Chemistry Commons^™

Ultrasensitive And Highly Selective Ni₃Te₂ As A Nonenzymatic Glucose Sensor At Extremely Low Working Potential, Bahareh Golrokh Amin, Umanga De Silva, Jahangir Masud, Manashi Nath

Chemistry Faculty Research & Creative Works

Developing Nonenzymatic glucose biosensors has recently been at the center of attention owing to their potential application in implantable and continuous glucose monitoring systems. In this article, nickel telluride nanostructure with the generic formula of Ni₃Te₂ has been reported as a highly efficient electrocatalyst for glucose oxidation, functional at a low operating potential. Ni₃Te₂ nanostructures were prepared by two synthesis methods, direct electrodeposition on the electrode and hydrothermal method. The electrodeposited Ni₃Te₂ exhibited a wide linear range of response corresponding to glucose oxidation exhibiting a high sensitivity of 41.615 mA cm …

The Protective Effect Of N-Acetylcysteine Amide Against Paraquat-Induced Neurotoxicity, Burhan Ates, Nigar Vardi, Hakan Parlakpinar, Merve Goksin Karaaslan, Ismet Yilmaz, Nuran Ercal

Chemistry Faculty Research & Creative Works

N-acetylcysteine amide (NACA) is a new antioxidant molecule with powerful radical scavenging properties. The aim of this study was to investigate neuroprotective effects of NACA against paraquat (PQ) toxicity in the midbrains of rats by using motor coordination tests and biochemical and histological analysis. Thirty adult Wistar albino rats were divided into three groups: Group 1: control (n = 10), Group 2: PQ (10 mg/kg) (n = 10), and Group 3: PQ (10 mg/kg) + NACA (100 mg/kg) (n = 10). NACA was administrated intraperitoneally 30 min before PQ injection. Performance was measured for a period of 28 days. The …

Computational Investigation On Electronic Structures And Properties Of 4,6-Bis(Nitroimino)-1,3,5-Triazinan-2-One: An Insensitive Munition Compound, Katarina M. Pittman, Harley R. Mcalexander, Gregory S. Tschumper, Manoj K. Shukla

Chemistry Faculty Research & Creative Works

In order to minimize unintentional detonation, munitions researchers have focused on the development of chemical compounds that are insensitive to external stimuli while maintaining their effectiveness. Although these compounds, known as high-performance insensitive munition compounds, are promising in terms of potency and stability, their environmental impacts have either not been fully understood or are yet to be investigated. In the present research, we have performed a quantum chemical investigation on electronic structures and properties of an insensitive munition compound 4,6-bis(nitroimino)-1,3,5-triazinan-2-one (DNAM). The density functional theory using the B3LYP and M06-2X functionals and MP2 methodology were used for geometry optimization of …

Enantioselective Copper Catalyzed Alkyne-Azide Cycloaddition By Dynamic Kinetic Resolution, En Chih Liu, Joseph J. Topczewski

Chemistry Faculty Research & Creative Works

The copper(I) catalyzed alkyne-azide cycloaddition (CuAAC), a click reaction, is one of the most powerful catalytic reactions developed during the last two decades. Conducting CuAAC enantioselectively would add a third dimension to this reaction and would enable the direct synthesis of α-chiral triazoles. Doing so is demanding because the two precursors have linear geometries, and the triazole product is a flat heterocycle. Designing a chiral catalyst is further complicated by the complex mechanism of CuAAC. We report an enantioselective CuAAC (E-CuAAC), enabled by dynamic kinetic resolution (DKR). The E-CuAAC is high yielding and affords up to 99:1 er. The E-CuAAC …

Molecular Dynamics Simulations Of Substrate Release From Trypanosoma Cruzi Udp-Galactopyranose Mutase, Rodrigo Cossio-Pérez, Gustavo Pierdominici-Sottile, Pablo Sobrado, Juliana Palma

