Chemistry Commons^™

Rational Design Of Self-Assembled Nanostructures Based On Polymers Synthesized Via Aqueous Reversible Addition-Fragmentation Chain Transfer Polymerization, Stacey Kirkland York

Dissertations

Recent advances in reversible addition-fragmentation chain transfer (RAFT) polymerization have allowed the rational, bottom-up design of biorelevant assemblies. Utilizing foresight, polymers can be tailored to self-assemble into nano-, micro-, and macroscopic structures. Given the size scale on which rationally-designed polymers can be tailored, they hold significant promise in the biomedical field. For example, nanoscale materials can be designed to carry small-molecule and gene therapeutics while macroscopic structures can be tailored for cell growth scaffolds. The design process begins by selecting monomers, chain transfer agents, and reaction conditions which will yield the desired polymer architecture and composition.

The work herein builds …

Investigation Of Novel Quasiliving Polyisobutylene Chain-End Functionalization (Quenching) Methods, David Lee Morgan

Dissertations

This volume recounts efforts toward the development and understanding of chain functionalization techniques involving the direct addition of nucleophiles to quasiliving polyisobutylene (PIB). Nucleophiles included in the study were sterically hindered organic bases, (di)sulfides, N-substituted pyrroles, and alkoxybenzenes. A kinetic investigation of the end-quenching of TiCl4-catalyzed quasiliving PIB with sterically hindered amines was used to determine the mode of interaction with TiCl4 and the active species responsible for -proton abstraction. 2,5-disubstituted-N-hydropyrroles formed pyrrole-TiCl3 adducts that were active in formation of exo-olefin chain ends; whereas, with other sterically hindered amines, only an equilibrium fraction of the amine that did not complex …

Bunching Effect In Single-Molecule T4 Lysozyme Nonequilibrium Conformational Dynamics Under Enzymatic Reactions, Yuanmin Wang, H. Peter Lu

Chemistry Faculty Publications

The bunching effect, implying that conformational motion times tend to bunch in a finite and narrow time window, is observed and identified to be associated with substrate enzyme complex formation in T4 lysozyme conformational dynamics under enzymatic reactions. Using single-molecule fluorescence spectroscopy, we have probed T4 lysozyme conformational motions under the hydrolysis reaction of polysaccharide of E. coli 13 cell walls by monitoring the fluorescence resonant energy transfer (FRET) between a donor acceptor probe pair tethered to T4 lysozyme domains involving open close hinge-bending motions. On the basis of the single-molecule spectroscopic results, molecular dynamics simulation, and a random walk …

A Synthetic Approach Toward Novel Β-Lactams, Mohamed Hashim

Theses and Dissertations - UTB/UTPA

β-lactam antibiotics which is a class by itself, covers a wide range of antibiotics that includes penicillin, penicillin derivatives, cephalosporins, carbapenems, and any antibiotic agent that contains a 2-azetidinone ring.[2] In recent past research it has been established that β-lactams show therapeutic and anticancer activity with low toxicity. [2] It has also been reported by our lab that N-chrysenyl and N-phenanthrenyl 3-acetoxy-4-aryl-2- azetidinone can exhibit potent selective anticancer activity towards prostate, colon, pancreatic cancer and leukemia at low concentrations, all of this was revealed by means of a structure activity study. [2] The goal of our research is the synthesis …

Production And In Vitro Investigation Of Vitamin B12-Based Bioprobes, Amy Rabideau

Renée Crown University Honors Thesis Projects - All

Vitamin B₁₂ (B₁₂)-based bioprobes were produced and investigated in vitro for studying the B₁₂ uptake pathway in certain cancer cell lines and their target-specific capabilities as imaging and/or contrast agents in vivo. An intrinsic factor (IF)-bound B₁₂ conjugate (B₁₂-ReBQBA) was produced containing rhenium(I) for in vitro analysis of the cubilin-expressing placental choriocarcinoma cell line. B₁₂-ReBQBA has millimolar toxicity in vitro and excitation and emission wavelengths in the visible region, 488 nm and 560 nm, respectively. The rhenium metal in this bioprobe can be readily exchanged for the metastable radioactive metal technetium-99m …

