Chemistry Commons^™

Phosphate Esters, Thiophosphate Esters And Metal Thiophosphates As Lubricant Additives, David W. Johnson, John E. Hils

Chemistry Faculty Publications

Phosphate esters, thiophosphate esters and metal thiophosphates have been used as lubricant additives for over 50 years. While their use has been extensive, a detailed knowledge of how they work has been a much more recent development. In this paper, the use of phosphate esters and thiophosphate esters as anti-wear or extreme pressure additives is reviewed with an emphasis on their mechanism of action. The review includes the use of alkyl phosphates, triaryl phosphates and metal containing thiophosphate esters. The mechanisms of these materials interacting with a range of iron and steel based bearing material are examined.

Can Inhibitor-Resistant Substitutions In The Mycobacterium Tuberculosis Β-Lactamase Blac Lead To Clavulanate Resistance?: A Biochemical Rationale For The Use Of Β-Lactam–Β-Lactamase Inhibitor Combinations, Sebastian G. Kurz, Kerstin A. Wolff, Saugata Hazra, Christopher R. Bethel, Andrea M. Hujer, Kerri M. Smith, Yan Xu, Lee W. Tremblay, John S. Blanchard, Liem Nguyen, Robert A. Bonomo

Chemistry Faculty Publications

The current emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis calls for novel treatment strategies. Recently, BlaC, the principal β-lactamase of Mycobacterium tuberculosis, was recognized as a potential therapeutic target. The combination of meropenem and clavulanic acid, which inhibits BlaC, was found to be effective against even extensively drug-resistant M. tuberculosis strains when tested in vitro. Yet there is significant concern that drug resistance against this combination will also emerge. To investigate the potential of BlaC to evolve variants resistant to clavulanic acid, we introduced substitutions at important amino acid residues of M. tuberculosis BlaC (R220, A244, S130, and …

5-Azido-2-Aminopyridine, A New Nitrene/Nitrenium Ion Photoaffinity Labeling Agent That Exhibits Reversible Intersystem Crossing Between Singlet And Triplet Nitrenes, Maxim S. Panov, Valentyna D. Voskresenska, Mikhail N. Ryazantsev, Alexander N. Tarnovsky, R. Marshall Wilson

Chemistry Faculty Publications

The photochemistry of a new photoaffinity labeling (PAL) agent, 5-azido-2-(N,N-diethylamino)pyridine, was studied in aprotic and protic solvents using femtosecond-to-microsecond transient absorption and product analysis, in conjunction with ab initio multiconfigurational and multireference quantum chemical calculations. The excited singlet SI state is spectroscopically dark, whereas photoexcitation to higher-lying singlet excited S-2 and S-3 states drives the photochemical reaction toward a barrierless ultrafast relaxation path via two conical intersections to S-1, where N-2 elimination leads to the formation of the closed-shell singlet nitrene. The singlet nitrene undergoes intersystem crossing (ISC) to the triplet nitrene in aprotic and protic solvents as well as …

Cyclometalated Iridium(Iii) Complexes With Deoxyribose Substituents, Ayan Maity, Jung-Suk Choi, Thomas S. Teets, Nihal Deligonul, Anthony J. Berdis, Thomas G. Gray

Chemistry Faculty Publications

Fundamental study of enzymatic nucleoside transport suffers for lack of optical probes that can be tracked noninvasively. Nucleoside transporters are integral membrane glycoproteins that mediate the salvage of nucleosides and their passage across cell membranes. The substrate recognition site is the deoxyribose sugar, often with little distinction among nucleobases. Reported here are nucleoside analogues in which emissive, cyclometalated iridium(III) complexes are “clicked” to C-1 of deoxyribose in place of canonical nucleobases. The resulting complexes show visible luminescence at room temperature and 77 K with microsecond-length triplet lifetimes. A representative complex is crystallographically characterized. Transport and luminescence are demonstrated in cultured …

