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- (2S,4R)-4-Fluoro-pyrrolidinium-2-carboxyl-ate.Hobart, David B. Jr.; Merola, Joseph S. (International Union of Crystallography, 2012-08-01)The crystal structure of the title compound, C(5)H(8)FNO(2), at 100 K, displays inter-molecular N-H⋯O hydrogen bonding between the ammonium and carboxyl-ate groups as a result of its zwitterionic nature in the solid state. The five-membered ring adopts an envelope conformation with the C atom at the 3-position as the flap. The compound is of inter-est with respect to the synthesis and structural properties of synthetic collagens. The absolute structure was determined by comparison with the commercially available material.
- Acetylcholinesterase of the sand fly, Phlebotomus papatasi (Scopoli): construction, expression and biochemical properties of the G119S orthologous mutantTemeyer, Kevin B.; Tong, Fan; Totrov, Maxim M.; Tuckow, Alexander P.; Chen, Qiao-Hong; Carlier, Paul R.; Pérez de León, Adalberto A.; Bloomquist, Jeffrey R. (2014-12-10)Background Phlebotomus papatasi vectors zoonotic cutaneous leishmaniasis. Previous expression of recombinant P. papatasi acetylcholinesterase (PpAChE1) revealed 85% amino acid sequence identity to mosquito AChE and identified synthetic carbamates that effectively inhibited PpAChE1 with improved specificity for arthropod AChEs compared to mammalian AChEs. We hypothesized that the G119S mutation causing high level resistance to organophosphate insecticides in mosquitoes may occur in PpAChE1 and may reduce sensitivity to inhibition. We report construction, expression, and biochemical properties of rPpAChE1 containing the G119S orthologous mutation. Methods Targeted mutagenesis introduced the G119S orthologous substitution in PpAChE1 cDNA. Recombinant PpAChE1 enzymes containing or lacking the G119S mutation were expressed in the baculoviral system. Biochemical assays were conducted to determine altered catalytic properties and inhibitor sensitivity resulting from the G119S substitution. A molecular homology model was constructed to examine the modeled structural interference with docking of inhibitors of different classes. Genetic tests were conducted to determine if the G119S orthologous codon existed in polymorphic form in a laboratory colony of P. papatasi. Results Recombinant PpAChE1 containing the G119S substitution exhibited altered biochemical properties, and reduced inhibition by compounds that bind to the acylation site on the enzyme (with the exception of eserine). Less resistance was directed against bivalent or peripheral site inhibitors, in good agreement with modeled inhibitor docking. Eserine appeared to be a special case capable of inhibition in the absence of covalent binding at the acylation site. Genetic tests did not detect the G119S mutation in a laboratory colony of P. papatasi but did reveal that the G119S codon existed in polymorphic form (GGA + GGC). Conclusions The finding of G119S codon polymorphism in a laboratory colony of P. papatasi suggests that a single nucleotide transversion (GGC → AGC) may readily occur, causing rapid development of resistance to organophosphate and phenyl-substituted carbamate insecticides under strong selection. Careful management of pesticide use in IPM programs is important to prevent or mitigate development and fixation of the G119S mutation in susceptible pest populations. Availability of recombinant AChEs enables identification of novel inhibitory ligands with improved efficacy and specificity for AChEs of arthropod pests.
- An adaptive variational algorithm for exact molecular simulations on a quantum computerGrimsley, Harper R.; Economou, Sophia E.; Barnes, Edwin Fleming; Mayhall, Nicholas J. (Springer Nature, 2019-07-08)Quantum simulation of chemical systems is one of the most promising near-term applications of quantum computers. The variational quantum eigensolver, a leading algorithm for molecular simulations on quantum hardware, has a serious limitation in that it typically relies on a pre-selected wavefunction ansatz that results in approximate wavefunctions and energies. Here we present an arbitrarily accurate variational algorithm that, instead of fixing an ansatz upfront, grows it systematically one operator at a time in a way dictated by the molecule being simulated. This generates an ansatz with a small number of parameters, leading to shallow-depth circuits. We present numerical simulations, including for a prototypical strongly correlated molecule, which show that our algorithm performs much better than a unitary coupled cluster approach, in terms of both circuit depth and chemical accuracy. Our results highlight the potential of our adaptive algorithm for exact simulations with present-day and near-term quantum hardware.
