Strong fish gelatin hydrogels double crosslinked by transglutaminase and carrageenan

Gelatin hydrogels are usually soft and thermally unstable. Here, strong fish gelatin hydrogels were successfully prepared by double crosslinking gelatin with transglutaminase (TGase) and kappa-carrageenan, and the mechanical properties and thermal stability of the double crosslinked gelatin hydrogels were significantly improved. Results showed that the gel strength, compression fracture stress and storage modulus of the double crosslinked gelatin hydrogels all reached the largest value when the concentration of TGase was 20 U/g gelatin. The double crosslinked gelatin hydrogels were also thermally stable due to the existence of the covalent crosslinks. The effect of TGase concentration on the physical properties and microstructure of the double crosslinked hydrogels were analyzed, and the differences between double crosslinked gelatin hydrogels and gelatin hydrogels single crosslinked by TGase or carrageenan were also systematically compared. This article is of great significance for expanding the application of natural polymer-based hydrogels.