mPEG-PLA共聚物胶束对DHA的增溶及光保护作用

以聚乙二醇单甲醚（mPEG）和外消旋丙交酯（D，L-LA）为原料，采用开环聚合法合成聚乙二醇单甲醚-聚乳酸（mPEG-PLA）共聚物，并用溶剂挥发法制备包载双氢青蒿素（DHA）的共聚物胶束（DHA/mPEG-PLA）。利用红外光谱（FT-IR）、核磁共振氢谱（¹H-NMR）和接触角测量仪研究了共聚物的结构和性质；利用激光粒度分析仪和扫描电镜（SEM）研究了胶束的粒径和形貌。结果表明mPEG-PLA共聚物的临界胶束浓度（CMC）为7.71 mg/L。DHA/mPEG-PLA共聚物胶束呈球形，平均粒径（118.1±1.9） nm，载药量和包封率分别为（2.7±0.1）%和（77.1±0.3）%。胶束对DHA的水相表观溶解度增大约1.5倍。紫外光光照39 h，纯DHA在混悬液中降解率达37%且持续增长，胶束中DHA降解率达到10%后基本保持不变。

Solubilizing and Light Protecting Effect of mPEG-PLA Copolymer Micelles on DHA

The methoxy poly(ethylene glycol)-poly(lactic acid)(mPEG-PLA) copolymer was synthesized by ring opening polymerization using methoxy poly(ethylene glycol)(mPEG) and D,L-lactide(D,L-LA).The dihydroartemisinin (DHA)-loaded copolymer micelles(DHA/mPEG-PLA) were prepared via solvent evaporation method.The chemical structure and property of copolymer were characterized by Infrared Spectroscopy(IR), proton Nuclear Magnetic Resonance(¹H-NMR) and contact angle measuring instrument.The size and morphology of the micelles were investigated by Nano ZS90 Zetasizer and Scanning Electron Microscopy(SEM).Results showed that the critical micelle concentration(CMC) of copolymer was 7.71 mg/L.The DHA/mPEG-PLA copolymer micelles were spherical in shape with average particle sizes of (118.1±1.9) nm,the entrapment efficiency and the loading capacity were (77.1±0.3)% and (2.7±0.1)%, respectively.The apprarent solubility of DHA in micellar solution was increased about 1.5 times as compared with DHA in aqueous solution.After 39 h of UV irradiation,the degradation rate of DHA in suspension was 37% and it still showed a rising trend,while the degradation rate in micelles tended to be a constant(10%).