两种聚酯微球的体外降解机制研究

Study on the Degradation of Poly(d,l-lactide-co-glycolide) and Poly(Lactic Acid) Microspheres in vitro

目的 :研究聚乳酸 羟基乙酸及聚乳酸微球降解的过程及机制。方法 :用 5种方法分别研究 :①扫描电子显微镜观察微球外观形态及表面状态 ;②测定干燥失重 ;③凝胶渗透色谱法测定聚合物的平均相对分子量 ;④测定介质pH值 ;⑤测定介质中乳酸含量。结果 :聚乳酸 羟基乙酸微球的降解呈现明显外形改变和蚀解 ,聚乳酸微球降解表现为明显的溶胀和伴有孔洞形成。两者均降解成为分子量分布小的低聚物 ,介质中乳酸量明显增加以及pH显著下降。共聚物微球的降解速度随羟基乙酸比例的增加而加快。结论 :聚乳酸 羟基乙酸微球的降解为表面溶蚀与本体蚀解结合机制 。

AIM:To study the in vitro deg radation and it's mechanism of poly-d,l-lactide-co-glycolide (PLGA) and poly-d,l-lactic acid (PLA) microspheres METHOD:Using fi ve approaches:(1)assessment of surface morphology of microspheres by scannin g electro n microscopy;(2)assay of weight loss of drying weight loss;(3)assay of mole c ular weight of polymers by gel permeation chromatography;(4)assay of pH in the media;(5)assay of lactic acid in the media by HPLC RESULT: The de gradation of PLGA microspheres presented obvious externality change an d erosion The degradation of PLA microspheres presented distinct swell,accompanying with holes forming The rates of PLGA microspheres were accel erated by increasing the amount of glycolic acid in PLGACONCLUSION: The me chanism of PLGA mirospheres degradation is both surface erosion and bulk erosio n;the mechanism of PLA mirospheres degradation is bulk erosion