中文摘要：

研究试图通过本体改性,将生物素接枝到聚乙二醇接枝聚乳酸（PPLA）上,以改善聚乳酸微球在药物缓释应用中血液循环时间短和无主动靶向性的缺点。在本实验室制备的聚乙二醇接枝改性聚乳酸的基础之上,采用N-羟基琥珀酰亚胺活化酯法,将生物素接枝到PPLA上,制备生物素改性聚乳酸（BPLA）。通过茚三酮显色、核磁共振（1 H-NMR）,差示扫描量热（DSC）,静态水接触角、荧光蛋白标记法对材料进行表征与检测。结果表明,生物素已经共价接枝到聚乳酸上;与PPLA相比,BPLA明显降低了对牛血清白蛋白（BSA）的吸附,有望提高聚乳酸微球在血液循环系统中的停留时间;同时能与生物素的配体亲和素结合,有望通过生物素和亲和素的高亲和性实现主动靶向,可能使BPLA在药物缓释中有潜在应用价值。

英文摘要：

The aim of this research is to overcome the drawbacks of PLA in drug delivery system,which are short blood circulation time and non-active targeting.Based on PEG-graft-PLA（PPLA） developed in our lab,biotin was grafted onto PLA to produce BPLA by NHS-activated method.The ninhydrin coloration,1H-NMR,DSC,water contact angle test,fluorescence labeled protein absorption test were used to characterize BPLA.Results from ninhydrin coloration,1H-NMR,DSC,water contact angle test showed the biotin had been covalently grafted onto PPLA.Fluorescence labeling test demonstrated that the new BPLA had the property of decreasing the nonspecific protein（BSA） absorption and increasing specific protein absorption（Avidin） evidently compared with PPLA.It was predicted that BPLA could increase the blood circulation time,meanwhile can combine with its ligand-avidin through high affinity or combine with the biotionylated protein via avidin as arm,which may have the active targeting in drug delivery system.