- Addressing the Achilles' heel of pseudocapacitive materials: Long-term stabilityLiu, Tianyu; Li, Yat (2020-09)Electrode materials with high energy densities and long-lasting performances are crucial to durable and reliable electrochemical energy storage devices for modern information technologies (eg, Internet of things). In terms of supercapacitors, their low energy densities could be enhanced by using pseudocapacitive electrodes, but meanwhile, their ultralong lifetimes are compromised by the limited charge-discharge cycling stabilities of pseudocapacitive materials. This review article discusses on the cycling instability issues of five common pseudocapacitive materials: conjugated polymers (or conducting polymers), metal oxides, metal nitrides, metal carbides, and metal sulfides. Specifically, the article includes the fundamentals of the failure modes of these materials, as well as thoroughly surveys the design rationales and technical details of the cycling-stability-boosting tactics for pseudocapacitive materials that reported in the literature. Additionally, promising opportunities, future challenges, and possible solutions associated with pseudocapacitive materials are discussed.
- Ammonium Bisphosphonate Polymeric Magnetic Nanocomplexes for Platinum Anticancer Drug Delivery and Imaging with Potential Hyperthermia and Temperature-Dependent Drug ReleaseZhang, Rui; Fellows, Benjamin; Pothayee, Nikorn; Hu, Nan; Pothayee, Nipon; Jo, Ami; Bohórquez, Ana C.; Rinaldi, Carlos; Mefford, Olin Thompson; Davis, Richey M.; Riffle, Judy S. (Hindawi, 2018-08-05)Novel magnetite-ammonium bisphosphonate graft ionic copolymer nanocomplexes (MGICs) have been developed for potential drug delivery, magnetic resonance imaging, and hyperthermia applications. The complexes displayed relatively uniform sizes with narrow size distributions upon self-assembly in aqueous media, and their sizes were stable under simulated physiological conditions for at least 7 days. The anticancer drugs, cisplatin and carboplatin, were loaded into the complexes, and sustained release of both drugs was observed. The transverse NMR relaxivities (s) of the complexes were 244 s−1 (mM Fe)−1 which is fast compared to either the commercial T2-weighted MRI agent Feridex IV® or our previously reported magnetite-block ionomer complexes. Phantom MRI images of the complexes demonstrated excellent negative contrast effects of such complexes. Thus, the bisphosphonate-bearing MGICs could be promising candidates for dual drug delivery and magnetic resonance imaging. Moreover, the bisphosphonate MGICs generate heat under an alternating magnetic field of 30 kA·m−1 at 206 kHz. The temperature of the MGIC dispersion in deionized water increased from 37 to 41°C after exposure to the magnetic field for 10 minutes, corresponding to a specific absorption rate of 77.0 W·g−1. This suggests their potential as hyperthermia treatment agents as well as the possibility of temperature-dependent drug release, making MGICs more versatile in potential drug delivery applications.
- Amorphous solid dispersions of enzalutamide and novel polysaccharide derivatives: investigation of relationships between polymer structure and performanceWilson, Venecia R.; Lou, Xiaochun; Osterling, Donald J.; Stolarik, DeAnne F.; Jenkins, Gary J.; Nichols, Brittany L. B.; Dong, Yifan; Edgar, Kevin J.; Zhang, Geoff G. Z.; Taylor, Lynne S. (Nature Research, 2020-10-28)Amorphous solid dispersion (ASD) is a widely employed formulation technique for drugs with poor aqueous solubility. Polymers are integral components of ASDs, but mechanisms by which polymers lead to the generation and maintenance of supersaturated solutions, which enhance oral absorption in vivo, are poorly understood. Herein, a diverse group of newly synthesized cellulose derivatives was evaluated for their ability to inhibit crystallization of enzalutamide, a poorly soluble compound used to treat prostate cancer. ASDs were prepared from selected polymers, specifically a somewhat hydrophobic polymer that was extremely effective at inhibiting drug crystallization, and a less effective, but more hydrophilic, crystallization inhibitor, that might afford better release. Drug membrane transport rate was evaluated in vitro and compared to in vivo performance, following oral dosing in rats. Good correlation was noted between the in vitro diffusion cell studies and the in vivo data. The ASD formulated with the less effective crystallization inhibitor outperformed the ASD prepared with the highly effective crystallization inhibitor in terms of the amount and rate of drug absorbed in vivo. This study provides valuable insight into key factors impacting oral absorption from enabling ASD formulations, and how best to evaluate such formulations using in vitro approaches.
