中文摘要：

对制备的新型聚乙二醇（PEG）接枝聚乳酸（PLA）在水中的自组装性能进行研究，探讨其作为纳米药物载体的可行性和稳定性．目测法得到其溶解度为（2．16～4．32）×10^-2mg·mL^-1；荧光法得到聚合物的临界胶束浓度为1．12×10^-3mg·mL^-1：透射电子显微镜观察显示该聚合物在水中的自组装聚集体为纳米级球形；动态激光光散射测试微球的粒径和Zeta电位发现，在微球的制备过程中，聚合物的亲／疏水性比例、水相介质及水溶液的pH值对它影响显著；而制备后，稀释和冷冻对它无显著影响，改变微球的环境pH值至酸性，出现聚集，至碱性无影响．研究结果显示，该聚合物在水和磷酸钠盐缓冲液中可形成稳定的纳米微球，通过微球的制备条件和存在环境可控制其粒径和Zeta电位，因此根据应用需要，通过控制其粒径和Zeta电位，可能提高微球的在体血液循环时间并实现靶向缓释．

英文摘要：

Amphiphilic polymers have vivid odds in the nano-drug system for its special self-assembly character. Here the self-assembly properties of polyethylene glycol （PEG）-graft-poly（lactic acid） （PLA） （PEG-g-PLA, PPLA） were investigated to explore its potential application to drug delivery. The dissolubility of PPLA in water was （2.16～4.32）× 10^-2 mg·mL^-1 according to eye judgment. The critical micelle concentration was 2.16× 10^-2 mg·mL^-1 obtained from a fluorospectrophotometer. The self-assembled aggregates of PPLA in water were nanoscale spheres observed by a transmission electron microscope. The particle size and zeta potential tests by dynamic light scattering revealed that during preparation, the ratio of hydrophilicity/hydrophobicity, the aqueous medium and the pH had great influences; while dilution, freezing and pH change to basic condition had no effect after preparation, but pH change to acidic condition made the nanoparticles precipitate. The results demonstrated that the particle size and zeta potential could be easily controlled so as to control their stay in some special tissues and realize a target.