Chemistry Commons^™

Understanding Mechanistic Details Of Neuroinflammatory Pathways Stimulated By The Alzheimer's Disease Amyloid-Beta Protein, Shana Usery

Dissertations

Alzheimer’s disease (AD) is characterized by neuroinflammation. Senile plaques composed of aggregated amyloid-β protein (Aβ) are found in AD patients’ brains. The Aβ is formed by the proteolytic cleavage of the amyloid precursor protein (APP) resulting in Aβ fragments that are 39-42 amino acids in length. The two most common peptides are Aβ(1-40) and Aβ(1-42), which differ by two amino acids, isoleucine and alanine. Within the brain of AD patients, Aβ monomer self-assembles to form several aggregate morphologies, including oligomers, protofibrils, and fibrils. Activated microglial cells and associated secreted proinflammatory cytokines surround these plaques producing a localized inflammatory environment in …

Fast And Sensitive Genome-Hashing Software And Its Application In Using Ngs As A Detection Agent For Bacterial Presence In Oral Metagenomic Samples, Paul Michael Gontarz

Dissertations

Next generation sequencing has increased the throughput of sequenced DNA into the range of billions of nucleotides sequenced per day. With the increased speed of DNA sequencing and the short length of reads produced by next generation sequencers, a significant challenge has been created in quickly and accurately assembling the hundreds of millions of short reads created by modern sequencing instruments into their full genomic sequences. With the increase in throughput in next generation sequencing and the decrease in time and cost to perform DNA sequencing, novel applications for DNA sequencing are being considered. Among them is a methodology by …

Development Of Flexible Batteries Using Nano-Carbons And Polymers, Zhiqian Wang

Dissertations

Flexible electronics such as wearable equipment, displays, cell phones and smart cards require flexible power sources like batteries. In this thesis, the development of flexible batteries and supercapacitors are presented. Different types of flexible batteries including zinc carbon batteries, primary alkaline batteries, secondary alkaline batteries and zinc air cells are presented, These were designed, fabricated and improved using polymers and nano-carbons like carbon nanotubes (CNTs). CNTs are found to be effective as conductive additives compared to the traditional graphite. Purification is important to remove impurities that lead to side reactions/ corrosions. However, further treatment like carboxylation lead to higher electric …

Novel Spectroscopic Tools To Differentiate Molecule-Dna Binding Interactions, Sense Dna And Track Dna Melting, Saad Hmoud Alotaibi

Dissertations

The discovery of DNA as a genetic material and its double helical structure led to numerous studies directed at understanding molecule-DNA interactions. These studies have played an integral role in medical diagnostics, forensics, imaging and therapeutics. Typically, molecule-DNA interactions have two prominent modes: intercalation and minor groove binding. Several optical techniques are available that can monitor molecule-DNA binding interactions, but they cannot differentiate between intercalation and minor-groove binding. The major goals of the research are to develop novel optical spectroscopic tools that can differentiate molecule-DNA binding interactions, selectively and sensitively detect one form of DNA over another, and track DNA …

Mechanochemical Investigation Of A Glassy Epoxy-Amine Thermoset Subjected To Fatigue, Stephen Finley Foster

Dissertations

Covalent bonds in organic molecules can be produced, altered, and broken through various sources of energy and processes. These include photochemical, thermochemical, chemical, and mechanochemical processes. Polymeric materials derive their physical properties from the time scale of motion, summation of intermolecular forces, and number of chain entanglements and crosslinks. Glassy thermoset polymers experience mechanical fatigue during dynamic stress loading and properties diminish with inevitable material failure at stress levels below the ultimate tensile strength (UTS). Damage modeling has been successful in predicting the number of cycles required to induce failure in a specimen due to stress. However, it does not …

Investigations Of The Photocatalytic Activity And Self-Cleaning Properties Of Polyhedral Oligomeric Silsesquioxane (Poss) Containing Titania Thiol-Ene Films, Lacrissia Unsonta Jefferson

Dissertations

In this document the film composition, self-cleaning aspect, photocatalytic efficiency, and methods employed to analyze a novel photocatalytic titania-containing thin film was evaluated. A primary objective of this research project was to assess the conditions required to achieve a stable titania dispersion for the photocatalytic coating and to determine the extent to which the presence of additives contributes to this process. Modified titania dispersions were prepared and characterized via dynamic light scattering (DLS), transmission electron microscopy (TEM), fourier transmission infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Characterization details of the previous focus on the influence of polyhedral oligomeric silsesquioxane (POSS) …

