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25 March 2011, Volume 27 Issue 2

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Cover and Content of Chemical Research in Chinese Universities Vol.27 No.2(2011)

2011, 27(2):  0. 

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Articles

Hydrothermal Synthesis and Characterization of Pyrochlore Titanate R₂Ti₂O₇(R=Gd³⁺, Tb³⁺, Dy³⁺)

PENG Wen, HU Bin, CHEN Yan, HU Wei-wei, GUO Li, YUAN Hong-ming* and FENG Shou-hua

2011, 27(2):  161-165. 

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Pyrochlore titanate oxides, R2Ti2O7(R=Gd3+, Tb3+, Dy3+), were synthesized under mild hydrothermal conditions. The crystal growth of pyrochlore titanate oxides and taking place of chemical reaction in the hydrothermal processing were sensitive to the alkalinity, temperature, reaction time, the nature of the rare earth ion and the composition of initial reaction mixture. The as-prepared samples were characterized by powder X-ray diffraction, scanning electron microscopy, Raman spectrum and variable temperature dc magnetic susceptibility(SQUIDS). The magnetic studies gave 7.29×10–23 A•m2/Gd3+ and –8.28 K, 8.75×10–23 A•m2 /Tb3+ and –19.7 K, and 8.85×10–23 A•m2/Dy3+ and 0.84 K effective moments and Weiss constants for Gd2Ti2O7, Tb2Ti2O7 and Dy2Ti2O7, respectively.



Unprecedented α-Octamolybdate Derivative Containing Hexad-track Cu―bpe Chains, 2{[Cu(bpe)]₆[α-Mo₈O₂₆]_3/2}•[Cu(bpe)]₃•3H₂O

SHA Jing-quan, LI Xin, PENG Jun*, ZONG Xi-ming, ZHANG Yu-hong and YAN Hong

2011, 27(2):  166-169. 

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A new inorganic-organic hybrid constructed from α-octamolybdate polyoxometalates modified by hexad- track Cu―bpe chains, 2{[Cu(bpe)]6[α-Mo8O26]3/2}•[Cu(bpe)]3•3H2O[1, bpe=bis(4-pyridyl)ethylene], has been synthesized and structurally characterized. X-Ray diffraction analysis reveals that each α-octamolybdate cluster links six transition metal complex chains and the title compound has represented the highest connective number of M―N chains modified octamolybdate POMs to date. Note that there are two crystallographically unique [α-Mo8O26]n– clusters and eight unique copper sites, which play an important role in the overall architecture of hybrid compounds. Additionally, the electrochemical properties of the title compound were studied.



Novel Chiral PNNP-Ru Complexes: Synthesis and Application in Asymmetric Transfer Hydrogenation of Ketones

CHENG Zhi-bo, YU Shen-luan, LI Yan-yun, DONG Zhen-rong, SUN Guo-song, ...

2011, 27(2):  170-173. 

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The efficient catalytic systems generated in situ from RuCl2(PPh3)3 and chiral ligands N,N-bis[2-(di-o- tolylphosphino)-benzyl]cyclohexane-1,2-diamine(2) were employed for asymmetric transfer hydrogenation of aromatic ketones, giving the corresponding optically active alcohols with high activities(up to 99% conversion) and excellent enantioselectivities(up to 96% e.e.) under mild conditions. The chiral ruthenium(II) complex (R,R)-3 has been prepared and characterized by NMR and X-ray crystallography.



Synthesis and Photoluminescence of Eu-doped ZnO Nanosheets

WANG Dan-dan, YANG Jing-hai*, CAO Jian, LANG Ji-hui, GAO Ming and LIU Xiao-yan

2011, 27(2):  174-176. 

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Eu-doped ZnO nanosheets were synthesized successfully by means of the hydrothermal method. The X-ray diffraction(XRD) pattern shows that the sample is a single phase with the ZnO-like wurtzite structure. And the X-ray photoelectron spectrum suggests that there are Eu3+ ions in the matrix of the sample. Eu3+-related red emissions resulted from energy transfer were observed for the nanosheets under UV laser excitation. The UV, green and yellow emissions were also seen in the photoluminescence spectra.



1-Methyl-3-octylimidazolium Polyoxomolybdate Ionic Liquid with Low Melting Point and High Stability: Preparation and Photocatalytic Activity

DONG Tao, XU Yan-qing*, CHEN Fa-wang, CHI Ying-nan and HU Chang-wen*

2011, 27(2):  177-180. 

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The polyoxometalate(POM)-imidazole ionic liquid(IL) [C8mim]2[Mo6O19](C8mim=1-methyl-3-octylimi- dazolium) with a low melting point of 82.6 °C was successfully prepared and characterized by FTIR, XPS, NMR, TG and so on. The polyoxomolybdate-based IL has high stability, and its decomposing temperature reaches 321 °C, which is higher than that of 1-alkyl-3-methylimidazolium halides IL. Further photocatalytic performances of the IL were measured via degrading dye rhodamine B(RB) in aqueous solution under the UV light irradiation. The experiments show that the conversion of RB reaches 80.5% after 90 min under UV-light and the degradation efficiency depends on the pH value of the solution, irradiation time and the dosage of the IL and so on.



Coating Multi-walled Carbon Nanotubes with Uniform Silica Shells: Independent of Surface Chemistry

LI Ling, DENG Xiao-yong*, BAI Ming-kun, WU Ming-hong* and LIU Yuan-fang

2011, 27(2):  181-184. 

