Molecular dynamics simulation study on zwitterionic structure to maintain the natural behavior of polyalanine13 in aqueous environment

Molecular dynamics simulations are applied to the initial stage of polyalanine13 conformational transi- tion from α-helix to random coil in aqueous environment and the interaction of polyalanine13 with zwitterionic and hydrophobic surfaces respectively in the same condition. The analysis of secondary structure, hydrogen bonds, RMSD, dihedral distribution, and the degree of adsorption are performed. The results show that zwitterionic structure maintains the natural behavior of polyalanine13 in water to a better extent, which should be an indirect proof of the hypothesis of "maintain of normal structure."     

Research of the relationship of intracellular acidification and apoptosis in Hela cells based on pH nanosensors

In this paper,the relationship of intracellular acidification and apoptosis in Hela cells induced by vin-cristine sulfate has been studied by use of the ratiometric pH nanosensors that have been developed by our group,employing fluorescein isothiocyanate(FITC) doped as the pH-sensitive dye and Tris(2,2'-bipyidyl) dichlororuthenium(II) hexahydrate(RuBpy) doped as reference dye. The pH change of the Hela cells induced by vincristine sulfate has been monitored in vivo,in situ and real time by use of the ratiometric pH nanosensors. The experimental results show that the pH of the apoptotic Hela cells induced by vincristine sulfate has been acidified from 7.11 to 6.51,and the percentage of intra-cellular acidification is correlated with the induced concentration and incubation time of the vincristine sulfate. The further study of the percentage of intracellular acidification and the percentage of apop-tosis of Hela cells at the same time reveals that apoptosis of Hela cells induced by vincristine sulfate is preceded by intracellular acidification. These results would provide theoretical foundation for the therapy of cancer through interfering the pH of cells by use of vincristine sulfate or other anti-cancer drugs.     

Sulfonate-based fluorescent probes for imaging hydrogen peroxide in living cells

Based on the mechanism of H₂O₂-mediated hydrolysis of sulfonates, two fluorescein disulfonates compounds (FS-1 and FS-2) were designed and synthesized as the highly selective and sensitive fluorescent probes for imaging H₂O₂ in living cells. The probes were detected with elemental analysis, IR, ¹H NMR and ¹³C NMR. Upon reaction with H₂O₂, the probes exhibit strong fluorescence responses and high selectivity for H₂O₂ over other reactive oxygen species and some biological compounds. Furthermore, the sulfonate-based probes, as novel fluorescent reagents, are cell-permeable and can detect micromolar changes in H₂O₂ concentrations in living cells by using confocal microscopy. Supported by the National Basic Research Program of China (Grant No. 2007CB936000), the National Natural Science Funds for Distinguished Young Scholar (Grant No. 20725518), Major Program of the National Natural Science Foundation of China (Grant No. 90713019), the National Natural Science Foundation of China (Grant No. 20875057), the Natural Science Foundation of Shandong Province, China (Grant No. Y2007B02), and the Science and Technology Development Programs of Shandong Province, China (Grant No. 2008GG30003012)     

Preparation of electrolyte membranes for micro tubular solid oxide fuel cells

Yttria-stabilized zirconia (YSZ) micro tubular electrolyte membranes for solid oxide fuel cells (SOFCs) were prepared via the combined wet phase inversion and sintering technique. The as-derived YSZ mi- cro tubes consist of a thin dense skin layer and a thick porous layer that can serve as the electrode of fuel cells. The dense and the porous electrolyte layers have the thickness of 3-5 μm and 70-90 μm, respectively, while the inner surface porosity of the porous layer is higher than 28.1%. The two layers are perfectly integrated together to preclude the crack or flake of electrolyte film from the electrode. The presented method possesses distinct advantages such as technological simplicity, low cost and high reliability, and thus provides a new route for the preparation of micro tubular SOFCs.     

湿法脱硫中亚硫酸盐非催化氧化本征动力学

亚硫酸盐的氧化是湿法烟气脱硫工艺中的重要过程. 利用间歇式反应装置, 研究了亚硫酸盐非催化氧化的本征反应动力学. 结果表明, 该反应分为两个阶段进行, 即富氧区的快速反应和贫氧区的慢速反应. 在富氧区, 亚硫酸盐和溶解氧的分级数分别为1.0和1.0, 反应的表观活化能为49.3 kJ•mol^－1; 在贫氧区, 亚硫酸盐和溶解氧的分级数分别为2.0和0, 反应的表观活化能为122.6 kJ•mol^－1. 对反应的机理进行了预测, 结果与实验现象有较好的吻合.     

