Biomimetic strengthening polylactide scaffold materials for bone tissue engineering

In this paper, a new polylactide (PLA)-based scaffold composite by biomimetic synthesis was designed. The novel composite mainly consists of nano-hydroxyapatite (n-HA), which is the main inorganic content in natural bone tissue for the PLA. The crystal degree of the n-HA in the composite is low and the crystal size is very small, which is similar to that of natural bone. The compressive strength of the composite is higher than that of the PLA scaffold. Using the osteoblast culture technique, we detected cell behaviors on the biomaterial in vitro by SEM, and the cell affinity of the composite was found to be higher than that of the PLA scaffold. The biomimetic three-dimensional porous composite can serve as a kind of excellent scaffold material for bone tissue engineering because of its microstructure and properties. Translated from Journal of Hunan University (Natural Sciences), 2006, 33(2) (in Chinese)     

1,2,2,6,6-五甲基哌啶醇与紫外吸收剂和猝灭剂在对聚丙烯膜光稳定作用中并用效应的研究

<正> 最近的研究发现,五甲基哌啶醇与四甲基哌啶醇的光稳定机理有一定的不同。我们还观察到2,2,6,6-四甲基哌啶醇与2-羟基-4-辛氧基二苯甲酮(UV-531)同时添加到聚丙烯膜中具有明显的协同效应。本实验探讨了1,2,2,6,6-五甲基哌啶醇(PMP)与几种紫外吸收剂及猝灭剂的并用效应,并比较四甲基哌啶醇及五甲基哌啶醇与紫外吸收剂并用效应的差别。     

Magnesium-mediated sp3 C–H activation in cascade cyclization of 1-arylethynyl-2-alkyl-o-carboranes: efficient synthesis of carborane-fused cyclopentanes

This work reports an unprecedented cascade cyclization of 1-arylethynyl-2-alkyl-o-carboranes promoted by magnesium-mediated sp³ C–H activation. Treatment of 1-arylethynyl-2-alkyl-o-carboranes with MeMgBr gives a series of carborane-fused cyclopentanes in very good yields. Deuterium labelling and control experiments suggest that HMgBr, resulting in situ from the nucleophilic substitution of cage B–H bonds with Grignard reagent, initiates the reaction, in which magnesium-promoted intramolecular sp³ C–H activation serves as a key step. This work not only offers a new route for the synthesis of carborane-fused cyclopentanes, but also sheds some light on Mg-mediated C–H activation and functionalization.

An unprecedented cascade cyclization of 1-arylethynyl-2-alkyl-o-carboranes with Grignard reagent for synthesizing carborane-fused cyclopentanes has been disclosed, in which magnesium-mediated intramolecular sp³ C–H activation serves as a key step.     

Porous and electrically conductive polypyrrole-poly(vinyl alcohol) composite and its applications as a biomaterial

Bulk modification of polypyrrole (PPY) with poly(vinyl alcohol) (PVA) was carried out by the electropolymerization of pyrrole in the presence of PVA in the reaction solution, with tetraethylammonium perchlorate (TEAP) as the electrolyte. The surface morphology of the as-synthesized PPY-TEAP-PVA film was investigated using scanning electron microscopy, and the film was further characterized using X-ray photoelectron spectroscopy, electrical conductivity, the water contact angle, and BET surface area measurements. The PPY-TEAP-PVA composite is electrically conductive, hydrophilic, and microporous with a high surface area. Its potential as a biomaterial was investigated with respect to its blood compatibility and function as a substrate for biosensor fabrication and cell culture. The presence of PVA in the film attenuates blood protein adsorption, and the porous nature of the PPY-TEAP-PVA film results in a 10-fold increase in the amount of glucose oxidase covalently immobilized on the film over that on a nonporous PPY film. PC12 cell attachment and growth on the PPY-TEAP-PVA film was also shown to be enhanced compared with that on tissue culture polystyrene. The attached cells proliferated and formed a monolayer on the film surface after 48 h of seeding.     

医用可生物降解高分子材料

对目前医用可生物降解高分子材料的研究及应用状况分化学合成，天然和生物技术合成三类作了综述。对材料的生物相容性、可生物降解性及物理机械性能进行了分析和比较。并就医用生物降解高分子材料的发展趋势作了预测。     

碱性分子筛上不同吸附物的TPD研究

借助吸附不同酸性物的程序升温方法研究了碱金属交换的Ｘ型分子筛的碱性。发现吸附物对分子筛碱性的ＴＰＤ表征有很大影响。主要与吸附物的分子体积和酸强度两种因素有关，并对这些影响因素进行了分析。结果表明；甲醇做吸附物对用ＴＰＤ表征分子筛的碱性相对比较可靠。     

N-(1-异丙基-2-羧基-4-甲基二环[2.2.2]-5-辛烯-3-羰基)-N''''-芳基(硫)脲的合成

在无溶剂绿色化学条件下,将α-萜品烯-马来酸酐加成物(1)与取代苯(硫)脲发生N-酰化反应,合成了4个N-(1-异丙基-2-羧基-4-甲基二环[2.2.2]-5-辛烯-3-羰基)-N'-芳基(硫)脲化合物(3a～3d),并由IR、UV-Vis、MS、1H NMR、13C NMR和元素分析确认了目标产物的结构.生物活性测试表明,其中3个化合物(3a、3b和3c)具有植物激素作用.     

Expression of human β-defensin-2 with multiple joined genes in Escherichia coli

Human β-defensin (HBD)-2 is a small cationic peptide with a broad range of antimicrobial activity. In this study, multiple copies of the hBD2 gene were linked in tandem, and a number of different Escherichia coli expression vectors were evaluated, including pQE-30, pBV220, pET-28a(+), and pGEX-4T-2. No expression of multiple joined genes was detectable in the pQE-30 expression system, whereas in pBV220 with one or two joined hBD2 genes and in pET-28a(+) with one, two, or four copies, target proteins were expressed at a low level. Only when pGEX-4T-2 was applied as expression plasmid with one or two joined hBD2 genes were target proteins expressed in high level, and the expressed fusion proteins account for 26 and 16% of the total insoluble proteins, respectively. In the pGEX-4T-2 and pET-28a(+) expression systems, the effects of multiple joined genes on the growth of host strains and plasmid stability were examined. Host cells containing plasmid carrying fewer copies of hBD2 genes were faster in cell growth. Plasmid stability decreased with an increase in multiple joined genes, which was especially noticeable in the pET-28a(+) system. Furthermore, the presence of glucose in culture medium brought about a positive effect on plasmid stability when using pET28-nhBD2 as expression vectors.     

Polarography of uranium(VI) and lead(II) complexes with l-glutamine

The complexes of uranium(VI) and lead(II) with 1-glutamine were investigated polarographically. For uranium(VI), the complexes UO(2)G(+2), UO(2)G(2)(+2) and UO(2)(OH)Ga(2)(+) were identified at pH < 2.5, pH 2.5-4.1 and pH 4.1-5.2 respectively. With lead(II), complexes PbG(+2), Pb(OH)G(+) and Pb(OH)G(2)(+) were formed at pH 2.0-5.0, pH 5.0-7.0, and pH 7.0-8.5, respectively. The concentration dissociation constant of Pb(OH)G(2)(+) was found to be pK(c) = 10.16 +/- 0.04 at ionic strength 0.6.