Novel enzyme-based hydrogels for drug delivery were prepared by combining dextran with 5,5'-azodisalicylic acid using isophorone diisocyanate as the cross-linking agent. The structure of the resultant dextran/5,5'-azodisalicylic acid hydrogels was determined by infrared spectra, and the properties of the hydrogels; were characterized by swelling measurements and scanning electron microscopy analysis. It was found that changing the concentration of 5,5'-azodisalicylic acid affected the crosslinking density of the hydrogels and resulted in significant differences in the water swelling property and degradability of the hydrogels. Compared with their degradability, the degradation of the hydrogels seemed to be more pronounced by azoreductase in cecum content medium than that by hydrolysis in phosphate buffer solution (PBS). Also, the release rate of the protein in cecum content medium was faster than that in PBS. Attributing to the results of the resultant hydrogels described earlier, it could be concluded that dextran/5,5'-azodisalicylic acid hydrogels could be used as a potential enzyme-based carrier for colon-specific drug delivery. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3944-3953, 2009