Chemistry Faculty Research & Creative Works

The enzyme UDP-galactopyranose mutase (UGM) represents a promising drug target for the treatment of infections with Trypanosoma cruzi. We have computed the Potential of Mean Force for the release of UDP-galactopyranose from UGM, using Umbrella Sampling simulations. The simulations revealed the conformational changes that both substrate and enzyme undergo during the process. It was determined that the galactopyranose portion of the substrate is highly mobile and that the opening/closing of the active site occurs in stages. Previously uncharacterized interactions with highly conserved residues were also identified. These findings provide new pieces of information that contribute to the rational design of …

Radical Scavenging Of Poly(Methyl Methacrylate) Bone Cement By Rifampin And Clinically Relevant Properties Of The Rifampin-Loaded Cement, G. A. Funk, E. M. Menuey, K. A. Cole, Thomas P. Schuman, K. V. Kilway, T. E. Mciff

Chemistry Faculty Research & Creative Works

Objectives: The objective of this study was to characterize the effect of rifampin incorporation into poly(methyl methacrylate) (pMMA) bone cement. While incompatibilities between the two materials have been previously noted, we sought to identify and quantify the cause of rifampin's effects, including alterations in curing properties, mechanical strength, and residual monomer content.

Methods: Four cement groups were prepared using commercial pMMA bone cement: a control; one with 1 g of rifampin; and one each with equimolar amounts of ascorbic acid or hydroquinone relative to the amount of rifampin added. The handling properties, setting time, exothermic output, and monomer loss were …

Examination Of The Structures, Energetics, And Vibrational Frequencies Of Small Sulfur-Containing Prototypical Dimers, (H2s)2 And H2o/H2s, Katelyn M. Dreux, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The optimized geometries, vibrational frequencies, and dissociation energies from MP2 and CCSD(T) computations with large correlation consistent basis sets are reported for (H₂S)₂ and H₂O/H₂S. Anharmonic vibrational frequencies have also been computed with second-order vibrational perturbation theory (VPT2). As such, the fundamental frequencies, overtones, and combination bands reported in this study should also provide a useful road map for future spectroscopic studies of the simple but important heterogeneous H₂O/H₂S dimer in which the hydrogen bond donor and acceptor can interchange, leading to two unique minima with very similar energies. …

Flavin Oxidation In Flavin-Dependent N-Monooxygenases, Reeder M. Robinson, Catherine A. Klancher, Pedro J. Rodriguez, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Siderophore A (SidA) from Aspergillus fumigatus is a flavin-containing monooxygenase that hydroxylates ornithine (Orn) at the amino group of the side chain. Lysine (Lys) also binds to the active site of SidA; however, hydroxylation is not efficient and H₂O₂ is the main product. The effect of pH on steady-state kinetic parameters was measured and the results were consistent with Orn binding with the side chain amino group in the neutral form. From the pH dependence on flavin oxidation in the absence of Orn, a pKa value >9 was determined and assigned to the FAD-N5 atom. In the …

Bending Wave Based Characterization Of Viscoelastic Materials, Max Miller, Sadeq Malakooti, Tahereh Taghvaee, Ning Xiang, Hongbing Lu, Nicholas Leventis

Chemistry Faculty Research & Creative Works

Obtaining broadband dynamic mechanical properties of viscoelastic materials is challenging. Commercially available characterization equipment is typically limited to about 500 Hz. Ultrasonic testing is a common strategy but requires time-temperature superposition extrapolation to audible frequencies. These techniques are indirect and sensitive to inhomogeneities. Modal methods do not yield broadband data and can fail for materials with high loss factors. A new relatively simple characterization method, relying on bending wave excitation and laser Doppler vibrometer measurement, is proposed. Complex elastic moduli and phase speeds are now attainable over the entire range of building acoustics frequencies. The materials under test are an …

Cis/Trans Energetics In Epoxide, Thiirane, Aziridine And Phosphirane Containing Cyclopentanols: Effects Of Intramolecular Oh···O,S,N And P Contacts, Ben E. Smith, Jeremy M. Carr, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

A recent computational analysis of the stabilizing intramolecular OH···O contact in 1,2-dialkyl-2,3-epoxycyclopentanol diastereomers has been extended to thiiriane, aziridine and phosphirane analogues. Density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2) and CCSD(T) coupled-cluster computations with simple methyl and ethyl substituents indicate that electronic energies of the cis isomers are lowered by roughly 3 to 4 kcal mol⁻¹ when the OH group of these cyclopentanol systems forms an intramolecular contact with the O, S, N or P atom on the adjacent carbon. The results also suggest that S and P can participate in these stabilizing intramolecular interactions as effectively …

Dynamical Interference In The Vibronic Bond Breaking Reaction Of Hco, Shanyu Han, Xianfeng Zheng, Steve A. Ndengue, Yu Song, Richard Dawes, For Full List Of Authors, See Publisher's Website.

