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04 January 2010, Volume 26 Issue 1

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Content of Chemical Research in Chinese Universities Vol.26 No.1(2010)

2010, 26(1):  0. 

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Articles

Primary Organicamine Templated Indium Iodate (H₂en)KIn(IO₃)₆·2(H₂O) with Hydrogen-bonded Helices

LIU Guo-zong, LIU Xiao-min, DING Hong, NING De-kuan, LI Guang-hua, SHI Zhan*,...

2010, 26(1):  1-4. 

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The first primary organicamine templated indium iodate with the formula (H₂en)KIn(IO₃)₆·2(H₂O) was hydrothermally synthesized via reaction at 100 °C for 7 d and characterized by single-crystal X-ray diffraction and thermal analysis. The compound crystallized in a triclinic system with space group P1, a=0.69803(14) nm, b=0.70863(14) nm, c=1.2091(2) nm, α=76.417(4)°, β=79.953(4)°, γ=72.206(3)°, V=0.55012(19) nm³. Structure determination indicates that it is made up of zero-dimensional units each of which consists of [In(IO₃)₆]^3- anion, potassium, water and ethylenediamine cation. The most striking feature of the compound is that it possesses helical hydrogen bonds formed by organic amine template, water molecules and inorganic network.

Facile Preparation of Mn₂O₃ Nanowires by Thermal Decomposition of MnCO₃

WANG Hong-zhe, ZHAO Hui-ling, LIU Bing, ZHANG Xing-tang, DU Zu-liang*,...

2010, 26(1):  5-7. 

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Mn₂O₃ nanowires with diameters of about 130 nm and lengths up to tens of micrometers were synthesized by the thermal decomposition of MnCO₃ precursors. It was identified that the growth of the cubic Mn₂O₃ nanowires was preferential along the [001] direction. The intermediate stage containing melting state and the particles of manganese oxide played an important role for the formation of Mn₂O₃ with one-dimensional structure. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the morphology and crystal structure of the precursors and final products. Thermogravimetry analysis was also carried out to find the mechanism for the formation of Mn₂O₃ nanowires. The growth of the nanowires was proposed to be dominated by the conventional melt-growth mechanism.

Catalytic Oxidative Coupling of 1-Phenyl-1H-tetrazole-5-thiol(HL) and Complex [Cu(I)₆L₆] with a Chair Configuration

TAN Di, YANG Jun-wei, TONG Shan-ling* and YAN Yan*

2010, 26(1):  8-10. 

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Both a persulfide crystal of L-L(1), the oxidative coupling product of 1-phenyl-1H-tetrazole-5-thiol(HL), and a neutral copper(I) complex of Cu₆L₆(2) were self-assembled and their crystal architectures were characterized by CCD method. HL was converted into the persulfide L-L(1) over a metalloporphyrin catalyst with enzymatic characters under ambient conditions. Whlie in the crystal architecture of Cu₆L₆(2), 6 copper(I) ions were ligated by 6L^- anions to construct a Cu₆ ring, which just resembled the chair configuration of cyclohexane. Notably, both compounds 1 and 2 exhibit strong photoluminescence in solid state.

Rapid Profiling of Alkaloids in Several Medicinal Herbs by Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

LU Lin, YUE Hao, SONG Feng-rui, TSAO Rong, LIU Zhi-qiang* and LIU Shu-yin

2010, 26(1):  11-16. 

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A simple method was developed for rapid and direct profiling of alkaloids in medical herbs via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS). The dry herbs were first ground to powder and passed through a stainless steel sieve, mixed with the matrix solution to form a homogeneous suspension, which was then directly applied to MALDI analysis. Several matrices were investigated and 2,5-dihydroxybenzoic acid(DHB) was chosen as the optimized one, and the particle with small size was found to favor the analysis. Using this method, the profiles of alkaloids in several medical herbs were readily obtained, and the   toxicities of crude and processed Radix Aconiti Lateralis Preparata were compared via the relative intensities of the peaks of the corresponding toxic components shown in their MALDI spectra. This method therefore provides a rapid and reliable protocol for obtaining profiles of alkaloids in medical herbs by using MALDI-TOF MS.

Rapid Purification and Identification of Osteopontin from Human Milk by HPLC Coupled to FT-ICR-MS

SHI Lei*, YANG Tie-zheng and ZUBAREV A. Roman

2010, 26(1):  17-22. 