Highly Visible Light Active Tio2-Xnx Heterojunction Photocatalysts, Vinodkumar Etacheri, Michael Seery, Steven Hinder, Suresh Pillai

Articles

Nitrogen doped anatase-rutile heterojunctions are successfully synthesized through an ethylene-diaminetetraacetic acid (EDTA) modified sol-gel process.An FT-IR study of EDTA modified TiO2 gel confirms the existence of an ionic intermediate (as indicated by a Δν value of 233 cm-1).Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Raman spectroscopy are employed to study the phase evolution, phase purity, and crystallite size of samples. Formations of O-Ti-N and N-Ti-N bonds in calcined samples are confirmed using XPS and FT-IR spectro- scopy. AllEDTAmodified samples show significantly higher visible light photocatalytic activity than the unmodified sample. The most active nitrogen doped heterojunction obtained at 400C …

Chemical Characterization Of Botanical Products: Comprehensive Speciation By Liquid Chromatography Particle Beam Mass Spectrometry, Joaudimir Castro Georgi

All Dissertations

The dietary supplement industry has expanded and many of these supplements have become an important aspect of people's everyday lives. In 1994, the U.S. Dietary Supplement Health and Education Act (DSHEA) classified numerous nutraceutical/botanical products as dietary supplements because of their beneficial medicinal properties and provided the necessary regulation to the supplement producers. Since then, the interest of the scientific community towards dietary supplements has grown intensively and numerous studies have been carried out in order to understand the chemical behavior of the active molecules in the human body. The development towards analytical methods for the quantification of the active …

Trace Analysis Of Volatile Organic Compounds In The Water Of The Arroyo Colorado And The Lower Laguna Madre Utilizing E.P.A.Sw846 Method 8260, Humberto Valdez

Theses and Dissertations - UTB/UTPA

Volatile organic compounds (VOC) can cause a major environmental concern since they create a hazard to public health and the environment. This study focused on determining concentration of VOCs in Arroyo Colorado waters and the Lower Laguna Madre (LLM) utilizing GC/MS. Little is known on the concentration and composition of VOCs. Toluene was the most common VOC. Concentrations ranged from 0.0010 mg/L to 0.0039 mg/L. Analysis of a sediment pore water sample collected near the mouth of the Arroyo Colorado also detected toluene (0.0023 mg/L). This study showed that VOCs were concentrated near the county boat launch and somewhat downstream. …

The Lipid Acyl-Chain Dynamics In Giant Liposomes And Characterization Of Domain 4 Of The Wilson Disease Protein, Wilson Okumu

Dissertations

Steady-state and nanosecond time-resolved fluorescence of the nitro-2, 1, 3- benzoxadiazol-4-yl (NBD) probe and line tension force were determined in phospholipids acyl-chain dynamics in giant liposomes made from a homologous series of phosphatidylcholines (PC). The fluorescence spectroscopy of a NBD probe attached to the headgroup (NBD PE) or the tail (NBD PC) of the phospholipid were used to determine the rate of dithionite quenching in a homologous series of phospholipids. Similar experiments were performed in the gel and the fluid phases of the l,2-dimyristoyl-s«-glycero-3-phosphocholine (DMPC ). Nanosecond time scale lifetimes and anisotropy measurements were obtained by a 470 nm LED …

Non-Natural Nucleotides As Probes For The Mechanism And Fidelity Of Dna Polymerases, Irene Lee, Anthony J. Berdis

Chemistry Faculty Publications

DNA is a remarkable macromolecule that functions primarily as the carrier of the genetic information of organisms ranging from viruses to bacteria to eukaryotes. The ability of DNA polymerases to efficiently and accurately replicate genetic material represents one of the most fundamental yet complex biological processes found in nature. The central dogma of DNA polymerization is that the efficiency and fidelity of this biological process is dependent upon proper hydrogen-bonding interactions between an incoming nucleotide and its templating partner. However, the foundation of this dogma has been recently challenged by the demonstration that DNA polymerases can effectively and, in some …

Conformational Motion Associated With Catalysis In Indole-3-Glycerol Phosphate Synthase From S. Solfataricus, Tomasz Kurcon