Isosteric And Nonisosteric Base Pairs In Rna Motifs: Molecular Dynamics And Bioinformatics Study Of The Sarcin–Ricin Internal Loop, Marek Havrila, Kamila RéBlová, Craig L. Zirbel, Neocles B. Leontis, JiřÍ ŠPoner

Chemistry Faculty Publications

The sarcin-ricin RNA motif (SR motif) is one of the most prominent recurrent RNA building blocks that occurs in many different RNA contexts and folds autonomously, that is, in a context-independent manner. In this study, we combined bioinformatics analysis with explicit-solvent molecular dynamics (MD) simulations to better understand the relation between the RNA sequence and the evolutionary patterns of the SR motif. A SHAPE probing experiment was also performed to confirm the fidelity of the MD simulations. We identified 57 instances of the SR motif in a nonredundant subset of the RNA X-ray structure database and analyzed their base pairing, …

Probing Vibrationally Mediated Ultrafast Excited-State Reaction Dynamics With Multireference (Caspt2) Trajectories, Patrick Z. El-Khoury, Saju Joseph, Igor Schapiro, Samer Gozem, Massimo Olivucci, Alexander N. Tarnovsky

Chemistry Faculty Publications

Excited-state trajectories computed at the complete active space second-order perturbation theory (CASPT2) reveal how vibrational excitation controls the molecular approach to the intersection space that drives the photodissociation of a prototypical halogenated methyl radical, namely CF2I. Translating the Franck-Condon structure along the ground-state CASPT2 vibrational modes in this system followed by propagating the displaced structures in the first excited doublet state simulates specific vibrational excitations and vibrationally mediated dynamics, respectively. Three distinct situations are encountered: the trajectories (i) converge to an energetically flat segment of the intersection space, (ii) locate a segment of the intersection space, and (iii) access a …

Function And Distribution Of Apolipoprotein A1 In The Artery Wall Are Markedly Distinct From Those In Plasma, Joseph A. Didonato, Ying Huang, Kulwant S. Aulak, Orli Even-Or, Gary Gerstenecker, Valentin Gogonea, Yuping Wu, Paul L. Fox, W.H. Wilson Tang, Edward F. Plow, Jonathan D. Smith, Edward A. Fisher, Stanley L. Hazen

Chemistry Faculty Publications

Background—Prior studies show that apolipoprotein A1 (apoA1) recovered from human atherosclerotic lesions is highly oxidized. Ex vivo oxidation of apoA1 or high-density lipoprotein (HDL) cross-links apoA1 and impairs lipid binding, cholesterol efflux, and lecithin-cholesterol acyltransferase activities of the lipoprotein. Remarkably, no studies to date directly quantify either the function or HDL particle distribution of apoA1 recovered from the human artery wall. Methods and Results—A monoclonal antibody (10G1.5) was developed that equally recognizes lipid-free and HDL-associated apoA1 in both native and oxidized forms. Examination of homogenates of atherosclerotic plaque–laden aorta showed >100-fold enrichment of apoA1 compared with normal aorta (P<0.001). Surprisingly, buoyant density fractionation revealed that only a minority (<3% of total) of apoA1 recovered from either lesions or normal aorta resides within an HDL-like particle (1.063≤d≤1.21). In contrast, the majority (>90%) …

Suspended Lipid Bilayer For Optical And Electrical Measurements Of Single Ion Channel Proteins, Suneth P. Rajapaksha, Xuefei Wang, H. Peter Lu

Chemistry Faculty Publications

Making and holding an artificial lipid bilayer horizontally in an aqueous solution within the microscopic working distance of similar to 100 mu m are essential for simultaneous single molecule imaging and single ion-channel electrical current recording. However, preparation of such a lipid bilayer without a solid support is technically challenging. In a typical supported lipid bilayer, the asymmetric local environments and the strong perturbation of the underneath solid or dense surface can diverge the normal behavior of membrane proteins and lipids. On the other hand, the suspended lipid bilayers can provide a native local environment for the membrane proteins and …

