respond smartly to a variety of stimuli. Thus there is an interest in the development of sustainable molecular gelators capable of being applied to applications, …

Free Energy-Based Virtual Screening And Optimization Of Rnase H Inhibitors Of Hiv‑1 Reverse Transcriptase, Baofeng Zhang, Michael P. D'Erasmo, Ryan P. Murelli, Emilio Gallicchio

Publications and Research

We report the results of a binding free energy-based virtual screening campaign of a library of 77 α-hydroxytropolone derivatives against the challenging RNase H active site of the reverse transcriptase (RT) enzyme of human immunodeficiency virus-1. Multiple protonation states, rotamer states, and binding modalities of each compound were individually evaluated. The work involved more than 300 individual absolute alchemical binding free energy parallel molecular dynamics calculations and over 1 million CPU hours on national computing clusters and a local campus computational grid. The thermodynamic and structural measures obtained in this work rationalize a series of characteristics of this system useful …

Electrochemical Properties Of Melting Gel Coatings, Lisa C. Klein, Ahmad Dengah, Kutaiba Al-Marzoki, Gabriela Rodriguez, Andrei Jitianu, Jadra Mosa, Mario Amapricio

Publications and Research

Organic-inorganic melting gel coatings were applied to titanium alloy substrates to decrease their corrosion and extend their lifetime in an electrochemical application. Melting gels containing phenyl substitutions were coated onto the substrates. The ratio of diphenyl dimethoxysilane (DPhDMS) to methanol was varied to change the thickness of the coatings. The coatings were inspected visually to see that there is good adhesion between the coating and the substrate. Nanoindenter tests were performed to determine hardness

Ionophoric Polyphenols Selectively Bind Cu2+, Display Potent Antioxidant And Anti-Amyloidogenic Properties, And Are Non-Toxic Toward Tetrahymena Thermophila, Alberto Martinez, Ralph Alcendor, Tanzeen Rahman, Magdalena Podgorny, Ismaila Sanogo, Rebecca Mccurdy

Publications and Research

Alzheimer’s disease (AD) is the most common form of dementia affecting more than 28 million people in the world. Only symptomatic treatments are currently available. Anticipated tri-fold increase of AD incidence in the next 50 years has established the need to explore new possible treatments. Accumulation of extracellular amyloid-b (Ab) plaques, intracellular tangles in the brain, and formation of reactive oxygen species (ROS) are the major hallmarks of the disease. The active role of some metal ions, especially Cu²⁺, in promoting both Ab aggregation and reactive oxygen species formation has rendered ionophoric drugs as a promising treatment strategy. …

Atomistic Corrective Scheme For Supercell Density Functional Theory Calculations Of Charged Defects, Tengfei Cao, Angelo Bongiorno

Publications and Research

A new method to correct formation energies of charged defects obtained by supercell densityfunctional calculations is presented and applied to bulk, surface, and low-dimensional systems. The method relies on atomistic models and a polarizable force field to describe a material system and its dielectric properties. The polarizable force field is based on a minimal set of fitting parameters, it accounts for the dielectric screening arising from ions and electrons separately, and it can be easily implemented in any software for atomistic molecular dynamics simulations. This work illustrates both technical aspects and applications of the new corrective scheme. The method is …

Photooxidation Chemistry And Photodynamic Therapy: Pointsource Delivery Of Singlet Oxygen, Sensitizer And Nitrosamine Drugs, Ashwini Anil Ghogare

Dissertations, Theses, and Capstone Projects

Eradication of residual tumor cells that are directly adjacent to vital tissue is a daunting challenge to surgeons. Because the field needs advances in intraoperative settings and a means for high-precision delivery of singlet oxygen for photodynamic therapy (PDT) of cancers, this dissertation outlines the development and application of a “pointsource” fiber optic device. The device offers highly localized and simultaneous delivery of sensitizer drug, light, and oxygen (components necessary for PDT) for cancer cell eradication in-vitro and in-vivo. The following chapters describe (a) the photokilling activity and precision of pointsource PDT in monolayer ovarian and brain cancer cells …