Chemistry Faculty Research & Creative Works

First-principles treatments of quantum molecular reaction dynamics have reached the level of quantitative accuracy even in cases with strong non-Born-Oppenheimer effects. This achievement permits the interpretation of puzzling experimental phenomena related to dynamics governed by multiple coupled potential energy surfaces. We present a combined experimental and theoretical study of the photodissociation of formyl radical (HCO). Oscillations observed in the distribution of product states are found to arise from the interference of matter waves-a manifestation analogous to Young's double-slit experiment.

Application Of A Hygroscopicity Tandem Differential Mobility Analyzer For Characterizing Pm Emissions In Exhaust Plumes From An Aircraft Engine Burning Conventional And Alternative Fuels, Max B. Trueblood, Prem Lobo, Donald E. Hagen, Steven C. Achterberg, Wenyan Liu, Philip D. Whitefield

Chemistry Faculty Research & Creative Works

In the last several decades, significant efforts have been directed toward better understanding the gaseous and particulate matter (PM) emissions from aircraft gas turbine engines. However, limited information is available on the hygroscopic properties of aircraft engine PM emissions which play an important role in the water absorption, airborne lifetime, obscuring effect, and detrimental health effects of these particles. This paper reports the description and detailed labbased performance evaluation of a robust hygroscopicity tandem differential mobility analyzer (HTDMA) in terms of hygroscopic properties such as growth factor (GF) and the hygroscopicity parameter (κ). The HTDMA system was subsequently deployed during …

Bio-Inspired Polydopamine Surface Modification Of Nanodiamonds And Its Reduction Of Silver Nanoparticles, Yun Zeng, Wenyan Liu, Risheng Wang

Chemistry Faculty Research & Creative Works

Surface functionalization of nanodiamonds (NDs) is still challenging due to the diversity of functional groups on the ND surfaces. Here, we demonstrate a simple protocol for the multifunctional surface modification of NDs by using mussel-inspired polydopamine (PDA) coating. In addition, the functional layer of PDA on NDs could serve as a reducing agent to synthesize and stabilize metal nanoparticles. Dopamine (DA) can self-polymerize and spontaneously form PDA layers on ND surfaces if the NDs and dopamine are simply mixed together. The thickness of a PDA layer is controlled by varying the concentration of DA. A typical result shows that a …

The Rotational Spectrum And Potential Energy Surface Of The Ar-Sio Complex, Michael C. Mccarthy, Steve Alexandre Ndengue, Richard Dawes

Chemistry Faculty Research & Creative Works

The rotational spectra of five isotopic species of the Ar-SiO complex have been observed at high-spectral resolution between 8 and 18 GHz using chirped Fourier transform microwave spectroscopy and a discharge nozzle source; follow-up cavity measurements have extended these measurements to as high as 35 GHz. The spectrum of the normal species is dominated by an intense progression of a-type rotational transitions arising from increasing quanta in the Si-O stretch, in which lines up to v = 12 (~14 500 cm^-1) were identified. A structural determination by isotopic substitution and a hyperfine analysis of the Ar-Si¹⁷O …

Polymer Coated Gold-Ferric Oxide Superparamagnetic Nanoparticles For Theranostic Applications, Muhammad Raisul Abedin, Siddesh Umapathi, Harika Mahendrakar, Tunyaboon Laemthong, Holly Coleman, Denise Muchangi, Santimukul Santra, Manashi Nath, Sutapa Barua

