聚乳酸微球的体外降解

目的:研究聚乳酸微球降解的规律及机制.方法:用5种方法研究聚乳酸微球降解过程:扫描电子显微镜观察微球表面形态;测定失重;凝胶渗透色谱法测定聚合物的平均相对分子质量;测定pH;紫外分光光度法测定乳酸含量.结果:聚乳酸的降解过程有两个阶段,初期主要发生聚合物分子链断裂,后期主要发生聚合物片段溶蚀.其降解速度随平均相对分子质量增加而减慢.结论:聚乳酸是可生物降解材料,降解有规律,是优良的药物控释材料.

Study on the degradation of polylactide microspheres in vitro

Objective: To study the rules and mechanism of the degradation of polylactide microspheres. Methods: Assessment of surface morphology of microspheres by scanning electron microscopy; assessment of weight loss; determination of molecular mass of polymers by gel permeation chromatography; determination of pH; determination of lactic acids by UV spectrophotometry. Results: The degradation possessed two phase characteristics. During the early stages of the degradation, it was suggested that the high molecular mass polymers were cleaved into lower molecular mass fractions. However, during the late stages, there was a period of erosion and weight loss of the polymers. Each method confirmed that degradation was much slower for polymers with a higher molecular mass. Conclusion: The polylactide was biodegradable and the polymer degradation showed good regularity. The polylactide may be appropriate for the development of drug controlled release systems.