Multianalyte Sensing Of Addictive Over-The-Counter (Otc) Drugs, Tsuyoshi Minami, Nina A. Esipenko, Ali Akdeniz, Ben Zhang, Lyle Isaacs, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

A supramolecular sensor array composed of two fluorescent cucurbit[n]uril-type receptors (probe 1 and probe 2) displaying complementary selectivities was tested for its ability to detect and quantify drug-related amines. The fluorimetric titration of the individual probes showed highly variable and cross-reactive analyte-dependent changes in fluorescence. An excellent ability to recognize a variety of analytes was demonstrated in qualitative as well as quantitative assays. Importantly, a successful quantitative analysis of several analytes of interest was achieved in mixtures and in human urine. The throughput and sensitivity surpass those of the current state-of-the-art methods that usually require analyte solid-phase extraction …

Mapping The Excited State Potential Energy Surface Of A Retinal Chromophore Model With Multireference And Equation-Of-Motion Coupled-Cluster Methods, Samer Gozem, Federico Melaccio, Roland Lindh, Anna I. Krylov, Alexander A. Granovsky, Celestino Angeli, Massimo Olivucci

Chemistry Faculty Publications

The photoisomerization of the retinal chromophore of visual pigments proceeds along a complex reaction coordinate on a multidimensional surface that comprises a hydrogen-out-of-plane (HOOP) coordinate, a bond length alternation (BLA) coordinate, a single bond torsion and, finally, the reactive double bond torsion. These degrees of freedom are coupled with changes in the electronic structure of the chromophore and, therefore, the computational investigation of the photochemistry of such systems requires the use of a methodology capable of describing electronic structure changes along all those coordinates. Here, we employ the penta-2,4-dieniminium (PSB3) cation as a minimal model of the retinal chromophore of …

Conversion Of Iodide To Hypoiodous Acid And Iodine In Aqueous Microdroplets Exposed To Ozone, Elizabeth A. Pillar, Marcelo I. Guzman, Jose M. Rodriguez

Chemistry Faculty Publications

Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O₃) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O₃ and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O₃ at variable iodide (I^–) concentration (0.010–100 μM) for solutions aerosolized at 25 °C, which reveal remarkable differences in the reaction intermediates …

Number Of Sialic Acid Residues In Ganglioside Headgroup Affects Interactions With Neighboring Lipids, Shelli L. Frey, Ka Yee C. Lee

Chemistry Faculty Publications

Monolayers of binary mixtures of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and asialo-(GA₁), disialo-(GD_1b) and trisialo-(GT_1b) gangliosides were used to determine the effect of ganglioside headgroup charge and geometry on its interactions with the neighboring zwitterionic lipid. Surface pressure versus molecular area isotherm measurements along with concurrent fluorescence microscopy of the monolayers at the air-water interface were complemented with atomic force microscopy imaging of monolayers deposited on solid substrates. Results were used to further develop a proposed geometric packing model that the complementary geometry of DPPC and monosialoganglioside GM₁ headgroups affects their close molecular packing, …

Myeloperoxidase, Paraoxonase-1, And Hdl Form A Functional Ternary Complex, Ying Huang, Zhiping Wu, Meliana Riwanto, Shengqiang Gao, Bruce S. Levison, Xiaodong Gu, Xiaoming Fu, Matthew A. Wagner, Christian Besler, Gary Gerstenecker, Renliang Zhang, Xin Min Li, Anthony J. Didonato, Valentin Gogonea, W.H. Wilson Tang, Jonathan D. Smith, Edward F. Plow, Paul L. Fox, Diana M. Shih, Aldons J. Lusis, Edward A. Fisher, Joseph A. Didonato, Ulf Landmesser, Stanley L. Hazen

