PLGA基载药复合微球的制备及其释放性能

以聚乳酸-羟基乙酸(PLGA)为载体材料,牛血清蛋白(BSA)为蛋白模型药物,采用复相乳化溶剂法制备PLGA载药微球,探索载药微球制备过程中囊芯比、初乳水油比、分散剂浓度、超声乳化时间对微球粒径大小、载药率、包封率的影响。结果表明,最优载药微球的制备条件为:囊芯比1∶1,初乳水油比3∶5,分散剂质量分数0.5%,超声乳化时间2 min。在此条件下,所得PLGA微球的粒径为268.7 nm,载药率30.88%,包封率46.95%;电镜照片表明微球表面连续光滑,粒径分布较均匀。采用静电吸附法用阳离子聚电解质壳聚糖对最佳条件下的PLGA载药微球进行表面修饰,扫描电镜表明复合后微球粒径变大,能谱分析表明复合后微球中有N元素存在,即复合微球中存在壳聚糖,电荷测试表明微球表面带正电;体外释放实验表明PLGA-CS复合载药微球的缓释时间延长,释药初期的突释性明显改善。

Preparation and drug release properties of PLGA complex microparticles

Poly( lactic?co?glycolic acid) ( PLGA) microparticles were prepared by an emulsion?solvent evaporation tech?nique using bovine serum albumin ( BSA) as model drug. When the ratio of shell to core was 1∶1, ratio of water to oil 3∶5, dispersant concentration 0.5%, and the ultrasonic emulsification time 2 min, PLGA microparticles were 268.7 nm in diameter, characterized by the laser light scattering technique, and the drug content and drug encapsulation efficiency in this case were 30.88% and 46.95%, respectively. Scanning electron microscopy ( SEM) and transmission electron mi?croscope ( TEM) showed the products were spherical in shape and uniform in dimension. When the PLGA microparticles surface was modified with chitosan ( CS) by adsorption technique, the microparticle became larger in diameter. The presence of N element and the positive zeta potential of modified microparticles revealed the presence of CS on the sur?face of the PLGA microparticles. In vitro drug release test showed that the burst release of modified microparticles eased and the release time was prolonged compared with unmodified PLGA microparticles.