New dextrin-vinylacrylate hydrogel : studies on protein diffusion and release

New dextrin hydrogels with degrees of substitution (DS) from ca. 10% (DS 10) to 70% (DS 70) were prepared by radical polymerization of aqueous solutions of vinylacrylate (VA)-derivatized dextrin. A preliminary analysis on the potential of these hydrogels for the controlled release of bioactive molecules was carried out. The protein (bovine serum albumin) diffusion coefficients on the hydrogels were calculated using the lag-time analysis. Values in range 10−7 cm2/s were obtained for DS 20 and DS 40 and a smaller value of 10−8 cm2/s arised upon DS increasing to 70%, revealing the dependence of the diffusivity on the crosslinking density. The release of BSA from dextrin-VA hydrogels, in the presence of amyloglucosidase was shown to be mainly dependent on the diffusion and, to a smaller extent, on the degradation kinetics. The protein release can be tailored from days to months by varying the DS.This research was supported by Fundacao para a Ciencia e a Tecnologia under Grant SFRH/BD/17482/2004 and FUNCARB POC-TI/BIO/45356/2002