Fabrication of antibacterial sericin based hydrogel as an injectable and mouldable wound dressing

Hydrogel-based wound dressings are ideal materials as they could provide a moist environment to promote wound healing. Silk sericin is a natural macromolecular protein produced by silkworms and has positive effects on fibroblasts and keratinocytes. Sodium alginate is a natural polysaccharide known as a mouldable matrix. To develop novel hydrogel wound dressings, sodium alginate was functionalized with silk sericin to yield an injectable and mouldable semi-interpenetrating network hydrogel (SA/Se) using calcium ions as the crosslinking agents. Meanwhile, silver nanoparticles (AgNPs) were synthesized in situ by the phenolic hydroxyl group of tyrosine in sericin to enhance the antibacterial activity of the hybrid hydrogel. UV-visible spectroscopy, fluorescence spectroscopy, transmission electron microscope, X-ray photoelectron spectroscopy and energy dispersive spectroscopy demonstrated the successful synthesis of AgNPs with average size of 15.7 nm in SA/Se-Ag0.2. Field emission scanning electron microscopy showed the macroporous structure of the hydrogel. The hybrid hydrogel had a swelling ratio of 32 and more than 5% of retention ratio after 50 h. It exhibited effective antibacterial activity through irreversibly disrupting bacterial membrane structure to result in bacterial lysis and death. Cell counting kit-8 assay suggested the hybrid hydrogel was highly cytocompatible. The animal experiment showed the wound contraction ratio in SA/Se-Ag0.2 group was 99% after 12 days, indicating it can effectively promote wound healing. This novel hydrogel is promising for wound healing and tissue engineering.