Dec 2008, Volume 3 Issue 4

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  • LI Xin, ZHU Xiaoqing, CHENG Jinpei
    There is an increasing interest in the study of NO chemical affinities of organic nitrites, for the biological and physiological effects of organic nitrites seem to be due to their ability to release NO. In this paper, NO chemical affinities of ten substituted benzyl nitrites were determined by titration calorimetry combined with a thermodynamic cycle in acetonitrile solution. The results show that ?Hhet(O–NO)s of benzyl nitrites are substantially larger than the corresponding ?Hhomo(O–NO)s, suggesting that these O-nitroso compounds much more easily release NO radicals by the O–NO bond homolytic cleavage. It is believed that the structural and energetic information disclosed in this work should be useful in understanding chemical and biological functions of organic nitrites.
  • XU Xuetang, DUAN Wengui, HUANG Mei, PENG Qinghua, LIU Xiongmin
    In the presence of the ionic liquid [bmim]Br/AlCl3 as green reaction medium, methyl 12-benzoyldehydroabietate was synthesized through Friedel-Crafts acylation reactions on the aromatic ring of methyl dehydroabietate. The optimum synthetic conditions of the target product were found to be as follows: molar ratio of methyl dehydroabietate to [bmim]Br to AlCl3 to benzoyl chloride 1:4:8:8, reaction temperature 40°C, reaction time 2 h. The target product was analyzed and characterized by means of IR, MS, NMR and elemental analysis. The results show that this novel method has the advantages of mild condition, short reaction time and environmental benignity.
  • LIU Qiuye, LI Wenyou, HE Xiwen, CHEN Langxing, ZHANG Yukui, GAI Qingqing, GAI Qingqing
    Molecularly imprinted polymers (MIPs), based on photografting surface-modified polystyrene beads as matrices, were prepared with acrylamide as the functional monomer, bovine hemoglobin as the template molecule and N, N′-methylene bisacrylamide as the crosslinker in a phosphate buffer. The results of IR, scanning electron microscope (SEM) and elemental analyses demonstrated the formation of a grafting polymer layer on the polystyrene-bead surface. Subsequent removal of the template left behind cavities on the surface of the polymer matrix with a shape and an arrangement of functional groups having complementary binding sites with the original template molecule. The adsorption studies showed that the imprinted polymers have a good adsorption capacity and specific recognition for bovine hemoglobin as the template molecule. Our results demonstrated that the polymer prepared via the photografting surface-modified method exhibited better selectivity for the template. Attempts to employ the new method in molecular imprinting techniques may introduce new applications for MIPs and facilitate probable protein separation and purification.
  • LIU Pengyan, LIU Lei, ZHANG Li, JIANG Ning, LIU Zhanli, WANG Yun
    A molecularly imprinted polymer (MIP), with special molecule recognition properties of ciprofloxacin (CIP), was prepared by thermal polymerization in which ciprofloxacin acted as template molecule, ?-methacrylic acid (MAA) acted as functional monomer and trimethylolpropane trimethylacrylate (TRIM) acted as crosslinker. The optimized ratio was determined to be n(CIP): n(MMA):n(TRIM) = 1:6:16 by investigation of the effects of different concentrations of functional monomer and the crosslinker on the MIP’s recognition properties. Equilibrium binding experiment was used to investigate the adsorption dynamics, the binding ability to template molecule and the substrate selectivity. Scatchard analysis was used to study the MIP’s binding characteristic to template molecule. The results indicated that MIP has higher adsorption ability and selectivity. The equilibrium distribution coefficient KD was 41.64 and the separation factor ? was 1.62. Scatchard analysis showed that two different kinds of binding sites were produced in the polymer matrix and their dissociation constants were calculated to be Kd1 = 5.249 × 10-5 mol·L-1, Kd2 = 2.237 × 10-3 mol·L-1.