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Milk as a key element for infant nutrition represents the only source of feeding for newborns and infants, breast-feeding milk normally contains several bioactive proteins or peptides useful for the development of the immune system that protects infants from diseases. Osteopontin(OPN) plays a distinct role during the processes of lactation. Some studies on OPN isolated and purified from the human milk via HPLC on SCX and C₄ columns adopted biological mass spectrometry. After digesting the purified OPN sample with trypsin, the typical correlative polypeptide fragments GDSVVYGLR and QNLLAPQTLPSK are identified by FT-ICR-MS. The rapid identification of OPN is assumed to be reasonably well behaving in a standard bottom-up experiment. It shows that nano-spray HPLC combined with FT-ICR-MS and Mascot search can be used as a high efficient method for the identification of purified OPN and its polypeptide fragments. Further study will provide more academic theories of their different modifications and the bioactivity as well.

Application of Colloidal Gold to Fluorophotometric Determination of Human IgG

DENG Xin-yu, GAO De-jiang, TIAN Yuan, CHEN Yan-hua, YU Ai-min, ZHANG Han-qi,...

2010, 26(1):  23-26. 

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A method for the determination of human immunoglobulin G(IgG) based on a colloidal gold label by  fluorospectrophotometry was developed. The sandwich immunoreaction among goat-anti-human IgG, human IgG and goat-anti-human IgG labeled with colloidal gold nanoparticles was applied in this experiment. First, a sandwich immunocomplex was formed on the surface of 96 well clear polystyrene high bind stripwell^TM microplate. After the formation of the sandwich immunocomplex, a solution was added to dissociate the immunocomplex at room tempe- rature. Then the solution of each well was transferred into the corresponding test tube. Thirdly, the rhodamine B solution was injected into each test tube. The rhodamine B chloraurate was extracted into ether that was measured with a spectrofluorometer. The experimental results indicate that the fluorescence intensity increased with the increase of human IgG concentration. The fluorescence intensity of rhodamine B chloraurate at 570 nm was proportional to the logarithm of human IgG concentration in a range from 10 to 5×10⁵ ng/mL. It was shown that the determination of human IgG was easily made with the proposed fluorospectrophotometry.

Differentiation of Four Pairs of Isomers by Comparing Their Relative Abundances of Fragment Ions

SUN Ming-qian, LU Jian-qiu, ZHANG Hong-gui*, ZHANG Qun-shu, XIAO Nan,...

2010, 26(1):  27-32. 

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Based on the LC-ESI/MSⁿ technique, the four pairs of isomers of psoralen and isopsoralen, imperatorin and isoimperatorin, neohesperidin and hesperidin, naringin and narirutin were distinguished mainly by comparison of the relative abundances of their major fragment ions. Because of the effect of the hydrogen on the C8 of psoralen, the intensity of the fragment ion formed by the loss of CO₂ was relatively increased. By comparing the abundance of the product ions formed by the loss of CO and 2CO, the isomers of psoralen and isopsoralen could be distinguished. This method can also be used to distinguish the isomers of imperatorin and isoimperatorin. Because of the different connected position between glucose and rhamnose, in the mass spectrum of neohesperidin, the relative abundances of ions at m/z 489 and 343 generated by the ring-cross cleavage of glycan were more than 10%, while in the mass spectrum of hesperidin, they were all less than 1%. This approach can also be used to distinguish the isomers of naringin and narirutin. Although the fragmentation pathways were similar, according to the tiny difference of structure, the change of relative intensity of main fragment ions could be observed and it could be used to distinguish some isomers more accurately and quickly. 

Development and Validation of a Reverse-phase High Performance Liquid Chromatography Method for Determination of Exenatide in Poly(lactic-co-glycolic acid) Microspheres

LIU Bin, DONG Qing-guang, SHI Lin, WANG Meng-shu, LI Chun, WU Yong-ge, ...

2010, 26(1):  33-37. 

