Fabrication and characterization of biodegradable KH560 crosslinked chitin hydrogels with high toughness and good biocompatibility.

Chitin hydrogels have multiple advantages of nontoxicity, biocompatibility, biodegradability, and three-dimensional hydrophilic polymer network structure similar to the macromolecular biological tissue. However, the mechanical strength of chitin hydrogels is relatively weak. Construction of chitin hydrogels with high mechanical strength and good biocompatibility is essential for the successful applications in biomedical field. Herein, we developed double crosslinked chitin hydrogels by dissolving chitin in KOH/urea aqueous solution with freezing-thawing process, then using KH560 as cross-linking agent and coagulating in ethanol solution at low temperature. The obtained chitin/ KH560 (CK) hydrogels displayed good transparency and toughness with compressed nanofibrous network and porous structure woven with chitin nanofibers. Moreover, the optimal CK hydrogels exhibited excellent mechanical properties (σ = 1.92 ± 0.21 Mpa; ε = 71 ± 5 %), high swelling ratio, excellent blood compatibility, biocompatibility and biodegradability, which fulfill the requirements of biomedical materials and showing potential applications in biomedicine.