Interaction Of Spliceosomal U2 Snrnp Protein P14 With Its Branch Site Rna Target, William Perea Vargas

Dissertations, Theses, and Capstone Projects

Newly transcribed precursor messenger RNA (pre-mRNA) molecules contain coding sequences (exons) interspersed with non-coding intervening sequences (introns). These introns must be removed in order to generate a continuous coding sequence prior to translation of the message into protein. The mechanism through which these introns are removed is known as pre-mRNA splicing, a two-step reaction catalyzed be a large macromolecular machine, the spliceosome, located in the nucleus of eukaryotic cells. The spliceosome is a protein-directed ribozyme composed of small nuclear RNAs (snRNA) and hundreds of proteins that assemble in a very dynamic process. One of these snRNAs, the U2 snRNA, is …

Light-Activated Photocurrent Degradation And Self-Healing In Perovskite Solar Cells, Wanyi Nie, Jean-Christophe Blancon, Amanda J. Neukirch, Kannatassen Appavoo, Hsinhan Tsai, Manish Chhowalla, Muhammad A. Alam, Matthew Y. Sfeir, Claudine Katan, Jacky Even, Sergei Tretiak, Jared J. Crochet, Gautam Gupta, Aditya D. Mohite

Publications and Research

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. However, a key challenge is their lack of stability over prolonged solar irradiation. Few studies have investigated the effect of light soaking on hybrid perovskites and have attributed the degradation in the optoelectronic properties to photochemical or field-assisted ion migration. Here we show that the slow photocurrent degradation in thin-film photovoltaic devices is due to the formation of light-activated meta-stable deep-level trap states. However, the devices can self-heal completely by resting them in the dark for <1 min or the degradation can be completely prevented by operating the devices at 0°C. We investigate several physical mechanisms to explain the microscopic origin for the formation of these trap states, among which the creation of small polaronic states involving localized cooperative lattice strain and molecular orientations emerges as a credible microscopic mechanism requiring further detailed studies.

A Direct Mechanism Of Ultrafast Intramolecular Singlet Fission In Pentacene Dimers, Eric G. Fuemmeler, Samuel N. Sanders, Andrew B. Pun, Elango Kumarasamy, Tao Zeng, Kiyoshi Miyata, Michael L. Steigerwald, X.-Y. Zhu, Matthew Y. Sfeir, Luis M. Campos, Nandini Ananth

Publications and Research

Interest in materials that undergo singlet fission (SF) has been catalyzed by the potential to exceed the Shockley–Queisser limit of solar power conversion efficiency. In conventional materials, the mechanism of SF is an intermolecular process (xSF), which is mediated by charge transfer (CT) states and depends sensitively on crystal packing or molecular collisions. In contrast, recently reported covalently coupled pentacenes yield ∼2 triplets per photon absorbed in individual molecules: the hallmark of intramolecular singlet fission (iSF). However, the mechanism of iSF is unclear. Here, using multireference electronic structure calculations and transient absorption spectroscopy, we establish that iSF can occur via …

The Synthesis Of Angucyclines Using An Intramolecular Bradsher Cycloaddition, Abdullah Allaoa, Tony E. Nicolas

Publications and Research

The Angucyclines are natural products which possess a broad spectrum of biological properties. Of particular interest are the natural products which contain the cis-hydroxyl motif at the AB ring junction. Their synthesis is particularly challenging. Our model study has resulted in the synthesis of a model of the angucyclines with the required cis-hydroxyl features. The present work will apply the previously developed chemistry to an intramolecular version which will lead to the synthesis of the ABC ring system

From Mollusks To Medicine: A Venomics Approach For The Discovery And Characterization Of Therapeutics From Terebridae Peptide Toxins, Aida Verdes, Prachi Anand, Juliette Gorson, Stephen Jannetti, Patrick Kelly, Abba Leffler, Danny Simpson, Girish Ramrattan, Mandë Holford