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Exenatide(synthetic exendin-4), which has been approved by the Food and Drug Administration(FDA) for the adjunctive treatment of patients with type 2 diabetes, is an incretin mimetic agent. The development and validation of a RP-HPLC method for the quantification of the exenatide in poly(lactic-co-glycolic acid)(PLGA) microspheres is described. Separation was performed on a C₄ column via a mobile phase consisting of ACN:KH₂PO₄(0.02 mol/L, pH=2.5) gradient elution from 30:70 to 45:55(volume ratio) in 30 min. Multi-diode array detection(DAD) appears to be most appropriate to evaluate the spectral purity of exenatide. The limits of detection and quantification of exenatide were 0.4 and 1.2 μg/mL, respectively. The calibration curve of exenatide was linear in a range of 0.025―0.2 mg/mL with a correlation coefficient of 0.9995. The results of validation study show that this method is specific, accurate(recovery>95%), precise(RSD<2.0%) and robust.

Syntheses, Crystal Structures and Complexing Properties of 1,3-Distal Calix[4]arene Schiff Bases

LI Liang, GU Wei-wei and YAN Chao-guo*

2010, 26(1):  38-45. 

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Novel 1,3-distal p-tert-butylcalix[4]arene Schiff bases were efficiently synthesized in three steps. At first p-tert-butylcalix[4]arene was reacted with N-2-hydroxyethylphthalimide catalyzed by TPP/DEAD or alkylated with ω-haloalkylphthalimide in the system of K₂CO₃/KI/CH₃COCH₃ to give 1,3-distal diphthalimidoalkyl calixarenes, which were in turn hydrazinolyzed to give diaminoalkyl calixarenes. Then with the aid of the condensation of active calixarene amines with salicylaldehyde, 2-hydroxy-1-naphthaldehyde or pyridine-2-carboxaldehyde, a series of 1,3-distal calixarene Schiff bases was prepared in satisfied yields. The single crystal structures and complexing  properties of these Schiff bases for transition metal ions were studied.

Two New Furostanol Saponins from Tribulus Terrestris L.

XU Ya-juan, XU Tun-hai*, XIE Sheng-xu, SI Yun-shan and XU Dong-ming

2010, 26(1):  46-49. 

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Two new furostanol glucosides, named tribufurosides G and H, were isolated from Tribulus terrestris L. The structures of the two new furostanol glucosides were elucidated as 26-O-β-D-glucopyranosyl-(25R)-5α-furost-12-one-3β,22α,26-tetraol-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside(1) and 26-O-β-D-glucopyranosyl-(25S)-5α-12-one-2α,3β,22α,26-tetraol-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyra-nosyl-(1→4)-β-D-galactopyranoside(2) by 1D, 2D NMR techniques, ESI-MS analysis as well as chemical methods.

Proline-based Amino Pyridine Dipeptides as Efficient Organocatalysts for Direct Aldol Reaction

GAO Jun-long, ZHENG Liang-yu, ZHANG Suo-qin*, ZHANG Xin-min, SUN Guo-dong, ...

2010, 26(1):  50-54. 

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A series of proline-based amino pyridine dipeptide organocatalysts was synthesized and applied in direct asymmetric intermolecular aldol reaction. These catalysts showed good solubility in organic solvents, good yields (73%―97%) and enantioselectivitives(74%―94%). Among them, dipeptide organocatalyst(2) was found to be the most efficient one for the asymmetric aldol reaction between cyclohexanone and 4-nitrobeznaldehyde. After optimi- zing the catalytic reaction conditions, we found that the catalyst showed high yield(97%), enantioselectivity(e.e., up to 92%) and anti-diastereoselectivity(up to 95:5) at mild room temperature without any additives.

Practical and Efficient Acylation and Tosylation of Sterically Hindered Alcohols Catalyzed with 1-Methylimidazole

WU Qin-pei*, LIU Hua, LIU Hai-xia, CHEN Xi, WANG Hao, ZHANG Qing-shan, ...

2010, 26(1):  55-59. 

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Acylation of sterically hindered alcohols is frequently encountered in synthetic chemistry. An efficient and mild procedure for tosylation and esterification of sterically hindered hydroxyl groups with p-TsCl, Ac₂O and Bz₂O in the presence of 1-methylimidazole is described. It was observed that auxiliary base, triethylamine, accelerates the acylation reaction.

Efficient Synthesis of 3,5,6,8-Tetrahydro-4H-thiopyrano[4',3':4,5]thieno[2,3-d]pyrimidin-4-ones via an Iminophosphorane

LI Wen-jing, LIU Min, FENG Ling-ling* and DING Ming-wu*

2010, 26(1):  60-65. 