Aqueous Raft Polymerization Of Glycopolymers For Peptide Interaction Studies And Antimicrobial Peptide Mimics For Antimicrobial Activity And Selectivity Studies, Sarah Elizabeth Exley

Dissertations

The first section of this work describes the synthesis and characterization of novel glycopolymers synthesized to model GM1 gangliosides, a glycolipid found in neuronal cells. Glucose and galactose were attached to N-hydroxyethyl acrylamide, using chemistry that granted control over the stereochemistry at the C1’ carbon of each saccharide, and polymerized via aqueous RAFT (aRAFT). Homopolymers, targeting either 30 or 300 DP, and copolymers, with N-dimethyl acrylamide, were prepared as a glycopolymer platform for investigation of amyloid β (Aβ), a naturally occurring peptide associated with Alzheimer’s disease, aggregation. Aβ aggregation kinetics and aggregate size in the presence of glycopolymer were determined. …

Synthetic Approaches To The Understanding Of Dna Nucleobase Methylation, Jagruti Rana

Dissertations

DNA methylation is a major source of genetic variation and cancer. Methylation occurs when nucleophilic DNA bases react with methylating agent methyl methanesulfonate (MMS), dimethyl sulfate (DMS), N-methyl-N-nitrosourea (MNU), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), etc. N7-methyl-2'-deoxyguanosine (N7-methyl-dG, or ^7MedG) adduct is the most abundant DNA methylation products for most methylating agents. DNA polymerase actions on ^7MedG are difficult to study due to its instability against ring- opening hydrolysis and deglycosyl ati on. Oligonucleotides containing a single chemical adduct of ^7MedG cannot be chemically synthesized. In addition, ^7MedG is unstable in vivo …

Design, Synthesis, And Biological Evaluation Of Folate Targeted Photosensitizers For Photodynamic Therapy, Laura Jean Donahue

Dissertations

Photodynamic therapy (PDT) is used to treat cancer, and involves a highly conjugated molecule, called a photosensitizer (PS), which is excited by wavelengths of light from visible to infrared. Photosensitizers that are highly conjugated will absorb longer wavelengths (600 – 900 nm), and have the potential to destroy cells of deeper tissue cancers. In PDT, a PS is administered to the patient, and after an appropriate time delay, the tissue is then exposed to light of a specific wavelength necessary for excitation of the PS. A transfer of energy can take place between the excited PS and oxygen that is …

Synthesis And Testing Of Photosensitizer-Folate Conjugates And Potential Photosensitizers For Photodynamic Therapy, Jeffrey A. Trautmann

Dissertations

Dissertation Proposal for Jeffrey Trautmann

Photodynamic Therapy (PDT) is a technique that destroys oncogenic (cancerous) cells. It has been used in several countries since the 1980’s. Molecules that contain chromophores can function as photosensitizers, and will absorb light at various wavelengths (that being dependent upon the extent of their conjugation). Certain functional groups, upon absorption of light, can be used to convert O2 to singlet oxygens which are destructive to the cellular environment. Once an in-vitro cell contains a high enough concentration of photosensitizer material and light is able to reach the photosensitizer material, PDT can be used effectively to …

Electrochemical Synthesis Of Nanostructured Noble Metal Films For Biosensing, Jay Kishan Bhattarai

Dissertations

Nanostructures of noble metals (Au and Ag) are of interest because of their important intrinsic properties. Noble metals by themselves are conductive, physically robust, chemically inert, and strongly bind to thiols. However, when the nanostructures are formed, they in addition possess high surface area and unique optical properties tunable by adjusting the shape and size. All of these properties make nanostructures of noble metals suitable candidates to be used as a transducer for biosensing. Individual nanostructures might be easier to prepare but difficult to handle to be used as a transducer. Therefore, we prepared and analyzed nanostructured films/coating of noble …

Magnetic Nickel Nanoparticles: Synthesis, Environmental Lmplications And Potential Role As Drug Carriers, Setare Tahmasebi Nick

Dissertations

The design and synthesis of well-defined magnetic particles with nanoscale dimensions is opening new avenues in understanding their fundamental chemical and physical properties. Our work describes a novel facile procedure for the synthesis of homogenous isotropic and anisotropic magnetic nickel nanoparticles. These nanoparticles were produced using a wet-chemical process and characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), powder x-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA). Magnetic measurements were acquired using a superconducting quantum interference device (SQUID) magnetometer. While there is significant interest in using magnetic nanoparticles for biological …

Continuous Polymer Reactor Design, David Sujay Kingsley

Dissertations

Twin screw extruders can be used as continuous polymer reactors to process polymers, which are conventionally made through batch reactors. Batch processes have certain undesirable qualities such as improper mixing and the inability to precisely control the reaction, which leads to variation between batches and potential exotherms. The work presented in this dissertation investigates the use of continuous polymer reactor designs to efficiently process renewable sourced thermoplastic polyurethanes (TPU), and prepreg epoxy matrix prepolymers.