  • WANG Lihui, WANG Bo, SUN Jie, LI Lianhong, LIU Dayu
    A microfluidic chip featuring laminar flow-based parallel gradient-generating networks was designed and fabricated. The microchip contains 5 gradient generators and 30 cell chambers where the resulting concentration gradients of drugs are delivered to stimulate on-chip cultured cells. The microfluidics exploits the advantage of lab-on-a-chip technology by integrating the generation of drug concentration gradients and a series of cell operations including seeding, culture, stimulation and staining into a chip. The microfluidic network was patterned on a glass wafer, which was further bonded to a PDMS film. A series of weir structures were fabricated on the cell culture reservoir to facilitate cell positioning and seeding. Cell injection and fluid delivery were controlled by a syringe pump. Steady parallel concentration gradients were generated by flowing two fluids in each network. Over time observation shows that the microchip was suitable for cell seeding and culture. The microchip described above was applied in studying the role of reduced glutathione (GSH) in mediating chemotherapy sensitivity of MCF-7 cells. MCF-7 cells were treated with concentration gradients of As2O3 and N-acetyl cysteine (NAC) for GSH modulation, followed by exposure to adriamycin. GSH levels were down-regulated upon As2O3 treatment and up-regulated upon NAC treatment. Suppression of intracellular GSH by treatment with As2O3 has been shown to increase sensitivity to adriamycin. Conversely, elevation of intracellular GSH by treatment with NAC leads to increased drug resistance. The integrated microfluidic chip is able to perform multiparametric pharmacological profiling with easy operation, and thus holds great potential for extrapolation to the cell based high-content drug screening.
  • DENG Cun
    The principle of spontaneous monolayer dispersion holds that active components of many supported catalysts will disperse spontaneously onto the surface of the carrier. The monolayer dispersion threshold of the active component on the surface of the carrier can be measured by X-ray diffraction phase-quantitative extrapolation method, etc. By measuring the monolayer dispersion threshold, beneficial information on the surface structure and dispersion of supported catalysts can be obtained, and the optimal preparative processing conditions of the catalysts can be chosen. The proportion of the active component of many supported catalysts can be optimized while its monolayer dispersion threshold is observed. Mutation values of many physicochemical properties of supported catalysts are related to monolayer dispersion thresholds; the threshold effect on catalysts is apparent, and the proposal regarding the threshold effect provides instruction for the research on catalysts.
  • YIN Jinghua, LIAN Huiqin, ZHAO Jiyang, WU Xue, ZHOU Ziyan
    Photoisomerizations of 6-hydroxy-5,12-naphthacenequinone and its derivatives bearing methyl and phenyl group were theoretically investigated with density functional theory and ab initio CIS method at the B3LYP 6-31G basis set, respectively. The obtained potential energy curves revealed that a four-state cycle existed in the ground and excited states. It was also found that the activation energy for the methyl transfer was higher compared to that for the phenyl transfer, and this was consistent with the experimental results that the photoisomerization of the phenyl substituted derivative was more rapid than that of the methyl substituted derivatives. Further hybrid time-dependent density functional theory (TD-DFT) was used to investigate the absorption and fluorescence spectra of these compounds under solvent effect condition. The calculated values were in agreement with the experimental results and the excitation condition of photochromic reactions.
  • WANG Kai, ZHANG Zhi, GUO Qianni, BAO Xiaoping, LI Zaoying
    A water-soluble porphyrin dimer (Por Dimer) containing eight positive charges, bridged by 4,4′-dicarboxy-2,2′-bipyridine, has been synthesized. With Meso-tetrakis(N-methyl-pyridium-4-yl)porphyrin (H2TMPyP) as the reference compound, the water-soluble porphyrin dimer was investigated for its interaction with DNA by absorption, fluorescence, and circular dichroism (CD) spectroscopy. The apparent affinity binding constant (Kapp = 1.2 × 106) of Por Dimer binding to CT DNA was measured by a competition method with ethidium bromide (EB) (that of H2TMPyP was 6.9 × 106). The cleavage ability of Por Dimer to pBR322 plasmid DNA was studied by gel electrophoresis. The results suggest that the binding modes of Por Dimer were complex and involve both intercalation and outside binding.
  • HE Xiaoli, LU Lude, WANG Xin, YANG Xujie, HE Xiaoli, GUO Xuan
    Three tetraorganodistannoxanes containing silicon were synthesized and their catalytic properties in esterification and acetalization were observed via the reactions of acetic acid with isoamyl alcohol and butyraldehyde with glycol. The factors affecting the reaction, such as the catalyst dosage, reaction time and solvent, etc. were discussed. The results show that the three tetraorganodistannoxanes displayed similar good catalytic activities compared to dichlorotetrabutyldistannoxane in esterification and acetalization. When the dosage of [ClBu2SnOSn-(CH2SiMe3)2Cl]2 was 1.5% based on the mass of reactant, the yield of isoamyl acetate was 91.8% and the yield of butyraldehyde glycol acetal 94.2%. The different alkyl and bridging groups on Sn sites in the structure of tetraorganodistannoxanes showed some influence on the catalytic activities of these compounds.