Publications and Research

Animal venoms comprise a diversity of peptide toxins that manipulate molecular targets such as ion channels and receptors, making venom peptides attractive candidates for the development of therapeutics to benefit human health. However, identifying bioactive venom peptides remains a significant challenge. In this review we describe our particular venomics strategy for the discovery, characterization, and optimization of Terebridae venom peptides, teretoxins. Our strategy reflects the scientific path from mollusks to medicine in an integrative sequential approach with the following steps: (1) delimitation of venomous Terebridae lineages through taxonomic and phylogenetic analyses; (2) identification and classification of putative teretoxins through omics …

Titanocene−Gold Complexes Containing N‑Heterocyclic Carbene Ligands Inhibit Growth Of Prostate, Renal, And Colon Cancers In Vitro, Yiu Fung Mui, Jacob FernáNdez-Gallardo, Benelita T. Elie, Ahmed Gubran, Irene Maluenda, Mercedes Sanau, Marıá Contel

Publications and Research

We report on the synthesis, characterization, and stability studies of new titanocene complexes containing a methyl group and a carboxylate ligand (mba = −OC(O)-p-C6H4-S−) bound to gold(I)−N-heterocyclic carbene fragments through the thiolate group: [(η5-C5H5)2TiMe(μ-mba)Au(NHC)]. The cytotoxicities of the heterometallic compounds along with those of novel monometallic gold−N-heterocyclic carbene precursors [(NHC)Au(mbaH)] have been evaluated against renal, prostate, colon, and breast cancer cell lines. The highest activity and selectivity and a synergistic effect of the resulting heterometallic species was found for the prostate and colon cancer cell lines. The colocalization of both titanium and gold metals (1:1 ratio) in PC3 prostate cancer …

Discovery And Characterisation Of A Novel Toxin From Dendroaspis Angusticeps, Named Tx7335, That Activates The Potassium Channel Kcsa, Ivan O. Rivera-Torres, Tony B. Jin, Martine Cadene, Brian T. Chait, Sébastien F. Poget

Publications and Research

Due to their central role in essential physiological processes, potassium channels are common targets for animal toxins. These toxins in turn are of great value as tools for studying channel function and as lead compounds for drug development. Here, we used a direct toxin pull-down assay with immobilised KcsA potassium channel to isolate a novel KcsA-binding toxin (called Tx7335) from eastern green mamba snake (Dendroaspis angusticeps) venom. Sequencing of the toxin by Edman degradation and mass spectrometry revealed a 63 amino acid residue peptide with 4 disulphide bonds that belongs to the three-finger toxin family, but with a unique modification …

Glass Polymorphism In Glycerol–Water Mixtures: Ii. Experimental Studies, Johannes Bachler, Violeta Fuentes-Landete, David A. Jahn, Jessina Wong, Nicolas Giovambattista, Thomas Loerting

Publications and Research

We report a detailed experimental study of (i) pressure-induced transformations in glycerol–water mixtures at T = 77 K and P = 0–1.8 GPa, and (ii) heating-induced transformations of glycerol–water mixtures recovered at 1 atm and T = 77 K. Our samples are prepared by cooling the solutions at ambient pressure at various cooling rates (100 K s1–10 K h1) and for the whole range of glycerol mole fractions, wg. Depending on concentration and cooling rates, cooling leads to samples containing amorphous ice (wg Z 0.20), ice (wg r 0.32), and/or ‘‘distorted ice’’ (0 o wg r 0.38). Upon compression, we …

Sulfur-Mediated Photochemical Energy Harvesting In Nanoporous Carbons, Alicia Gomis-Berenguer, Mykola Seredych, Jesus Iniesta, Joao C. Lima, Teresa J. Bandosz, Conchi O. Ania

Publications and Research

This work provides new insights in the field of applied photochemistry based on semiconductor-free nanoporous carbons and its application to sunlight energy harvesting. Using carbon materials of increasing average pore size, chemical functionalization to introduce a variety of O- and S-containing functional groups and monochromatic light, we have shown the dependence of the photochemical conversion of phenol in the confinement of the carbons nanopore space with the wavelength of the irradiation source, the dimensions of the pore voids and their surface chemistry. The photochemical conversion of phenol inside the carbons pore space was found to be very sensitive to the …