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3,5,6,8-Tetrahydro-4H-thiopyrano[4',3':4,5]thieno[2,3-d]pyrimidin-4-ones(7) were synthesized via the base catalytic reactions of amines or phenols with carbodiimides(5), which were obtained from the aza-Wittig reactions of iminophosphoranes(4) with aromatic isocyanates.

Photodynamic Therapy of Cancer Cells with Methanesulfonate Salts of 5-Aminolevulinic Acid and Its Derivatives

QIU Xue-peng*, KOSOBE Toshiyuki and KAWASHIMA Norimichi1*

2010, 26(1):  66-69. 

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A series of 5-aminolevulinic acid and its alkylester methanesulfonates was exploited to photodynamic therapy(PDT) of human lymphocytic cells, U-937 in vitro. The PDT efficiency is influenced by the concentration and incubation time. Generally, for ALA and its alkylester methanesulfonates, the cell survival rate decreases and the accumulation ability of PpIX increases with the concentration and incubation time. We found that the longer carbon chain methanesulfonates(C5-S, C6-S, C8-S) exhibit better PDT effect than ALA methanesulfonate. This possibly provides a promising route to the clinical application of PpIX-mediated PDT to cancer cell.

Differential Proteomic Analysis of Endometriosis

ZHANG Li-hui, LIU Hong-yan, LI He-lian, ZHANG Xing-yi and SUN Mei*

2010, 26(1):  70-74. 

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Differential proteins expressing in ectopic and eutopic endometria were investigated by means of proteomic analysis. Five patients in secretary phase were diagnosed as endometriosis by laparoscopy. The five ectopic endometria(two at stage II, two at stage III and one at stage IV) and five eutopic endometria were surgically excised. One-dimensional electrophoresis coupled with liquid chromatography and mass spectrometry was used to screen and identify differential proteins. Three differential bands in one-dimensional electrophoresis were resolved by liquid chromatography and mass spectrometry and 14 up-regulated proteins were identified, including collagen α-1, α-2, α-3(VI), α-1(XIV) chain, actin, annexin A2, EMILIN-1, ferritin light polypeptide variant, fucosyltransferase 10, myosin-9, protein S100-A9, KIAA1783 protein, and two hypothetical proteins. Our data provides a list of potential biomarkers for endometriosis. The identifications may be used to develop new diagnoses for endometriosis.

Preparation of Tolterodine Metabolite Loaded Biodegradable PLGA Microspheres

TENG Le-sheng, JIANG Chao-jun, LIN Xiang-you, DONG Yuan-chen, LI Chun-mei, ...

2010, 26(1):  75-80. 

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Biodegradable polymer poly(lactic-co-glycolic acid)(PLGA) was used to encapsulate the pharmacological activity metabolite of tolterodine by means of O/W emulsion solvent evaporation method via homogenization in the emulsification process. The influences of preparation parameters were investigated. The results indicate that increa- sing PLGA concentration from 15% to 40% made the encapsulation efficiency of 5-hydroxymethyl derivative of tolterodine(5-HMT) increased from 55.39% to 76.32%, and the particle size increased from 34.33 μm to 70.78 μm. In addition, when homogenization speed increased from 850 r/min to 2300 r/min, both particle size and encapsulation efficiency of microspheres decreased. An increase in the volume of aqueous phase led to higher encapsulation efficiency and bigger particle size. Increasing temperature made encapsulation efficiency and particle size change significantly. While reaction temperature increased from 20 ℃ to 50 ℃, the encapsulation efficiency decreased from 70.44% to 24.07%, and particle size increased from 38.66 μm to 69.38 μm. High reaction temperature(over 40 ℃) may lead to porous surface of microspheres. Porous surface, encapsulation efficiency and particle size influenced on the in vitro release of 5-HMT together.

Comparative Proteomic Analysis of Human Benign Prostatic Hyperplastic Tissue Before and After Irradiation with Radioactive Nuclide

CHEN Li-bo, ZHAO Jie, ZHAO Guo-qing, XU Yan-li, LI Jun, GAO Shi and MA Qing-jie

2010, 26(1):  81-85. 

