Chemistry Commons^™

Molecular Recognition Of Insulin By A Synthetic Receptor, Jordan M. Chinai, Alexander B. Taylor, Lisa M. Ryno, Nicholas D. Hargreaves, Christopher A. Morris, P John Hart, Adam R. Urbach

Chemistry Faculty Research

The discovery of molecules that bind tightly and selectively to desired proteins continues to drive innovation at the interface of chemistry and biology. This paper describes the binding of human insulin by the synthetic receptor cucurbit[7]uril (Q7) in vitro. Isothermal titration calorimetry and fluorescence spectroscopy experiments show that Q7 binds to insulin with an equilibrium association constant of 1.5 × 10⁶ M⁻¹ and with 50−100-fold selectivity versus proteins that are much larger but lack an N-terminal aromatic residue, and with >1000-fold selectivity versus an insulin variant lacking the N-terminal phenylalanine (Phe) residue. The crystal structure of the …

Fabrication And Selective Functionalization Of Amine-Reactive Polymer Multilayers On Topographically Patterned Microwell Cell Culture Arrays, Adam H. Broderick, Samira M. Azarin, Maren E. Buck, Sean P. Palecek, David M. Lynn

Chemistry: Faculty Publications

We report an approach to the fabrication and selective functionalization of amine-reactive polymer multilayers on the surfaces of 3-D polyurethane-based microwell cell culture arrays. "Reactive" layer-by-layer assembly of multilayers using branched polyethyleneimine (BPEI) and the azlactone- functionalized polymer poly(2-vinyl-4,4′-dimethylazlactone) (PVDMA) yielded film-coated microwell arrays that could be chemically functionalized postfabrication by treatment with different amine-functionalized macromolecules or small molecule primary amines. Treatment of film-coated arrays with the small molecule amine d-glucamine resulted in microwell surfaces that resisted the adhesion and proliferation of mammalian fibroblast cells in vitro. These and other experiments demonstrated that it was possible to functionalize different structural …

Investigating A Model Reversed-Phase Liquid Chromatography Stationary Phase With Vibrationally Resonant Sum Frequency Generation Spectroscopy, Arthur D. Quast

Theses and Dissertations

Reversed-phase liquid chromatography (RPLC) is a widely used technique for analytical separations but routinely requires empirical optimization. Gaining a better understanding of the molecular reasons for retention may mean more efficient separations with fewer trial and error runs to obtain optimized separations. Vibrationally resonant sum frequency generation (VR-SFG) is a surface specific technique that has allowed for in situ examination of model RPLC stationary phases under various solvent and pressure conditions. In order to improve on past work with model RPLC stationary phases two challenges had to be overcome. First, improved vibrational mode assignments of the C18 stationary phase were …

Direct Imaging Of Two-State Dynamics On The Amorphous Silicon Surface, S. Ashtekar, Gregory E. Scott, J. Lyding, M. Gruebele

Chemistry and Biochemistry

Amorphous silicon is an important material, amidst a debate whether or not it is a glass. We produce amorphous Si surfaces by ion bombardment and vapor growth, and image discrete Si clusters which hop by two-state dynamics at 295 K. Independent of surface preparation, these clusters have an average diameter of ~5 atoms. Given prior results for metallic glasses, we suggest that this cluster size is a universal feature. The hopping activation free energy of 0.93 ± 0.15 eV is rather small, in agreement with a previously untested surface glass model. Hydrogenation quenches the two-state dynamics, apparently by increasing surface …

Review Of Science For Science Librarians: Graphene, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

Graphene is, in many ways, a simple substance. Made of a single atomic layer of graphite, graphene has emerged as a material providing many surprises and having immense scientific and industrial potential. In 2010, scientists Andre K. Geim and Konstantin S. Novoselov received the Nobel Prize in Physics for their isolation of graphene and for their research pertaining to the ultrathin material. In his presentation speech, Professor Per Delsing described how we all have made graphene each time we write with a pencil: microscopic bits of graphite and graphene flake away as the pencil moves across the paper (Delsing 2010). …

