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Now showing items 65 - 80 of 109

  • Translation of Protein Charge and Hydrophilicity to Materials Surface Properties using Thermal Treatment in Fluorous Media

    Wang, Li-Sheng   Gopalakrishnan, Sanjana   Lee, Yi-Wei   Zhu, Jiaxin   Nonnenmann, Stephen   Rotello, Vincent  

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  • Translation of protein charge and hydrophilicity to materials surface properties using thermal treatment in fluorous media

    Wang, Li-Sheng   Gopalakrishnan, Sanjana   Lee, Yi-Wei   Zhu, Jiaxin   Nonnenmann, Stephen S.   Rotello, Vincent M.  

    Protein-based materials provide an inherently biocompatible and sustainable platform for the generation of functional materials. Translating protein properties into protein films resistant to aqueous degradation is crucial formost applications such as tissue engineering and controlled drug delivery. Current methods to stabilize protein films use three main strategies: employing the relatively limited variety of naturally self-assembling proteins, using added crosslinkers or heat curing. While the cross-linking strategy generates functionally diverse structures, unreacted additives retained in cross-linked protein films can adversely affect their final behavior. Traditional heat curing results in hydrophobic surface and loss of protein inherent properties. We demonstrate here a scalable, additive-free, fluorous media assisted thermal treatment for the fabrication of stable, hydrophilic protein films. This approach is general in terms of protein building block, retaining much of their native structure and surface properties upon heating. We demonstrate the versatility of this strategy through fabrication of antifouling coatings on complex three-dimensional surfaces. The utility of these films as biomaterials is highlighted through the generation of highly biocompatible non-fouling surfaces and regulation of cellular adhesion through choice of protein precursor.
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  • Activation of sphingosine kinase mediates suppressive effect of interleukin-6 on human multiple myeloma cell apoptosis.

    Li, Qing-Fang   Wu, Chu-Tse   Duan, Hai-Feng   Sun, Hui-Yan   Wang, Hua   Lu, Zhuo-Zhuang   Zhang, Qun-Wei   Liu, Hong-Jun   Wang, Li-Sheng  

    Interleukin 6 (IL-6) influences the growth and survival of multiple myeloma (MM) cells via the activation of multiple signalling cascades. Although sphingosine kinase (SPHK) signalling is known to play important roles in the regulation of cell proliferation and apoptosis, the role of SPHK activation in IL-6 signalling and in the pathology of MM remains unclear. This study found that IL-6 activated SPHK in MM cells, which mediates the suppressive effects of IL-6 on MM cell apoptosis. Both MM cell lines and primary MM cells constitutively expressed SPHK, and treatment of MM cells with IL-6 resulted in activation of SPHK in a concentration-dependent manner. Specific inhibitors of the phosphatidylinositol-3 kinase and extracellular signal-regulated kinase/mitogen-activated protein kinase pathways blocked the IL-6-induced activation of SPHK. It was further demonstrated that IL-6-induced activation of SPHK inhibited dexamethasone-induced apoptosis of MM cells. IL-6 stimulation or retroviral-mediated overexpression of SPHK1 in MM cells resulted in increased intracellular SPHK activity and upregulation of myeloid cell leukaemia-1 (Mcl-1), leading to increased cell proliferation and survival. Conversely, inhibition of SPHK1 by small interfering RNA reduced IL-6-induced upregulation of Mcl-1 and blocked the suppressive effect of IL-6 on MM cell apoptosis. Taken together, these results delineate a key role for SPHK activation in IL-6-induced proliferation and survival of MM cells, and suggest that SPHK may be a potential new therapeutic target in MM.
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  • Bioinformatic Analysis Suggests That Three Hub Genes May Be a Vital Prognostic Biomarker in Pancreatic Ductal Adenocarcinoma

    Chang, Xin   Yang, Mei-Feng   Fan, Wei   Wang, Li-Sheng   Yao, Jun   Li, Zhao-Shen   Li, De-Feng  

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  • Endocut Versus Conventional Blended Electrosurgical Current for Endoscopic Biliary Sphincterotomy: A Meta-Analysis of Complications

