Chitin is a
biopolymer, which has been proven to be a biomedical material candidate, yet the weak mechanical properties seriously limit their potentials. In this work, a
chitin-based double-network (DN)
hydrogel has been designed as a potential superficial repairing material. The
hydrogel was synthesized through a double-network (DN) strategy composing hybrid regenerated
chitin nanofiber (RCN)-
poly (ethylene glycol diglycidyl ether) (PEGDE) as the first network and
polyacrylamide (PAAm) as the second network. The hybrid RCN-PEGDE/PAAm DN
hydrogel was strong and tough, possessing Young's modulus (elasticity) E 0.097 ± 0.020 MPa,
fracture stress σf 0.449 ± 0.025 MPa, and work of fracture Wf 5.75 ± 0.35 MJ·m-3. The obtained DN
hydrogel was strong enough for surgical requirements in the usage of soft
tissue scaffolds. In addition,
chitin endowed the DN
hydrogel with good bacterial resistance and accelerated fibroblast proliferation, which increased the NIH3T3 cell number by nearly five times within 3 days. Subcutaneous implantation studies showed that the DN
hydrogel did not induce
inflammation after 4 weeks, suggesting a good biosafety in vivo. These results indicated that the hybrid RCN-PEGDE/PAAm DN
hydrogel had great prospect as a rapid soft-tissue-repairing material.