Progress Toward Theonellamide F, Jennifer Dawn Bettale

Theses and Dissertations

Theonellamide is a bicyclic peptide isolated from a marine sponge, which shows interesting biological activity. It contains several unnatural amino acids, among which are (2S,3R)-3-hydroxyasparagine (L-erythro-β-hydroxyasparagine) (β-OHAsn) and τ-L-histindino-D-alanine (τ-HAL). Although there were previous synthetic efforts toward each of these unnatural amino acids, the efforts were not ideal due to expensive starting material, time-consuming steps, and poor regioselectivity. The presented work demonstrates an inexpensive, enantioselective synthesis of β-OHAsn, which can be completed in a matter of weeks, as well as several attempts at a novel regiospecific approach toward τ-HAL, including work on a model study.

Antibacterial Activity Of Conjugated Electrolytes, Thomas S. Corbitt

Chemistry and Chemical Biology ETDs

A series of water soluble, cationic, anionic and zwitterionic conjugated polyelectrolytes (CPEs) with main chains based on an arylene ethynylene repeat unit structure with tetraalkylammonium and/or alkylsulfonate side groups were found to exhibit significant antibacterial activity. A number of these complexes also showed pronounced light-induced modulation of their effectiveness, with either biocidal enhancement or suppression, depending on such properties as singlet oxygen sensitization potential and lipophilicity. These collected studies examine the biocidal activity of the CPEs, as determined by Confocal Laser Scanning Microscopy (CLSM) and Flow Cytometry, correlating this activity with the photophysical properties of the polymers. We demonstrate biocidal …

Chemistry In Second Life. Part 2. A World Of Education And Networking, Andrew Lang, Jean-Claude Bradley

College of Science and Engineering Faculty Research and Scholarship

Second Life visualisations can be scripted for immersive educational activities and real-life collaborative research. Social networking through Second Life is another spin-off for both chemists and chemistry students.

Lipid Peroxidation And Neurodegenerative Disease, Tanea Reed

Chemistry Faculty and Staff Scholarship

Lipid peroxidation is a complex process involving the interaction of oxygen-derived free radicals with polyunsaturated fatty acids, resulting in a variety of highly reactive electrophilic aldehydes. Since 1975, lipid peroxidation has been extensively studied in a variety of organisms. As neurodegenerative diseases became better understood, research establishing a link between this form of oxidative damage, neurodegeneration, and disease has provided a wealth of knowledge to the scientific community. With the advent of proteomics in 1995, the identification of biomarkers for neurodegenerative disorders became of paramount importance to better understand disease pathogenesis and develop potential therapeutic strategies. This review focuses on …

The Effects Of Cure Schedule On Properties Of Glass-Fiber Reinforced Epoxy Matrix Composites, Trevor J. Lee

Materials Engineering

Two different two-component resin systems were cured, via Differential Scanning Calorimetry, for the times recommended by their respective manufacturers. The resin cure schedules were designed to simulate typical and attainable processing conditions; they were cured at 120°F, 140°F, and 160°F, and in-mold post-cured at 200°F, 230°F, and 260°F. The resulting scans were then compared to a baseline cure for each resin system, consisting of two heating-cooling cycles at a constant rate of temperature change. These baseline cures were then used to determine the percent cure of each sample and the shift in glass transition temperature between the baseline cure and …

Artificial Muscle Project: Process Development Of Polydimethyl Siloxane Thin Films For Use In Dielectric Electroactive Polymer Artificial Muscle Actuators, Vincent J. Gayotin, Richard W. Morrison, Paul A. Preisser

