Mechanism and characteristics of protein release from lactitol-based cross-linked hydrogel

Lactitol-based cross-linked hydrogel was synthesized, and model proteins (o r-chymotrypsin, p-lactoglobulin, bovine serum albumin (BSA), and gamma -glo bulin) were incorporated into the cross-linked hydrogel. The larger molecul ar-weight proteins have lower diffusivity (D-e) in the hydrogel. Increasing temperature accelerated the diffusion rate of proteins; however, the diffu sion did not follow the Arrhenius equation at temperatures above 37 degrees C. The swelling ratio of the hydrogel was slightly decreased after heating for 2 h at 37 and 45 degreesC, and significantly reduced after lh at 60 deg reesC. Therefore, diffusion of beta -lactoglobulin and BSA may be decreased by hydrogel shrinking at temperature over 37 degreesC. The model proteins have high affinities to buffer solution compared to the hydrogel network st ructure, resulting in high partition coefficients (K > 1) which do not affe ct the calculation of D-e values. Incorporated protein release follows the theory of hindered diffusion.