Chemistry Faculty Publications

Myeloperoxidase (MPO) and paraoxonase 1 (PON1) are high-density lipoprotein–associated (HDL-associated) proteins mechanistically linked to inflammation, oxidant stress, and atherosclerosis. MPO is a source of ROS during inflammation and can oxidize apolipoprotein A1 (APOA1) of HDL, impairing its atheroprotective functions. In contrast, PON1 fosters systemic antioxidant effects and promotes some of the atheroprotective properties attributed to HDL. Here, we demonstrate that MPO, PON1, and HDL bind to one another, forming a ternary complex, wherein PON1 partially inhibits MPO activity, while MPO inactivates PON1. MPO oxidizes PON1 on tyrosine 71 (Tyr71), a modified residue found in human atheroma that is critical for …

Toward An Understanding Of The Retinal Chromophore In Rhodopsin Mimics, Mark M. Huntress, Samer Gozem, Konstantin R. Malley, Askat E. Jailaubekov, Chrysoula Vasileiou, Mikas Vengris, James H. Geiger, Babak Borhan, Igor Schapiro, Delmar S. Larsen, Massimo Olivucci

Chemistry Faculty Publications

Recently, a rhodopsin protein mimic was constructed by combining mutants of the cellular retinoic acid binding protein II (CRABPII) with an all-trans retinal chromophore. Here, we present a combine computational quantum mechanics/molecular mechanics (QM/MM) and experimental ultrafast kinetic study of CRABPII. We employ the QM/MM models to study the absorption (lambda(a)(max)), fluorescence (lambda(f)(max)), and reactivity of a CRABPII triple mutant incorporating the all-trans protonated chromophore (PSB-KLE-CRABPII). We also study the spectroscopy of the same mutant incorporating the unprotonated chromophore and of another double mutant incorporating the neutral unbound retinal molecule held inside the pocket. Finally, for PSB-KLE-CRABPII, stationary fluorescence spectroscopy …

Assessment Of Density Functional Theory For Describing The Correlation Effects On The Ground And Excited State Potential Energy Surfaces Of A Retinal Chromophore Model, Miquel Huix-Rotllant, Michael Filatov, Samer Gozem, Igor Schapiro, Massimo Olivucci, Nicolas Ferré

Chemistry Faculty Publications

In the quest for a cost-effective level of theory able to describe a large portion of the ground and excited potential energy surfaces of large chromophores, promising approaches are rooted in various approximations to the exact density functional theory (DFT). In the present work, we investigate how generalized Kohn-Sham DFT (GKS-DFT), time-dependent DFT (TDDFT), and spin-restricted ensemble-DFT (REKS) methods perform along three important paths characterizing a model retinal chromophore (the penta-2,4-dieniminium cation) in a region of near-degeneracy (close to a conical intersection) with respect to reference high-level multiconfigurational wave function methods. If GKS-DFT correctly describes the closed-shell charge transfer state, …

Thermodynamic Characterization Of Five Key Kinetic Parameters That Define Neuronal Nitric Oxide Synthase Catalysis, Mohammad Mahfuzul Haque, Jesus Tejero, Mekki Bayachou, Zhi-Qiang Wang, Mohammed Fadlalla, Dennis J. Stuehr

Chemistry Faculty Publications

NO synthase (NOS) enzymes convert L-arginine to NO in two sequential reactions whose rates (kcat1 and kcat2) are both limited by the rate of ferric heme reduction (kr). An enzyme ferric heme –NO complex forms as an immediate product complex and then undergoes either dissociation (at a rate that we denote as kd) to release NO in a productive manner, or reduction (kr) to form a ferrous heme –NO complex that must react with O2 (at a rate that we denote as kox) in a NO dioxygenase reaction that regenerates the ferric enzyme. The interplay of these five kinetic parameters …

Structure, Theoretical Studies And Coupling Reactions Of Some New Cyclic Boronic Esters, Andrew Kuttler, Sravanthi Durganala, Albert Fratini, Alexander Morgan, Vladimir Benin