Materials Engineering

An artificial muscle design was created founded on the principles of a dielectric electroactive polymer (DEAP), which is fundamentally similar to a capacitor. A polydimethyl siloxane (PDMS)-based elastomer, Sylgard 184 from Dow Corning, was chosen for the design and spun coat onto polystyrene (PS) Petri dishes at varying speeds to create a thin film, using speeds of 2000 rpm, 3000 rpm, 4000 rpm, 5000 rpm, and 6000 rpm. The film thicknesses were measured optically through use of a microscope with coupled computer imaging software to generate a characteristic curve of film thickness to spin speed, achieving a minimum film thickness …

Human P38 Mitogen-Activated Protein Kinase Inhibitor Drugs Inhibit Plasmodium Falciparum Replication, Michael J. Brumlik, Standwell Nkhoma, Mark J. Kious, George R. Thompson, Thomas F. Patterson, John Siekierka, Tim J.C. Anderson, Tyler J. Curiel

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

We recently demonstrated that human p38 mitogen-activated protein kinase (MAPK) inhibitors reduced in vitro and in vivo replication of the protozoan parasites Toxoplasma gondii and Encephalitozoon cuniculi. In this study, we assessed the efficacy of five p38 MAPK inhibitors to block the replication of Plasmodium falciparum in human erythrocytes cultured ex vivo and demonstrate that the pyridinylimidazole RWJ67657 and the pyrrolobenzimidazole RWJ68198 reduced P. falciparum replication, yielded trophozoites that were greatly diminished in size at 24. h, and that these two agents interfered with stage differentiation. Interestingly, the chloroquine-resistant strain W2 was significantly more sensitive to these drugs than was …

Heteroepitaxial Growth Of Colloidal Nanocrystals Onto Substrate Films Via Hot-Injection Routes, Krishna P. Acharya, Elena Khon, Timothy O’Conner, Ian Nemitz, Anna Klinkova, Rony S. Khnayzer, Pavel Anzenbacher Jr., Mikhail Zamkov

Chemistry Faculty Publications

Hot-injection synthesis of colloidal nanocrystals (NCs) in a substrate-bound form is demonstrated. We show that polycrystalline films submerged into hot organic solvents can nucleate the heteroepitaxial growth of semiconductor NCs, for which the ensuing lattice quality and size distribution are on the par with those of isolated colloidal nanoparticles. This strategy is demonstrated by growing lead chalcogenide NCs directly onto solvent-submerged TiO(2) substrates. The resulting PbX/VTiO(2) (X = S, Se, Te) nanocomposites exhibit heteroepitaxial interfaces between lead chalcogenide and oxide domains and show an efficient separation of photoinduced charges, deployable for light-harvesting applications. The extendibility of the present method to …

Fast Excited-State Deactivation In N(5)-Ethyl-4a-Hydroxyflavin Pseudobase, Dapeng Zhou, Ekaterina Mirzakulova, Renat Khatmullin, Igor Schapiro, Massimo Olivucci, Ksenija D. Glusac

Chemistry Faculty Publications

We present a study of the excited-state behavior of N(5)-ethyl-4a-hydroxyflavin (Et-FlOH), a model compound for bacterial bioluminescence. Using femtosecond pump-probe spectroscopy, we found that the Et-FlOH excited state exhibits multiexponential dynamics, with the dominant decay component having a 0.5 ps lifetime. Several possible mechanisms for fast excited-state decay in Et-FlOH were considered: (i) excited-state deprotonation of the -OH proton, (ii) thermal deactivation via (1)n,pi* -> (1)pi,pi* conical intersection, and (iii) excited-state release of OH(-) ion. These mechanisms were excluded based on transient absorption studies of two model compounds (N(5)-ethyl-4a-methoxyflavin, Et-FlOMe, and N(5)-ethyl-flavinium ion, Et-Fl(+)) and based on the results of …

Synthesis And Characterization Of Linear And Branched Polylactic Acid For Use In Food Packaging Applications, Kyle C. Bentz