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A facile and general method was described to coat six types of multi-walled carbon nanotubes, functionalized by either noncovalent or covalent way, with smooth silica shells. 3-Aminopropyltriethoxysilane(APTES) and pH value play important roles in the coating process and the thickness of silica shell could be controlled by the added amount of silicon alkoxides. After the removal of multi-walled carbon nanotubes by calcination, the silica nanotubes were successfully prepared.



Rapid and Sensitive Liquid Chromatography-Tandem Mass Spectrometry for Quantification of Glycyrrhetic Acid in Human Plasma

TIAN Li, GAO Xiao-li*, CHEN Xiao-yan, ZHONG Da-fang, ZHANG Yi-fan, ...

2011, 27(2):  185-189. 

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A simple, rapid and sensitive liquid chromatography-tandem mass spectrometry(LC-MS/MS) for the  determination of glycyrrhetic acid in human plasma with ginsenoside Rh2 as internal standard was developed and  validated. The plasma samples were prepared via liquid-liquid extraction with ethyl acetate. Chromatographic separation was accomplished on a Venusil MP-C18(50 mm?2.1 mm, 5 μm i.d.) column at 25 °C. The mobile phase consisted of acetonitrile/5 mmol·L–1 ammonium acetate(10:90, volume ratio) at a flow rate of 0.4 mL/min. Negative electrospray ionization was utilized as the ionization source. Glycyrrhetic acid and internal standard were determined via the mutiple reaction monitoring of precursor→production ion transitions at m/z 469→425, 409 and m/z 621→161, respectively. Each sample was chromatographed within 2.5 min. The lower limit of quantification was 0.50 ng/mL for 200 μL of plasma sample and the linear range was from 0.50 ng/mL to 800 ng/mL. The intra- and inter-day precisions were less than 8.76% in terms of relative standard deviation(RSD), and the accuracy was within a range of –3.25%—1.32% in terms of relative error(RE). The method was successfully applied to the pharmacokinetic studies of glycyrrhetic acid in healthy male Chinese volunteers after a single oral administration of 75 mg of glycyrrhizin.



β-Cyclodextrin Enhanced Fluorimetric Method for Determination of Amoxicillin in Dosage

TANG Hui-nan, GENG Wei-dong, LIU Mou-sheng and YANG Ya-ling*

2011, 27(2):  190-192. 

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A simple sensitive spectrofluorimetric method was developed for the determination of amoxicillin. Amoxicillin in the presence of formaldehyde produces a fluorescent pyrazine derivative, whose fluorescence intensity can be enhanced by forming an inclusion complex with β-cyclodextrin. Optimum conditions for the determination of amoxicillin were also investigated. Fluorimetric detection was carried out at λex=365 nm and λem=445 nm. The linear range of this method for the determination of amoxicillin is 0.1―10 mg/L and the limit of detection is 0.03 mg/L (IF=102.16ρ–9.6, r=0.9994). The developed method is practical and can be successfully applied to determine the content of amoxicillin in capsules and tablets with satisfactory results.



Lectin Conjugated Gold Nanoparticle-based Colorimetric Assay for Studying the Interactions of Antibiotic with Living Cell

WANG Jin-e, WANG Cheng-ke, LIU Dian-jun and WANG Zhen-xin*

2011, 27(2):  193-197. 

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The interactions of antibiotic with living cells were studied by lectin conjugated gold nanoparticles(GNPs) based colorimetric assay. Because of the high affinity of lectin for saccharides, the lectin conjugated GNPs are able to employ as indicators for monitoring the antibiotic induced changes of glycosyl complexes. The interactions of a well known antibiotic, tunicamycin, with two different cell lines, HeLa and SHG-44, were selected to establish this assay. In the presence of tunicamycin, the dose- and time-dependence on the decreasing of binding affinity of lectin conjugated GNPs with living cells were demonstrated by conventional microscopic and UV-Vis spectroscopic studies. The experimental result demonstrates that our approach can be used to identify antibiotic induced expression difference of glycosyl complexes on different cellular surfaces and determine drug activity quantitatively. For further confirming the capability of the GNP-based assay, the system was also studied by confocal laser scanning microscopy(CLSM) and classic flow cytometry(FCM) assay, and satisfactory results were obtained.



Solid-phase Microextraction with Benzoxy-calix[6]arene Fiber Coupled to Gas Chromatography for the Analysis of Polycyclic Aromatic Hydrocarbons in Water

YE Chang-wen, ZHANG Xue-na, HUANG Jiang-yan, LI Xiu-juan* and PAN Si-yi

2011, 27(2):  198-202. 

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Headspace solid-phase microextraction(HS-SPME) with sol-gel calix[6]arene-containing fiber followed by gas chromatography with a flame ionization detector was used to examine the composition and distribution of seven polycyclic aromatic hydrocarbons(PAHs) in water. The novel SPME fiber exhibited higher extraction efficiency to PAHs compared with poly(dimethylsiloxane) and other calixarene-containing fibers. Extraction/retention mechanism based on the interactions between calixarenes and PAHs was discussed. Owing to the good selectivity and high extraction capability of this calixarene fiber, low detection limits were obtained in a range of 0.34―6.50 ng/L and the relative standard deviation values were ≤12.3% for all of the analytes. The linear ranges of the proposed method were five orders of magnitude for the tested compounds, with linear correlation coefficients(r) greater than 0.998. The method was applied to the determination of polycyclic aromatic hydrocarbons in nine water sources in Wuhan City, China. Standard addition method was selected for the quantification and the recovery values were in a satisfactory range. Total PAHs concentrations in the nine surface water samples were found to vary between undetectable and 8.840 μg/L with two- and three-ring PAHs predominating.



