Chemistry Commons^™

Acrb Trimer Stability And Efflux Activity, Insight From Mutagenesis Studies, Linliang Yu, Wei Lu, Yinan Wei

Chemistry Faculty Publications

The multidrug transporter AcrB in Escherichia coli exists and functions as a homo-trimer. The assembly process of obligate membrane protein oligomers, including AcrB, remains poorly understood. In a previous study, we have shown that individual AcrB subunit is capable of folding independently, suggesting that trimerization of AcrB follows a three-stage pathway in which monomers first fold, and then assemble. Here we destabilized the AcrB trimer through mutating a single Pro (P223) in the protruding loop of AcrB, which drastically reduced the protein activity. We replaced P223 separately with five residues, including Ala, Val, Tyr, Asn, and Gly, and found that …

Development And Optimization Of Organic Based Monoliths For Use In Affinity Chromatography, Erika L. Pfaunmiller

Department of Chemistry: Dissertations, Theses, and Student Research

Affinity chromatography is an important and useful tool for studying biological interactions, such as the binding of an antibody with an antigen. Monolithic supports offer many advantages over traditional packed bed supports in affinity chromatography, including their ease of preparation, low back pressures and good mass transfer properties. Monoliths can be broken down into two basic categories: organic (polymer) and inorganic (silica) monoliths. There are many varieties of polymer based monoliths; however, a large focus has been on co-polymers of glycidyl methacrylate (a functional monomer) and ethylene dimethacrylate (a cross-linking agent). The solvents of choice for making this type of …

Designed Synthesis Of Halogenated Borazine-Linked Polymers And Their Applications In Gas Storage And Separation, Thomas Reich

Theses and Dissertations

The synthesis of highly porous organic polymers with predefined porosity has attracted considerable attention due to their potential in a wide range of applications. Of particular interest in porous organic polymers is their potential use in automotive applications as well as separation processes whereby advancements could result in a reduction in carbon dioxide emissions and the production of natural gas in a more economically friendly manner. Along these pursuits, seven borazine-linked polymers (BLPs) have been synthesized through the introduction of p-phenylenediamine, 1,3,5-tris-(4-aminophenyl)benzene, benzidine, or tetra-(4-aminophenyl)methane with boron tribromide or boron trichloride followed by the thermolysis reaction of the resulting in …

Organ-Distribution Of The Metabolite 2-Aminothiazoline-4-Carboxylic Acid In A Rat Model Following Cyanide Exposure, Ilona Petrikovics, David E. Thompson, Gary A. Rockwood, Brian A. Logue

Chemistry and Biochemistry Faculty Publications

The reaction of cyanide (CN⁻) with cystine to produce 2-aminothiazoline-4-carboxylic acid (ATCA) is one of the independent detoxification pathways of cyanide in biological systems. In this report, in vivo production of ATCA and its distributions in plasma and organs were studied after a subcutaneous sublethal dose of 4 mg/kg body weight potassium cyanide (KCN) administration to rats. At this sublethal dose of KCN, ATCA concentration was not significantly increased in the plasma samples, however, it was found significantly increased in liver samples. These results suggested that ATCA might not be a good diagnostic biomarker in plasma for sublethal …

Citrate Binding To The Membrane Protein Proteorhodopsin, Farhana F. Syed

Chemistry - Dissertations

Proteorhodopsin (pR) is an intrinsic membrane protein with an important role in solar-energy storage of the biosphere. Earlier work in our lab has shown that polyhistidine-tagged pR can be purified by means of selective precipitation with citrate under specific conditions, as can a number of mutants based on this His₆-tagged pR. Purification of a heterologously-expressed trans-membrane protein by a simple salt such as citrate is novel. However, such a phenomenon leads to several questions: How does citrate cause pR precipitation? Does the polyhistidine-tag assist in such a precipitation? Is this precipitation pH-specific? Does citrate affect the function of …

Synthesis And Biosynthesis Of Polyketide Natural Products, Atahualpa Pinto

Chemistry - Dissertations

Traditionally separate disciplines of a large and broad chemical spectrum, synthetic organic chemistry and biochemistry have found in the last two decades a fertile common ground in the area pertaining to the biosynthesis of natural products. Both disciplines remain indispensable in providing unique solutions on numerous questions populating the field. Our contributions to this interdisciplinary pursuit have been confined to the biosynthesis of polyketides, a therapeutically and structurally diverse class of natural products, where we employed both synthetic chemistry and biochemical techniques to validate complex metabolic processes. One such example pertained to the uncertainty surrounding the regiochemistry of dehydration and …

