A water-soluble photocrosslinkable chitosan derivative prepared by Michael-addition reaction as a precursor for injectable hydrogel

With the goal of obtaining photopolymerized hydrogels for use as tissue engineering scaffolds, a water-soluble (methacryloyloxy) ethyl carboxyethyl chitosan was prepared as a photopolymerizable prepolymer through Michael-addition reaction between chitosan and ethylene glycol acrylate methacrylate. N-substitution of chitosan was verified by both 1H NMR and 13C NMR The degree of N-substitution, measured via 1H NMR, was easily varied from 0.10 to 0.35 by varying the molar ratio of ethylene glycol acrylate methacrylate to chitosan. Using a Vero cell line, the water-soluble photocrosslinkable chitosan derivative was found to be noncytotoxic up to a concentration of 1.0 mg/mL. The precursor was blended with D-2959 photoinitiator in solution, and UV-irradiated to create hydrogels. FTIR verified the nearly complete conversion of the double bonds in the gel. Indirect cytotoxicity assessment of the hydrogel indicated that the hydrogel was non-toxic to Vero cells.