Chemistry Faculty Publications

The present report describes the X-ray structural and theoretical studies of some new pinacolboronate esters, and it also outlines the use of the target structures in Suzuki coupling reactions to produce new aromatic or heteroaromatic esters and amides. X-ray structural analysis of the studied compounds revealed that the pinacolborane ring's position with respect to the benzene ring varies, depending on the particular environment. An ortho-positioned carboxylic ester (methyl ester) causes a nearly perpendicular orientation of the pinacolborane unit with respect to the benzene ring, whereas an ortho-positioned amide (N,N-dimethylamide) causes the pinacolborane unit to orient itself nearly coplanar. A plausible …

One-Pot Enol Silane Formation-Mukaiyama–Mannich Addition Of Ketones, Amides, And Thioesters To Nitrones In The Presence Of Trialkylsilyl Trifluoromethanesulfonates, C. Wade Downey, Carolyn M. Dombrowski, Erin N. Maxwell, Chelsea L. Safran, Odamea A. Akomah

Chemistry Faculty Publications

Ketones, amides, and thioesters form enol silanes and add to N-phenylnitrones in one pot in the presence of trimethylsilyl trifluoromethanesulfonate and trialkylamine. The reaction is general to a range of silyl trifluoromethanesulfonates and N-phenylnitrones. The b-(silyloxy)amino carbonyl products are stable to chromatography and can be isolated in 63-99% yield.

Thimerosal Exposure And The Role Of Sulfation Chemistry And Thiol Availability In Autism, Janet K. Kern, Boyd E. Haley, David A. Geier, Lisa K. Sykes, Paul G. King, Mark R. Geier

Chemistry Faculty Publications

Autism spectrum disorder (ASD) is a neurological disorder in which a significant number of the children experience a developmental regression characterized by a loss of previously acquired skills and abilities. Typically reported are losses of verbal, nonverbal, and social abilities. Several recent studies suggest that children diagnosed with an ASD have abnormal sulfation chemistry, limited thiol availability, and decreased glutathione (GSH) reserve capacity, resulting in a compromised oxidation/reduction (redox) and detoxification capacity. Research indicates that the availability of thiols, particularly GSH, can influence the effects of thimerosal (TM) and other mercury (Hg) compounds. TM is an organomercurial compound (49.55% Hg …

Amyloid Β-Peptide (1–42)-Induced Oxidative Stress In Alzheimer Disease: Importance In Disease Pathogenesis And Progression, D. Allan Butterfield, Aaron M. Swomley, Rukhsana Sultana

Chemistry Faculty Publications

Significance: Alzheimer disease (AD) is an age-related neurodegenerative disease. AD is characterized by progressive cognitive impairment. One of the main histopathological hallmarks of AD brain is the presence of senile plaques (SPs) and another is elevated oxidative stress. The main component of SPs is amyloid beta-peptide (Aβ) that is derived from the proteolytic cleavage of amyloid precursor protein.

Recent Advances: Recent studies are consistent with the notion that methionine present at 35 position of Aβ is critical to Aβ-induced oxidative stress and neurotoxicity. Further, we also discuss the signatures of oxidatively modified brain proteins, identified using redox proteomics approaches, during …

Controlled Formation Of Emissive Silver Nanoclusters Using Rationally Designed Metal-Binding Proteins, Vasily A. Morozov, Michael Y. Ogawa

Chemistry Faculty Publications

The metal-binding properties of rationally designed, synthetic proteins were used to prepare a series of emissive silver nanoclusters having predictable sizes and emission energies. Metal-binding a-helical coiled coils were designed to exist as peptide trimers, tetramers, and hexamers and found to uniquely bind 6, 8, and 12 Ag+ ions, respectively. Subsequent treatment with a chemical reducing agent produced a series of peptide-bound Ag-0 nanoclusters that display a strong visible fluorescence whose emission energies depend on the number of bound metal ions in excellent agreement with theory.