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The expressed proteins were extracted from human benign prostatic hyperplastic tissues obtained with transurethral resection of the prostate before and after their irradiation with radioactive nuclide. The proteins were separated by two-dimensional gel electrophoresis and analyzed by mass spectrometry. Four proteins were differentially expressed and were identified with a database search. Three were associated with the regulation of cell motion and one was lactate dehydrogenase B, which plays an important role in the process of cell energy metabolism and cell state changes in tissue. The comparative proteomic analysis indicates that after irradiation with radioactive nuclide, changes occur in human benign prostatic hyperplastic cells, and associated proteins are expressed. Analysis of these proteins should help to identify the mechanism involved when human prostatic hyperplasia is treated by irradiation with radioactive nuclide.

Optimization of Fermentation Medium for Epothilones Production with Sequential Statistical Approach

MENG Fan-xin, LI You-xin, GUO Wei-liang, LU Jia-hui, DU Lin-na and TENG Li-rong*

2010, 26(1):  86-91. 

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A sequential statistical approach was applied to optimizing the fermentation medium of epothilones(Epos) production by means of a mutant which was obtained by treating polyangium cellulosum ATCC 15384 with nitrite and ultraviolet. The effects of different carbon sources and nitrogen sources on the fermentation medium were tested, and the suitable ones were selected. Then a uniform design was employed to design the experiments. A linear model was developed for identifying the significant components in fermentation medium, while a third degree polynomial model was used for studying the relationship between the concentration of the components in fermentation medium and the yield of Epos(YEPs). A pattern search method was used for searching the optimum fermentation medium in the test space, which was as follows(g/L): potassium nitrate 8.00, soybean peptone 17.60, potassium hydrogen phosphate 1.00, beef extraction 6.46, yeast extraction 1.00, calcium chloride 0.25, sodium chloride 1.00 and ferric chloride 0.02. The optimum fermentation medium was expected to result in a yield of Epos(YEPs) of 2.48 mg/L. The validation experiments with the optimum medium were performed in triplicate and the average yield of Epos was 2.45 mg/L which was 7.78 times higher than that of Epos prepared without optimization.

Synthesis of Ethyl Oleate Catalyzed by Solid Superacid SO₄^2–/TiO₂/La³⁺

YANG Lei*, GUO Hui and HUANG Yu-dong

2010, 26(1):  92-97. 

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Rare-earth compound solid superacid SO₄^2–/TiO₂/La³⁺ was prepared. Its catalytic activity was examined under different synthetic conditions for the esterification of propanoic acid and n-butyl alcohol as probing reaction. The optimum conditions were also found, which were the pH=8, the depositing time was 24 h, the mass fraction of La(NO₃)₃ used in solid superacid was 5%, the concentration of H₂SO₄ was 1.25 mol/L, the soaking time in H₂SO₄ was 16 h and the calcining temperature was 500 °C. The ethyl oleate was synthesized from oleic acid and ethanol in the presence of SO₄^2–/TiO₂/La³⁺. The optimum reaction conditions were obtained which were the reaction time was 6 h, molar ratio of oleic acid to ethanol was 1:4 and the mass fraction of catalyst was 4%.

Gold Catalysts Supported on Crystalline Fe₂O₃ and CeO₂/Fe₂O₃ for Low-temperature CO Oxidation

LIU Rui-hui, ZHANG Cun-man and MA Jian-xin*

2010, 26(1):  98-104. 

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High active and stable gold catalysts supported on crystalline Fe₂O₃ and CeO₂/Fe₂O₃ were prepared via the deposition-precipitation method. The catalyst with a Au load of 1.0% calcined at 180 °C showed a CO conversion of 100% at –8.9 °C, while Au/CeO₂/Fe₂O₃ converted CO completely at –16.1 °C. Even having been calcined at 500 °C, Au/Fe₂O₃ still exhibited significant catalytic activity, achieving full conversion of CO at 61.6 °C. The catalyst with a low Au load of 0.5% could convert CO completely at room temperature and kept the activity unchanged for at least 150 h. N₂ adsorption-desorption measurements show that the crystalline supports possessed a high specific surface area of about 200 m²/g. Characterizations of X-ray diffraction and transmission electron microscopy indicate that gold species were highly dispersed as nano or sub-nano particles on the supports. Even after the catalyst was calcined at 500 °C, the Au particles remained in a nano-size of about 6―10 nm. X-ray photoelectron spectra reveal that the supported Au existed in metallic state Au⁰. The modification of Au/Fe₂O₃ by CeO₂ proved to be beneficial to the inhibition of crystallization of Fe₂O₃ and the stabilization of gold particles in dispersed state, consequently promoting catalytic activity.

