Synthesis and characteristics of pH-sensitive semi-interpenetrating polymer network hydrogels based on konjac glucomannan and poly(aspartic acid) for in vitro drug delivery

A novel pH-sensitive semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared by using konjac glucomannan (KGM) and poly(aspartic acid) (PAsp) with trisodium trimetaphosphate (STMP) as the cross-linking agent. The effects of component ratio, cross-linking density (STMP concentration), pH and ionic strength on the swelling properties of hydrogels were investigated. The structure of the semi-IPN hydrogels were characterized by fourier transform infrared spectroscopy (FT-IR), surface area analyzer and scanning electron microscopy (SEM). The equilibrium swelling characteristics were investigated at 37 °C in buffer solutions of pH 2.2 and 7.4 as simulated gastric and intestinal fluids, respectively. At pH 2.2, the release amount of 5-Fluorouracil (5-FU) incorporated into the hydrogels was about 23% within 180 min, while this value approached to 95% at pH 7.4. These results showed that the semi-IPN hydrogels could be a suitable polymeric carrier for site-specific drug delivery in the intestine.