Characterization Of Freshwater Natural Dissolved Organic Matter (Dom): Mechanistic Explanations For Protective Effects Against Metaltoxicity And Direct Effects On Organisms, Hassan A. Al-Reasi, Chris M. Wood, D. Scott Smith

Chemistry Faculty Publications

Dissolved organic matter (DOM) exerts direct and indirect influences on aquatic organisms. In order to better understand how DOM causes these effects, potentiometric titration was carried out for a wide range of autochthonous and terrigenous freshwater DOM isolates. The isolates were previously characterized by absorbance and fluorescence spectroscopy. Proton binding constants (pK_a) were grouped into three classes:acidic (pK_a ≤ 5), intermediate (5 < pK_a ≤ 8.5) and basic (pK_a > 8.5). Generally, the proton site densities (L_T) showed maximum peaks at the acidic and basic ends around pK_a values of 3.5 and 10, respectively. More …

Characterization By Nmr Of Reactants And Products Of Hydrofluoroether Isomers, Cf3(Cf2)3och3 And (Cf3)2c(F)Cf2och3, Reacting With Isopropyl Alcohol, Howard Knachel, Vladimir Benin, William E. Moddeman, Janine C. Birkbeck, Thomas A. Kestner, Tayna L. Young

Chemistry Faculty Publications

The 3M Company product Novec™ 71IPA DL, a mixture of methoxyperfluorobutane, methoxyperfluoroisobutane and 4.5 wt.% isopropyl alcohol, has been found to be very stable at ambient temperature, producing fluoride at the rate of ~1 ppm/year. Our earlier kinetic and theoretical studies have identified the reaction mechanism. This paper identifies the ¹H and ¹⁹F NMR chemical shifts, multiplicities, and coupling constants of reactants and the major products that result from aging the mixture in sealed Pyrex NMR tubes for periods up to 1.8 years at temperatures from 26 °C to 102 °C. Chemical shifts and coupling constants of fluorine …

Inverse Versus Normal Dithienylethenes: Computational Investigation Of The Photocyclization Reaction, AuréLie Perrier, StéPhane Aloise, Massimo Olivucci, Denis Jacquemin

Chemistry Faculty Publications

The understanding of the intimate electronic processes in photochromes is essential to optimize the properties of light-controllable devices. For one of the most studied classes of molecular switches, namely, dithienylethenes, the relative efficiencies of the normal and inverse structures remained puzzling. Indeed, despite a larger ratio of the active antiparallel conformers for the latter, the quantum yields of cyclization of inverse dithienylethenes do not exceed those of its normal counterpart. In the present contribution, we provide the first explanation of this experimental outcome using multireference ab initio quantum chemistry. We demonstrate the existence of a fluorescent intermediate on the S-1 …

Single-Step Electrochemical Functionalization Of Double-Walled Carbon Nanotube (Dwcnt) Membranes And The Demonstration Of Ionic Rectification, Xin Zhan, Ji Wu, Zhiqiang Chen, Bruce J. Hinds

Chemistry Faculty Publications

Carbon nanotube (CNT) membranes allow the mimicking of natural ion channels for applications in drug delivery and chemical separation. Double-walled carbon nanotube membranes were simply functionalized with dye in a single step instead of the previous two-step functionalization. Non-faradic electrochemical impedance spectra indicated that the functionalized gatekeeper by single-step modification can be actuated to mimic the protein channel under bias. This functional chemistry was proven by a highly efficient ion rectification, wherein the highest experimental rectification factor of ferricyanide was up to 14.4. One-step functionalization by electrooxidation of amine provides a simple and promising functionalization chemistry for the application of …

A Phase 1 Study Of Trc102, An Inhibitor Of Base Excision Repair, And Pemetrexed In Patients With Advanced Solid Tumors, Michael S. Gordon, Lee S. Rosen, David Mendelson, Ramesh K. Ramanathan, Jonathan Goldman, Lili Liu, Yan Xu, Stanton L. Gerson, Stephen P. Anthony, William D. Figg, Shawn Spencer, Bonne J. Adams, Charles P. Theuer, Bryan R. Leigh, Glen J. Weiss