Synthesis of Mesoporous Cu-Mn-Al₂O₃ Materials and Their Applications to Preferential Catalytic Oxidation of CO in a Hydrogen-rich Stream

FANG De-ren, REN Wan-zhong, LIU Zhong-min*, XU Xiu-feng, ZHANG Hui-min, ...

2010, 26(1):  105-109. 

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A series of mesoporous Cu-Mn-Al₂O₃(CMA) materials was synthesized at moderate temperature and their structures were characterized by XRD, N₂ physical adsorption and TPR techniques. It was found that using metal complex ion[Cu(NH₃)₄²⁺-Mn(NH₃)₆²⁺] as raw materials is easier to form good-structure mesoporous Cu-Mn-Al₂O₃ materials than using its nitrate salt [Cu(NO₃)₂-Mn(NO₃)₂]. The TPR tests results indicate that CuO and MnO_x were homogeneously dispersed in the mesoporous materials. Their catalytic application to preferential catalytic oxidation of CO in a hydrogen-rich stream was studied. The activity varies in the order of CMA(1:1, molar ratio)＞   CMA(1:2)＞CMA(2:1)＞CMA(CP)＞CMA(1:0)≈CMA(0:1). The CMA(1:0) and CMA(0:1) have lower activity compared to other samples, implying that there existed coordination effect between Cu-Mn in the samples. The selectivity varied in the order of CMA(0:1)≥CMA(1:2)＞CMA(1:1)＞CMA(2:1)＞CMA(1:0) at higher temperature   (≥120 °C), indicating that increasing the Cu content enhanced the conversion of H₂. The sample CMA(CP) made by coprecipitation method has a lower CO oxidation activity and selectivity than its counter-parts of mesoporous Cu-Mn-Al₂O₃ materials[CMA(1:2)], this attributed to the lower surface area of the former and poor interaction of CuO with  MnO_x.

Catalytic Characteristics of Lipase Immobilized in CTAB/TX-100 MBG

SONG Shao-fang* and LUAN Yu-xia

2010, 26(1):  110-113. 

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CTAB/TX-100 microemulsion-based gel(MBG), which could be soaked in aqueous solution for a long time without mechanical strength and shape changes, was successfully prepared. Lipase immobilized in this gel had a higher activity than that in CTAB MBG when catalyzed the esterification reaction between n-hexanoic acid and n-octanol and its enantioselectivity was slightly higher when catalyzed the stereoselective esterification reaction between racemic ibuprofen and n-octanol. In aqueous solution, lipase in CTAB/TX-100 MBG could catalyze smoothly the hydrolysis reaction of olive oil and could be reused many times without the evident change of MBG mechanical strength although its activity decreased 41.8% after nine-time recycles.

Solid-liquid Metastable Equilibria in Quaternary System (NaCl+Na₂CO₃+Na₂SO₄+H₂O) at 273.15 K

WANG Rui-lin and ZENG Ying*

2010, 26(1):  114-117. 

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The metastable phase equilibria of the quaternary system NaCl+Na₂CO₃+Na₂SO₄+H₂O were studied at 273.15 K. The salts’ solubilities, densities and pH values of the equilibrated solution in this system were determined. According to the experimental data, the metastable equilibrium phase diagram, the diagram of density vs. composition and pH vs. composition diagram were plotted. The phase diagram consists of five univariant curves, four crystallization fields and two invariant points. The four crystallization fields correspond to sodium carbonate decahydrate (Na₂CO₃·10H₂O), sodium sulfate decahydrate(Na₂SO₄·10H₂O), sodium chloride(NaCl) and burkeite(2Na₂SO₄·Na₂CO₃), respectively. The crystallization field of sodium sulfate decahydrate(Na₂SO₄·10H₂O) is the largest, which indicates that sodium sulfate is easy to saturate and crystallize from solution at 273.15 K.

Theoretical Design of Catalytic Domain of Abzyme Se-scFv2F3 by Introducing a Catalytic Triad

LUO Quan, ZHOU Yi-han, YAO Yuan and LI Ze-sheng*

2010, 26(1):  118-121. 