    Li, De-feng   Yang, Mei-feng   Chang, Xin   Wang, Nan-nan   Tan, Fang-fang   Xie, Hai-na   Fang, Xue   Wang, Shu-ling   Fan, Wei   Wang, Jian-yao   Yu, Zhi-chao   Wei, Cheng   Xiong, Feng   Liu, Ting-ting   Luo, Ming-han   Wang, Li-sheng   Li, Zhao-shen   Yao, Jun   Bai, Yu  

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  • Bridging Vinylidene Complexes of RhMn and Evidence for Migratory Insertions To Give Terminal Vinyl Groups

    Wang, Li-Sheng   Cowie, Martin  

    The reaction of the heterobinuclear complex [RhMn(CO)(4)(dppm)(2)] (1) (dppm = Ph(2)PCH(2)PPh(2)) with 3-butyn-2-one at -40 degrees C yields the alkyne-bridged product [RhMn(CO)(4)(mu-HC2C(O)Me)(dppm)(2)] (3), which undergoes a 1,2-hydrogen shift, yielding two isomers of the vinylidene-bridged species [RhMn(CO)(4)(mu-CC)(H)C(O)Me)(dppm)(2)] (4) as the temperature is raised. Compound 4 undergoes facile CO loss to give [RhMn(CO)(3)(CO)(3)(mu-eta(1):eta(2)-CC(H)C(O)Me)(dppm)(2)] (5) in which the ketonic moiety of the bridging vinylidene group coordinates to Mn, filling the open coordination site left vacant by the departing CO. Protonation of the alkyne- or vinylidene-bridged species 3-5 yields a series of vinyl complexes. Addition of methyl triflate to 4 and 5 yields the respective methyl-substituted vinyl complexes, analogous to the protonation products. In the alkylation of 5 at low temperature an intermediate, [RhMn(CH3)(CO)(3)(mu-eta(1):eta(2)-CC(H)C(O)Me)(dppm)(2)][SO3CF3 (12), having a vinylidene bridge and a methyl group terminally bound to Rh, is obtained. The rearrangement of 12 to a vinyl complex upon warming presents evidence for a migratory insertion involving these groups. The structure of 5 was determined by X-ray crystallography. This compound crystallizes in the monoclinic space group P2(1)/n (nonstandard setting of P2(1)/c [No. 14]) with a = 14.489(1) Angstrom, b = 15.754(2) Angstrom, c = 24.104(2) Angstrom,beta = 91.41(1) Angstrom, V = 5500(1) Angstrom(3), and Z = 4. On the basis of 3980 observations the structure has refined to R = 0.058 and R(w) = 0.063.
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  • Solid-Liquid Phase Equilibrium of N,N '-(Methylenedi-4,1-phenylene)bis(phosphoramidic acid) Tetraphenyl Ester in Selected Solvents

    Du, Chao-Jun   Wang, Li-Sheng   Yu, Guo-Min   Sun, Gui-Qin  

    N,N'-(Methylenedi-4,1-phenylene)bis(phosphoramidic acid) tetraphenyl ester (PNBTE), a flame retardant with high thermal stability, was synthesized and characterized by elemental analysis (EA), mass spectrometry (MS), infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR). The thermal properties of PNBTE were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The solubilities of PNBTE in selected solvents were measured by a gravimetric method. The experimental data were correlated with Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) equations. The calculated results showed good agreement with the experimental data. The solubility parameter of PNBTE was estimated by the Scatchard-Hildebrand model; meanwhile, the dissolution enthalpy and entropy, and molar Gibbs energy of PNBTE in the selected solvents are also calculated by the van't Hoff equation.
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  • Activity coefficients at infinite dilution of organic solutes in 1-octyl-3-methylimidazolium nitrate using gas-liquid chromatography