Chemistry Faculty Publications

Introduction TRC102 potentiates the activity of cancer therapies that induce base excision repair (BER) including antimetabolite and alkylating agents. TRC102 rapidly and covalently binds to apurinic/apyrimidinic (AP) sites generated during BER, and TRC102-bound DNA causes topoisomerase II-dependent irreversible strand breaks and apoptosis. This study assessed the safety, maximum-tolerated dose (MTD), pharmacokinetics and pharmacodynamics of TRC102 alone and in combination with pemetrexed. Purpose Patients with advanced solid tumors received oral TRC102 daily for 4 days. Two weeks later, patients began standard-dose pemetrexed on day 1 in combination with oral TRC102 on days 1 to 4. The pemetrexed-TRC102 combination was repeated every …

2,2',5',6-Tetrachloro-4-[(1S)-1-Methylpropoxy]Biphenyl, Hans-Joachim Lehmler, Huimin Wu, Sean Parkin

Chemistry Faculty Publications

In the title molecule, C₁₆H₁₄Cl₄O, the dihedral angle between the least-square planes of the benzene rings is 84.40 (7)°. No unusual intermolecular interactions are present.

Polymerized Hemin As An Electrocatalytic Platform For Peroxynitrite's Oxidation And Detection, Serban F. Peteu, Tiyash Bose, Mekki Bayachou

Chemistry Faculty Publications

Peroxynitrite (ONOO−) constitutes a major cytotoxic agent, implicated in a host of pathophysiological conditions, thereby stimulating a tremendous interest in evaluating its role as an oxidant in vivo. Some of the detection methods for peroxynitrite include oxidation of fluorescent probes, EPR spectroscopy, chemiluminescence, immunohistochemistry, and probe nitration; however, these are more difficult to apply for real-time quantification due to their inherent complexity. The electrochemical detection of peroxynitrite is a simpler and more convenient technique, but the best of our knowledge there are only few papers to date studying its electrochemical signature, or reporting amperometric microsensors for peroxynitrite. Recently, we have …

Topography-Guided Spreading And Drying Of 6,13-Bis(Triisopropylsilylethynyl)-Pentacene Solution On A Polymer Insulator For The Field-Effect Mobility Enhancement, Chang-Min Keum, Jin-Hyuk Bae, Min-Hoi Kim, Hea-Lim Park, Marcia M. Payne, John E. Anthony, Sin-Doo Lee

Chemistry Faculty Publications

We report on the enhancement of the field-effect mobility of solution-processed 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) by unidirectional topography (UT) of an inkjet-printed polymer insulator. The UT leads to anisotropic spreading and drying of the TIPS-pentacene droplet and enables to spontaneously develop the ordered structures during the solvent evaporation. The mobility of the UT-dictated TIPS-pentacene film (0.202 ± 0.012 cm²/Vs) is found to increase by more than a factor of two compared to that of the isotropic case (0.090 ± 0.032 cm²/Vs). The structural arrangement of the TIPS-pentacene molecules in relation to the mobility enhancement is described within an …

Sensing Of Carboxylate Drugs In Urine By A Supramolecular Sensor Array, Yuanli Liu, Tsuyoshi Minami, Ryuhei Nishiyabu, Zhuo Wang, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

A supramolecular sensor array consisting of eight chemosensors embedded in a hydrogel matrix was used to sense carboxylate drugs. The discriminatory power of the array has been evaluated using principal component analysis and linear discriminant analysis. The eight-member sensor array has been shown to accurately identify 14 carboxylates in water with 100% classification accuracy. To demonstrate the potential for practical utility in the physiological environment, analysis of carboxylate drugs in human urine was also performed achieving 100% correct classification. In addition, the array performance in semiquantitative identification of nonsteroidal anti-inflammatory drugs has been investigated, and the results show that the …