- Annual Report Executive Summary, 2006-07 Department of Chemistry(Department of Chemistry, 2007)
- Annual Report Executive Summary, 2007-08 Department of Chemistry(Department of Chemistry, 2008)
- Annual Report Executive Summary, 2008-09 Department of Chemistry(Department of Chemistry, 2009)
- Annual Report Executive Summary, 2009-10 Department of Chemistry(Department of Chemistry, 2010)
- Antimalarial 5,6-Dihydro-alpha-pyrones from Cryptocarya rigidifolia: Related Bicyclic Tetrahydro-alpha-Pyrones Are ArtifactsLiu, Yixi; Rakotondraibe, L. Harinantenaina; Brodie, Peggy J.; Wiley, Jessica D.; Cassera, Maria B.; Miller, James S.; Ratovoson, F.; Rakotobe, Etienne; Rasamison, Vincent E.; Kingston, David G. I. (American Chemical Society, 2015-06-01)
- Antiproliferative Compounds from Cleistanthus boivinianus from the Madagascar Dry ForestLiu, Yixi; Young, Kelly; Rakotondraibe, L. Harinantenaina; Brodie, Peggy J.; Wiley, Jessica D.; Cassera, Maria B.; Callmander, Martin W.; Rakotondrajaona, R.; Rakotobe, Etienne; Rasamison, Vincent E.; TenDyke, Karen; Shen, Yongchun; Kingston, David G. I. (American Chemical Society, 2015-07-01)
- Antiproliferative Trihydroxyalkylcyclohexenones from Pleiogynium timorienseEaton, A. L.; Rakotondraibe, L. Harinantenaina; Brodie, P. J.; Goetz, M.; Kingston, David G. I. (American Chemical Society, 2015-07-01)
- Antiproliferative triterpenoid saponins from Leptaulus citroides Baill. from the Madagascar rain forestSu, Qingxi; Brodie, Peggy J.; Liu, Yixi; Miller, James S.; Andrianjafy, Naina M.; Antsiferana, Rabodo; Rasamison, Vincent E.; Kingston, David G. I. (Springer, 2016)Bioassay-guided fractionation of EtOH extracts obtained from the roots and wood of the Madagascan plant Leptaulus citroides Baill. (Cardiopteridaceae) led to the isolation of ethyl esters of three new triterpenoid saponins (1–3) and the known sesquiterpenoid cinnamosmolide (4). The structures of 1–3 were elucidated by extensive 1D and 2D NMR experiments and mass spectrometry. Compounds 1, 2, and 4 showed moderate cytotoxicity against the A2780 human ovarian cancer cell line with IC50 values of 2.8, 10.2 and 2.0 lM, respectively.
- Aqua-bis-(4-methyl-benzene-sulfonato-κO)(η(5)-penta-methyl-cyclo-penta-dien-yl)rhodium(III) monohydrate.Roy, Christopher P.; Boyer, Pauline M.; Merola, Joseph S. (International Union of Crystallography, 2013-05-01)The title half-sandwich rhodium(III) complex, [Rh(C10H15)(C7H7O3S)2(H2O)]·H2O, consists of a π-bonded penta-methyl-cyclo-penta-dienyl group, two σ-bonded tosyl-ate groups and an aqua ligand. The structure displays both inter- and intra-molecular O-H⋯O hydrogen bonding. The inter-molecular hydrogen bonding results in an extended helical chain along a 21 screw axis parallel to c, due to hydrogen bonding from the coordinating water ligand to the lattice water mol-ecule and then to a sulfonate O atom of a different asymmetric unit.
- Aryl ethynyl phthalic anhydrides and polymers with terminal or pendant amines prepared with aryl ethynyl phthalic anhydrides(United States Patent and Trademark Office, 1996-02-20)Arylethynyl phthalic anhydrides have been synthesized and shown to have particular application as endcappers or pendant groups in high performance/high temperature thermosets which include amine terminal or amine pendant groups.
- Assembly of Bio-Nanoparticles for Double Controlled Drug ReleaseHuang, Wei; Zhang, Jianfei; Dorn, Harry C.; Zhang, Chenming (PLOS, 2013-09-06)A critical limiting factor of chemotherapy is the unacceptably high toxicity. The use of nanoparticle based drug carriers has significantly reduced the side effects and facilitated the delivery of drugs. Source of the remaining side effect includes (1) the broad final in vivo distribution of the administrated nanoparticles, and (2) strong basal drug release from nanoparticles before they could reach the tumor. Despite the advances in pH-triggered release, undesirable basal drug release has been a constant challenge under in vivo conditions. In this study, functionalized single walled carbon nanohorn supported immunoliposomes were assembled for paclitaxel delivery. The immunoliposomes were formulated with polyethylene glycol, thermal stable and pH sensitive phospholipids. Each nanohorn was found to be encapsulated within one immunoliposome. Results showed a highly pH dependent release of paclitaxel in the presence of serum at body temperature with minimal basal release under physiological conditions. Upon acidification, paclitaxel was released at a steady rate over 30 days with a cumulative release of 90% of the loaded drug. The drug release results proved our hypothesized double controlled release mechanism from the nanoparticles. Other results showed the nanoparticles have doubled loading capacity compared to that of traditional liposomes and higher affinity to breast cancer cells overexpressing Her2 receptors. Internalized nanoparticles were found in lysosomes.