  • LIU Xinhua, ZHU Jing, PAN Chunxiu, LI Bo, SONG Bao‘an
    (E)-3-(2-chlorophenyl)-1-(2,4-dichlorophenyl)prop-2-en-1-one was prepared from 2-chlorobenzaldehyde followed by cyclization with hydrazine monohydrate. Eight new 3-(2,4-Di-chlorophenyl)-5-(2-chlorophenyl)-4,5- dihydro-N-acylpyrazole derivatives were synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy. The experimental results show that the inhibition ratio of compounds 3f towards H. Oryzae and P. oryzae at 50 mg·L-1 is 55.2% and 57.1%, respectively. The inhibition ratio of compounds 3g towards H. Oryzae, P. oryza, S. Sclerotiorum at 50 mg·L-1 is 53.3%, 60.0%, 50.4% respectively.
  • HE Shuhua, HE Deyong, ZHANG Zhujun
    A novel chemiluminescence system for the determination of bismerthiazol is first described in this paper. It is based on the chemiluminescence reaction of bismerthiazol and Ce(IV) in nitric acid solution. The emission intensity could be enhanced greatly by Rhodamine B. The chemiluminescence intensity was proportional to bismerthiazol concentration over the range 30–1000 ?g/L. The detection limit was 12 ?g/L (3?) and the relative standard deviation is 2.4% for 500 ?g/L of bismerthiazol (n = 11). The proposed method was successfully applied to the determination of bismerthiazol in water and in rice. The recovery was 96.4%–104.1%.
  • CUI Zhihua, YANG Jinzong, TANG Lijun
    Chlorosulfonyl-containing naphthol azo compounds were prepared by reaction of the corresponding sulfonate-containing naphthol azo dyes with thionyl chloride in the presence of a catalytic quantity of N,N-dimethylformamide and various solvents. The yields and reaction selectivity of chlorosulfonyl-containing naphthol azo compounds were discussed according to the properties of solvents. It was demonstrated that high chemical selectivity and high yield were achieved by using benzene, toluene or thionyl chloride as solvent. Additionally, on account of unstable properties of sulfonyl chloride compounds in MS and 1H-NMR analyses, a new analytical method using stable sulfonamide is put forward to verify the chemical structures of the corresponding sulfonyl chloride compounds indirectly.
  • QIAN Yanling, WANG Jianhua, ZHU Baoku, ZHANG Mei, DU Chunhui, XU Youyi
    Amphiphilic comb-like polysiloxane (ACPS) containing polyether side chains was used as the modification reagent in the preparation of hydrophilic porous poly(vinylidene fluoride) (PVDF) membranes via a phase inversion process. The effects of ACPS on morphology, crystallinity, mechanical properties, reservation of ACPS in the phase inversion process, chemical structure, hydrophilicity and filterability performance of porous PVDF membranes were discussed. It was found that the addition of ACPS would result in the delayed demixing which yields “sponge-like” sublayers and longer crystallization time during the membrane formation process. It was revealed that O/F ratios of the bulk membrane were almost the same as those of the corresponding casting solutions which obviously indicated the high reservation of ACPS in the membrane formation process. The fact that the O/F ratios in the membrane surface layers were much higher than those in the bulk membrane proved the enrichment of ACPS on the surface. The filterability experiments and water contact angle testing proved the hydrophilicity of the blend membranes. Through a schematic model, the mechanism relating the membrane structure and performance was interpreted. From the observed results, it can be concluded that ACPS acts as a potential candidate material for preparing PVDF membranes with extraordinary hydrophilicity and filterability.
  • WANG Dongsha, LIU Yanjun
    A two-step swelling procedure was adopted to synthesize mono-dispersed and highly cross-linked poly (St-divinylbenzene) particles with PSt micro-spheres (1.80 ?m in diameter). The PSt micro-spheres were prepared by a dispersion polymerization method and used as seeds. The effects of monomer concentration, ratio of ethanol to water, swelling reagents, crosslinking reagents, swelling temperature and agitation speed on particle size were investigated in detail. The morphologies and size distributions of these micro-spheres were examined by SEM and particle size analysis (PSA). The Tg of the micro-spheres was measured by DSC. The results indicate that the particles (6.20 ?m in diameter) exhibit excellent mono dispersed property and high crosslinking degree when the concentration of the swelling reagent was 25%, the concentration of the crosslinking reagents was 23%, the swelling temperature was 30°C and the stirring speed was 150 r/min.