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The single chain antibody scFv2F3 can be converted into selenium-containing Se-scFv2F3 by chemical mutation of the Ser residues. With antibody fragment 1NQB as a template, the catalytic domain of scFv2F3 was built by using homology modeling and molecular dynamics(MD) simulations. On the basis of the 3D model, we discussed the importance of Ser52 as the chemical modification site and redesigned the protein groups nearby Ser52 via introducing a catalytic triad. The following 10 ns MD results show that the designed Ser52-Trp29-Gln72 catalytic triad is stable enough and high close to the local structural features of native glutathione peroxidases(GPX). Our results may be useful for creating a new abzyme with higher catalytic efficiency and stability.

Mesoscale Simulation for Polymer Migration in Confined Uniform Shear Flow

HE Yan-dong, WANG Yong-lei, Lü Zhong-yuan* and LI Ze-sheng

2010, 26(1):  122-127. 

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The structure and dynamics of confined single polymer chain in a dilute solution, either in equilibrium or at different shear rates in the uniform shear flow fields, were investigated by means of dissipative particle dynamics simulations. The no-slip boundary condition without density fluctuation near the wall was taken into account to mimic the environment of a nanochannel. The dependences of the radius of gyration, especially in three different directions, and the density profile of the chain mass center on the strength of the confinement and the Weissenberg number(W_n) was studied. The effect of the interaction between polymer and solvent on the density profile was also investigated in the cases of moderate and strong W_n. In the high shear flow, the polymer migrates to the center of the channel with increasing W_n. There is only one density profile peak in the channel center in the uniform shear flow, which is in agreement with the results of the experiments and theory.

Computational Investigation on the Ethylene-induced Esterase from Citrus Sinensis

HAN Wei-wei*, ZHAN Dong-ling, ZHAO Xi and WANG Song

2010, 26(1):  128-135. 

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In order to understand the interaction between ethylene-induced esterase(EIE, EC 3.1.1.) from Citrus sinensis and α-naphthyl acetate, a 3D model of EIE was generated based on the crystal structure of the tobacco salicylic acid binding protein 2(SABP2). With the aid of the molecular mechanics and molecular dynamics methods, the final refined model was obtained and its reliability was further assessed. In this study, the docking results show that the main-chain amide of residue His85 and residue Val18 can form hydrogen bonds to the carbonyl oxygen group of α-naphthyl acetate. MM-PBSA method was applied to calculating the binding free energy between EIE mutants and α-naphthyl acetate. Our calculated binding free energy of each of the two mutant complexes is increased compared with that of the one of the wild type, which is unfavorable to the reaction. It is well consistent with the experimental data. The above results clearly indicate that His85 and Val18 in EIE function as the oxyanion role and take part in the catalytic reaction. The new structural insights obtained from this computational study are expected to stimulate further biochemical studies on the structures and mechanisms of EIE and other members of the plant α/β hydrolases.

Bovine Serum Albumin Loaded Solid Lipid Nanoparticles Prepared by Double Emulsion Method

LI Zhen, LI Xin-wei, ZHENG Li-qiang*, LIN Xiao-hong, GENG Fei and YU Li

2010, 26(1):  136-141. 

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Solid lipid nanoparticles loaded with bovine serum albumin(BSA) were prepared by a double emulsion method. As the mass fraction of the model drug BSA increased from 0 to 15%, the particle size gradually increased. The physical stability of the nanoparticles was investigated by zeta potential measurement and they were shown to be quite stable. Fluorescence spectroscopy confirmed that the loaded position of BSA was on the interface between the inner aqueous phase and the solid lipid phase. Both Fourier-transform infrared spectroscopy and circular dichroism spectra indicate that BSA in the nanoparticles was not destroyed, but the secondary structure was disrupted slightly.

Linear Dynamic Viscoelastic Response of Melts for Crosslinkable Polyethylene Insulation Cable Granules During Cross-linking

YANG Hong-mei*, YANG Yong-zhu, HE Xiao, ZHENG Qiang and ZHOU Hou-qiang

2010, 26(1):  142-147. 

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Two commercial crosslinkable polyethylene insulation cable granules, designed for 110 and 35 kV voltage insulation, with similar crosslinking temperature but different melting temperature, were chosen as experimental samples for examining their linear dynamic responses during cross-linking. It has been found that the gel contents of cable compounds for 110 and 35 kV insulation are almost the same after they have been cross-linked at the same temperature, pressure and time. And the sample melts show the similar dependence of the dynamic storage modulus, G´, on strain. On the other hand, the dynamic temperature ramp test and the dynamic time sweep test indicate that the samples exhibit different dynamic viscoelastic responses during their crosslinking. An expression for describing their crosslinking process was proposed via probing rheokinetics of crosslinking for the two samples .