Inhibition Of Cysteine Protease By Platinum (Ii) Diamine Complexes, Chaitanya Rapolu

Masters Theses & Specialist Projects

Chemotherapy is the first line of treatment used in cancer. Chemotherapy drugs such as cisplatin, carboplatin and oxaliplatin are used in treatment. Cisplatin enters the cell through copper transporter CTR1 by passive diffusion and bind to DNA and proteins. Cisplatin is found to inhibit several enzymes targeting cysteine, histidine and methionine residues, which are expected to be responsible for its anticancer activity. A better understanding of how the size and shape and leaving ligands of platinum complexes affect cysteine protease, papain enzyme are studied. This could give new ways to optimize anticancer activity. The activity of papain enzyme was measured …

Controlling Biofouling By Surface Engineering And Molecular Inhibition, Debjyoti Bandyopadhyay

Chemistry - Dissertations

The common theme that binds together all the chapters in this dissertation is anti-biofouling chemistry. By utilizing tools of surface engineering and molecular inhibition, a hypothesis driven, systematic approach of controlling the different forms of biofoulings such as protein adsorption, mammalian cell adhesion and biofilm formation is presented. Chapter 1 provides a brief introduction about topics relevant for understanding the studies presented in subsequent chapters. Chapter 2 reports the synthesis of enantiomerically pure alkanethiols that terminate with different stereoisomer's of sugar alcohols, and the effect of chirality of these polyol-terminated self-assembled monolayers (SAMs) on resisting protein adsorption.

Chapter 3 …

A Century Of Chemistry Instruction At The College In Arlington: 1895-1995 (A Memoir And Scrapbook), Thomas James Cogdell

Chemistry & Biochemistry Faculty Publications - Archive

No abstract provided.

Chemical Modification On Gold Slides To Gain Better Control Of Patterning Techniques, Ragini Vuppalapati

Masters Theses & Specialist Projects

Nanolithography is a rapidly evolving field that requires new combinations of techniques to improve patterning and to assist in fabricating electromechanical devices. An increasing number of applications require surfaces with defined regions of different chemical functionality. In our previous project optimum conditions for lithographic patterning were determined and potential blockers were identified to reduce force on the tip.

This work is focused on identifying good chemical modifications that will allow better control of basic patterning and to investigate the minimum force of patterning required while using each chemical system. The primary aim is to gain better control of basic pattern …

Activity Of Analogs Of Anticancer Drugs On The Serine Protease Enzymes Subtilisin And Chymotrypsin, Dhatri Ravipati

Masters Theses & Specialist Projects

The anticancer activity of several platinum compounds is due to the formation of complexes with DNA. We hypothesize that the size and shape of the platinum compounds would impact interaction with proteins, and these interactions may be partly responsible for the anticancer activity. Chymotrypsin and subtilisin are serine proteases that have a histidine residue in the active site. We are investigating the inhibition of the digestive enzymes chymotrypsin and subtilisin by analogs of the anticancer drug cisplatin and trying to discern trends in the inhibition as the active site residues vary. In our research, we found that the enzyme subtilisin …

Modification And Characterization Of Fluorescent Conjugated Polymer Nanoparticles For Single Molecule Detection, Yueli Zheng

All Dissertations

Single molecule tracking using fluorescent dye or nanoparticle labels has emerged as a useful technique for probing biomolecular processes. Considerable interest arises in the development of nanoparticle labels with brighter fluorescence in order to improve the spatial and temporal resolution of single molecule detection and to facilitate the application of single molecule detection methods to a wider range of intracellular processes. The McNeill laboratory recently reported that conjugated polymer nanoparticles exhibit fluorescence cross-sections roughly 10-100 times higher than other luminescent nanoparticles of similar size, excellent photostability (2.2×108 photons emitted per nanoparticle prior to photobleaching), and saturated emission rates roughly 100 …

Adhesion And Durability Of Coatings On Polypropylene Exterior Sidings, Logan Riekio Stark

Master's Theses

Plastics have become a universal material for use in a myriad of commercial and consumer products. One such product, exterior siding, is the focus of this project. Although siding products were originally made from wood, vinyl siding, which offered superior performance, was introduced in the 1950’s. More recently, polypropylene (PP) siding has been introduced; PP provides a stronger product, which allows for deeper patterns and better edge detailing. PP siding, compared to traditional wood siding, doesn’t warp, crack, or degrade as easily with extended exposure to the elements, and is cheaper to maintain. However, even plastic siding must be coated. …

