相分离-溶胀法制备生物可降解PELA多孔纳米微球

采用相分离-溶剂去除法制备纳米尺度的单甲氧基聚乙二醇-聚乳酸共聚物(PELA)微球，分析了纳米微球在溶液中的形成机理；用有机溶剂对纳米微球进行溶胀制孔，制备出具有不同孔道特征的纳米微球. 结果表明，以乙醇+丙酮为油相、去离子水为水相，油相中PELA含量6.5 g/L、水相中SDS含量1%、油与水相体积比1:6、油相中乙醇含量50%(j)条件下，所制微球粒径为78.48 nm. 溶胀时间为0.5 h时，以甲苯为溶胀剂所制PELA微球具有中空单孔结构，以二氯甲烷为溶胀剂所制PELA微球具有多孔结构. 用相同方法制备了具有孔结构的聚乳酸、聚(乳酸-羟基乙酸)共聚物纳米微球，其与PELA的成孔趋势相同. 以模拟体液考察多孔PELA纳米微球的降解性能，30 d可充分降解.

Preparation of Biodegradable Porous PELA Nanoparticles with Phase Separation and Solvent Extraction

Monomethoxy-poly(ethylene glycol)-b-poly-DL-lactide (PELA) nanoparticles were fabricated by phase separation and solvent extraction. The optimum particles were obtained by using ethanol and acetone as the oil phase and deionized water as the aqueous phase at PELA concentration in oil phase 6.5 g/L, ethanol concentration in oil 50(j), SDS concentration in water phase 10 g/L and volume ratio of oil to water 1:6, respectively. The average particle size was 78.48 nm. The forming mechanism of such nanoparticles was first discussed based on such a formation procedure. Porous nanoparticles were further prepared by solvent swelling and controlled evaporation. A hollow structure with single hole in the surface was obtained by toluene as the solvent, while that a multi-cell structure and porous surface by dichloromethane, the swelling time was 0.5 h. Besides PELA, poly(lactic acid) and poly(lactic-co-glycolic acid) nanoparticles with similar morphology were also prepared by similar procedures. The degradation performance of porous PELA nanoparticles with simulated body fluid showed that the adequate degradation was achieved after 30 d.