Structural characterisation of a water-soluble polysaccharide from tissue-cultured Dendrobium huoshanense C.Z. Tang et S.J. Cheng

A water-soluble polysaccharide TC-DHPA4 with a molecular weight of 8.0 × 10⁵ Da was isolated from tissue-cultured Dendrobium huoshanense by anion exchange and gel permeation chromatography. Monosaccharide analysis revealed that the homogeneous polysaccharide was made up of rhamnose, arabinose, mannose, glucose, galactose and glucuronic acid with a molar ratio of 1.28:1:1.67:4.71:10.43:1.42. The sugar residue sequence analysis based on the GC-MS files and NMR spectra indicated that the backbone of TC-DHPA4 consisted of the repeated units:→6)-β-Galp-(1→6)-β-Galp-(1→4)-β-GlcpA-(1→6)-β-Glcp-(1→6)-β-Glcp-(→. The sugar residue sequences β-Glcp-(1→)-α-Rhap-(1→3)-β-Galp-(1→, β-Glcp-(1→4)-α-Rhap-(1→3)-β-Galp-(1→, β-Galp-(1→6)-β-Manp-(1→3)-β-Galp-(1→, and α-l-Araf-(1→2)-β-Manp-(1→3)-β-Galp-(1→ were identified as the branches attached to the C-3 position of (1→6)-linked galactose in the backbone.     

Efficient synthesis and characterization of new photoactive dextran esters showing nanosphere formation

Different types of photoactive dextran derivatives with high degree of substitution were prepared by an efficient and mild esterification of the biopolymer with 2-methoxycinnamic acid, [(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetic acid, and azobenzene-4-carboxylic acid via in situ activation of the carboxylic acid groups with N,N'-carbonyldiimidazole. The structures of the novel dextran esters were evaluated by means of NMR spectroscopy applying the perpropionylated samples. Perpropionylation yields samples soluble in chloroform and acetonitrile that are very useful solvents not only for NMR but also for UV-vis spectroscopic studies. The photochemistry was studied by NMR and UV-vis spectroscopy in the dissolved state and the changes observed may be used to control the properties. The photoactive dextran esters form spherical nanoparticles of a size below 200 nm that are of interest in the design of smart materials.     

NOVEL pH-SENSITIVE DRUG DELIVERY SYSTEM BASED ON NATURAL POLYSACCHARIDE FOR DOXORUBICIN RELEASE

A novel pH-sensitive nanoparticle drug delivery system (DDS) derived fl'om natural polysaccharide pullulan for doxorubicin (DOX) release was prepared.Pullulan was functionalized by successive carboxymethylization and amidation to introduce hydrazide groups.DOX was then grafted onto pullulan backbone through the pH-sensitive hydrazone bond to form a pullulan/DOX conjugate.This conjugate self-assembled to form nano-sized particles in aqueous solution as a result of the hydrophobic interaction of the DOX.Tr...     

多糖及多糖衍生物水处理剂的研究进展

叙述了国内外多糖及多糖衍生物水处理剂的现状,简单地介绍了多种新型多糖及多糖衍生物水处理剂的原料、合成方法及其在水处理中的应用,并对多糖及多糖衍生物水处理剂的发展方向进行了展望。     

降解前后异枝麒麟菜硫酸多糖对草酸钙晶体生长的调控作用

采用过氧化氢法降解产于印尼的海藻异枝麒麟菜硫酸多糖(ESPS). 降解前ESPS的平均分子量为1410000, 硫酸基(OSO2-3)含量为16.0%(w); 而降解后其分子量显著下降至4819, 硫酸基含量则略微下降至15.2%. 采用体外模拟方法研究了降解前后ESPS对草酸钙晶体生长的抑制作用. 扫描电子显微镜(SEM)和X射线衍射(XRD)结果表明, 降解后ESPS能使一水草酸钙(COM)晶体数量进一步减少, 晶粒尺寸进一步减小. 当降解ESPS浓度从0.006 g·L-1分别增加到0.010 和0.050 g·L-1时, COM晶体平均尺寸由11.5 μm×2.9 μm分别减小到9.2 μm×2.9μm 和6.0 μm×2.5 μm, 晶体数量由3357 mm-2分别减少到2298和1532 mm-2, COM 的(101)面衍射峰强度I(101)与(010)面对应的(020)衍射峰强度I(020)之比(I(101)/I(020))由5.54 分别增加到16.2 和20.0. 结果显示, 具有小分子量的降解ESPS对草酸钙晶体成核与生长的抑制效果明显优于大分子量的未降解ESPS.     

