带有可调通道的嵌段共聚物胶束对药物的控制释放

用聚丙烯酸叔丁酯-b-聚乙二醇(PtBA45-b-PEG114)和聚丙烯酸叔丁酯-b-聚4-乙烯基吡啶(PtBA60-b-P4VP80)制备了复合胶束. 该胶束在pH=2.5的酸性水溶液中形成以PtBA为核, PEG和P4VP为壳的稳定球型结构. 在pH=12时, 壳层的P4VP链段变为疏水, 塌缩在PtBA的核上形成内壳, PEG链段继续保持溶解状态, 与成核的PtBA连接并穿过塌陷的P4VP内壳, 形成胶束的冠, 由于PEG处于溶解状态, 其分子链间有比较大的空隙, 可以控制一些小分子通过, 在胶束的表面形成通道. 该通道类似于生物膜的蛋白通道, 可以控制PtBA核与外界进行能量或物质交换的速度. 以布洛芬为模型分子, 负载在胶束内进行药物控制释放研究的结果表明, 胶束表面的通道可以起到明显控制布洛芬释放速度的作用, 并且药物的释放速度与通道在胶束表面的比例成正比.

Controlled Release for Drug by Complex Micelles of Block Copolymers with Tunable Channels

Complex micelles with insoluble PtBA block as core and PEG as well as P4VP as mixed shell were prepared with self-assembling of poly(tert-butyl acrylate)-b-poly(ethylene glycol)(PtBA45-b-PEG114) and poly(tert-butyl acrylate)-b-poly(4-vinylpyridine)(PtBA60-b-P4VP80) in water at pH=2.5. The result of dynamic light scattering(DLS) indicates that the complex micelles show a larger size than that of the individual micelles comprised of PtBA45-b-PEG114 or PtBA60-b-P4VP80 respectively. Increasing the pH value from 2.5 to 12, the P4VP chains will collapse upon the PtBA core because of their deprotonation, and hydrophilic PEG chains will pass through collapsed P4VP layer from the core and stabilize the whole micelle. Thus, channels inside the P4VP layer will form around insoluble PEG chains. Ibuprofen is loaded in these complex micelles at pH=2.5, and then releasing with increasing pH value to 12. The results indicate that channels on the surface of PtBA core can control the release of ibuprofen, and the release velocity is directly proportional to the percentage of channels on the micelles.