Master's Theses

Polylactic acid (PLA) resins of various molecular weights and molecular weight distributions were synthesized. Linear, narrow molecular weight distribution (MWD) PLA resins were synthesized, as well as resins containing both high molecular weight branched structures and low molecular weight chains and oligomers. Narrow MWD resins were synthesized for use as adhesives for corrugated paperboard and broad MWD resins were synthesized for use as a waterborne coating. PLA resins were dispersed for use as a waterborne coating. Success has been made at forming films utilizing various plasticizers and surfactants as well as polyvinyl alcohol as dispersing agents. A cold dispersion procedure …

Applications Of Argentation Solid Phase Extraction To The Capsaicinoids: Purification Of Commercial Standards And Isolation Of Homodihydrocapsaicin (8-Methyl) From 'Bhut Jolokia', Robert Q. Thompson, Kathleen Loa

Faculty & Staff Scholarship

Argentation solid phase extraction was employed to purify commercial standards of capsaicin (6-ene-8-methyl) and dihydrocapsaicin (8-methyl). The purity was improved from 96.7% to 99.6% and from 89% to 96%, respectively, with 75% and 60% yield, respectively. Reversed phase solid phase extraction, argentation solid phase extraction, and preparative liquid chromatography with a C30 phase were used to isolate capsaicinoids from the fruits of 'Bhut Jolokia' peppers. The compounds capsaicin (6-ene-8-methyl) and dihydrocapsaicin (8-methyl) comprised 74% and 21% of the total mass of capsaicinoids. respectively. The remaining 5% of the capsaicinoids mass included the compounds: nordihydrocapsaicin (7-methyl), N-vanillylnonanamide, two homocapsaicin isomers, N …

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

Chemistry Faculty Publications

This is the second part of a multi-part production on Maxwell’s equations of electromagnetism. The ultimate goal is a definitive explanation of these four equations; readers will be left to judge how definitive it is. A note: for certain reasons, figures are being numbered sequentially throughout this series, which is why the first figure in this column is numbered 8. I hope this does not cause confusion. Another note: this is going to get a bit mathematical. It can’t be helped: models of the physical universe, like Newton’s second law F = ma, are based in math. So are Maxwell’s …

The Preparation Of Functional Surfaces, Philip Thomas Dirlam

Master's Theses

Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates in reversible manner. Glass slides and capillaries were functionalized with hydrophobic dieneophiles resulting in a  non-wetting surface.  A retro Diels-Alder reaction facilitated by the thermal treatment of the surface’s function to cleave the hydrophobic dieneophile and resulted in the fabrication of a hydrophilic surface. Contact angle (CA) measurements were used as preliminary measurements for monitoring the changes in surface energy exhibited during the initial hydrophobic state (CA - 70±3°), after attachment of the dieneophile creating  a hydrophobic state (CA - 101±9°) followed by reestablishment of the hydrophilic state …

Physico-Chemical And Microbiological Parameters In The Deterioration Of Virgin Coconut Oil, Ian Ken D. Dimzon, Melodina F. Valde, Jaclyn Elizabeth R. Santos, Mark Joseph Garrovillas, Henson M. Dejarme, Jo Margarette W. Remollo, Fabian M. Dayrit

Chemistry Faculty Publications

The deterioration of virgin coconut oil (VCO) due to physico-chemical oxidation and hydrolysis and microbiological processes was studied. The physico-chemical oxidation of VCO in the air at room temperature was negligible. Oxidation of VCO was observed only in the presence of air, UV radiation, ferric ion (Fe3+), and high free fatty acid (FFA) content. Chemical hydrolysis was performed at varying moisture levels and temperatures. The rate of hydrolysis to produce FFAs was measured using 31P NMR under conditions of saturated water (0.22%) and 80°C was found to be 0.066 µmol/g-hr (expressed as lauric acid). At 0.084% moisture and 80°C, the …