Chemistry Faculty Research & Creative Works

Background: Engineered inorganic nanoparticles (NPs) are essential components in the development of nanotechnologies. For applications in nanomedicine, particles need to be functionalized to ensure a good dispersibility in biological fluids. In many cases however, functionalization is not sufficient: the particles become either coated by a corona of serum proteins or precipitate out of the solvent. We show that by changing the coating of magnetic iron oxide NPs using poly-l-lysine (PLL) polymer the colloidal stability of the dispersion is improved in aqueous solutions including water, phosphate buffered saline (PBS), PBS with 10% fetal bovine serum (FBS) and cell culture medium, and …

Novel Porous Polymer Compositions For The Synthesis Of Monolithic Bimodal Microporous/Macroporous Carbon Compositions Useful For Selective Co₂ Sequestration, Nicholas Leventis, Chariklia Sotiriou-Leventis, Malik Adnan Saeed

Chemistry Faculty Research & Creative Works

The present invention discloses novel porous polymeric compositions comprising random copolymers of amides, imides, ureas, and carbamic-anhydrides, useful for the synthesis of monolithic bimodal microporous/macroporous carbon aerogels. It also discloses methods for producing said microporous/macroporous carbon aerogels by the reaction of a polyisocyanate compound and a polycarboxylic acid compound, followed by pyrolytic carbonization, and by reactive etching with CO₂ at elevated temperatures. Also disclosed are methods for using the microporous/macroporous carbon aerogels in the selective capture and sequestration of carbon dioxide.

Solid State Nmr Spectroscopy/Imaging In Situ Measuring Devices And Methods For Calibration And Determining One Or More Quantitative Properties Of A Target Sample, Lingyu Chi, Ming Huang, Rex E. Gerald, Klaus Woelk

Chemistry Faculty Research & Creative Works

In situ measuring devices, methods of making the same, and methods of using the same are provided herein. The in situ measuring devices can include a capillary tube having a reference material sealed inside the capillary tube, where the capillary tube is positioned inside of a solid state or MAS NMR rotor. A target sample can also be positioned in the interior of the solid state or MAS NMR rotor but is sequestered from the reference material by a capillary tube wall. The in situ measuring devices can be used in solid state MAS NMR spectroscopy to quantify one or …

Solid State Nmr Spectroscopy/Imaging In Situ Measuring Devices And Methods For Calibration And Determining One Or More Quantitative Properties Of A Target Sampleabstract, Lingyu Chi, Ming Huang, R. Gerald Ii, Klaus Woelk

Chemistry Faculty Research & Creative Works

In situ measuring devices, methods of making the same, and methods of using the same are provided herein. The in situ measuring devices can include a capillary tube having a reference material sealed inside the capillary tube, where the capillary tube is positioned inside of a solid state or MAS NMR rotor. A target sample can also be positioned in the interior of the solid state or MAS NMR rotor but is sequestered from the reference material by a capillary tube wall. The in situ measuring devices can be used in solid state MAS NMR spectroscopy to quantify one or …

Graphene-Based Materials For The Fast Removal Of Cytokines From Blood Plasma, Mykola Seredych, Bernard Haines, Viktoriia Sokolova, Paul Cheung, Fayan Meng, Lon Stone, Lyuba Mikhalovska, Sergey Mikhalovsky, Vadym Mochalin, Yury Gogotsi

Chemistry Faculty Research & Creative Works

There is a range of medical conditions, which include acute organ failure, bacterial and viral infection, and sepsis, that result in overactivation of the inflammatory response of the organism and release of proinflammatory cytokines into the bloodstream. Fast removal of these cytokines from blood circulation could offer a potentially efficient treatment of such conditions. This study aims at the development and assessment of novel biocompatible graphene-based adsorbents for blood purification from proinflammatory cytokines. These graphene-based materials were chosen on the basis of their surface accessibility for small molecules further facilitated by the interlayer porosity, which is comparable to the size …

Evidence For The Formation Of A Radical-Mediated Flavin-N5 Covalent Intermediate, Yumin Dai, Hannah Valentino, Pablo Sobrado

Chemistry Faculty Research & Creative Works

The redox-neutral reaction catalyzed by 2-haloacrylate hydratase (2-HAH) leads to the conversion of 2-chloroacrylate to pyruvate. Previous mechanistic studies demonstrated the formation of a flavin-iminium ion as an important intermediate in the 2-HAH catalytic cycle. Time-resolved flavin absorbance studies were performed in this study, and the data showed that the enzyme is capable of stabilizing both anionic and neutral flavin semiquinone species. The presence of a radical scavenger decreases the activity in a concentration-dependent manner. These data are consistent with the flavin iminium intermediate occurring by radical recombination.