Adsorptive desulfurization of diesel with mesoporous aluminosilicates

Mesoporous aluminosilicates (MAS) bearing microporous zeolite units and mesoporous structures were synthesized by the hydrothermal method. Adsorptive desulfurization ability of model oil and hydrotreated diesel was studied. The effects of template concentration, crystalization time and calcination time were investigated. The desulfurization ability of adsorbents was improved by transitional metal ion-exchanging. The adsorptive desulfurization of diesel was carried out on a fixed-bed system. The results show that the adsorptive capacity is MAS>MCM-41>NaY. The improvement of desulfurization ability of MAS by Cu⁺ is more significant than that of Ag⁺. Supported by National Basic Research Program of China (Grant No. 2006CB202507), National High-tech R&D Program (Grant No. 2006AA02Z209), and the National Natural Science Foundation of China (Grant No. 20806086)     

Direct electrochemistry behavior of Cytochrome c on silicon dioxide nanoparticles-modified electrode

A newfangled direct electrochemistry behavior of Cytochrome c (Cyt c) was found on glassy carbon (GC) electrode modified with the silicon dioxide (SiO2) nanoparticles by physical adsorption. A pair of stable and well-defined redox peaks of Cyt c′ quasi-reversible electrochemical reaction were obtained with a heterogeneous electron transfer rate constant of 1.66×10-3 cm/s and a formal potential of 0.069 V (vs. Ag/AgCl) (0.263 V versus NHE) in 0.1 mol/L pH 6.8 PBS. Both the size and the amount of SiO2 nanoparticles could influence the electron transfer between Cyt c and the electrode. Electrostatic interaction which is between the negative nanoparticle surface and positively charged amino acid residues on the Cyt c surface is of importance for the stability and reproducibility toward the direct electron transfer of Cyt c. It is suggested that the modification of SiO2 nanoparticles proposes a novel approach to realize the direct electrochemistry of proteins.     

Preparation and photoactivity of thermosensitive polymer supported metallophthalocyanine

A novel reactive metallophthalocyanine derivative,zinc tetra(2,4-dichloro-1,3,5-triazine)aminophthalo-cyanine(Zn-TDTAPc),was prepared and immobilized on poly(N-isopropylacrylamide)(PNIPAAm) by covalent bonding to obtain a thermosensitive polymer(Zn-TDTAPc-g-PNIPAAm).Compared with zinc tetraaminophthalocyanine(Zn-TAPc),Zn-TDTAPc-g-PNIPAAm exhibits excellent solubility in water and in most organic solvents.Furthermore,it has a special thermosensitive property in water and the lower critical solution temperature(LCST) is 34.1℃.It was found that both dissolved and precipitated Zn-TDTAPc-g-PNIPAAm present high photoactivity evidenced by the experiment of photocatalytic degra-dation of 1,3-diphenylisobenzofuran(DPBF) in the presence of Zn-TDTAPc-g-PNIPAAm.These proper-ties suggest that it can be used potentially in photodynamic therapy(PDT).     

Zwitterionic phosphorylcholine-protected water-soluble Ag nanoparticles

The water-soluble Ag nanoparticles capped with novel zwitterionic thioalkylated phosphorylcholine were synthesized. The Ag nanoparticles showed remarkable stability in saline media with salt concentrations as high as 2.0 mol/L and plasma using UV-vis absorption spectroscopy. Similarly, compared with tiopronin and citrate-protected Ag nanoparticles, the zwitterionic phosphorylcholine Ag nanoparticles did not precipitate out of solution when charged polyelectrolytes or biopolymers were added. The zwitterionic phosphorylcholine might be a better ligand for stabilizing metal nanoparticles. Supported by the National Natural Science Foundation of China (Grant Nos. 20774082 and 50703036), National High Technology Research and Development Program of China (Grant Nos. 2006AA03Z329 and 2006AA032444) and Science and Technology Projects of Zhejiang Province (Grant No. 2007C24G2010020)     

Preparation of polystyrene-grafted titanate nanotubes by <Emphasis Type="Italic">in situ</Emphasis> atom transfer radical polymerization

