【作者】 曾庆慧；

【导师】 周长忍；

【作者基本信息】 暨南大学 ， 材料科学与工程， 2007， 硕士

【摘要】 壳聚糖（CS）和聚乳酸（PLA）是目前国内外应用最广泛的生物材料。为改善壳聚糖的降解速率和聚乳酸的生物相容性，合成同时具备天然材料和合成材料优势的壳聚糖接枝聚乳酸材料（CS-g-PLLA），本研究首先在低温常压下利用微波辐射快速高效地合成了具有较高分子量和纯度，良好结晶性、热稳定性和力学性能的PLLA材料。以此为基础，首次采用生物酶为活性催化剂，以含羟基和氨基的壳聚糖为共引发剂，在常压低温微波辐射下引发L-LA开环共聚，合成了CS-g-PLLA，避免了金属催化剂的使用，提高了反应效率。系统研究了微波反应条件、催化剂种类和用量、投料比对产物接枝率和性能的影响。结果表明共聚物接枝率可控，反应时间为30min，50℃时，在1.0wt％的猪胰酶催化作用下可得接枝率最大为178.75％的共聚物；FTIR和¹³C-NMR分析结果证明产物为符合预期分子结构的CS-g-PLLA共聚物；DSC、TG和X-RD分析结果表明随着L-LA和CS投料比的增大，共聚物的接枝率增大，结晶性降低。为指导该接枝共聚物在组织工程及其它生物医学领域的实际应用，本文还从体外降解、细胞毒性和溶血试验三个方面初步考察了材料的生物学性能，结果表明所得共聚物的降解速率比单纯CS快且可通过调节产物的接枝率进行调控；体外细胞培养和溶血试验结果表明，使用猪胰酶为催化剂制备的CS-g-PLLA能有效地避免金属催化剂残留物带来的细胞毒性，并显著改善材料的血液相容性。更多还原

【Abstract】 Nowadays, chitosan （CS） and polylactide （PLA） are widely used in the field of biomaterials. To improve the slow degradation rate of CS and biocompatibility of PLA, make up for native material and synthetic material’s deficiencies, we synthesized the chitosan-graft-poly （L-lactide） copolymer （CS-g-PLLA）. Under microwave irradiation we prepared PLLA which exhibited high purity, good crystallinity and satisfactory mechanical performance, then to make the biomaterials’ biocompatibility more better, we firstly used porcine pancreatic lipase （PPL） as the catalyst, which completily asepsis, to get the CS-g-PLLA. We can operate with much lower temperature than ever before and under ordinary pressure. The copolymer was synthesized under different reaction time, temperature, reagent mole ratio and different kinds and dosages of catalyst. The copolymers were characterized by FTIR, ¹³C-NMR, DSC, TG and X-RD, and used weight method to get the grafting percentage. The copolymers’ grafting percentage can be controled by change of the feeding molar ratio of L-lactide and chitosan. The results of these spectra showed that the product was CS-g-PLLA copolymer; the crystallinity of raw CS was destroyed and the products’ thermal stability descented after the copolymerization. And the grafting percentage of the products can be controled.The results of vitro degradation test by lysozyme in PBS indicated that the copolymers had a higher weight loss in PBS than that of pure CS, and degradation rate increased with the increasing the feeding molar of L-LA, so we can adjust the degradation velocity of the products and PH value by change of the feeding molar ratio of L-lactide and chitosan, which can reduce acidity of the degradation product of the pure PLLA. Cell culture of vitro was assessed using the MTT assay, the results show that in vitro the copolymers’ biocompatibility is more better than PLLA, and the PPL catalysis system’s cell viabilitys was much better than the tin octoate catalysis systerm. So using the PPL as the catalyst maybe a really good method to synthesis the biomaterials because of it is non-cytotoxicity and totally harmless to human. The results of hemolysis test indicated that the copolymers consistent with the standard of the hemolysis test’s requirement, and the PPL system is the best.更多还原