Theses, Dissertations and Culminating Projects

Indole-3-glycerol phosphate synthase from Sulfolobus solfataricus (SsIGPS) belongs to a broad family of (βα)₈-barrel enzymes. It catalyzes the fifth step in tryptophan biosynthesis, converting l-(o-carboxylphenylamino)-l-deoxyribulose-5-phosphate (CdRP) to indole-3-glycerol phosphate (IGP). Site selective mutagenesis was used to introduce a single cysteine in two loops near the active site, generating two recombinant proteins, each containing a single cysteine handle. The two construct were labeled, each with two different thiol-reactive probes generating four labeled constructs that were used for this study. Steady-state kinetic parameters of the labeled mutants and the wild type SsIGPS were well characterized using fluorescence spectroscopy. Subsequent experiments …

Dna Polymerases: Perfect Enzymes For An Imperfect World, Anthony J. Berdis

Chemistry Faculty Publications

This Special Thematic Issue explores the molecular properties of DNA polymerases as extraordinary biological catalysts. In this short introductory chapter, I briefly highlight some of the most important concepts from the articles contained within this Special Issue. The contents of this Special Issue are arranged into distinct sub-categories corresponding to mechanistic studies of faithful DNA polymerization, studies of "specialized" DNA polymerases that function on damaged DNA, and DNA polymerases that are of therapeutic importance against various diseases. Emphasis is placed on understanding the dynamic cellular roles and biochemical functions of DNA polymerases, and how their structure and mechanism impact their …

Analysis Of Ammonia And Volatile Organic Amine Emissions In A Confined Poultry Facility, Hanh Hong Thi Dinh

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The National Air Emission Monitoring Study (NAEMS) project was funded by the Agricultural Air Research Council (AARC) to evaluate agricultural emissions nationwide. Utah State University (USU) is conducting a parallel study on agricultural emissions at a Cache Valley poultry facility. As part of this parallel study, samples of animal feed, eggs and animal waste were collected weekly from three manure barns (designated: manure barn, barn 4 - manure belt and barn 5 - high rise) from May 2008 to November 2009.

These samples were analyzed to determine ammonia content, total Kjeldahl nitrogen content and ammonia emission. The yearly average calculated …

Nanomaterials From Biologically Active Molecules: Self-Assembly And Molecular Recognition, Min Yu

Dissertations

This dissertation describes the development of molecular assemblies and molecular recognition of phospholipids (PLs) that exhibit potential applications in emerging nanotechnologies. It consists of two parts: (1) structural features of PLs responsible for recognition of synthetic copolymers, and (2) design, synthesis and analysis of magnetic nanotubes obtained from PLs with a common theme of colloidal synthesis served as a platform for film formation and nano-assemblies of nanotubes. Poly(methyl methacrylate/n-butyl acrylate) (p-MMA/nBA) colloidal particles that were stabilized by 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) PLs were synthesized, and upon the particle coalescence, PL stratification resulted in the formation of surface localized ionic clusters (SLICs). These …

Chromatographic Studies Of Drug-Protein Binding In Diabetes, Kathryn (Krina) S. Joseph

Department of Chemistry: Dissertations, Theses, and Student Research

Drug-protein binding can have a dramatic impact on the distribution and metabolism of a drug. This manuscript describes the use of high-performance affinity chromatography to examine the binding of various compounds to human serum albumin (HSA) in normal and diabetic disease states. The first study examined the use of four coumarin compounds as possible alternatives to warfarin as a probe for Sudlow site I on HSA. High-performance affinity chromatography and immobilized HSA columns were used to compare and evaluate the binding properties of these probe candidates. It was found from this group that 4-hydroxycoumarin was the best alternative to warfarin …

A Proposal For The Mechanism Of The Iron-Ascorbate, Fenton, And Hydroxyl Radical-Quenching Series, Jonathan Velasco

Theses and Dissertations - UTB/UTPA

The Fenton reaction between [Fe(II)] and [HOOH] is observed in the presence of ascorbic acid, [AscH-], during [Fe(III)] and HO• reduction; this is done as part of consecutive redox reactions between [Fe(III)] and [Fe(II)]. As a result, the rate orders with respect to [Fe(III)], ascorbic acid, and [HOOH] are of (approximately) 2nd, 1st, and 4 th order, respectively. However, the rate constants for each reaction in this study show patterns when measured against solution pH; empirically, reactions proceed faster at smaller pH and vice versa.