Thiolene-Based Microfluidic Flow Cells For Surface Plasmon Resonance Imaging, Gareth Sheppard, Takao Oseki, Akira Baba, Derek L. Patton, Futao Kaneko, Leidong Mao, Jason Locklin

Faculty Publications

Thiolene-based microfluidic devices have been coupled with surface plasmon resonance imaging (SPRI) to provide an integrated platform to study interfacial interactions in both aqueous and organic solutions. In this work, we develop a photolithographic method that interfaces commercially available thiolene resin to gold and glass substrates to generate microfluidic channels with excellent adhesion that leave the underlying sensor surface free from contamination and readily available for surface modification through self-assembly. These devices can sustain high flow rates and have excellent solvent compatibility even with several organic solvents. To demonstrate the versatility of these devices, we have conducted nanomolar detection of …

Tension Directly Stabilizes Reconstituted Kinetochore-Microtubule Attachments, Bungo Akiyoshi, Krishna K. Sarangapani, Andrew F. Powers, Christian R. Nelson, Steve Reichow, Hugo Arellano-Santoyo, Tamir Gonen, Jeffrey A. Ranish, Charles L. Asbury, Sue Biggins

Chemistry Faculty Publications and Presentations

Kinetochores are macromolecular machines that couple chromosomes to dynamic microtubule tips during cell division, thereby generating force to segregate the chromosomes. Accurate segregation depends on selective stabilization of correct ‘bi-oriented’ kinetochore-microtubule attachments, which come under tension due to opposing forces exerted by microtubules. Tension is thought to stabilize these bi-oriented attachments indirectly, by suppressing the destabilizing activity of a kinase, Aurora B. However, a complete mechanistic understanding of the role of tension requires reconstitution of kinetochore-microtubule attachments for biochemical and biophysical analyses in vitro. Here we show that native kinetochore particles retaining the majority of kinetochore proteins can be …

Part A: The Use Of Nonionic Associative Polymers For The Thickening And Emulsifying Of Personal Care Products/ Part B: The Synthesis Of A Manganese Sod Mimetic For Reactive Coatings, Mallory Lynn Mcmahon

Master's Theses

Part A

The use of nonionic associative thickeners was proposed for personal care applications.  Various limitations of current rheology modifiers used in personal care were discussed.  Nonionic associative polymers were examined as both thickeners and emulsifiers.  The structure/property relationship for nonionic polymers and their ability to thicken and emulsify were fully examined.  Results showed an increase in thickening efficiency for nonionic associative polymers with higher log(P) (partition coefficient) values.  This was due to the formation of smaller aggregates and increased bridging between aggregates.  The connection between oil polarity, log(P) of the associative polymer, and emulsion stability showed no relationship however; …

Unlv Stars Unabridged Report, University Of Nevada, Las Vegas

Reports (USI)

University of Nevada, Las Vegas, by earning a 2011 Silver Rating in the Sustainability Tracking, Assessment & Ratings System (STARS), is ahead of the curve among public universities – and improving.

STARS is a voluntary, self–reporting framework developed by the Association for the Advancement of Sustainability in Higher Education (AASHE) to help measure sustainability performance over time and among colleges and universities nationwide. The UNLV Sustainability Council oversaw STARS, which by measuring sustainability can help UNLV to reduce energy consumption and waste, improve education, attract research, and generate jobs.

A rating of Silver puts UNLV in great company – with …

Electrochemistry Of Technetium Analogues Rhenium And Molybdenum In Room Temperature Ionic Liquid, Pauline Nancy Serrano

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rhenium was used as an analog for Technetium to study the electrochemical redox properties because the two elements share the same stable oxidation states in aqueous solutions. However, Tc-99 is radioactive and is not readily available for experimentation purposes. Molybdenum is also of interest because when Mo-99 is irradiated, the decay products are Tc-99m and Tc-99. Approximately 30% Tc-99m is eluted from the Mo columns for radiopharmaceutical use with the remaining Mo-99 source decaying to Tc-99 which is discarded as radioactive hospital waste. Currently there are no viable procedures for the reclamation of the radioactive Tc-99 from either fission streams …

