Effect of Cryogenic Treatment on the Rheological Properties of Gelatin Hydrogels

Gelatin has the ability to form a gel when cooled below the sol-gel temperature. In this study, the effects of various cryo-parameters, including the number of freeze-thaw cycles, cooling rate, thawing rate, and gelatin concentration, on the material properties were examined. The rheological properties of the cryogels improved with increasing cryo-cycles and decreasing cooling and thawing rates as well as were superior to those of the corresponding hydrogels formed at room temperature. In addition, the critical gelation concentration decreased after repeated cryo-treatments. Methacrylamide-modified gelatin was also treated cryogenically, followed by in situ UV irradiation to enable radical cross-linking. The cross-linking efficiency of specific gelatin concentrations improved with freeze-thawing. Cryogelation can be used to fine-tune the mechanical properties of hydrogels. This is of relevance to tissue engineering where porous gelatin hydrogels are used as biomaterials.