Deng X, Zhou S, Li X, Zhao J, Yuan M
Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, P.O. Box 415, 610041, Chengdu, China.
J Control Release. 2001 Apr 2;71(2):165-73. doi: 10.1016/s0168-3659(01)00210-3.
Poly-dl-lactide-poly(ethylene glycol) (PELA) block copolymers containing same the content (10%) of polyethylene glycol (PEG) were synthesized with five different molecular weight of PEG by ring-opening polymerization. PELA microspheres containing human serum albumin (HSA) were elaborated by solvent extraction method based on the formation of double w/o/w emulsion. In vitro matrix degradation and protein release of these microspheres were performed in phosphate-buffered saline (PBS) (154 mM, pH 7.43). The degradation profiles were characterized by measuring the loss of microspheres mass, the decrease of polymer intrinsic viscosity, the decrease of pH value of degradation medium, the reduction of polymer number-average molecular weight (M(n)) and the change of molecular weight polydispersity (M(w)/M(n)). The release profiles were investigated from the measurement of protein presented in the release medium at various intervals. It showed that the matrix degradation and protein release profiles were highly polymer-dependent. The extent of burst release in the initial protein release increased with the decrease of molecular weight of PELA copolymer. It is suggested that these matrix polymers may be optimized as carriers in protein (antigen) delivery system for different purposes.
通过开环聚合法，使用五种不同分子量的聚乙二醇（PEG）合成了含有相同含量（10%）聚乙二醇的聚-dl-丙交酯-聚（乙二醇）（PELA）嵌段共聚物。基于双水包油包水乳液的形成，采用溶剂萃取法制备了含有人类血清白蛋白（HSA）的PELA微球。在磷酸盐缓冲盐水（PBS）（154 mM，pH 7.43）中对这些微球进行体外基质降解和蛋白质释放实验。通过测量微球质量损失、聚合物特性粘度降低、降解介质pH值下降、聚合物数均分子量（M(n)）降低以及分子量多分散性（M(w)/M(n)）变化来表征降解曲线。通过在不同时间间隔测量释放介质中蛋白质的含量来研究释放曲线。结果表明，基质降解和蛋白质释放曲线高度依赖于聚合物。在初始蛋白质释放中，突释程度随着PELA共聚物分子量的降低而增加。建议这些基质聚合物可针对不同目的优化用作蛋白质（抗原）递送系统中的载体。