Ultrasonic Nebulization Extraction Coupled with Gas Chromatography-Mass Spectrometry for Analysis of Volatile Components in Traditional Chinese Patent Medicine

LIANG Yue, WANG Lu, WANG Zi-ming, YU Cui, ZHANG Han-qi and SHI Yu-hua*

2011, 27(2):  203-207. 

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The ultrasonic nebulization extraction(UNE) was developed and applied to the extraction of volatile components from traditional Chinese patent medicine Xiaoyao Pills. Several parameters of ultrasonic nebulization extraction including the sample particle size, solvent volume, extraction time and ultrasonic power were studied and selected. As a result, 2.4 g of sample with particle size of 80 mesh was extracted with 15 mL of n-hexane for 20 min at an ultrasonic power of 35 W. The volatile components were analyzed by gas chromatography-mass spectrometry (GC-MS) under the optimal conditions and 57 compounds were identified. The precision, repeatability and stability of the proposed method were also studied. Compared with ultrasonic-assisted extraction(UAE) and hydrodistillation(HD) extraction, the proposed method is more efficient, faster and easier to be operated at room temperature with smaller sample and energy consumption. It is suggested that the ultrasonic nebulization extraction can be used as a novel alternative method for the extraction of volatile components from traditional Chinese patent medicine.



Resonance Rayleigh Scattering and Resonance Nonlinear Scattering Methods for Determination of Methylene Blue with 12-Tungstophosphoric Acid

HU Xiao-li*, LIU Sa, LIU Shao-pu, LIU Zhong-fang and SONG Yan-qi

2011, 27(2):  208-211. 

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In a pH=0.65―1.5 NaAc-HCl medium, methylene blue(MB) reacts with 12-tungstophosphoric acid  (TPA) by virtue of electrostatic attraction and hydrophobic force to form a 3:2 ion-association complex. As a result, the intensities of resonance Rayleigh scattering(RRS), second-order scattering(SOS) and frequency doubling scatte- ring(FDS) are enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS are located at 316, 647 and 311 nm. The increments of scattering intensity(?I) are directly proportional to the concentration of MB in a certain range. The methods exhibited high sensitivity, and the detection limits(3s) for MB are 2.3 ng/mL(RRS method), 5.6 ng/mL(SOS method) and 6.4 ng/mL(FDS method), respectively. The effects of coexisting substances have been examined, and the results indicate that the methods have good selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum, and the recoveries are 97.5%―105.0%. The results are in good agreement with those obtained by the pharmacopoeia method. In this work, the optimum conditions of the reaction and the influencing factors were investigated. In addition, the reaction mechanism and the reasons of the enhancement of resonance light scattering were discussed.



Effect of Interaction of Non-residual Fractions on Adsorption of Atrazine onto Surficial Sediments and Natural Surface Coating Samples

LI Yu*, LI Shan-shan, GAO Qian and WANG Ao

2011, 27(2):  212-216. 

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To quantify the effect of the interaction of non-residual fractions[Fe oxides(Fe), Mn oxide(Mn), organic materials(OMs)] in the surficial sediments and the natural surface coating samples on the adsorption of atrazine(AT), an AT multiple regression adsorption model(AT-MRAM) was developed. The AT-MRAM improves upon the previous AT additional adsorption model(AT-AAM) with superior goodness-of-fit test(adjusted R2=ca.1.000), F-test and t-test(P<0.01), and reveals the effect of the interaction among the components in the surficial sediments(SSs) and na- tural surface coatings samples(NSCSs) on the adsorption of AT, which was neglected by the AT-AAM. Meanwhile, the AT-MRAM was also verified through adsorption experiments of AT and the relative deviation between predicted maximum adsorption of AT and the experimental one is less than 15%. The resulted information shows that Mn is prone to interact with other non-residual components, the total maximum adsorption of AT is inversly proportional to the level of Mn, and Fe and OMs facilitate the adsorption of AT. The results also indicate that the adsorption of AT is not only dominated by Fe, OMs, Fe/OMs, but also restrained by Fe/Mn, Fe/Mn/OMs, with lesser roles attributed to Mn, and the estimated AT distributions among the components do not agree with that previously predicted by the AT-AAM, especially with the relative contribution of Mn to the adsorption of AT, revealing significant contribution of the interactions among non-residual components in controlling the behavior of AT in aquatic environments.



Isolation and Identification of Two New Polyhydroxylated Sterols from Soft Coral Sinularia sp.

LIAO Xiao-jian, TANG Li-dan, LIANG Yuan-wei, GENG Hua-wei and XU Shi-hai*

2011, 27(2):  217-220. 

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Two new polyhydroxysteroids, 12β,16β,20-trihydroxycholesta-1,4-dien-3-one 16-acetate(1) and 24-  methyl-12β,16β,20-trihydroxycholesta-1,4-dien-3-one(2) were isolated from octocoral Sinularia sp. Their structures were elucidated primarily on the basis of 1D and 2D NMR and the mass spectroscopic studies. The cytotoxicity of these compounds against three tumor cell lines was also reported.



Polymer Supported Synthesis of Multi-substituted Pyrimidine-4-one Derivatives via Pbf-activated Thiourea

LI Ji-zhen*, KOU Jing-ping and MI Yu-hua

2011, 27(2):  221-223. 

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Efficient polymer supported synthesis of multi-substituted pyrimidine-4-one derivatives was described. Target products were produced from fluorenylmethoxycarbonyl(Fmoc) protected β-amino acid loaded on hydro-  xymethyl resin through deprotection, N-alkylation, guanidine formation, and cleavage of 2,2,4,6,7-pentamethyl dihydrobenzofuran-sulfonyl(Pbf) by trifluoracetic acid(TFA) followed with cyclization. The procedure has the advantages of easy operation, mild reaction conditions, and forming multiple substituents.



