Preparation and Characterization of Biocompatible Hydrogels Based on a Chitosan-Polyacrylamide Copolymer

Hydrogels comprised of natural and synthetic polymers are widely used in the biomedical field due to their distinguishing properties, such as softness, flexibility, swelling, and biocompatibility. In this study, we obtained and characterized hydrogel materials based on chitosan/acrylamide copolymer as potential matrices for biomedical applications. FTIR studies confirmed the formation of chitosan/polyacrylamide graft copolymer. Kinetics of gel formation was investigated with the rheological tests and the change of reaction mixture viscosity in the shear mode was measured. Scanning electron microscopy revealed a porous surface with micron- and submicron-sized gels. The kinetics of swelling/drying processes in the obtained hydrogels were studied at varying pH values. A significant decrease in the equilibrium swelling degree in an alkaline medium was observed, dropping from 50 g/g in the first cycle to 36 g/g in the second cycle. Mechanical characteristics of the chitosan/polyacrylamide hydrogel-shaped samples were tested both in compression and tension modes. It was found that for the samples swollen at pH 6.8, the tensile and compression strengths were 37 kPa and 19 kPa, respectively. The biological activity of the obtained hydrogels was evaluated by the MTT test. The kinetics of drug release from hydrogels in phosphate buffer was studied using lidocaine hydrochloride as a model compound.