Steric Control Of The Rate-Limiting Step Of Udp-Galactopyranose Mutase, Gustavo Pierdominici-Sottile, Rodrigo Cossio-Pérez, Isabel Da Fonseca, Karina Kizjakina, John J. Tanner, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Galactose is an abundant monosaccharide found exclusively in mammals as galactopyranose (Galp), the six-membered ring form of this sugar. In contrast, galactose appears in many pathogenic microorganisms as the five-membered ring form, galactofuranose (Galf). Galf biosynthesis begins with the conversion of UDP-Galp to UDP-Galf catalyzed by the flavoenzyme UDP-galactopyranose mutase (UGM). Because UGM is essential for the survival and proliferation of several pathogens, there is interest in understanding the catalytic mechanism to aid inhibitor development. Herein, we have used kinetic measurements and molecular dynamics simulations to explore the features of UGM that control the rate-limiting step (RLS). We show that …

Kinetic Solvent Viscosity Effects As Probes For Studying The Mechanisms Of Enzyme Action, Giovanni Gadda, Pablo Sobrado

Chemistry Faculty Research & Creative Works

The study of enzyme reaction mechanisms is fundamentally important to our understanding of biochemistry, cellular metabolism, and drug development. This Perspective focuses on the use of kinetic solvent viscosity effects (KSVEs) to study enzyme reactions. This technique is easily implemented and uses steady-state kinetic analyses to probe whether substrate binding is diffusion-controlled and whether product release is the rate-limiting step in the catalytic cycle. In addition, KSVEs can identify isomerization steps that are important for catalysis. The use of KSVEs in combination with other techniques, such as kinetic isotope effects, pH effects, and site-directed mutagenesis, can provide a detailed view …

Flexible To Rigid Nanoporous Polyurethane-Acrylate (Puac) Type Materials For Structural And Thermal Insulation Applications, Nicholas Leventis, Chariklia Sotiriou-Leventis, Abhishek Bang

Chemistry Faculty Research & Creative Works

Novel urethane-acrylate (UAC) Star monomers and polyurethane-acrylate (PUAC) aerogel polymers derived therefrom are described herein, along with other novel, related monomers and polymers. Also described herein are processes for preparing the UAC Star monomers, the PUAC aerogel polymers, and the other related monomers and polymers. The PUAC and related polymers herein are useful in various applications including in structural and thermal insulation.

Scalable, Hydrophobic And Highly-Stretchable Poly(Isocyanurate-Urethane) Aerogels, Sadeq Malakooti, Saman Rostami, Habel Gitogo Churu, Huiyang Luo, Jenna Clark, Fabiola Casarez, Owen Rettenmaier, Soheil Daryadel, Majid Minary-Jolandan, Chariklia Sotiriou-Leventis, Nicholas Leventis, Hongbing Lu

Chemistry Faculty Research & Creative Works

Scalable, low-density and flexible aerogels offer a unique combination of excellent mechanical properties and scalable manufacturability. Herein, we report the fabrication of a family of low-density, ambient-dried and hydrophobic poly(isocyanurate-urethane) aerogels derived from a triisocyanate precursor. The bulk densities ranged from 0.28 to 0.37 g cm^-3 with porosities above 70% v/v. The aerogels exhibit a highly stretchable behavior with a rapid increase in the Young's modulus with bulk density (slope of log-log plot > 6.0). In addition, the aerogels are very compressible (more than 80% compressive strain) with high shape recovery rate (more than 80% recovery in 30 s). Under …