    Duan, Jia-Dong   Wang, Li-Sheng   Jiang, Kan   Wang, Xin-Xin  

    Activity coefficients at infinite dilution and gas-liquid partition coefficients (K-L) of 25 organic solutes, including alkanes, alkenes, alkylbenzenes, alcohols, acetonitrile, ethyacetate, acetone, tetrahydrofuran, dichloromethane, trichromethane, and tetrchloromrthane in the ionic liquid 1-octyl-3-methylimidazolium nitrate ([OMIM][NO3]), have been determined by means of gas-liquid chromatography over a temperature range of 303.15-363.15K with the ionic liquid as the stationary phase. From the dependence of experimental activity coefficients, the partial molar excess enthalpies at infinite dilution and the solubility parameters of the organic solutes in the ionic liquid [OMIM][NO3] have been determined. (C) 2012 Elsevier B.V. All rights reserved.
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  • Experimental measurement and modeling of solubility of LiBr and LiNO(3) in methanol, ethanol, 1-propanol, 2-propanol and 1-butanol

    Li, Mi-Yi   Wang, Li-Sheng   Wang, Kun-Peng   Jiang, Bo   Gmehling, Juergen  

    The solubility of lithium bromide and lithium nitrate in solvents methanol, ethanol, 1-propanol, 2-propanol and 1-butanol were measured in the range between 298.15 and 338.15 K using an analytical gravimetric method. An empirical equation was used to fit the experimental solubilities and the Pitzer model with inclusion of Archer's ionic strength was used for the calculation of osmotic coefficients. The experimental data of system pressures (p) for the correlation of LiBr + ethanol, LiBr + 2-propanol at T (298.15-333.15 K) and LiNO(3) + ethanol at T (298.15-323.15 K) were obtained from published literatures. Moreover, the parameters of the Pitzer model were re-correlated and were used to predict mean ion activity coefficients. A procedure was also presented to predict the solubility products of salts in pure organic solvent. (C) 2011 Elsevier B.V. All rights reserved.
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  • Comment on Wang et al “Extracorporeal Shock Wave Lithotripsy for Chronic Pancreatitis Patients With Stones After Pancreatic Surgery”

    Xu, Zheng-Lei   Yao, Jun   Wang, Li-Sheng  

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  • Determination and correlation of solubilities of 1,2-bis (2-oxo-5,5-dimethyl-1,3,2-dioxyphosphacyclohexyl-2-imino) ethane in selected solvents

    Qi, Chun-Mei   Wang, Li-Sheng   Du, Jun-Chao   Yu, Guo-Min   Sun, Gui-Qin  

    1,2-Bis (2-oxo-5,5-dimethyl-1,3,2-dioxyphosphacyclohexyl-2-imino) ethane (BPEA) was prepared, and characterized by elemental analysis (EA), mass spectra (MS), infrared spectroscopy (IR) and nuclear magnetic resonance (NMR). The melting point and the enthalpy of fusion of BPEA were performed on differential scanning calorimetry (DSC), and the thermal stability of BPEA was tested by thermogravimetric analysis (TGA). The solubility of BPEA in selected solvents was measured by a static analytical method. The experimental data were correlated with different thermodynamic models, such as the empirical equation and non-random two liquid (NRTL), Wilson, Scatchard-Hildebrand, and universal quasi chemical (UNIQUAC) equations. The calculated results showed good agreement with the experimental data in the temperature range studied. (C) 2013 Elsevier B.V. All rights reserved.
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  • Solid-Liquid Phase Equilibrium of N,N '-Piperazinebis(neopentylglycol)phosphoramidate in Selected Solvents from T =3D (293.15 to 333.15) K

    Zhao, Dong-Fang   Wang, Li-Sheng   Sun, Jian   Chen, Chuan-Ming  

    A phosphorus flame retardant named N,N'-piperazinebis(neopentylglycol)phosphoramidate (PBNGP) was synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy, mass spectra, and nuclear magnetic resonance. Its thermal properties were evaluated via thermograviinetric analysis and differential scanning calorimetry. The solubilities of PBNGP in selected solvents at T =3D (293.15 to 333.15) K and atmospheric pressure were measured via a static-analytic method. The experimental data were correlated with Scatchard Hildebrand, Buchowski-Ksiazczak, Wilson, nonrandom two liquid, and universal quasichemical equations. The calculated results showed that all of these models can reproduce the experimental data well, and the Wilson model gives the best correlation, with an overall relative standard deviation of 0.70%. The solubility parameter of PBNGP was calculated using the Scatchard Hildebrand methodology.
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  • Improvement of the SRK equation of state for representing volumetric properties of petroleum fluids using Dortmund Data Bank