Development And Extrapolation Of An Undergraduate Laboratory Experiment To An Elastomeric Spinal Muscular Atrophy Brace, Richard Sterling Brose

Master's Theses

Ever since the advent of polymer science, polyurethanes have played a huge role in the industrial world. They have been used in endless applications from furniture padding to aircraft coatings, to binders for insensitive munitions. It is therefore important that the chemistry of polyurethanes is well understood as well as the ability to draw relationships between the raw materials selected and the end-use properties of the polymer. Because of the multitude of practical applications, the development of an undergraduate polymer chemistry laboratory focused on polyurethane elastomers is developed and described herein. Polymer chemistry students are exposed to hydroxyterminated polybutadiene (HTPB) …

Anti-Solvent Precipitation And Subsequent Film Formation Of Hydrophobic Drugs For Drug Delivery, Xiangxin Meng

Dissertations

It is estimated that about forty percent of the drug molecules being developed by the pharmaceutical industry are hydrophobic in nature, leading to poor water solubility and bioavailability in the gastrointestinal tract. Dissolution is a limiting factor in their in vivo performance, and increasing their dissolution rate is a major challenge. It has been proven that the dissolution rate is directly proportional to the specific surface area, which can be effectively increased by reducing the particle size. Therefore, considerable efforts have gone into developing reliable and efficient methods for the manufacture of fine particles. Particle size reduction technologies such as …

Application Of Raman Spectroscopy In Pharmaceuticals, Anna Zarow

Dissertations

Experimental research on the use of Raman spectroscopy as an in- and on-line sensing tool and a complementary characterization technique for pharmaceutical applications is presented in this thesis. In the first chapter following a broad overview, the use of Raman spectroscopy, together with x-ray powder diffraction, scanning electron microscopy (SEM) and differential scanning calorimetry, for multilevel characterization of cryomilled powders, and the melt-grown amorphous phase of griseofulvin, a model active pharmaceutical ingredient (API), is presented and discussed in detail. A key feature was the observation of a broad inelastic background superimposed on the Raman spectra of cryomilled powders, which is …

Thermochemistry And Bond Energies Of Acetohydrazide, Amides And Cyclic Alkyl Ethers, Sumit Charaya

Theses

Structure, thermochemical properties, bond energies and internal rotation potentials of Acetic Acid Hydrazide (CH₃CONHNH₂), Acetamide (CH₃CONH₂) and N-methyl Acetamide (CH3CONHCH3) and their radicals corresponding to loss of hydrogen atom have been studied. Gas phase standard enthalpies of formation and bond energies were calculated using the DFT methods B3LYP/6-31G(d,p), B3LYP/6-31G(2d,2p) and the composite CBS-QB3 methods employing a series of work reactions to further improve accuracy of the ΔH_f°(298K). Molecular structures, vibration frequencies and internal rotor potentials were calculated at DFT level. The enthalpies of the parent molecules CH₃-C=ONHNH_{2 …}

Synthesis Towards Synthetic Adenosine Receptor, Rajni Gupta

Theses

Adenosine is a biologically important molecule as it acts as local modulator with cytoprotective function in the body. Adenosine accumulates in the extracellular space in response to metabolic stress and cell damage, and elevations in extracellular adenosine level are found in conditions like myocardial ischemia, hypoxia, inflammation and trauma. Its abnormal concentration therefore could be a marker of many diseases. Therefore determining its concentration can help understand the physiological state of the body. However its selective detection by synthetic receptors is not possible till date.

Efforts have been made here to design molecular tweezer for adenosine. Multistep synthesis was done …

Introduction For Professor Zha Quan-Xing, Wuhan University, Members Of Cas, Laboratory Electrochemistry

Journal of Electrochemistry

No abstract provided.