  • CHEN Long, WANG Peng, CHEN Yanmo, ZHANG Yu, ZHU Meifang
    In this paper, the crystallization behavior, thermal degradation properties, rheological behavior and the spinnability of poly(?-hydroxybutyrate-co-hydroxyvalerate) (PHBV) fiber were studied. Experimental results indicated that the spherulite growth rate of PHBV was very slow and its size was very large. PHBV began to degrade above 170°C. The flowing curve indicated that the processing temperature and the residential time had important effects on PHBV melts. When the equipment of melting spinning was improved and processing conditions were strictly controlled, the mechanical properties of the PHBV filament can comply with the requirements of the American Pharmacopoeia.
  • ZHANG Jun, GUO Jinwu, LI Suqin, SONG Bangcai, YAO Kaisheng
    ?-tricalcium phosphate (?-TCP) is a key component of natural bone like hydroxyapatite. Pure and uniformly nanosized ?-tricalcium phosphate powders were synthesized using a sol-gel self-propagating combustion method by using citric acid as a reductant and using fuel and nitrate as the oxidant. The thermal decomposition of nitrate-citrate xero-gel was studied by thermogravimetric-differential thermal analysis (TG/DTA) and the process mechanism of self-propagating combustion were discussed. The resulting powders calcined at 1023, 1173 and 1273 K were characterized by Ca/P ratio analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the as-prepared powders were pure ?-tricalcium phosphate having regular porous surface very similar to coral.
  • CHENG Yanling, MA Liuqiang, LI Ruohui
    Magnetic polymer microspheres have been considered as a kind of new biopolymer materials with great advantages in bioseparation engineering and biomedicine engineering because they have not only polymer functional groups but also magnetic characteristics. Styrene-acrylic acid copolymer (p(S-AA)) magnetic microspheres were synthesized by dispersion polymerization with Fe3O4 as core and p(S-AA) as shell. The microspheres were characterized by SEM, size analysis, molecular weight and solid content measurement. All of them indicate that the microspheres are small in size, narrow in distribution, stable in chemistry and rich in functional groups on their surface.
  • PENG Yin, BAO Ling
    ZnO nanorings were synthesized on a large scale by an easy solution-based method at 70°C for 5 h using hexamethylenetramine (C6H12N4, HMT) and Zn(NO3)2·2H2O as raw materials in the presence of surfactant poly(acrylamide-co-diallyldimethylammonium chloride) (PAM-CTAC). The structure and morphology of the products were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The influence of experimental conditions such as concentration of surfactant and reactants, reaction temperature on the structure and morphology of the products were investigated. A probable formation mechanism of ZnO nanorings in the presence of surfactant PAM-CTAC was discussed. The results show that the products are wurtzite hexagonal ZnO nanorings with an inner diameter of 220 nm and a wall thickness of 70 nm. Reaction temperature and concentration of reactants influence the shape and size of ZnO nanorings but PAM-CTAC plays the key role in the formation of ZnO nanorings. Through adjusting the concentration of PAM-CTAC, controlled-synthesis of ZnO nanorings can be realized. A room temperature photoluminescence (PL) spectrum of ZnO obtained shows that the full width at half maximum (FWHM) of the UV emission (∼ 7 nm) is much narrower than that of commercial ZnO bulk crystals (∼ 18 nm). The narrow FWHM confirms the uniformity and narrow size distribution of the synthesized ZnO crystals.
  • ZHAN Tianrong, YANG Huijuan
    Using 3-O-methyl-D-chiro-inositol as starting material, the title compound 5 was synthesized by condensation of adenine and methanesulfonate 3. Additionally, compounds 8 and 9 were prepared through the opening of the epoxide ring in 7 by adenine. The key intermediate 7 was obtained in good yield via an epoxidation from mono-mesylate 6. The process of opening of epoxide ring appeared to be regioselective in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).