Hydrogen Bonding In The Mixed Hf/Hci Dimer: Is It Better To Give Or Receive?, Sarah N. Johnson, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The ClH⋯FH and FH⋯ClH configurations of the mixed HF/HCl dimer (where the donor⋯acceptor notation indicates the directionality of the hydrogen bond) as well as the transition state connecting the two configurations have been optimized using MP2 and CCSD(T) with correlation consistent basis sets as large as aug-cc-pV(5 + d)Z. Harmonic vibrational frequencies confirmed that both configurations correspond to minima and that the transition state has exactly one imaginary frequency. In addition, anharmonic vibrational frequencies computed with second-order vibrational perturbation theory (VPT2) are within 6 cm⁻¹ of the available experimental values and deviate by no more than 4 cm^{−1 …}

Salt-Assisted Ultrasonic Disaggregation Of Nanodiamond, Vadym Mochalin, Kostiantyn Turcheniuk, Caleb Trecazzi

Chemistry Faculty Research & Creative Works

Methods for disaggregating nanodiamond clusters, for example, by using ultrasound to break apart nanodiamond aggregates in a sodium chloride aqueous slurry. Compositions, such as aqueous nanodiamond dispersions and dry particulate compositions that may be produced using these methods.

Structural Evidence For Rifampicin Monooxygenase Inactivating Rifampicin By Cleaving Its Ansa-Bridge, Li Kai Liu, Yumin Dai, Heba Abdelwahab, Pablo Sobrado, John J. Tanner

Chemistry Faculty Research & Creative Works

Rifampicin monooxygenase (RIFMO) decreases the potency of rifampicin (RIF) by converting it to oxidative products. Further decomposition of RIF has been observed in bacteria producing RIFMO and contributes to RIFMO-mediated drug resistance. Here we report the first crystal structure of RIFMO in complex with the hydroxylated RIF product. The 2.10 Å resolution structure reveals a breach of the ansa aliphatic chain of RIF between naphthoquinone C2 and amide N1. Our data suggest that RIFMO catalyzes the hydroxylation of RIF at the C2 atom followed by cleavage of the ansa linkage, which leads to inactivation of the antibiotic by preventing key …

Epoxy Phosphonate Ester As A Coupling Agent For Transition Metal And Metal Oxide Surfaces, Thomas P. Schuman

Chemistry Faculty Research & Creative Works

A method for surface modification of a substrate comprising surface oxide and/or hydroxy groups, with a compound comprising an ester group and an epoxy ring, wherein the epoxy group remains intact after the reacting. A method for surface modification of a substrate comprising surface oxide and/or hydroxy groups, with a compound comprising an ester group and a functionalized epoxy ring, wherein the functionalized epoxy group remains intact after the reacting. A composite material comprising surface-modified metal oxide nanoparticles dispersed within a polymeric material, wherein the surface modification comprises a compound comprising an ester group and an epoxy ring is also …

Erratum: Author Correction: Identification Of Aspergillus Fumigatus Udp-Galactopyranose Mutase Inhibitors (Scientific Reports (2017) 7 1 (10836)), Julia S. Martin Del Campo, Meital Eckshtain-Levi, Nancy J. Vogelaar, Pablo Sobrado

Chemistry Faculty Research & Creative Works

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Rapid Adsorption Of Proinflammatory Cytokines By Graphene Nanoplatelets And Their Composites For Extracorporeal Detoxification, Yishan Zheng, Nicholas Pescatore, Yury Gogotsi, Boris Dyatkin, Ganesh Ingavle, Vadym Mochalin, Tochukwu Ozulumba, Sergey Mikhalovsky, Susan Sandeman

Chemistry Faculty Research & Creative Works

Sepsis is a complex clinical syndrome that features excessive release of cytokines and other inflammatory mediators that could lead to organ dysfunction. Despite different treatment and management options, sepsis associated high morbidity and mortality rates remain. This has prompted intensive research into alternative therapeutic approaches such as targeted removal of sepsis related molecules using extracorporeal hemoperfusion. In this study, we explore the use of graphene nanoplatelets (GNP) as low-cost alternative hemosorbents for rapid removal of a broad spectrum of proinflammatory cytokine markers. Firstly, the physical characteristics, cytotoxicity, and cytokine marker adsorption profile of GNP were assessed. The results not only …