An efficient two-step preparation of photocrosslinked gelatin microspheres as cell carriers to support MC3T3-E1 cells...

Gelatin microspheres have been commonly used in tissue engineering, but their application is often limited by the uncontrollability and potential cytotoxicity of traditional chemical cross-linking method. Methylacrylamide modification and photocrosslinking provide a controllable and cytocompatible cross-linking method for gelatin hydrogels, however, microspheres fabricated by this single photopolymerization process is uncontrollable. In this study, we show that increasing the gelling ability of gelatin methacrylamide (GMA) at low temperatures is vital to prepare photocrosslinked gelatin microspheres, which in turn improves the controllability and compatibility of conventional chemical cross-linking methods. We detailed characterized the rheological performance with varying temperature and demonstrated that the gelling capability of GMA could be improved by increasing GMA solution concentration and reducing methacrylate substitution. The physicochemical properties of the photocrosslinked microspheres can be modulated via methacrylamide modification, as evidenced by the positive correlation between the physicochemical optimization of the hydrogel bulk and the degree of methacrylate substitution. Next, we successfully fabricated GMA spheres by a two-step process of low-temperature gelation followed by photopolymerization crosslinking. Finally, we show that the microcarriers exhibited favorable supporting for MC3T3-E1 cell proliferation, spreading, and osteogenic differentiation. This study provided a controllable and cytocompatible photocrosslinking procedure for GMA microspheres with broad application prospects, of course, not limited to cell microcarriers.