Smart controlled release of acarbose from glucose-sensitive hydrogels comprising covalently modified carboxylated pullulan and concanavalin A

A hydrogel comprising covalently modified carboxylated pullulan and concanavalin A (CPUL-ConA) was prepared with glucose-sensitivity in a simulated small intestinal fluid containing glucose. The acarbose-encapsulated CPUL-ConA (Acar/CPUL-ConA) hydrogel, with an acarbose encapsulation ratio of 0.63, was prepared by immersing the dried CPUL-ConA hydrogel in an acarbose/PBS (pH 7.2) solution. In the simulated gastric fluid, less than 20% acarbose was released from the Acar/CPUL-ConA hydrogel, which could be beneficial to protecting the stomach. In contrast, more than 80% acarbose was smartly controlled released from the Acar/CPUL-ConA hydrogel in the simulated small intestine fluid containing glucose. Scanning electron microscopy provided further evidence of the smart release of acarbose from the Acar/CPUL-ConA hydrogel in simulated gastrointestinal fluids, which is advantageous to inhibiting alpha-glucosidase activity and subsequently reducing the postprandial blood glucose levels, as well as helpful for reducing the gastrointestinal dysfunction of acarbose. Rheological analysis indicated that the Acar/CPUL-ConA hydrogel showed characteristics of chemical crosslinked hydrogels. There was no obvious shear thinning behavior, suggesting that the Acar/CPUL-ConA hydrogel could be stable under gastric and intestinal peristalsis. Therefore, the Acar/CPUL-ConA hydrogel is anticipated to improve the therapeutic efficacy of postprandial hyperglycemia and type 2 diabetes.