Fabrication of Fluorescent Porphyrin/Polystyrene Composite Nanospheres by Electrospinning

SONG Yan, ZHAN Nai-qian, YU Miao, YANG Qing-biao, ZHANG Chao-qun, ...

2010, 26(1):  148-151. 

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Fluorescent polystyrene(PS)/porphyrin(TPPA) composite nanospheres were successfully fabricated by electrospinning. The SEM images clearly show that owing to adding TPPA in PS, the averaged diameter of the composite nanospheres became smaller, from 1500 to 580 nm. Fourier-transform infrared(FTIR) spectra determined the chemical composition of the resulting PS/TPPA composite nanospheres. The photoluminescent(PL) spectral analysis indicates that the peak position of the composite nanospheres in either solid state or water is identical to that of pure TPPA, at about 652 nm, and is still unchangeable when they are left for at least 20 d, indicating the stable photoluminescent property of the fluorescent composite nanospheres.

Crystallization Behavior and Thermal Properties of PP/MgAl LDH Nanocomposites Prepared in Non-polar Solution

CUI Zhe, ZHANG Guo-ying and QU Bao-jun*

2010, 26(1):  152-156. 

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Polypropylene(PP)/MgAl layered double hydroxide(MgAl LDH) nanocomposites were synthesized by refluxing PP and dodecyl sulfate-intercalated MgAl LDH[MgAl(DS)] in non-polar xylene. Their structure, thermal and crystallization properties were studied via X-ray diffraction(XRD), transmission electron microscopy(TEM), thermogravimetric analysis(TGA), differential scanning calorimetry(DSC), and polarized light microscopy(PLM). The nanoscaled dispersion of MgAl(DS) nanolayeres in the PP matrix was verified by the disappearance of the d₍₀₀₃₎ XRD diffraction peak of MgAl(DS) and observation of TEM image. The DSC data show that the SDS/LDH inorganic components negatively affect the crystallization properties of PP and decrease the size of PP spherulites because the inorganic components act as additional nuclei. The PP/MgAl LDH nanocomposites have a faster charring progress in a temperature range of 250―430 °C and a better thermal stability above 320 °C than pure PP.

Evolution of Morphology and Properties of Sulfonated Poly(ether ether ketone ketone) Membranes Fabricated via Electrospinning

MA Hai-song, HAO Xiu-feng, LI Xian-feng, ZHAO Cheng-ji, FU Tie-zhu, NA Hui, ...

2010, 26(1):  157-160. 

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Sulfonated poly(ether ether ketone ketone)(SPEEKK) membranes with different degrees of sulfonation(DS) were successfully prepared via electrospinning method. The morphology of the resulted membranes varies from nanospheres to nanofibers with increasing the concentration of SPEEKK. The conductivities of the membranes prepared  under the same condition increase with the DS increasing. The spherical morphological membranes with a DS of 1.2 show the highest proton conductivity, 0.55 S/cm, which is much higher than those of the membranes prepared via normal solution evaporation method. The results show that electrospinning is an efficient method to prepare high performance SPEEKK membranes with different morphologies.

Research Note

Antioxidant and Cytotoxic Phenolic Compounds of Areca Nut(Areca catechu)

ZHANG Xing, WU Jiao, HAN Zhuang, MEI Wen-li* and DAI Hao-fu*

2010, 26(1):  161-164. 

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Areca nut, the ripe fruit of the tree Areca catechu is ascribed a number of medicinal properties. The EtOAc extract of areca nut exhibited considerable antioxidant in the 1,1-diphenyl-2-picrydrazyl (DPPH) radical-scavenging assay. Bioassay-guided purification of the extract led to the isolation of 11 phenolic compounds, whose structures were determined by detailed spectroscopic analysis, including UV, IR, MS, 1D, 2D and ROESY NMR techniques. Of them, compound 1 was a new phenylpropanoid, compounds 1–9 and 11 were isolated from genus of Areca for the first time. All these compounds were examined for their antioxidant activities by the DPPH method, and the results showed that these compounds contributed to the antioxidant activity of areca nut. Compound 11 exhibited significant cytotoxic activity after examining all these compounds by using MTT assay.