Novel Method for Selective Debenzylation Under Maintenance of Fluoro Atom Substituted on β-Amino Acids

2011, 27(2):  224-227. 

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tert-Butyl (R)-3-amino-3-(3-fluorophenyl)propanoate(5) was prepared with conventional debenzylation method. However, the tert-butyl (R)-3-[(S)-1-phenylethyl-amino]-3-(3-fluorophenyl) propanoate(6) and tert-butyl (R)-3-amino-3-phenylpropanoate(7) were generated as the byproducts under the general catalytic hydrogenation Pd(OH)2/C-H2 conditions. So a series of experiments was performed to optimize the reaction conditions so that product 5 could be obtained with high purity and yield. Finally an effective catalytic system, Pd/C-HCOOH-CH3OH, was discovered.



Efficient Syntheses of 2-Substituted Benzimidazoles and Benzoxazoles from β-Keto Esters

XIAO Li-wei, ZHANG Min and SUN Wen-hua*

2011, 27(2):  228-231. 

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An efficient synthetic method was developed to synthesize 2-substituted benzimidazoles and benzo-  xazoles with β-keto esters as starting materials under mild reaction conditions, during which other functional groups are bearable from reactants to products.



Merger of Ezetimibe and Statin: a Potential Dual Inhibitor

HE Xing-lian, XU Xian-xiu, ZHENG Lian-you and BAI Xu*

2011, 27(2):  232-236. 

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A potential dual inhibitor(4) for exogenous absorption and endogenic synthesis of cholesterol was designed based on the conjugation of the β-lactam pharmacophore of ezetimibe and the δ-lactone pharmacophore of statins. The merger of ezetimibe and statin 4 was synthesized from p-hydroxybenzaldehyde through a ten-step route. 1H NMR analysis showed existence of four pairs of enantiomers(5.7:5.7:1:1, molar ratio). And compound 4 was found to lower total glucose(TG) level in rat serum via a high-cholesterol and high-fat feeding experiment.



Synthesis of New Flavanone Derivatives of Farrerol and Preliminary SAR Studies on Anti-VSMCs Vegetation Activity

SHI Lei, FENG Xiu-e, LIN Wen-han, FANG Lian-hua, DU Guan-hua and LI Qing-shan*

2011, 27(2):  237-240. 

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A series of new flavanone derivatives of farrerol was designed and synthesized as a potent inhibitor of vascular smooth muscle cells(VSMCs) vegetation according to a convenient method. The structures of all the synthesized compounds were confirmed by 1H NMR, 13C NMR and EIHR-MS. The biological activities of these compounds against VSMCs in vitro were evaluated. The assay results indicate that two compounds, 5,7-dihydroxy-6,8-dimethyl- 2-(2-nitrophenyl)chroman-4-one(7f) and 2,3-dibromo-4,5-dihydroxydiphenylmethanone(7j) exhibited high activity against VSMCs in vitro with IC50 values of 9.9 and 6.7 μmol/L, respectively, and the preliminary structure-activity relationship(SAR) was described.



Inhibitory Effects of Natural Compound Alantolactone on Human Non-small Cell Lung Cancer A549 Cells

ZONG Min-ru, ZHAO Ying-hao, ZHANG Kun, YANG Long-fei, ZHENG Yong-chen, ...

2011, 27(2):  241-244. 

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Alantolactone is a natural compound identified from the roots of Inula helenium L. that has multiple bio-activities. We examined its inhibitory effects on human non-small cell lung cancer(NSCLC) A549 cells. The antiproliferative effect of alantolactone on A549 cells was investigated via MTT[3′-(4,5dimethylthiazol-2-yl)-2,5-   diphenyl tetrazolium bromide] assay and its apoptosis-inducing effect was determined by Hoechst staining and flow cytometry. We found that alantolactone significantly inhibited the proliferation of A549 cells and induced morphological changes typical for apoptosis. Flow cytometry analysis indicates dose-dependent cell cycle retardation at G0/G1 and S stages. The results indicate that alantolactone could be an attractive small-molecular natural compound for further development as a therapeutic drug against NSCLC.



Construction, Expression and Purification of SUMO1-GST Fusion Protein

QIAO Xiao-fang, FANG Xue-dong* and LIU Jun*

2011, 27(2):  245-248. 

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Sumoylation is an important protein modification discovered recently. SUMO(small ubiquitin-related modifier) pathway regulates the protein stability and transcriptional activity with a 12-kDa small molecular protein, SUMO, ligated to the target protein. The purification of SUMO proteins is a key step to reveal their function. The purpose of this study was to construct the recombinant SUMO1 gene cloned to a pGEX-4T-1 vector to express and purify the SUMO1-GST fusion protein in Escherichia coli. First, the full length DNA sequence of SUMO1 gene was amplified by PCR and was ligated to pMD18-T vector. Then the SUMO1 gene was subcloned to pGEX-4T-1 prokaryotic expression vector between BamHI and XhoI sites, and transformed in Escherichia coli DH5α cells. The right colonies were identified by restrictive enzyme digestion and sequencing. The correct rebombinant plasmid of pGEX-4T-1-SUMO1 was transformed in Escherichia coli BL21 cells and then induced by IPTG(isopropyl- β-D-1- thiogalacto-pyranoside) to express the SUMO1-GST fusion protein. The highly purified SUMO1-GST(glutathione S-transferase) fusion protein was obtained by affinity chromatography. Finally, the properties of SUMO1-GST fusion protein were confirmed by Coomassie brilliant blue strain and Western blot analysis. The recombinant plasmid of pGEX-4T-1-SUMO1 was successfully constructed, and SUMO1-GST fusion proteins were successfully expressed.