This work successfully prepared nanohybrids by in situ atom transfer radical polymerization (ATRP) of styrene from titanate nanotubes (TNTs). Fourier-transform infrared (FT-IR), pronton nuclear magnetic resonance spectroscopy (¹H NMR), and thermal gravimetric analysis (TGA) were used to verify the successful graft of polystyrene (PS) chains from TNTs. Transmission electron microscopy (TEM) displayed that the obtained PS-g-TNTs nanohybrids had a core-shell structure of TNT core and PS shell. The grafted PS content was well controlled and increased with increasing of the monomer/initiator ratio. Further copolymerization of tert-butyl acrylate (tBA) from the surface of PS-g-TNTs was studied, illustrating the “living” characteristics of the surface-induced ATRP method used in this work. Supported by the Special Funds for Major State Basic Research Projects (Grant No. 2005CB623803), the National Basic Research Program (Grant Nos. 2007CB808000 & 2009CB930400), the National Natural Science Foundation of China (Grant Nos. 50633010 & 20874060), the Program for New Century Excellent Talents in University (Grant No. NCET-07-0558), the Basic Research Foundation of Shanghai Science and Technique Committee (Grant No. 07DJ14004), and Shanghai Leading Academic Discipline Project (Grant No. B202).     

Highly sensitive and selective ratiometric fluorescent copper sensors: Different binding affinities modulated by three separate side chains of naphthalimide

A series of compounds 1-11 with different side chains of naphthalimide as fluorescent copper sensors were designed and synthesized. Compounds 1, 9, 10 and 11 presented a high selectivity to Cu2+ in a neutral aqueous environment. Here 1, 9 and 10 showed selectivity and affinity to Cu2+ with an association constant of about ～106. It gave somewhat response to Ag+, Co2+, Ni2+ and Fe2+ while 1 detected copper. 9 and 10 displayed better selectivity by changing their hydrophobic side chains to the hydrophilic ones...     

Preparation and spectral characteristics of anthracene/tetracene mixed crystals

A series of tetracene-doped anthracene crystals with different doping concentrations (the highest molar ratio 100 1) are grown from solution. Crystal structures and optical characteristics of the above mixed crystals are investigated at room temperature. By changing the doping concentrations, the fluorescence can be adjusted from blue-green to green and even to yellow-green. The emission spectra of anthracene/tetracene (An/Te) mixed crystals reveal the sensitized fluorescence of tetracene and the partial quenching of anthracene emission. The data of transient photoluminescence (PL) decays illustrate that in An/Te mixed crystals, the decay of anthracene becomes faster, while the PL lifetime of tetracene is longer than that of the tetracene single crystals. All above experimental results suggest that there is excitation energy transfer from anthracene to tetracene in the mixed crystals. Supported by the National Natural Science Foundation of China (Grant No. 5057 3039) and the National Key Basic Research and Development Program of China (Grant No. 2006CB806200)     

Effect of polybrominated diphenyl ether on development of cultured hippocampal neuron

Polybrominated diphenyl ether (PBDE) is a persistently environmental pollutant ubiquitously found in wildlife and humans. Although concern on PBDE’s toxic effects is steadily increasing, its action on the central nervous system (CNS) remains largely unknown. To address this issue, the present study ex- amined the development inhibition of PBDE in neurons. The primary cultured hippocampal neurons of rat were exposed to the commercial decabromodiphenyl ether (deca-BDE), and the neurite length, bi- furcation, and synapse formation and maturation were evaluated, based on the confocal microscope imaging. The results showed that the development inhibition in neurons occurred at 15 μmol/L, indi- cating that PBDE is a potent neurotoxicant and it might obviously inhibit the development of cultured neurons.     

Synthesis of Fréchet-type dendritic homotriptycenes

A rapid and efficient synthesis of novel dendrimer homotriptycenes is presented. The dendronized 9,10-dihydroanthracen-9-ols 4, having high electron densities in the benzene rings of the Fréchet-type dendrons, exhibited in the presence of acid a quantitative transannular ring closure to the corresponding dendritic homotriptycenes. The electron-donating Fréchet-type dendrons enabled the intramolecular FC alkylation by a regioselective 1,7-elimination of H2O.     

Facile synthesis of small crystal ZSM-5 zeolite by acid-catalyzed hydrolysis of tetraethylorthosilicate

Small crystal zeolites ZSM-5 with sizes of 150–300 nm were synthesized using the colloidal silicate precursors as the silica source created by the acid-catalyzed hydrolysis of tetraethylorthosilicate with tetrapropylammonium bromide as the structure-directing agent within a short crystallization time of 20–35 h. The precursors and final products were detected by XRD, SEM, ICP and DLS. Supported by the National Natural Science Foundation of China (Grant No. 20776069), Key Natural Science Foundation for Universities of Jiangsu Province (Grant No. 06KJA53012), and Program for Changjiang Scholars and Innovative Research Team in University (Grant No. PCSIRT 0732)     

