Inulin hydrogels. II. In vitro degradation study

Abstract

Inulin hydrogels have been developed as potential new carriers for colonic drug targeting. Since site-specific drug release of this delivery system is based on its bacterial degradation in the colon, the enzymatic digestibility of the prepared inulin hydrogels was assessed by performing an in vitro study using an inulinase preparation derived from Aspergillus niger. The amount of fructose liberated from the inulin hydrogels by the action of inulinase was quantified using the anthrone method. The equilibrium swelling ratio as well as the mechanical strength of the hydrogels were studied before and after incubation in inulinase solutions. The data obtained by these different methods indicate that enzymatic digestion of the inulin hydrogels appeared to be enhanced by a prolonged degradation time, a higher inulinase concentration and a lower degree of substitution and feed concentration of the hydrogel polymer. The inulin hydrogels exhibited an increase in equilibrium swelling after degradation compared to the swelling before degradation, suggesting that inulinase enzymes are able to diffuse into the inulin hydrogel networks causing bulk degradation.