Aggregation Patterns of Proteasome in Injured Neurons Induced by Transient Cerebral Ischemia

GE Peng-fei, LIU Bin, FAN Wen-hai, LI Shu-lei, YANG Fu-wei, LUO Yi-nan*, ...

2011, 27(2):  249-253. 

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Proteasome activity reduction is an important pathological phenomenon, resulting in proteins aggregation and neuronal death in the injured neurons induced by transient ischemia. Our previous report showed that the trap of proteasome in the protein aggregates was a reason to lead to the reduction of proteasome activity. However, the patterns of proteasome entered into protein aggregates are not clear. In this study, we used a global ischemia model, Hematoxylin-Eosin staining, differential centrifuge, proteasome activity assay, sucrose gradient density centrifuge, and Western blot analysis to investigate this problem. Our results show that there are two aggregation patterns of proteasome after transient ischemia and reperfusion. One is that 26S proteasome is trapped by protein aggregates as a whole unit, and the other is that 19S or 20S is trapped in the protein aggregates, respectively, after 26S disassociates.



Activation of Growth-associated Protein by Intragastric Brazilein in Motor Neuron of Spinal Cord Connected with Injured Sciatic Nerve in Mice

CAO Jian, LI Li-sen, LIU Biao, LIU Hao-yu, ZHANG Hui, ZHAO Ming-ming and YIN Wei-tian*

2011, 27(2):  254-257. 

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The purpose of this study is to explore the expression of growth-associated protein(GAP-43) in spinal cord segments connected with injured sciatic nerve by the treatment with brazilein in mice. Unilateral sciatic nerve interruption and anastomosis were performed. Physiological saline(blank group), high dose, middle dose and low dose of brazilein were administrated intragastrically to healthy adult BALB/c mice in separate groups. L4―6 spinal segments connected with the sciatic nerve were harvested. Real-time PCR(Polymerase chain reaction) and Western blot analysis were performed to detect the expression of GAP-43 in spinal segments. Histological staining on myelin and the electrophysiology were performed to examine the sciatic nerve recovery. GAP-43 was activated in spinal cord L4―6 connected with injured sciatic nerve. In the survival time of 12 h, 24 h, 3 d, 5 d, 7 d and 14 d, GAP-43 expression in the motor neurons of spinal cord of the high dose group and that in the middle dose group were significantly higher than those on the low dose and blank groups. Myelin in the high dose group and that in the middle dose group were more mature and the potential amplitude and MNCV(motor nerve conduction velocity) in the high and middle dose groups were obviously higher than those in the low dose group and blank group. Brazilein facilitates the expression of GAP-43 in neurons in spinal cord L4―6 segments connected with injured sciatic nerve, which promotes nerve regeneration.



Imprinted Human Serum Albumin with Antioxidant Activity

SHEN Na, YAN Fei, GUO Yi, Lü Shao-wu, GONG Ping-sheng, XU Ya-wei, ...

2011, 27(2):  258-263. 

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In order to create a new mimic of glutathione peroxidase(GPx), bioimprinting was used to generate glutathione(GSH) binding site and chemical modification was used to incorporate catalytic group selenocystine(Sec). Human serum albumin(HSA) and S-substituted dinitrophenyl glutathione(GSH-S-DNP) were chosen as the imprinted matrix and imprinting template, respectively, to generate a GSH-imprinted protein(GSH-HSA) by bioimprinting. Sec was incorporated into the GSH-HSA by chemical modification to give a new GPx mimic(Se-GSH-HSA). Se-GSH-HSA displayed considerably higher GPx activity than non-printed HSA(Se-HSA). The enzymic properties and kinetics of Se-GSH-HSA were studied. Moreover, Se-GSH-HSA was confirmed to have stronger antioxidant ability to protect mitochondria against oxidative damage with ferrous sulfate/ascorbate-induced mitochondria damage model, indicating that Se-GSH-HSA has potential application in medicine.



Fusion Wheat Histone H4 Protein Increases Transfection Efficiency of Non-viral DNA Vector

WANG Chun-yan and ZHANG Yu-jing*

2011, 27(2):  264-268. 

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The lack of efficient and non-toxic gene delivery, preferably with non-viral DNA vectors, is generally regarded as a major limitation for gene therapy. In this study, a wheat histone H4 gene was cloned from Triticum aestivum, sequenced, modified and expressed in E. coli. The wheat histone H4 gene and reconstructed H4TL gene encoded wheat histone H4 and a recombinant protein of 141 amino acids with an approximate molecular weight of 15500. Gel electrophoresis mobility shift assays demonstrated that the purified protein had high affinity for DNA. Most significantly, the complex of plasmid pEGFP/C1 with H4TL was transfected with increased efficiency into MCF-7, HO8910, LNCap, A549 and HeLa cells in vitro. These results demonstrate that the targeting of non-viral vectors to tumor-specific receptors provides a cheap, simple and highly efficient tool for gene delivery.



Catechu Inhibiting Cathepsin B Activity and Motility of HT1080 Cells

YUAN Hao, YANG Jin-gang, WANG Zhong-yuan, ZHAO Shu-hua, YU Da-hai, ...

2011, 27(2):  269-272. 

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We reported that Catechu extract has a significant inhibitory effect on cathepsin B activity. The IC50 value for the Catechu extract against cathepsin B was 7.6 ?g/mL. In addition, we showed that HT1080 human fibrosarcoma cells express cathepsin B and Catechu modulate the invasion and motility of these cells. These data may provide molecular mechanisms for the therapeutic effects of Catechu.