Single Particle And Ensemble Spectroscopy Of Conjugated Polymer Nanoparticles And Their Development For Photodynamic Therapy, Jennifer Grimland

All Dissertations

Energy transport in conjugated polymers is the combination of energy transfer and exciton diffusion. There is considerable ongoing research in this field, converging to develop better organic photovoltaics, polymer light emitting diodes (PLEDs) and organic solar cells, to name a few. One way these phenomena can be explored is by doing solution dependent studies on conjugated polymer nanoparticles. With experiments on CP dots in an aqueous solution and the addition of a water miscible organic solvent in varying concentrations, dynamics occurring in the folding process can be better understood, and also exciton and fluorescence quenching properties can be extracted as …

Investigation Of A Novel Method For Polonium-210 Determination In Groundwater, Tara Matheny

All Theses

A novel method was investigated for the quantification of 210Po in water as an alternative to the standard method of spontaneous plating onto Ag disks followed by quantification with an alpha spectrometer. The novel method concentrated a 0.5L sample by MnO2 co-precipitation followed by dissolution of the precipitate into a solution. Polonium-210 was separated from the solution and quantified in a column containing a 50:50 by volume mixture of Pb resin (Eichrom Technologies, Inc.) mixed with granulated CaF2:Eu scintillator. The column containing 210Po is quantified on a liquid scintillation counter without the introduction of liquid cocktail. The minimum detectable concentration …

Method Development And Validation Of The Quantitation Of 19 Antipsychotics Using Deuterated Internal Standards, Anthony S. Epps

Chemistry Theses

Antipsychotic drugs or neuroleptics are used primarily for psychiatric disorders such as schizophrenia, psychosis, and bipolar disorder. In forensic science antipsychotics are drugs of considerable interest because of their potential abuse, involvement in suicides, and they are frequently associated with sudden death investigations. Well-characterized and fully validated analytical data is necessary to generate reproducible and reliable results. As a result, data can be correctly interpreted and objectively demonstrate in its applicability for the intended use. This research has developed and validated a method that is selective, sensitive and accurate using liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the simultaneous determination of …

Studies Toward The Development Of A Microelectrode Array For Detection Of Dopamine Through Redox Cycling, Anupama Aggarwal

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that cycles the reversible redox species between its oxidative states repeatedly on generator and collector electrodes. Two or more individually-addressable microelectrodes located close to each other allow redox cycling to be possible. Electrochemical behavior of a biologically important molecule, dopamine is examined under redox cycling conditions. To our knowledge, this is the first report on detection of physiological concentration of dopamine in presence of up to 100 times excess ascorbate with the use of redox cycling, without the involvement of polymer coating such as Nafion®.

Microfabrication was used to produce different geometries (parallel bands …

Dynamics And Catalytic Resolution Of Selected Chiral Organolithiums, Timothy Kum Beng

Graduate Theses and Dissertations

One of the most important developments of the last decade has been the emergence of new methods to dynamically resolve racemic organolithiums using stoichiometric amounts of the chiral ligand. When this concept is implemented successfully, it obviates the need for covalently attached chiral auxiliary based methods, asymmetric deprotonation, and asymmetric synthesis of a precursor stannane as ways to access enantioenriched organolithium compounds for use in asymmetric synthesis. Since certain electrophiles consume the chiral ligand, it is desirable to render this process catalytic in the chiral ligand.

As part of a larger study on the amenability of chiral organolithiums to a …

Multicomponent Reactions For The Preparation Of Fluorous Taged Pyrimidines And Thiopyrimidines And Their Derivatisation To Obtain Biaryl-Substituted Heterocycles, Bruno Piqani

Graduate Masters Theses

This thesis presents a work in the field of multicomponent reactions (MCRs), one-step condensation between a fluorous tagged aldehyde, β-keto ester and urea derivatives. This process in literature is known as "Biginelli Reaction". This dissertation describes a new Biginelli reaction element, using fluorous component as a limiting agent.

Chapter one is an introduction of MCRs. A brief historical review, key principles as well as applications in different fields such as academic research, synthetic organic chemistry, and medicinal applications are presented.