- An atomic force microscope tip as a light sourceLulevich, V.; Honig, Christopher D. F.; Ducker, William A. (AIP Publishing, 2005-12-01)We present a simple method for causing the end of a silicon nitride atomic force microscope (AFM) tip to emit light, and we use this emitted light to perform scanning near-field optical microscopy. Illumination of a silicon nitride AFM tip by blue (488 nm) or green (532 nm) laser light causes the sharp part of the tip to emit orange light. Orange light is emitted when the tip is immersed in either air or water; and while under illumination, emission continues for a period of many hours without photobleaching. By careful alignment of the incident beam, we can arrange the scattered light to decay as a function of the tip-substrate separation with a decay length of 100-200 nm. The exponential decay of the intensity means that the emitted light is dominated by contributions from parts of the tip that are near the sample, and therefore the emitted orange light can be used to capture high-resolution near-field optical images in air or water. (c) 2005 American Institute of Physics.
- Atomic resolution tracking of nerve-agent simulant decomposition and host metal-organic framework response in real spaceTerban, Maxwell W.; Ghose, Sanjit K.; Plonka, Anna M.; Troya, Diego; Juhas, Pavol; Dinnebier, Robert E.; Mahle, John J.; Gordon, Wesley O.; Frenkel, Anatoly I. (2021-01-04)Gas capture and sequestration are valuable properties of metal-organic frameworks (MOFs) driving tremendous interest in their use as filtration materials for chemical warfare agents. Recently, the Zr-based MOF UiO-67 was shown to effectively adsorb and decompose the nerve-agent simulant, dimethyl methylphosphonate (DMMP). Understanding mechanisms of MOF-agent interaction is challenging due to the need to distinguish between the roles of the MOF framework and its particular sites for the activation and sequestration process. Here, we demonstrate the quantitative tracking of both framework and binding component structures using in situ X-ray total scattering measurements of UiO-67 under DMMP exposure, pair distribution function analysis, and theoretical calculations. The sorption and desorption of DMMP within the pores, association with linker-deficient Zr6 cores, and decomposition to irreversibly bound methyl methylphosphonate were directly observed and analyzed with atomic resolution. Metal-organic frameworks have been shown to adsorb and decompose chemical warfare agents, but their mechanism of action is not completely understood. Here the authors quantitatively track the binding and decomposition product structures of nerve-agent simulant dimethyl methylphosphonate in host UiO-67 through in situ X-ray total scattering measurements, pair distribution function analysis, and density functional theory calculations.
- Atomic-Level Structural Dynamics of Polyoxoniobates during DMMP DecompositionWang, Qi; Chapleski, Robert C. Jr.; Plonka, Anna M.; Gordon, Wesley O.; Guo, Weiwei; Thuy-Duong Nguyen-Phan; Sharp, Conor H.; Marinkovic, Nebojsa S.; Senanayake, Sanjaya D.; Morris, John R.; Hill, Craig L.; Troya, Diego; Frenkel, Anatoly I. (Springer Nature, 2017-04-10)Ambient pressure in situ synchrotron-based spectroscopic techniques have been correlated to illuminate atomic-level details of bond breaking and formation during the hydrolysis of a chemical warfare nerve agent simulant over a polyoxometalate catalyst. Specifically, a Cs-8[Nb6O19] polyoxoniobate catalyst has been shown to react readily with dimethyl methylphosphonate (DMMP). The atomic-level transformations of all reactant moieties, the [Nb6O19](8)-polyanion, its Cs+ counterions, and the DMMP substrate, were tracked under ambient conditions by a combination of X-ray absorption fine structure spectroscopy, Raman spectroscopy, and X-ray diffraction. Results reveal that the reaction mechanism follows general base (in contrast to specific base) hydrolysis. Together with computational results, the work demonstrates that the ultimate fate of DMMP hydrolysis at the Cs-8[Nb6O19] catalyst is strong binding of the (methyl) methylphosphonic acid ((M) MPA) product to the polyanions, which ultimately inhibits catalytic turnover.