【作者】 韩颖达；

【导师】 刘晓非；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 本论文针对L-抗坏血酸(VC)在应用和处理中容易被氧化的缺点,利用壳聚糖在生物领域的特性,制备了两种新型的壳聚糖/VC复合物——壳聚糖L-抗坏血酸盐、2-O-壳聚糖基抗坏血酸。同时针对长期服用抗坏血酸容易在胃液中转化为草酸导致结石的问题,制备了乙基纤维素包衣的壳聚糖包裹抗坏血酸微胶囊,以期达到既能提高VC的稳定性,又能实现VC在肠液中的缓释效果。本论文系统地研究了这些壳聚糖/VC复合物的合成条件,通过抗坏血酸含量、产率、抗氧化性等分析测试确定了性能最优的制备条件,利用核磁共振光谱、红外光谱、扫描电镜考察产物的结构。结果表明:壳聚糖/L-抗坏血酸盐和2-O-壳聚糖基抗坏血酸具有较好的水溶性,壳聚糖大分子结构的存在,降低了各种氧化剂对VC的破坏作用,使VC在贮存和使用过程中不容易被氧化。同时,由于VC本身有着优良的抗菌性能,所以它也进一步增强了壳聚糖的抗菌能力和对血脂的吸附能力。本论文还利用反相乳化交联法,制备了壳聚糖/L-抗坏血酸微球,并在其外包覆乙基纤维素制成微胶囊。系统研究了壳聚糖分子量、水油比、反应时间、交联剂用量等因素对微球制备和VC释放行为的影响。结果表明:所制备的微胶囊不仅在肠液中具有显著的缓释效果,并且大大降低了VC在胃中的释放,达到肠溶的目的。更多还原

【Abstract】 For the disadvantage of L-ascorbic acid (vitamin C, VC) that it is easily to be oxidized during the treatment and process, two new kinds of derivative---chitosan ascorbate and 2-O-chitosan-ascorbic acid were studied. For the oxalic acid is formed in high yield from VC in gastric juice, the chitosan-VC micro sphere was prepared and then was microencapsulated into ethylic cellulose (EC).By designing appropriate experiments, the conditions of synthesizing chitosan-ascorbic acid complex were studied. The analysis of VC content, output rate, solubility helped us to get the optimal condition of synthesizing. The 13C NMR assignments, infrared spectrum permitted the identification of the structure of these complex. After the function test, it is found that chitosan ascorbate and 2-O-chitosan-ascorbic acid have good water-soluable ability. The existent of chitosan macro-molecular structure prevents the oxygen from destroying VC, so VC is to be protected. Since VC has good anti-bacteria ability and absorbability to serum lipoprotein, it enhances the same ability of chitosan.At the same time, L-ascorbic acid, used as a model drug, was efficiently entrapped within chitosan micro spheres using reversed-phase emulsion cross linking reaction and then was microencapsulated into ethylic cellulose. The morphology and release properties of microcapsules were tested. The influential factors of preparation conditions included molecular weight of chitosan, ratio of water and oil, reaction time, concentration of cross linker were discussed. The results of in vitro release studies show that the microcapsules prepared in this article are stable in gastric juice and can realize sustained release in intestine juice.更多还原