Chapter two discusses the general features of the Biginelli reaction, microwave, and fluorous chemistry with a distinctive look from the …

Quantum Mechanical And Molecular Mechanical Study Of Solvent Effects, Dejun Si

Department of Chemistry: Dissertations, Theses, and Student Research

Intermolecular interaction and solvent effects play important roles in determining physical and chemical properties of molecular systems, and must be considered in relevant quantum mechanical (QM) calculations. Due to the high computational cost, full and rigorous QM treatment of both solute and solvent molecules is impractical. Computationally efficient molecular mechanical (MM) methods can be used to describe solvent effects, and combined into QM methods to formulate QM/MM methods. Classical force field method and reaction-field method are the two most popular MM methods. However, the issue of effectively combining MM methods with high-level QM methods remains unsolved. This thesis presents several …

Gold Nanoparticle Generation Using In Situ Reduction On A Photoresist Polymer Substrate, Christopher J. Clukay

HIM 1990-2015

This report presents evidence that in-situ reduction of metal ions bound to a cross-linked polymer surface does not always result in nanoparticle formation solely at the interface, as is commonly assumed, but also as much as 40 nm deep within the polymer matrix. Tetrachloroaurate ions were bound using a variety of multi-functional amines to cured films of SU-8 -- a cross-linkable epoxide frequently used for micro- and nanofabrication -- and then treated using one of several reducing agents. The resulting gold-nanoparticle decorated films were examined by X-ray photoelectron spectroscopy and by plan-view and cross-sectional transmission electron microscopy. Reduction using sodium …

Maxwell's Equations, Part Iv, David W. Ball

Chemistry Faculty Publications

In this column, we continue our explanation of Maxwell’s equations, the seminal classical explanation of electricity and magnetism (and, ultimately, light). For those of you new to the series, consider finding the last few appearances of this column to get caught up. Alternately, you should be able to find past columns on our website, www.spectroscopymag.com and look for “The Baseline” link. Words of warning: for my own reasons, the figures are being numbered sequentially through this series of columns, which is why the first figure in this column is numbered 26. Also, we’re going to get a bit mathematical. Unfortunately …

Synthesis Of An Antimicrobial Textile Coating, William M. Morris

Chemistry and Biochemistry

A titania nanosol was synthesized and coated onto nylon/cotton blended textile substrates. The substrates were characterized via SEM for adhesion and nanoparticle formation, then subjected to antimicrobial efficacy tests. The titania nanosol was successfully coated on to textiles samples. Particles were observed to be around 2 by 3 micrometers and formed between the interstitial space of textile fibers. Although larger than typical nanoparticles, the coatings exhibited what seemed to be antimicrobial activity. Titania nanosol coated textile samples were subjected to Kirby Bauer Assay in the presence of S. aureus. The coated textile sample exhibited an inhibition of growth around its …

The Tetrafluoroborate Salt Of 4-Methoxybenzyl N-2-(Dimethylamino)Ethyl-N-Nitrosocarbamate: Synthesis, Crystal Structure And Dft Calculations, Helene Hedian, Vladimir Benin

Chemistry Faculty Publications

The tetrafluoroborate salt of 4-methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate was prepared in two steps, via the corresponding carbamate. Its crystal structure is monoclinic, space group P21/c. The unit cell dimensions are: a = 19.499(8) Å, b = 5.877(3) Å, c = 15.757(7) Å, α = 90°, β = 110.019(7)°, γ = 90°, V = 1696.5(12) Å3, Z = 4. The structure exhibits an unexpected, pseudo-gauche conformation with respect to the C2–C3 bond, due to a stabilizing hydrogen bond between the carbonyl oxygen (O1) and the hydrogen atom at the trialkylammonium center (H3n), with a distance between them of …

Electrochemistry Of Pani/Metal Composites In Basic Solutions, Tamthinhan Quy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyaniline (PANI) has been extensively investigated due to its unique conductivity, which is primarily dependent on the oxidation state of the material and the solution pH. PANI is an insulator when it is oxidized, and the solution pH exceeds four. Numerous attempts to extend PANI's conductivity to neutral and alkaline environments have been unsuccessful. However, our previous study has demonstrated that PANI/Pd composite is conductive and catalytically active in a basic solution, pH ∼ 12. Therefore, the conductivity and the electrochemical properties of PANI composites including PANI/Au, PANI/Pd and PANI/Pt were evaluated in basic solutions. The fundamental studies of PANI/metal …

Analysis Of Volatile Organic Compounds In Virgin Coconut Oil And Their Sensory Attibutes, Fabian M. Dayrit, Jaclyn Elizabeth R. Santos, Bianca J. Villarino, Anthony R. Zosa

