Preparation and characterization of oxidized starch/poly(N,N-dimethylaminoethyl methacrylate) semi-IPN cryogels and in vitro controlled release evaluation of indomethacin

Fabrication of novel semi-interpenetrating polymer network (semi-IPN) cryogels by cross-linking polymerization of N,N-dimethylaminoethyl methacrylate (DMAEM) in the presence of either oxidized potato starch (OPS) or oxidized wheat starch (OWS) and their characterization are presented in the paper. The influence of the nature of entrapped polymer on the properties of the composite cryogels was evaluated by the swelling kinetics, FT-IR spectroscopy, scanning electron microscopy, and response at external stimuli such as temperature, pH, and ionic strength. Indomethacin (IDM), taken as a model anti-inflammatory drug, was easily loaded into the composite cryogels by the solvent sorption-evaporation strategy. The in vitro release of IDM from the semi-IPN cryogels was low in simulated gastric fluid at pH 1.3, irrespective of the nature of the entrapped oxidized starch, and consistent in simulated intestinal fluid (SIF) at pH 7.4, the influence of the entrapped polysaccharide being evident. The release mechanism of IDM from the composite cryogels was discussed based on two kinetic models, finding that the drug release at 37 °C was pseudo-Fickian diffusion, regardless the cryogel composition.