Novel chitosan hydrogels reinforced by silver nanoparticles with ultrahigh mechanical and high antibacterial properties for accelerating wound healing.

Poor mechanical properties of chitosan hydrogels limit their applications as the wound dressing. To overcome this drawback, we abandoned the traditional glacial acetic acid method but adopted a LiOH/urea solvent system to synthesize chitosan hydrogel. Then reductive Ag nanoparticles were integrated into the chitosan hydrogel networks, aiming at reinforcing the mechanical properties and improving the antibacterial properties of chitosan hydrogel. The synthesized hydrogels were subsequently characterized using the FTIR, XRD, SEM, and TEM. In addition, swelling characteristics, mechanical properties, antibacterial abilities as well as wound healing efficacy on Sprague-Dawley rats were evaluated. The results showed that the novel hydrogel exhibited porous three-dimensional network and ultrahigh mechanical properties due to the inter-molecular and intra-molecular interactions. The compressive strength was 15.95 ± 1.95 MPa, >100 times stronger than that of the control group. Meanwhile, the hydrogels still remained structural integrity even if the strain exceeded 90%. Furthermore, compared with the controls, the hydrogels exhibited more excellent antibacterial performance and significantly (p < 0.05) increased the rate of the re-epithelialization and collagen deposition, effectively accelerating the wound healing. Therefore, the synthesized hydrogel with ultrahigh mechanical properties will be found potential applications in the fields of biomedicine.