Identification Of Phosphatases Involved In E2f-Associated Apoptosis, Liza D. Morales Smith

Theses and Dissertations - UTB/UTPA

Retinoblastoma (Rb) is a tumor suppressor protein that controls a critical checkpoint between the G1 phase and the S phase of the cell cycle. Rb is able to suppress cell proliferation by binding to the E2F family of transcription factors, inhibiting its ability to activate transcription of genes necessary for cell cycle progression. Mutations in proteins involved with the Rb/E2F pathway can result in hyper-proliferative cells that overtime can acquire and accumulate additional mutations, which could lead to tumorigenesis. To prevent hyper-proliferation, aberrant cells can be eliminated through apoptosis. E2F can induce apoptosis through two pathways: through transactivation of the …

Genotyping Of Tgif Polymorphisms Associated With Schizophrenia And Psychosis, George Vera Jr.

Theses and Dissertations - UTB/UTPA

Polymorphisms in Transforming Growth β-Induced Factor (TGIF) have been found to contribute to the risk of development of psychosis and related disorders. Identifying the genes responsible for causing schizophrenia and psychosis will allow for treatment at an earlier stage of development, saving the patient problems, time, and money. The purpose of this experiment is to determine the haplotype of DNA samples obtained from earlier experiments. The DNA samples were collected from people with schizophrenia in Costa Rica, Southern Texas, and Northern Mexico. The samples were tested using 5 single nucleotide polymorphisms (SNPs) and amplified using polymerase chain reaction (PCR). Haplotypes …

Synthesis Of Functional Copolymers Via Aqueous Raft Polymerization For Bioconjugation And Targeted Delivery Of Small Interfering Rna, Adam Wesley York

Dissertations

The versatility of reversible addition-fragmentation chain transfer (RAFT) polymerization has moved this controlled radical technique to the forefront of copolymer construction for bioapplications including polymeric drug/gene delivery vehicles. Strengths of the RAFT process include the capacity to control the polymerization of a wide variety of vinyl monomers under mild conditions, its tolerance to numerous chemical groups that allow the preparation of functional copolymers for facile modification, and the range of copolymer architectures with predetermined end group functionalities which may be synthesized. Given these strengths, RAFT polymerization was utilized in this research to synthesize functional/reactive copolymers for bioconjugation and targeted delivery …

Self-Assembly And Gold Nanoparticle Cross-Linking Of Stimuliresponsive Block Copolymers Synthesized Bt Reversible Addition-Fragmentation Chain Transfer Polymerization, Adam Eugene Smith

Dissertations

The ability of amphiphilic block copolymers to self-assemble into various morphologies in aqueous solution in response to specific stimuli has attracted widespread interest for potential applications as targeted drug delivery and diagnostic vehicles. Stimuli-responsive block copolymers afford a facile method for tuning the hydrophilic mass fraction to provide access to various solution morphologies. Reversible additionfragmentation chain transfer (RAFT) polymerization provides the ability to prepare stimuli-responsive block copolymers while maintaining precise control over the macromolecular characteristics (molecular weight, copolymer composition, functionality, etc.) that dictate nanostructure morphology.

This work may be divided into four sections. In the first section the synthesis and …

Polyisobutylene Chain End Transformations: Block Copolymer Synthesis And Click Chemistry Functionalizations, Andrew Jackson David Magenau

Dissertations

The primary objectives of this research were twofold: (1) development of synthetic procedures for combining quasiliving carbocationic polymerization (QLCCP) of isobutylene (IB) and reversible addition fragmentation chain transfer (RAFT) polymerization for block copolymer synthesis; (2) utilization of efficient, robust, and modular chemistries for facile functionalization of polyisobutylene (PIB). Two site transformation strategies were employed to create block copolymers effectively linking PIB with either poly(methylmethacrylate) (PMMA), polystyrene (PS), and poly(Nisopropylacrylamide) (PNIPAM) block segments. Functionalization of PIB was accomplished by utilizing two click chemistries, the azide-alkyne 1,3-dipolar cyclo addition and the thiol-ene hydrothiolation reaction, and by efficient transformation of the thiol functional …

