Novel hemocompatible nanocomposite hydrogels crosslinked with methacrylated gelatin

Methacrylated gelatin (MA-gelatin) is a gelatin derivative synthesized by the reaction with methacrylic anhydride; the degree of substitution (DS) of primary amines by methacrylamide groups in the gelatin is closely related to the dosage of methacrylic anhydride. In this work, MA-gelatin has been developed as a macromolecular crosslinker to prepare novel nanocomposite hydrogels (NC gels) based on polyacrylamide (PAAm) and LAPONITE (R) nanoclay. Compared with unmodified gelatin, MA-gelatin improves the stability of the LAPONITE (R) suspension in the pre-gel system. FTIR results confirm the success of gelatin modification, in agreement with the H-1 NMR result, and the copolymerization of MA-gelatin and acrylamide monomers in the NC gel network. The increasing DS of MA-gelatin thus reduces the equilibrium swelling ratio (ESR) and pore sizes, and enhances the mechanical properties of the NC gels, due to the macromolecular crosslinking effect. Unlike the small molecular crosslinker N,N'-methylenebisacrylamide (BIS), MA-gelatin shows a stronger influence on the swelling behaviours and mechanical properties of NC gels. Moreover, the MA-gelatin crosslinked NC gels exhibit decreased bovine serum albumin (BSA) adsorption, prolonged blood-clotting time and nonhemolytic nature, indicating the improved antithrombogenicity. The results show that MA-gelatin can be a hemocompatible macromolecular crosslinker for the fabrication of biomedical materials.