蛋白质与高分子的自组装

蛋白质是一类具有独特三维空间结构的生物高分子,其分子内部非共价键协同作用是形成三维空间结构的重要驱动力。同时,蛋白质分子与其他高分子之间也可以通过非共价键作用实现自组装。高分子链和蛋白质的结构特征是实现自组装的关键,溶液pH值、离子强度以及温度的变化会影响它们之间非共价键作用的类型和强度。本文归纳了水溶性高分子、嵌段共聚物和多糖与球状蛋白自组装的最新研究进展,分别从分子结构特征和溶液性质等因素讨论了其对高分子与蛋白质实现自组装的影响。其中,多糖与蛋白质的非共价键作用是化学与生物科学交叉领域最为活跃的研究课题之一,通过研究蛋白质与其他高分子的非共价键作用,对于理解和认识生命过程的本质与规律具有重要的意义,同时,在材料科学、纳米技术、食品科学等相关领域具有重要的应用价值。     

天然高分子复合羟基磷灰石材料的制备与应用

羟基磷灰石(HA)是人类与动物骨骼中主要无机物组成成分,因其具有良好的生物相容性、生物活性和骨传导作用,作为新型合成生物材料已应用于骨组织的修复与替代技术。本文在介绍HA主要制备方法(如:沉淀法、乳液法、水热反应法、溶胶-凝胶法、机械化学法、固态合成法、水解法、超声化学法、热解法、模板法和电沉积法等)和应用的基础上,重点综述了各类天然高分子与HA复合材料的制备及应用研究进展。天然高分子,如:纤维素、淀粉、甲壳素、壳聚糖、蛋白(包括胶原蛋白、明胶、角蛋白、丝蛋白和植物蛋白)等,与HA复合后制备的天然高分子复合羟基磷灰石材料,在保持其生物相容性的同时,又能改善复合材料的机械性能与生物活性,使其可用于医用材料、载体材料和吸附分离材料。最后,本文指出为了满足生物体内的特殊环境(如强的韧性、与骨生长速度匹配性能等)及不同领域的要求,天然高分子复合HA材料需要发展的方向。     

Multimode ultrasonic extraction of polysaccharides from maca (Lepidium meyenii): Optimization,purification, and in vitro immunoregulatory activity

This study evaluates the effect of multimodal ultrasound on the extraction efficiency and immunoregulatory activity of polysaccharides from Lepidium meyenii Walp. (LMP). The separation and purification of maca polysaccharides were investigated by the DEAE-52 cellulose column, and the monosaccharide compositions were identified by HPGPC. Their immune activity was analyzed by the secretion of cytokines (TNF-α and IL-6) from RAW 264.7 macrophage. The results showed that the optimal extraction conditions were energy aggregation alternation dual-frequency ultrasound (EADU) with frequency combinations of 20/35, extraction time of 15 min, material/water ratio of 1:10 g/mL, ultrasonic power intensity of 150 W/L, intermittent time ratio of 4 s/3 s, and extraction temperature of 50 ℃. The extraction rates of purified polysaccharides (US3) increased by 44.90%. The LMP extracted by EADU contained arabinose, galactose, and glucose in the molar ratios of 2.9:2.72:5.05. In addition, US3 promoted the release of TNF-α and IL-6 from RAW 264.7 better than RS3 (purified polysaccharides extracted by hot water), which indicated that US3 exerted remarkable immune activity. It could be an excellent functional additive in food or medicine.     

修复前后Vero细胞调控草酸钙晶体生长的差异

采用扫描电子显微镜(SEM)和流式细胞仪等多种方法研究了降解大豆多糖(SPS)对损伤的非洲绿猴肾上皮细胞(Vero)的修复作用;研究了修复前后Vero调控草酸钙(CaOxa)晶体形成的差异。经H2O2氧化损伤的Vero在被SPS修复后,其细胞活力、细胞外SOD活性及细胞内线粒体膜电位均增加,细胞形态逐渐恢复到接近正常细胞。在诱导草酸钙(CaOxa)晶体生长过程中,修复细胞可以减少棱角尖锐的一水草酸钙(COM)晶体生成,诱导更多的二水草酸钙(COD)晶体。三种状态Vero诱导的晶体尺寸从小到大顺序为:正常细胞<修复细胞<损伤细胞。本文结果表明,降解大豆多糖可以修复受损伤的Vero细胞,降低肾结石形成的危险性,提示SPS有可能是一种潜在的绿色防石药物。