Glucose-sensitive nano-films for insulin DDS

葡萄糖敏感薄膜已成功地制备使用刀豆球蛋白A和糖原或合成糖聚合物的基础上逐层沉积。薄膜的性能在很大程度上取决于聚合物材料的化学结构。糖原膜性能最好。糖原基膜在pH 7-9中稳定，并且在mM水平的葡萄糖存在下在几分钟内分解。其他糖如甘露糖和甲基化葡萄糖也诱导膜的分解，这取决于糖与伴刀豆球蛋白A的结合常数。为了评价胰岛素在纳米膜中的渗透性，将聚电解质层层沉积在含胰岛素的碳酸钙表面制备纳米胶囊，并监测胰岛素的释放行为。胰岛素从纳米胶囊的释放速率取决于用于胶囊制备的聚合物材料的类型。胰岛素从使用聚（乙烯亚胺）制备的胶囊中快速释放，而如果胶囊使用聚（烯丙胺）构建，则释放速率相对较慢。约10%的胰岛素释放从聚（烯丙胺）为基础的胶囊30分钟后。相比之下，70%的胰岛素释放从聚（乙烯亚胺）为基础的纳米胶囊。释放速率取决于胶囊膜的厚度。因此，证明了这些纳米膜可用于开发胰岛素的DDS系统。

Glucose-sensitive thin films have been successfully prepared using concanavalin A and glycogen or synthetic sugar polymers based on a layer-by-layer deposition. The properties of thin films significantly depended on the chemical structures of the polymeric materials. Glycogen afforded best property among the films. The glycogen-based films are stable in pH 7-9,and decomposed in a few minutes in the presence of glucose at mM level. Other sugars such as mannose and methylated glucose also induced decomposition of the films depending on the binding constants of the sugars to concanavalin A. The results can be explained reasonably based on a competitive binding of the sugars to concanavalin A in the films.In order to evaluate the permeability of insulin across the nano-films, insulin was encapsulated in nanocapsules which were fabricated by a layer-by-layer deposition of polyelectrolytes on the surface of calcium carbonate containing insulin and release behavior of the insulin was monitored. The release rate of insulin from the nanocapsules depended on the type of polymeric materials used for the capsule preparation. The insulin released rapidly from the capsules prepared using poly(ethyleneimine), while the release rate was relatively slow if the capsule was constructed using poly(allylamine). About 10% of insulin was released from the poly(allylamine)-based capsule after 30 min. In contrast, 70% of insulin was released from the poly(ethyleneimine)-based nanocapsule. The release rate was dependent on the thickness of the film of the capsules. Thus, it was demonstrated that these nano-films are useful for developing DDS systems for insulin.