    Wang, Li-Sheng   Gmehling, Jü   rgen  

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  • Plasma-Nitrided Ga2O3(Gd2O3) as Interfacial Passivation Layer for InGaAs Metal-Oxide-Semiconductor Capacitor With HfTiON Gate Dielectric

    Wang, Li-Sheng   Xu, Jing-Ping   Liu, Lu   Lu, Han-Han   Lai, Pui-To   Tang, Wing-Man  

    Plasma nitridation is used for nitrogen incorporation in Ga2O3(Gd2O3) (GGO) as interfacial passivation layer for an InGaAs metal-oxide-semiconductor capacitor with a HfTiON gate dielectric. The nitrided GGO (GGON) on InGaAs can improve the interface quality with a low interface-state density at midgap (1.0 x 10(12) cm(-2) eV(-1)), and result in good electrical properties for the device, e.g., low gate leakage current (8.5 x 10(-6) A/cm(2) at V-g =3D 1 V), small capacitance equivalent thickness (1.60 nm), and large equivalent dielectric constant (24.9). The mechanisms involved lie in the fact that the GGON interlayer can effectively suppress the formation of the interfacial In/Ga/As oxides and remove excess As atoms on the InGaAs surface, thus unpinning the Femi level at the GGON/InGaAs interface and improving the interface quality and electrical properties of the device.
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  • Solubilities of Phenylphosphinic Acid, Methylphenylphosphinic Acid, Hexachlorocyclotriphosphazene, and Hexaphenoxycyclotriphosphazene in Selected Solvents

    Tian, Na-Na   Wang, Li-Sheng   Li, Mi-Yi   Li, Yi   Jiang, Ru-Yi  

    Phenylphosphinic acid (PPA), methylphenylphosphinic acid (MPPA), hexachlorocyclotriphosphazene (HCCP), and hexaphenoxycyclotriphosphazene (HPCCP) were prepared and characterized by elemental analysis, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. Using a static analytical method, the solubilities of PPA, MPPA, HCCP, and HPCCP were measured in ten solvents and correlated with an empirical equation. The calculated results showed good agreement with the experimental data. Furthermore, using the Scatchard-Hildebrand model, activity coefficients have also been calculated and compared with the experimental values. The partial molar excess enthalpies at infinite dilution were also predicted.
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  • Overexpression of KAI1 induces autophagy and increases MiaPaCa-2 cell survival through the phosphorylation of extracellular signal-regulated kinases

    Wu, Chun-Yan   Yan, Jun   Yang, Yue-Feng   Xiao, Feng-Jun   Li, Qing-Fang   Zhang, Qun-Wei   Wang, Li-Sheng   Guo, Xiao-Zhong   Wang, Hua  

    KAI1, a metastasis-suppressor gene belonging to the tetraspanin family, is known to inhibit cancer metastasis without affecting the primary tumorigenicity by inhibiting the epidermal growth factor (EGF) signaling pathway. Recent studies have shown that hypoxic conditions of solid tumors induce high-level autophagy and KAI1 expression. However, the relationship between autophagy and KAI1 remains unclear. By using transmission electron microscopy, confocal microscopy, and Western blotting, we found that KAI1 can induce autophagy in a dose- and time-dependent manner in the human pancreatic cell line MiaPaCa-2. KAI1-induced autophagy was confirmed by the expression of autophagy-related proteins LC3 and Beclin 1. KAI1 induces autophagy through phosphorylation of extracellular signal-related kinases rather than that of AKT. KAI1-induced autophagy protects MiaPaCa-2 cells from apoptosis and proliferation inhibition partially through the downregulation of poly [adenosine diphosphate (ADP)-ribose] polymerase (PARP) cleavage and caspase-3 activation. (C) 2010 Elsevier Inc. All rights reserved.
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