Glucose-sensitive nano-films for insulin DDS

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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.