Ultrafast Spectroscopy And Energy Transfer In An Organic/Inorganic Composite Of Zinc Oxide And Graphite Oxide, Jeff A. Secor

Dissertations, Theses, and Capstone Projects

The energy transfers and nature of defect levels of an organic/inorganic composite of Zinc Oxide and Graphite are studied with multidimensional spectroscopy. The edge and surface states of each composite are uncovered using excitation emission experiments showing which defect states are mediating the energy transfer from the metal oxide to the graphite oxide. Multidimensional time resolved spectroscopy further describes the effect of the carbon phase on the energy transfer pathways in the material.

Water Condensation And Protein Adsorption On Hybrid Superhydrophobic-Hydrophilic Surfaces, Bikash Mondal

Dissertations, Theses, and Capstone Projects

This thesis describes the study of protein adsorption and water condensation on hybrid superhydrophobic-hydrophilic surfaces for various technological applications such as diagnostics, artificial organs and medical devices, water collection, and heat transfer.

In the chapter 1, a general introduction to wetting theories, superhydrophobic surface, and hybrid surfaces is given. In chapter 2, design and fabrication of a hybrid superhydrophobic surface for studying dropwise condensation and heat transfer is discussed. Effect of surface chemistry and wettability on protein adsorption is discussed in the chapter 3. Finally, in chapter 4, the protein adsorption study on hybrid superhydrophobic surfaces made by 3D-printing and …

Design Rules For The Nucleation, Growth, And Encapsulation Of Gold Nanoparticles With Applications To Cancer Imaging, Matthew A. Wall

Dissertations, Theses, and Capstone Projects

Surface-enhanced Raman scattering (SERS) nanoparticles are exciting candidates for high-precision cancer imaging due to their highly specific spectral signature (Raman “fingerprint”) and propensity for passive targeting of cancerous tissues. However, the signal intensity of currently available SERS nanoparticles is insufficient for cancer imaging via passive targeting in most solid tumors. The overarching aim of this body of work is to develop a new generation of SERS nanoparticles with sufficiently low limits of detection to enable robust detection of various solid tumors in vivo.

The complexity of SERS nanoparticles requires significant advances to the theoretical and experimental understanding of metal …

Synthesis And Characterization Of Segmented Fluorescent Conjugated Polymers Via Acyclic Diene Metathesis (Admet), Gagandeep Singh

Dissertations, Theses, and Capstone Projects

This doctoral thesis is focused on the novel and facile synthesis and characterization of segmented conjugated polymers featuring various electro-optically active segments, with or without heteroatom linkages. The polymers were synthesized, via acyclic diene metathesis (ADMET) using ruthenium-based Grubbs-type catalysts. All products are soluble, and have a well-defined all-trans microstructure without defects. Some of the polymers were also synthesized via Suzuki polycondensation for comparison purposes. All monomers utilized were designed and synthesized in the laboratory.

Segmented conjugated polymers have received a great deal of attention in organic electronics, such as organic light emitting-diodes, organic field-effect transistors and organic solar …

Synthesis Of Novel Aporphine-Inspired Neuroreceptor Ligands, Nirav R. Kapadia

Dissertations, Theses, and Capstone Projects

Aporphines are a group of tetracyclic alkaloids that belong to the ubiquitous tetrahydroisoquinoline family. The aporphine template is known to be associated with a range of biological activities. Aporphines have been explored as antioxidants, anti-tuberculosis, antimicrobial and anticancer agents. Within the Central Nervous Systems (CNS), aporphine alkaloids are known to possess high affinity for several clinically valuable targets including dopamine receptors (predominantly D₁ and D₂), serotonin receptors (5-HT_1A and 5-HT₇) and α adrenergic receptors. Aporphines are also inhibitors of the acetylcholinesterase enzyme – a clinical target for the treatment of Alzheimer’s disease. Considering the …