AI-2 Key Enzyme S-Ribosylhomocysteinase from Strain Klebsiella pneumoniae CICC 10011 Producing 2,3-Butanediol

DAI Jian-ying*, ZHANG Li-fu and XIU Zhi-long*

2011, 27(2):  273-276. 

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S-Ribosylhomocysteinase(LuxS) is the key enzyme in the synthetic pathway of a quorum sensing autoinducer AI-2. LuxS from a 2,3-butanediol produced strain Klebisella pneumoniae CICC 10011 was cloned and characterized. The luxS gene is composed of 540 bp with 172 amino acids encoded. The Km value for S-ribosylhomo- cysteine(SRH) was (27?1) ?mol/L, kcat was (0.112?0.004) s–1 and kcat/Km was 4.4?103 L?mol–1? s–1 at 25 ?C. LuxS was activated by divalent metal ions, the highest activity was detected with Co2+ form, followed by Mg2+, Ba2+, Mn2+, Fe2+ and Ca2+, and activation constant for Co2+ is (16?2) ?mol/L.



Immunofluorescent Labeling of Human HepG2 Cells with CdTe Quantum Dot Probe Conjugated with Anti-pan CK MAb

SUI Yu-jie, ZHANG Gui-zhen, WANG Qian, WANG Ya-li, WU Mei, DU Zhen-wu, ...

2011, 27(2):  277-281. 

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A relatively sensitive, specific, and photostable method for the detection of cytokeratin of cancer cells  via conjugation with cadmium telluride quantum dots(CdTe QDs) was described. Water soluble CdTe QDs were conjugated to anti-pan-cytokeratin(CK) monoclonal antibody(MAb) through coupling reagent [1-ethyl-3-(3-dimethyla- mino propyl)carbodiimide, EDC] and the conjugates were purified by dialysis. The expression of pan CK protein in HepG2 cells was observed by immunocytochemistry and direct immunofluorescence via QDs-Ab conjugates respectively. Fluorescence intensity and photostability of QDs were compared with those of FITC(fluorescein isothiocyanate). The results show that the QDs-Ab conjugates recognized specifically pan CK protein in HepG2 cells. Compared with FITC, CdTe QDs had higher brightness and photostability without obvious photobleaching under continuous exciting light illumination for 30 min and after the placement at room temperature for 3 d. The results indicate that conjugates of CdTe quantum dot with anti-pan CK MAb can be used for labeling cancer cells derived from epithelial tissues, which provides the basis for the detection of circulating tumor cells(CTCs).



Anti-tumor Immune Response Mediated by Newcastle Disease Virus HN Gene

PENG Li-ping, LI Xiao, SUN Li-li, WEN Zhong-mei, LIU Yan, GAO Peng, ...

2011, 27(2):  282-286. 

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Hemagglutinin-neuramidinase(HN) is one of the most important surface structure proteins of the Newcastle disease virus(NDV). HN not only mediates receptor recognition but also possesses neuraminidase(NA) activity, which gives it the ability to cleave a component of those receptors, NAcneu. Previous studies have demonstrated that HN has interesting anti-neoplastic and immune-stimulating properties in mammalian species, including humans. To explore the application of the HN gene in cancer gene therapy, we constructed a Lewis lung carcinoma(LLC) solid tumor model using C57BL/6 mice. Mice were injected intratumorally with the recombinant adenovirus expressing HN gene(Ad-HN), and the effect of HN was explored by natural killer cell activity assay, cytotoxic lymphocyte activity assay, T cell subtype evaluation, and Th1/Th2 cytokines analysis. The results demonstrate that HN not only can elicit clonal expansion of both CD4+ and CD8+ T cell populations and cytotoxic T lymphocyte(CTL) and killer cell response, but also skews the immune response toward Th1. Thus, vaccination with Ad-HN may be a potential strategy for cancer gene therapy.



Activity and Tissue Expression of Tyrosine Phosphatase PTP-MEG2

DONG Hong-bo, LI Guo-dong, WANG Shao-feng, FU Xue-qi* and ZHAO Zhi-zhuang Joe*

2011, 27(2):  287-290. 

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Protein tyrosine phosphatases(PTPs) are crucial regulators of signal transduction. Among them, PTP-MEG2 is an intracellular enzyme of 593 amino acid residues with a putative lipid-binding domain at the N-terminus. In the present study, we cloned the full-length form of the enzyme and expressed it in E. coli cells as a 6xHis-tagged protein. The majority of the expressed enzyme was found in the inclusion body of E. coli cell extracts. Upon extraction with a buffer containing urea, the recombinant enzyme was purified to near homogeneity on a single Ni-NTA-agarose column. This procedure resulted in the production of over 100 mg of purified recombinant PTP-MEG2 from 1 L E. coli cell culture. The purified protein displayed a single polypeptide band with expected molecular size on SDS-polyacrylamide gel electrophoresis under reducing conditions. Isolated under denatured conditions in urea, the purified enzyme was re-natured by dialyzing against a refolding buffer. The re-natured enzyme effectively dephosphorylated the common PTP substrate para-nitrophenylphosphate with a specific activity of 2000 units/mg. Meanwhile, the denatured enzyme was used to immunize a rabbit to produce antibodies. The resulting anti- serum had extremely high sensitivity and specificity. When used for Western blot analysis, the anti-serum revealed a wide expression of PTP-MEG2 in many tissues of mice. Together, we developed a highly effective way to purify a large amount of PTP-MEG2 and generated highly sensitive antibodies that can specifically detect endogenous expression of the enzyme in tissues.



