Radiation crosslinking of carboxymethyl hyaluronic acid

Carboxymethyl hyaluronic acid (CMHA) with degree of substitution of 0.5 was synthesized and crosslinked by gamma-irradiation in paste-like state (highly concentrated solution) at doses of 50-100 kGy without the addition of any initiators and crosslinking agents to obtain hydrogels with different properties. Gel fraction of 11-46% which is increasing with dose was obtained. Swelling in water of CMHA hydrogels ranged from 46 to 168 g H2O/g dry gel while swelling in physiological saline solution (0.9% NaCl) ranged from 21 to 31 g saline/g dry gel. FTIR spectra of the hydrogels revealed decarboxylation and cleavages of glycosidic bond and amide group.