The overall goal of this research is to highlight the modularity of twin screw extruders as continuous polymer reactors to synthesize the relevant polymers. Chapter I …

Utilization Of Aqueous Raft Prepared Copolymers To Improve Anticancer Drug Efficacy, Andrew Christopher Holley

Dissertations

The advent of controlled radical polymerization (CRP) techniques, along with advancements in facile conjugation chemistry, now allow synthetic tailoring of precise, polymeric architectures necessary for drug/gene delivery. Reversible addition- fragmentation chain transfer (RAFT) polymerization and its aqueous counterpart (aRAFT) afford quantitative control over key synthetic parameters including block length, microstructure, and placement of structo-pendent and structo-terminal functionality for conjugation of active agents and targeting moieties. The relevance of water-soluble and amphiphilic (co)polymers synthesized by RAFT for in vitro delivery of therapeutics in biological fluids is an especially attractive feature. In many cases, polymerization, binding, conjugation, …

Enzyme, Cosolvent, And Substrate Interactions In Ple Hydrolysis Reactions And Evaluation Of The Stability Of An Unnatural Glutathione Analogue, Maureen Elizabeth Smith

Dissertations

Prochiral diester malonates have been hydrolyzed in the presence of Pig Liver Esterase (PLE). Several of the diesters produced the respective half-ester in moderate to high enantioselectivity. A series of cosolvent assays were performed to evaluate the ability of the cosolvent to influence the enantioselective outcome of the hydrolysis reactions. Ethanol produced the largest changes in enantioselectivity of all solvents evaluated. The isoenzymes of PLE were also evaluated and provided very different enantioselective outcomes than that of crude PLE. A series of NMR titrations was performed to explore the interactions between the substrates and ethanol cosolvents.

Improvements to our previously …

Molecular Probes For The Detection Of Zn2+ And Fe3+ Ions, Erendra Manandhar

Dissertations

A number of molecular probes have been designed and synthesized for the detection of Zn²⁺ and Fe³⁺ ions. Two types of functional groups have been incorporated into the molecular scaffolds to utilize different fluorescent mechanisms. The first class of receptors contains a pyrene moiety. These molecular probes use the excimer mechanism for the detection of Zn²⁺ ion. The probes work well in an organic solvent with a detection limit of 20 nM (one ppb). Alternatives are made to make them water soluble, but this proved to be difficult. An interesting ion-induced self-assembly system will also be discussed. …

Tuning Responsiveness Of Polypeptide Based Block Copolymers For Drug Delivery, Ashley J. Johnson

Dissertations

The goal of this dissertation was to tune the pH response and self-assembled morphologies of amphiphilic polypeptide block copolymers for use as drug delivery vehicles. Poly(L-lysine) and poly(L-glutamtic acid) are responsive, ionizable polypeptides that undergo secondary structure transitions, from α-helix to random coil, whereby the change in conformation of the peptide chain results in changes to the global morphology of a self-assembled system. The main focus of this work was to understand how changes in the polymer composition and the local environment can lead to control over the behavior of the overall system. First, the responsive behavior of poly(L-lysine) block …

Spectroscopy And Gas-Phase Binding Of Modified Desferrioxamine B Indicator Displacement-Based Sensors, William Scott Jones

Dissertations

A coupling reaction has been used to successfully synthesize two novel probes utilizing coumarin derivatives as fluorophores. The structure, spectroscopy, and thermodynamics of these probes were characterized and studied. These probes, along with a classical probe using a N-methyl-anthranilate fluorophore, are used to take advantage of the ability of siderophores to coordinate Fe³⁺ ions which is coupled with the attractive phosphorescence properties of lanthanide ions. The use of lanthanide metals to create an indicator displacement assays is a novel application of these probes for the detection of Fe³⁺ ions. The use of Tb³⁺ ions as the indicator …