Direct Electrochemistry Transfer and Electrocatalysis of Hemoglobin Immobilized in Porous Mn2O3

SHI Lin-pu and GAO Qiu-ming*

2011, 27(2):  291-294. 

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Novel porous Mn2O3 with good crystallinity was synthesized via hard-template method. Hb-Mn2O3 nanocomposite was prepared and used for biosensor construction. The Hb-Mn2O3-Nafion modified electrode shows fast direct electron transfer and displays good electrocatalytic response to the reduction of H2O2. The response time is less than 5 s, the sensitivity is as high as 493 μA·L·mmol–1·cm–2 in a linear range of 1—100 μmol/L, and the detection limit is 0.16 μmol/L. This modified electrode also shows good stability and reproducibility. This indicates that the porous Mn2O3 provides a good matrix for enzyme immobilization and biosensor construction.



Chemically Modified Ordered Mesoporous Carbon/Polyaniline Composites for Electrochemical Capacitors

KONG Ling-bin*, ZHANG Jing, CAI Jian-jun, YANG Zhen-sheng, LUO Yong-chun, ...

2011, 27(2):  295-299. 

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Chemically modified ordered mesoporous carbon CMK-3 materials were prepared by means of an easy wet-oxidative method in 2 mol/L nitric acid aqueous solution. A large amount of oxygen-containing functional groups were introduced onto the CMK-3 surface. Modified CMK-3(m-CMK-3) and aniline monomer were polymerized via an in situ chemical oxidative polymerization method. Morphological characterizations of m-CMK-3/PANI (polyaniline) composites were carried out via field emission scanning electron microscopy(SEM). Their electrochemical properties were investigated with cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The m-CMK-3/PANI composites have excellent properties in capacitance, and the highest specific capacitance(SC) value was up to 489 F/g, suggesting their potential application in the electrode material for electrochemical capacitors.



Electrocatalytic Synthesis of Propylene Carbonate from CO2 and Propylene Oxide

ZHANG Li, WANG Huan, LI Rui-na, CHEN Bao-li and LU Jia-xing*

2011, 27(2):  300-303. 

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The electrocatalytic synthesis of propylene carbonate(PC) from CO2 and propylene oxide(PO) was studied under mild conditions(PCO2=1.01×105 Pa, t=25 °C). Influences of solvents, supporting electrolytes, the passed charge, the nature of electrodes and the current density(j) on the yield of PC were investigated to optimize the electrolytic conditions, with the maximal yield to be 46.2%, the selectivity of propylene carbonate is 100%. The reduction of propylene oxide in the absence and presence of CO2 was examined by cyclic voltammetry. The mechanism of the reaction initiated by the synergistic effect of halides ions of supporting electrolytes with nucleophilicity and the metal ions from scarification anode with Lewis acid acidity was proposed on the basis of our results.



Electronic Properties of Passive Films Formed on G3 and G30 Nickel-based Alloys in Bicarbonate/Carbonate Buffer Solution

LI Dang-guo, WANG Jia-dao and CHEN Da-rong*

2011, 27(2):  304-312. 

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The electronic properties of passive films formed on G3 and G30 alloys in bicarbonate/carbonate buffer solution were comparatively studied by electrochemical impedance spectra(EIS) and Mott-Schottky analysis, the chemical composition of the passive film formed on G3 alloy was detected by X-ray photoelectron spectroscopy (XPS). The results show that passive film on G3 alloy had better protection than that on G30 alloy. The transfer resistance, film resistance and diffusion resistance of the passive films on both alloys increased with increasing formation potential, prolonging formation time, increasing pH value, decreasing formation temperature, and decreasing chloride and sulphide ions concentration. Mott-Schottky plot reveals that the passive films on the two alloys show a p-n semi-conductive character. XPS analysis indicates that the passive film on G3 alloy was composed of an inner Cr oxide and an outer Fe, Mo/Ni oxides.



Comparison of Sin+ and Gen+(n=2―15) Cationic Structures

QIN Wei, ZANG Qing-jun, Lü Wen-cai*, WANG Cai-zhuang and HO Kai-ming

2011, 27(2):  313-317. 

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We designed and optimized a large number of the isomers of Si12+ at the level of density functional theory (DFT)-B3LYP/6-311++G(d) using the Gaussian 03 software package. An unambiguous structure of the Si12+ cluster is presented, whose IR spectrum agrees well with the experiment result. The most stable geometric structures of Gen+(n=2―15) clusters were determined by the all-electron PBE/DND method in DMol3 of the Material Studio Package, and compared with those of the corresponding Sin+ geometries. Most structures of Gen+ and Sin+ are similar except the ones of those for n=9, 12, 13 and 14, and the pentagonal bipyramid motif and the tri-capped trigonal prism(TTP) motif often appear in the Sin+ and Gen+(n=7―15) structures(except for Si14+).



Diffusion and Adsorption of Benzene and Propylene in MFI, MWW and BEA Zeolites: Molecular Dynamics and Grand Canonical Monte Carlo Simulations

SUN Xiao-yan, JIAO Wei, XIANG Shu-guang and LI Jian-wei*

2011, 27(2):  318-323. 

