Double-stimuli-responsive degradable hydrogels: interpenetrating polymer networks consisting of gelatin and dextran with different phase separation

Biodegradable interpenetrating polymer network (IPN)-structured hydrogels consisting of gelatin (Gtn) and dextran (Dex) were prepared by sequential crosslinking reactions of Gtn and methacryloylated Dex. Phase separation of these hydrogels is dominated by preparation conditions, i.e., above or below the sol-gel transition temperature (T_trans) of Gtn. Enzymatic degradation by either α-chymotrypsin or dextranase is hindered for the IPN-structured hydrogel prepared below T_trans whereas this hydrogel is perfectly degradable in the presence of both enzymes. Such a specific feature of enzymatic degradation was not observed for the hydrogel prepared above T_trans. These results suggest that double-stimuli-responsive degradation of IPN-structured hydrogels is related to their phase separation.