Chemistry Faculty Publications

The volatile compounds in the headspace of twenty-four commercial virgin coconut oil (VCO) samples prepared by different methods (i.e. expeller, centrifugation, and fermentation with and without heat) were analyzed by solid phase microextraction-gas chromatography mass spectrometry (SPME-GCMS). The following volatile organic compounds (VOCs) were identified: ethyl acetate, acetic acid, 2-pentanone, hexanal, n-octane, 2-heptanone, limonene, nonanal, octanoic acid, ethyl octanoate, δ-octalactone, ethyl decanoate, δ-decalactone, and dodecanoic acid. Fermentation-produced samples were found to have higher levels of acetic acid and free fatty acids in the headspace compared to VCO produced using the centrifuge and expeller methods. Descriptive sensory analysis of the VCO …

Opacity Of P(Mma-Maa)-Pmma Composite Latex System With Varying Maa Concentration, Gilbert U. Yu, Jerry T. Dy, Erwin P. Enriquez

Chemistry Faculty Publications

Polymer composites of core-shell morphology are commonly used in the paint industry as opacity enhancer. These are usually made of block copolymer systems wherein the core is formed from a polymer that swells in the presence of a solvent and surrounded by a high glass transition polymeric shell. Thus, upon drying, the swollen regions turn into voids while leaving a hard shell. Here, composites based on poly(methyl methacrylate-butyl acrylate) [P(MMA-BuA)] (seed stage), poly(methyl methacrylate-methacrylic acid) [P(MMA-MAA)] (second stage), and poly(methyl methacrylate) [PMMA] (third stage) were synthesized through a multistage sequential emulsion polymerization and their opacity was investigated. The second stage …

Chemical, Biological, And Preliminary In Vitro Studies Of Novel Vanadium(Iv) Complexes With Schiff Bases And Thiosemicarbazone Ligands, Nerissa Abigail Lewis

Master's Theses

9-Anthraldehyde-N(4)-methylthiosemicarbazone (MeATSC), potassium (E)-2-(2-hydroxybenzylideneamino)-3-(1H-indol-3-yl)propanoate (K[(Sal-L-tryp)] and 2-(2-hydroxybenzylamino)-3-(1H-indol-3-yl)propanoic acid (the reduced Schiff base) were prepared using known synthetic procedures. Two novel thiosemicarbazone ligands, (E)-N-ethyl-2-(4-hydroxy-3-methoxybenzylidene)hydrazinecarbothioamide (N-Ethhymethohcarbthio) and (E)-N-ethyl-2-(1-(thiazol-2-yl)ethylidene)hydrazinecarbothioamide (acetylethTSC), were also prepared. All ligands were characterized by FT IR and electrochemistry. N-Ethhymethohcarbthio were characterized by elemental analysis whereas the reduced Schiff base and K[(Sal-L-tryp)] were characterized by ESI MS. X-ray crystallography was also used to characterize acetylethTSC. The ligands were then reacted with [VO(Sal-L-tryp)(H2O)] (1) (Sal-L-tryp = N-salicylidene-L-tryptophanate) to produce the …

Continuous Analysis Of Photocatalytic Activity In Thin-Films And Coatings, Steven Michael Allee

Master's Theses

Materials that undergo photocatalytic reactions create evolved gases due to ultraviolet light decomposition. Current methods of measuring these gases typically result in destruction of the sample. A test fixture was developed to measure evolved gases in a nondestructive manner through the utilization of a flow-through sensor array system. Preliminary testing indicates responsive measurements down to parts-per-billion sensitivity for some gases and will be compared with mass spectrometry measurements. Further development of this process could lead to the ability to measure photocatalytic reaction gases on a continuous basis without interruption of the process or destruction of materials introduced to the system.

Effects Of Molecular Architecture On Fluid Ingress Behavior Of Glassy Polymer Networks, Matthew Blaine Jackson

Dissertations

This manuscript demonstrates the synthesis of glassy polymer network isomers to control morphological variations and study solvent ingress behavior independent of chemical affinity. Well-controlled network architectures with varying free volume average hole-sizes have been shown to substantially influence solvent ingress within glassy polymer networks. Bisphenol-A diglycidyl ether (DGEBA), bisphenol-F diglycidyl ether (DGEBF), Triglycidyl p-aminophenol (pAP, MY0510), Triglycidyl maminophenol (mAP, MY0610), and tetraglydicyl-4,4’-diamino-diphenyl methane (TGDDM, MY721) were cured with 3,3’- and 4,4’-diaminodiphenyl sulfone (DDS) at a stoichiometric ratio of 1:1 oxirane to amine active hydrogen to generate a series of network architectures with an average free volume hole-size (V_h) …