Drug discovery based on the structure of FKBP12: Design,synthesis and evaluation of <Emphasis Type="Italic">L</Emphasis>-1,4-thiazane-3-carboxylic acid derivatives as neuroimmunophilin ligands

By choosing neuroimmunophilin FKBP12 as a therapeutical target, we have attempted to discover a new structural drug for treating neurodegenerative disease. This drug should possess neurotrophic activity and not affect the immune system. Based on the crystal structure of FKBP12, FK506 and Calcineurin complex, a series of small organic molecules were designed. These molecules were to have the ability of binding to FKBP12 in a virtual screening. By using a solution parallel synthetic method, these compounds were synthesized. The neuroprotective and neuroregenerative activities of these compounds were evaluated by binding assays, PC12 cells survival and neurite outgrowth model, chick dorsal root ganglion cultures (DRG) and 6-OHDA lesioned mice sympathetic nerve endings model. The evaluation results of these compounds showed that compound N308 has great promise as a candidate for a neuroprotective and neuroregenerative agent. Supported by the National Basic Research Program of China (Grant No. G1998051107) and Hi-tech Research and Development Program of China (Grant No. 2002AA233051)     

Unprecedented synthesis of chiral calix[4](aza)crowns and its potent encapsulating methanol

Unprecedented synthesis of chiral (aza)crown ethers of calix[4]arene derivatives bearing a carboxyl amide bridge was described. The synthesis proceeds through condensation of the corresponding dinitriles with optically active 1,2-aminoalcohols,and is catalyzed by the ZnCl2 Lewis acid at elevated temperature in a very efficient one-pot process. The cavity of calix[4](aza)crowns can encapsulate methanol molecules by O—H...π interaction,which has been confirmed by X-ray crystal structures and ESI-MS.     

3D-QSAR and docking studies of estrogen compounds based on estrogen receptor β

Close attention has been paid to estrogen compounds because these chemicals may pose a serious threat to the health of humans and wildlife. Estrogen receptor (ER) exists as two subtypes, ERα and ERβ. The difference in amino acids sequence of the binding sites of ERα and ERβ might lead to a result that some synthetic estrogens and naturally occurring steroidal ligands have different relative affinities and binding modes for ERα and ERβ. In this investigation, comparative molecular similarity indices analysis...     

Simulation of micro-behaviors including nucleation,growth, and aggregation in particle system

A new method for the solution of population balance equations (PBE) describing the micro-processes such as nucleation, growth, aggregation of particle swarms in a multiphase system is proposed. The method is based on the fixed pivot moment and allows arbitrary number of moments to be tracked simultaneously. By expressing PBEs for both batch and continuous operations in a general form, and using weighted residual method to derive the moment equations, different moments can be tracked directly. The numerical density function is assumed to be a summation of several weighted Dirac Delta functions, and the integral and derivative terms in PBEs are transformed to a summation in order to reduce computational cost. Simulations of a batch nucleation-growth process and a continuous aggregation-growth process have demonstrated good agreement with the corresponding analytical solutions, with relative errors less than 10⁻⁸%. Simulation of a combined nucleation-growth-aggregation process, which does not have an analytical solution, is also included, so as to reproduce the micro-behaviors of such a complex system, demonstrating the feasibility and reliability of this method. Supported by the National Basic Research Program of China (Grant No. 2004CB720208), National Natural Science Foundation of China (Grant Nos. 40675011 and 10872159) and Key Laboratory of Mechanics on Disaster and Environment in Western China (Grant No. 200707)     

Theoretical study on the charge transport properties of triphenylene discogens with a phenylpropionyloxy or 3-phenylpropenoyloxy side chain

Charge transport is one of the most important properties in organic materials. Charge transport properties of triphenylene discogens with a phenylpropionyloxy or 3-phenylpropenoyloxy side chain have been investigated computationally on the basis of semi-classical Marcus theory. The results show that three triphenylene derivatives have high charge mobility. Title compounds have much better electronic mobility than the triphenylene. The triphenylenes containing 3-phenylpropenoyloxy have better hole mobility, but smaller electronic mobility than the triphenylenes with phenylpropionyloxy. For the triphenylene discogens with a phenylpropionyloxy, the longer the alkloxy chains, the better the positive charge transfer rate, but the smaller the negative charge transfer rate. Supported by the National Natural Science Foundation of China (Grant No. 50673069), the Research Foundation of Education Bureau of Sichuan Province, China (Grant No. 07ZA093), and Scientific Research Foundation of Sichuan Normal University for Innovation Groups ( Grant No. 025156)