Investigation Of Glassy State Molecular Motions In Thermoset Polymers, Jianwei Tu

Dissertations

This dissertation presents the investigation of the glassy state molecular motions in isomeric thermoset epoxies by means of solid-state deuterium (²H) NMR spectroscopy technique. The network structure of crosslinked epoxies was altered through monomer isomerism; specifically, diglycidyl ether of bisphenol A (DGEBA) was cured with isomeric amine curatives, i.e., the meta-substituted diaminodiphenylsulfone (33DDS) and para-substituted diaminodiphenylsulfone (44DDS). The use of structural isomerism provided a path way for altering macroscopic material properties while maintaining identical chemical composition within the crosslinked networks.

The effects of structural isomerism on the glassy state molecular motions were studied using solid-state ²H …

Computational And Experimental Investigation Into Yield Behavior And Cure Rate Dependence Of Thermoset Polymers, Christopher Harold Childers

Dissertations

This dissertation is broken down into two primary sections: firstly, the development and improvement of molecular dynamics simulations of thermoset matrix polymers including their use in understanding molecular response to applied strain deformation and secondly, the discernment of a cure heating ramp rate dependence of the final molecular and macro-molecular properties of thermoset matrix polymer.

The molecular dynamics section will discuss the development of molecular dynamics simulations of thermoset epoxy/amine matrix polymers, and the implementation of this work to determine the underlying molecular level events that cause thermoset matrix polymer yield. It will report a novel method for the determination …

Probing The Unfolding And The Stability Of The Last Four Metal Binding Domains Of Wilson Disease Protein Using Circular Dichroism And Novel Spectroscopic Techniques, Ibtesam Yaseen Alja’Afreh

Dissertations

Wilson disease protein is a copper-transporting P_1B type ATPase. It has large N-terminal copper binding domain which is composed of six homologous sub-domains. Each of these six domains is ~72 residues and connected to one another by linking regions of various lengths. They all possess similar ferrodoxin fold, and metal-binding motif, MXCXXC.

The need of having six metal binding domains and the manner in which they are communicating with each other is not well understood. To better understand how the last four metal binding domains function, I pursued a detailed biophysical characterization of these domains. Using molecular biology I …

Ultrafast Interfacial Electron Transfer Across Molecule-Tio2 Nanocomposites: Towards Solar Cells And Two Photon Absorption, Edwin Mghanga

Dissertations

Interfacial charge transfer (ICT) across the molecule-TiO2 nanoparticle interface has gained enormous research attention for applications in dye sensitized solar cells (DSSC), photo-catalysis, water splitting and nonlinear optics. DSSCs are promising clean alternative energy sources. However, current DSSCs suffer from lower efficiencies and higher cost. Better understanding of the ICT processes in DSSCs can help solve these problems. We have used two strategies to understand ICT in the context of DSSCs. Firstly, we used a computationally validated anchor group, acetylacetonate (acac) to bind molecules to the semiconductor surface and facilitate charge separation. Secondly, we used natural dye sensitizers, …

New Methods And Strategies For Orthogonal Oligosaccharide Synthesis, Scott James Hasty

Dissertations

Although scientists have been able to isolate certain classes of naturally occurring carbohydrates, the overall availability of pure natural isolates remains inadequate. As a result, chemical synthesis has been employed to access complex carbohydrates. Unfortunately, traditional oligosaccharide synthesis often requires laborious protecting-group manipulations that results in lower yields. Expeditious strategies effectively shorten the task of oligosaccharide assembly by minimizing the need for protecting-group manipulations between glycosylation steps, or even purification of the intermediates. Additionally, prediction of the stereoselective outcome of the coupling reaction between two sugar units is a major obstacle facing carbohydrate chemists. It is well known that 1,2-trans …

Design And Synthesis Of Chelating Compounds And Solid-Supported Chelators For Metal Depleted Solutions, Surendra Dawadi

Dissertations

Metals are essential to life, yet they can be toxic for biological systems when present in excessive amounts. The major source of metal overload in humans is diet; and in some cases, intravenous feeding. Thus the removal of toxic metal ions from contaminated clinical products such as total parenteral nutrition (TPN) solutions, and drinking and waste water is extremely important. The use of chelating resins, which are polymeric solids containing covalently immobilized chelating compounds, for the selective removal of metal ions from contaminated solutions has been conceptualized long ago. Herein, the design and synthesis of metal specific chelating compounds and …