  • LIU Yi, QIAN Yitai
    ?-Mn2V2O7 microtubes with a length of 15–25 ?m, 2.5–3.5 ?m external diameter, and ∼ 0.4 ?m wall thickness, as well as ?-Mn2V2O7 hollow microspheres with an average outer diameter of 2 ?m, were successfully synthesized in a suitable molar ratio of NH4VO3 and MnCO3 powders via a hydrothermal process. X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize the products, and the magnetic susceptibility curve was also measured. In the whole process, the concentration of Mn2+ cations derived from MnCO3 dissolution plays a crucial role in the formation of ?-Mn2V2O7 microtubes and hollow microspheres.
  • ZHANG Xiujuan, XU Yuanze, YI Xiaosu
    The phase separation processes of various thermoplastics-modified thermosetting systems which show upper critical solution temperature (UCST) or lower critical solution temperature (LCST) were studied with emphasis on the temperature dependency of the phase separation times. It was found that the phase separation time-temperature relationship follows the Arrhenius equation. The cure-induced phase separation activation energy Ea (ps) generated from the equation is independent of the method used to measure phase separation time. In our experimental ranges it is found that Ea (ps) is independent of the thermoplastic (TP) content,TP molecular weight and curing rate but it varies with the cure reaction kinetics and the chemical environments of the systems.
  • ZOU Peng, PAN Caiyuan
    The H-shaped block copolymers (PTMSPMA)2PEG(PMPSTMSPMA)2 with two compositions, (EG)91-b-(TMSPMA)92 and (EG)455-b-(TMSPMA)176 have been successfully synthesized by atom transfer radical polymerization (ATRP) of tri(methoxylsilyl)propyl methacrylate (TMSPMA) at room temperature in methanol. The initiation system applied was composed of 2,2-bis(methylene ?-bromoisobutyrate)propionyl terminated poly(ethylene glycol) (Br2PEGBr2) with Mn = 4000 or 20000, CuBr and 2,2′-bipyridine. The macroinitiator, Br2PEGBr2, was prepared by the reaction of two hydroxyl groups terminated PEG with 2,2-bis(methylene ?-bromoisobutyrate)propionyl chloride. The NMR spectroscopy and GPC measurements were used to characterize the structure and molecular weight and molecular weight distribution of the resultant copolymers. The H-shaped block copolymers Sam 1 and Sam 2 were self-assembled in DMF/water mixtures and then the trimethoxysilyl groups in PTMSPMA were cross-linked by condensation reaction in the presence of triethylamine. Stable large-compound vesicles with 10 nm diameter of cavities were formed for Sam 1 which contains a short PEG chain. However, the self-assembling of the Sam 2 in the selective solvents resulted in big vesicles aggregates. These two different morphologies of aggregates are attributed to their relative chain length of water soluble PEG. The vesicles formed from Sam1 with short PEG chains have big surface energy which will lead them to self-assemble further, forming large-compound vesicles.
  • XU Yanjie, CHEN Ligong
    The synthesis of ?-amino-?-keto-esters (?-oxo dipeptides) was studied. Corresponding ?-amino-?-keto-esters were prepared from BOC-(L)-Valine and BOC-(L)-isoleucine by coupling with (D,L)-threonine hydrochloride and oxidation with Dess-Martin periodinane (DMP) with a total yield of 48% and 38%, respectively.
  • WANG Cunwen, CHEN Wen, WANG Weiguo, WU Yuanxin, ZHANG Junfeng, YU Chuanbo
    The partial molar volumes of components in supercritical ammonia synthesis system are calculated in detail by the calculation formula of partial molar volume derived from the R-K equation of state under different conditions. The objectives are to comprehend phase behavior of components and to provide the theoretic explanation and guidance for probing novel processes of ammonia synthesis under supercritical conditions. The conditions of calculation are H2/N2 = 3, at a concentration of NH3 in synthesis gas ranging from 2% to 15%, concentration of medium in supercritical ammonia synthesis system ranging from 20% to 50%, temperature ranging from 243 K to 699 K and pressure ranging from 0.1 MPa to 187 MPa. The results show that the ammonia synthesis system can reach supercritical state by adding a suitable supercritical medium and then controlling the reaction conditions. It is helpful for the supercritical ammonia synthesis that medium reaches supercritical state under the conditions of the corresponding total pressure and components near the normal temperature or near the critical temperature of medium or in the range of temperature of industrialized ammonia synthesis.