Molecular Design And Patterning Of Biosurfaces On Poly(Tetrafluoroethylene) (Ptfe), Nattharika Aumsuwan

Dissertations

This dissertation describes the design, synthesis, and development of biocompatible poly(tetrafluoroethylene) (PTFE) surfaces that exhibit anti-microbial, anticoagulant, and dual functional surface properties. It consists of two parts: (1) design, synthesis, and analysis of antimicrobial and anti-coagulant PTFE surfaces, and (2) controllable micropatterning of anti-microbial and anti-coagulant species on the surface. PTFE was modified by Ar microwave plasma reactions in the presence of maleic anhydride, which upon hydrolysis creating COOH groups. These COOH primers were utilized as a platform for further surface reactions to attach polyethylene glycol (PEG) spacers, and penicillin (PEN) or ampicillin (AM) onto the PTFE surfaces. The use …

Towards Multiplexed Electrogenerated Chemiluminescent Detection, Shijun Wang

Dissertations

The main objective of this dissertation is to understand and study the principle of electrogenerated chemiluminescence (ECL) and its applications to detect biomolecules simultaneously. Four aspects of ECL were studied. In order to carry out multiplexed ECL detection, both classical and several novel ECL systems have been investigated.

In the first aspect, significant effect of chloride ions on the ECL behavior of the tris(2,2′-bipyridyl) ruthenium(II) (Ru(bpy)3 2+)/tri-n-propylamine (TPrA) system at Au electrode was investigated. At low concentrations (e.g., [Cl-] < 5 mM), the ECL was enhanced; at relatively high concentrations, however, the ECL intensity decreased with the increase of the [Cl-]. At [Cl-] = 90 mM, ~ 50% and 100% ECL inhibition was observed for the first and the second ECL wave, respectively. The electrogenerated chloroaurate anions (AuCl2 - and AuCl4 -) which were verified using an electrochemical quartz-crystal microbalance (EQCM) method were found to be responsible for the ECL inhibition. This study suggests that care must be taken when Au working electrode is used for ECL studies in chloride-containing buffer solutions (widely used in DNA probes) and/or with the commonly used chloride-containing reference electrodes since in these cases the ECL behavior may significantly disagree with that obtained using other electrodes and reaction media.

In the second aspect, the electrochemical behavior of a trinuclear ruthenium(II)- containing complex, [((phen)2Ru(dpp))2RhCl2]5+ (where phen = 1,10-phenanthroline, dpp = 2,3-bis-2-pyridylpyrazine), …

Aqueous Raft Synthesis Of Stimuli-Responsive, Amphiphilic Block Copolymers And Self-Assembly Behavior In Solution And Incorporation Into Lbl Films, Matthew Grady Kellum

Dissertations

Of all the living radical polymerization techniques, reversible addition– fragmentation chain transfer (RAFT) polymerization is arguably the most versatile in terms of the reaction conditions (e.g. temperature and solvent selection), monomer selection (e.g. neutral, anionic, cationic, and zwitterionic), and purification. Since the introduction of RAFT in 1998, the McCormick research group and others including the Lowe, Sumerlin, and Davis research groups have synthesized a wide range of (co)polymers with predetermined molecular weights, low polydispersities, and advanced architectures utilizing aqueous RAFT (ARAFT) polymerization. These research groups have also studied how various block copolymers exhibit stimuli-responsive behavior due to a change in …

Multi Stimuli-Responsive Copolymers Obtained From Colloidal Dispersions, Fang Liu

