Glucose-responsive insulin delivery microhydrogels from methacrylated dextran/concanavalin A: Preparation and in vitro release study

Glucose-responsive systems are very important for self-regulated insulin delivery. The aim of the present study was to evaluate the potential of insulin loaded microhydrogels fabricated from methacrylate derivatives of dextran (Dex-G) and concanavalin A (Con A-E) as a insulin delivery system releasing insulin in response to different glucose levels. Insulin-loaded microhydrogels were prepared through a reversed-phase emulsion crosslinking method. The morphology and size of obtained microhydrogels were characterized by SEM, fluorescence microscope and dynamic light scattering, which showed that these microhydrogels were formed with sphere-like shape and diameters less than 5 mu m. In vitro release of insulin from these microhydrogels and release kinetics were studied. The results indicated that insulin release was reversible in response to different glucose concentrations and the released insulin was shown to remain active since the tertiary structure was not destroyed. The degree of substitution (DS) of dextran methacrylate derivatives had effects on the release rate and surface burst release of the microhydrogels and high DS of Dex-G (DS 32) restricted the glucose sensitivity of the microhydrogels. The MTT assay from L929 cell line indicated that these microhydrogels possessed noncytotoxicity. The results suggested that these microhydrogels might be suitable for self-regulated insulin delivery and find potential applications in biomedical fields. (C) 2012 Elsevier Ltd. All rights reserved.