MODULATED DEGRADATION OF DEXTRAN HYDROGELS GRAFTED WITH Y(N-ISOPROPYLACRYLAMIDE-CO-N,N-DIMETHYLACRYLAMIDE) IN RESPONSE TO TEMPERATURE

Dextran hydrogels grafted with y(N-isopropylacrylamide-co-N,N-dimethyl acrylamide) were prepared, and their enzymatic degradation was examine d at different temperatures. Although swelling ratios for the hydrogel s are constant in a wide range of temperature, there is a drop of tran smittance of the hydrogels in the swollen state in relation to the low er critical solution temperature of (N-isopropylacrylamide-co-N,N-dime thylacrylamide). Temperature-dependent enzymatic degradation was obser ved in these hydrogels to depend on the molecular weight of the grafts . The degradability of the hydrogel with shorter grafts is independent of temperature. In contract, the degradability of the hydrogel with l onger grafts increases with increasing temperature . Such a modulated degradation of hydrogels is considered to be due to a change in the en tanglement between the grafted chain and dextran network by the hydrat ion behavior of the grafts.