Dissertations

This dissertation describes the design, synthesis, and development of multi stimuli-responsive random copolymers that exhibit collective responsiveness to temperature, pH or electromagnetic radiation. New colloidal particles of poly(N-(DL)-(1- Hydroxyymethyl) propylmethacrylamide/n-butyl acrylate) (p(DL-HMPMA/nBA) and poly(2-(N,N′-dimethylamino)ethyl methacrylate/n-butyl acrylate) (p(DMAEMA/nBA)) were synthesized, which upon coalesce to form solid continuous films. The presence of lower glass transition (Tg) nBA components not only facilitate film formation, but also provide sufficient free volume for polymer chain rearrangements. These studies showed that coalesced films exhibit 3D dimensional changes upon external stimuli, which are attributed to the collapse and conformational changes of stimuli-responsive components as well as buckling …

Developing A Biosensor For The Detection Of Bacteria: A Comparison Of Methods For Isolating Bacteria-Specific Antibodies, Scott Allen Walper

Dissertations

The antigen-antibody interaction is known to be a high affinity and highly specific interaction that can readily be used for the detection and identification of biological and chemical agents. These studies were conducted to develop an efficient and cost-effective method of obtaining bacteria-specific antibody molecules for integration into a fielddeployable biosensor. Antigen-binding molecules were obtained both as full-length IgG molecules from a hybridoma cell line and as recombinant single-chain Fv (scFv) antibodies isolated from naïve and immunize libraries. Monoclonal and recombinant antibody systems were compared on the effectiveness of producing new, target-specific molecules; the efficiency of production and purification of …

Synthesis, Characterization, And Deuterium Labeling Of Polyamides Studied By Nuclear Magnetic Resonance Spectroscopy, Christopher Allen Lange

Dissertations

The synthesis, characterization, and deuterium labeling of polyamides have been investigated. In Chapter II, selective deuterium labeling of various polyamides was demonstrated via a facile method which does not require organic solvent or catalyst. Quantitative solution-state NMR analysis showed deuterium incorporation at the carbon alpha to the carbonyl ranged from 20-75%. Incorporation in ε-caprolactam increased with repeated treatments. Isotopic shift effects for the deuterated materials were additive for all sites within experimental error.

In Chapter III, the effect of stoichiometric imbalances on the polymerization of poly(dodecamethylene terephthalamide)was investigated. Molecular weight was varied by polymerizing the monomer salt with excess diaminododecane, …

Structure-Property Relationships In The Formation Of Polyphenylsulfone Molecular Composites And Nanocomposites, Paul Joseph Jones

Dissertations

As the constituent phases in a polymer composite approach the molecular level, specific phenomena occur that can lead to significant changes in material properties when only minimal quantities of the additive are incorporated into the polymer matrix. Molecular composite and nanocomposites are state-of-the-art polymeric materials that contain nanostructured additives effectively dispersed within polymer matrices. The properties of molecular composites and nanocomposites are directly related to the interactions of the nanostructured additive and the polymer matrix. Subtle changes to the nanostructured additive can have profound effects on the ultimate properties of the composite material. Therefore, understanding the structure-property relationships in these …

A Study Of The Effective Interfacial Tension Between Miscible Fluids By Spinning Drop Tensiometer And Microfluidics, Gloria Dollie Viner

Dissertations

A miscible system is a system in which two fluids can completely dissolve in one another. A sharp concentration gradient can be observed in miscible systems. We studied the concentration gradient or miscible interface between IBA (isobutyric acid) and water, a miscible system near a consulate point (close to the system’s upper critical solution temperature [UCST]). The original hypothesis was that the sharp concentration gradient of IBA/water was due to barodiffusion, a diffusion effect driven by pressure. We tested this hypothesis by studying IBA/water at five different rotation rates and three different temperatures. At 20 oC, increasing rotation acceleration from …

Designing Molecular And Nanoscale Materials For Environmental Chemistry Processes, Wen Guo

Dissertations

This dissertation focuses on fundamental studies to identify materials that detect and degrade common organic environmental pollutants. Chapter 1 represents the overview of two widespread ground water contaminants: organohalides and organophosphorous compounds. Due to continuous usage of these compounds as well as their toxicity, reliable and sensitive methods for their detection and degradation are urgently needed. In Chapter 2 a description of molecular sensors designed with high sensitivity and selectivity to detect and distinguish between three organophosphorus (OP) pesticides are described. These sensors provide dual optical and electrochemical signals for detection, which minimizes false-positives. The signal transduction occurs in real …