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The diffusion and adsorption behaviors of benzene and propylene in zeolites MFI, MWW and BEA have been studied by molecular dynamics(MD) and grand canonical Monte Carlo(GCMC) simulations. The diffusion coefficients of benzene and propylene in MFI, MWW and BEA zeolites were calculated by simulating the mean-square displacements(MSD) at 298 and 600 K. Benzene and propylene showed the different adsorption rules in the channels of the three zeolites. For propylene, the molecular loadings decreased in the order: BEA(linear channel)>BEA   (tortuous channel)>MFI(linear channel)>MWW(12-membered rings, 12MR channel)>MFI(tortuous channel)>MWW (10-membered rings, 10MR channel); for benzene, the molecular loadings decreased in the order: BEA(linear channel)>BEA(tortuous channel)>MWW(12MR channel)>MFI(linear channel)>MFI(tortuous channel)>MWW(10MR channel). Besides, the adsorption isotherms of benzene and propylene in the three zeolites at 298 and 443 K were simulated. The results show that the different factors influenced the molecular adsorption at various temperatures and pressures, leading to the different rules for the adsorption of benzene and propylene molecules in the zeolites. At a low pressure, the unfavorable energy would make the loadings of propylene lower than those of benzene. When pressure was higher than 0.25 kPa, the adsorption of benzene in MFI would nearly reach saturation.



Influence of Solid-liquid Interaction and Temperature on the Dynamic Dewetting of a Thin Polymer Film: A Molecular Dynamics Study

ZHAO Li, XUE Xiang-gui and Lü Zhong-yuan*

2011, 27(2):  324-328. 

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Coarse-grained molecular dynamics simulations were carried out to investigate the dewetting behavior of a polymer thin film on partial wetting solid surface at the early stage of the dewetting process. Spontaneous dewetting is initiated by removing a band of strip from both the ends of the liquid polymer film which has achieved equilibrium. The solid-liquid interaction and temperature were varied to show their influence on the dewetting dynamics during dewetting as well as the shape evolution of the liquid polymer film. As is consistent with the results obtained in previous researches, the liquid film recedes at a constant speed initially with different solid-liquid couplings and tempe- ratures. Furthermore, smaller coupling parameters or higher temperatures tend to accelerate the recession speed of the liquid film and shorten the constant-speed recession duration. Obvious rims were not always observed. Both coupling parameter and temperature can influence the emergence of the rims.



Synthesis and Characterization of Chitosan-Albumin Conjugates as pH-Sensitive Biodegradable Hydrogels

GUO Jin-shan, LI Jian-zheng, JING Xia-bin, CHEN Xue-si and HUANG Yu-bin*

2011, 27(2):  329-333. 

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A new kind of biodegradable pH-sensitive drug delivery system was developed via chitosan-albumin conjugate hydrogel. Through changing the feeding modes of reactants, two types of hydrogels(comb-type and reticular-type) were synthesized by amidation reactions between 6-O-succinoylated N-phthaloyl chitosan and albumin. The structures and morphologies of the hydrogels were characterized by SEM. And their water swelling capacity, drug loading and releasing properties at different pH values were also investigated. It was found that the comb-type of hydrogels with looser space construction had better water swelling ratio(more than 400% of its original mass) than the reticular-type of ones did(about 180% of its original mass). In vitro release experiments of Rifampicin show that the hydrogels provided the controlled release of the entrapped drug for more than 50 h. The drug release rates of both types of hydrogels under acidic condition were lower than those under neutral or basic condition. The introduction of albumin not only improved the hydrophilicity of chitosan, but also provided the possibility of the carrier system combining other biologically active materials more easily to fulfill the delivery and therapy functions.



Synthesis and Drug Release Properties of Thermosensitive Poly(N-vinylacetamide-co-vinylacetate) Hydrogels

YANG Li-he, CHU Hong, CHEN Ming-qing*, HU Na and ZHAO Yi-fan

2011, 27(2):  334-338. 

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Thermosensitive poly[N-vinylacetamide-co-vinylacetate][P(NVA-co-VAc)] hydrogels were prepared via free radical copolymerization from hydrophilic NVA and hydrophobic VAc in the presence of butylenes-bis (N-vinylacetamide)(Bis-NVA) as crosslinker. Scanning electron microscopy(SEM) images reveal that the as-prepared hydrogels were of three-dimensional network with irregular cave structure. The prepared hydrogels with more NVA in the feed swelled faster and the swelling ratio of the hydrogels gradually decreased with temperature increasing from 10 °C to 60 °C. The dynamic swelling studies indicate that the swelling process of the hydrogels was controlled by diffusion of water molecules considered as Fickian-controlled case. The adsorption amount of model drug, sodium salicylate(SS) was higher in the hydrogels containing more NVA units, whose corresponding release could reach equilibrium in about 6 h.



Electrospun Poly(acrylonitrile-co-acrylic acid) Nanofibrous Membranes for Catalase Immobilization: Effect of Porphyrin Filling on the Enzyme Activity

KE Bei-bei, WAN Ling-shu, HUANG Xiao-jun and XU Zhi-kang*

2011, 27(2):  339-344. 

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Porphyrin-filled nanofibrous membranes were facilely prepared by electrospinning of the mixtures of poly(acrylonitrile-co-acrylic acid)(PANCAA) and porphyrins. 5,10,15,20-Tetraphenylporphyrin(TPP) and its metalloderivatives(ZnTPP and CuTPP) were studied as filling mediators for the immobilization of redox enzyme. Results indicate that the introduction of TPP, ZnTPP and CuTPP improves the retention activity of the immobilized catalase. Among these three porphyrins, the ZnTPP-filled PANCAA nanofibrous membrane exhibits an activity retention of 93%, which is an exciting improvement. This improvement is attributed to both the strong catalase-porphyrin affinity and the possible facilitated electron transfer induced by the porphyrin as evidenced by quartz crystal microbalance (QCM) and fluorescence spectroscopy studies.