单分散性PLGA磁性微球制备及其缓释性研究

为获得单分散性PLGA磁性微球，文中以纳米四氧化三铁明胶分散液作为内水相(W1)，PLGA（聚乳酸羟基乙酸共聚物）的二氯甲烷溶液作为油相(O)，PVA（聚乙烯醇）水溶液作为外水相(W2)，利用T型微通道并采用复合乳液法制备PLGA磁性微球，考察流速比和油相与内水相体积比对微球制备的影响。借助FTIR、SEM及VSM（振动样品磁强计）对磁性微球组分、形貌、粒径分布和磁学性能进行表征；并以阿司匹林作为药物模型进行缓释性测试。结果表明：流速比v(W2):v(W1/O)=120:1且体积比V(O):V(W1)=2:1时可均匀成球，其粒径分布系数CV值仅为4.66%，表现出良好单分散性；此时比饱和磁化强度可达1.52emu/g，兼具优异顺磁性。制得的载药微球在60h内表现出阶段性匀速释放，且有较好磁响应性，有望用于磁响应性药物载体。

Preparation and release performance of monodisperse PLGA magnetic microspheres

In order to obtain monodisperse PLGA magnetic microspheres, compsite emulsion method and T-shaped microchannel device were adopted and used in this paper. Gelatin aqueous solution dispersed with nano-Fe3O4 particles was acted as inner aqueous phase. PLGA dichloromethane solution was served as oil phase. And PVA aqueous solution was used as outer aqueous phase. The effect of flow velocity ratio and volume ratio on the preparation of magnetic microspheres was investigated. The ingredient, morphology, size distribution and magnetic performance of resulted samples were characterized by means of FTIR, SEM and VSM respectively. Drug release performance of the microspheres was tested by using aspirin as the loading model drug. The results show that homogeneous spherical shape of the microspheres can be obtained at flow velocity ratio of the outer aqueous phase to the W/O phase is 120:1, as well as the volume ratio of the oil phase to inner aqueous phase is 2:1. The coefficient of variation (CV) with the microsphere size distribution can reach to 4.66%, indicating its good monodispersity. And the saturation magnetization is 1.52emu/g, showing high magnetic responsiveness. Meanwhile, the microsphere exhibit good paramagnetism. The drug loading microspheres show uniform release by stages within 60h. The monodisperse PLGA magnetic microspheres prepared in this paper is expected to be used for magnetic responsiveness drug carrier.