Chemistry And Thermochemistry Of Selected Fatty Acids Using Correlation Gas Chromatography, Joe A. Wilson

Dissertations

Correlation gas chromatography (c-GC) is a special application of the gas chromatography technique and is used for the evaluation of both vaporization enthalpy and vapor pressures of organic compounds. Its use in measuring vaporization enthalpies has been extensively documented. This method is useful for measurements of both liquids and solids. For substances that are solids, since each analyte is dilutely adsorbed on the condensed phase of the gas chromatographic column, it is not crystalline. The vapor pressure that it exhibits behaves as an excellent model of the sub-cooled liquid as demonstrated by various thermochemical cycles. Thermochemical measurements are important to …

Nanoporous Gold Characterization, Structural Modification And Use As A Solid Support For Biomolecule Immobilization, Abeera Sharma

Dissertations

Nanoporous gold (NPG) has immense technological applications owing to a plethora of properties like large surface area to volume ratio, plasmonic properties, stable gold-thiolate bond formation and a wide range of pore sizes. The surface morphology of nanoporous gold has been altered previously by dealloying and thermal annealing to increase/decrease the pore size and change the surface area. We provide a novel electrochemical annealing technique for post dealloying modification wherein electrochemical sweep cycles in different electrolytes at positive potentials leads to a subsequent increase in pore sizes of nanoporous gold as studied using scanning electron microscopy. Tailoring the surface of …

Biophysical Characterization Of The First Four Metal-Binding Domains Of Human Wilson Disease Protein, Alia V.H. Hinz

Dissertations

Wilson disease protein (WLNP) is a P_1b-type ATPase crucial for maintaining copper homeostasis in humans. Mutations in this protein result in the autosomal recessive disorder Wilson disease, a condition characterized by copper accumulation in the liver and brain. WLNP provides copper for incorporation into cuproproteins and exports excess copper into the bile for excretion. There are six metal-binding domains (MBDs) in WLNP, found within the first 650 amino acids of this 1,465 amino acid protein. Though each MBD has a different amino acid sequence, all MBDs possess a similar ferredoxin fold with a conserved hydrophobic core and a …

Nanocarbon Immobilized Membrane For Separation And Analysis, Madhuleena Bhadra

Dissertations

Membrane processes classically cover a wide range of applications associated with various aspects of separation and purification. Over the last few years, membrane based processes have received much interest due to their compact and modular architecture, low energy consumption and cost effective separation. With the development of diverse nanomaterials which can serve as nanosorbents, or provide specific morphology for selective solute transport, recent years have witnessed the emergence of nanocarbon based membranes that can address some of the limitations of conventional membrane processes and make feasible the next generation of breakthroughs.

The objective of this research is the exploration of …

Biogeochemistry Of Trace Elements In The Mixing Zone Of The Mississippi And Atchafalaya Rivers And Chemical Distributions As Affected By The Deepwater Horizon Blowout, Dongjoo Joung

Dissertations

Selected trace elements (TEs), dissolved organic carbon, and nutrients were studied in Louisiana Shelf waters including the Mississippi (MR) and Atchafalaya (AR) River plumes during periods of high, intermediate, and low river discharges. Seasonal variations in TEs were observed at low salinity, reflecting seasonal changes in the river water endmembers. Shelf surface water dissolved Mo, Cs, U, Ni, and Cu showed conservative behavior with minor scattering in some high salinity waters. Based on associated mixing experiments, nutrient and chlorophyll distributions, as well as surface-bottom concentration contrasts, the non-conservative behavior of TEs was variously related to colloidal flocculation (Fe, Cr), biological …

Synthesis, Characterization And Potential Applications Of Palladium And Ruthenium Nanostructures, Clara Patrice Adams

Dissertations

Controlling the size and shape of metal nanostructures is important for tuning the intrinsic chemical and physical properties of materials, and consequently their potential technological applications. Modulating the morphology of metal nanostructures is essential to understanding the structure-function relationship (for example, optical, magnetic, catalytic, and electronic properties) under various environmental conditions. Our work describes the development of new procedures for the synthesis of well-defined isotropic and anisotropic nanoparticles consisting of palladium (Pd) and ruthenium (Ru). Characterization of the nanostructures was carried out using transmission electron microscopy (TEM), high resolution-TEM (HRTEM), powder x-ray diffraction (XRD), selected area electron diffraction (SAED) and …