Dual-stimuli-responsive drug release from interpenetrating polymer network-structured hydrogels of gelatin and dextran

Interpenetrating polymer network (IPN)-structured hydrogels of gelatin (Gtn) and dextran (Dex) were prepared with lipid microspheres (LMs) as a drug microreservoir, and LM release from these hydrogels was examined in relation to :heir dual-stimuli-responsive degradation. A phase morphology in the IPN-structured hydrogels was varied with the preparation temperature, i.e. above or below the sol-gel transition temperature (T-trans) of Gtn. The IPN-structured hydrogel prepared below T-trans exhibited a specific degradation-controlled LM release behavior: LM release from the hydrogel in the presence of either alpha-chymotrypsin or dextranase alone was completely hindered, whereas LM release was observed in the presence of both enzymes. It is concluded that dual-stimuli-responsive drug release can be achieved by specific degradation of a particular IPN-structured hydrogel. (C) 1998 Elsevier Science B.V.