Bio-based poly (γ-glutamic acid)-gelatin double-network hydrogel with high strength for wound healing

Building bio-based hydrogels with high strength and biocompatibility is still a challenge. Herein, we successfully constructed a hybrid double-network (DN) full biological hydrogel with excellent mechanical properties and biocompatibility by introducing a physically cross-linked gelatin (GEL) network in a covalently cross-linked poly (gamma-glutamic acid) (gamma-PGA) network. The gamma-PGA-GEL DN hydrogel demonstrated ultra-high compression performance (38 MPa), which was better than all currently reported gamma-PGA-based hydrogels, and its tensile performance (0.27 MPa) was also satisfactory. Due to the unique multi-crosslinked DN structure, the gamma-PGA-GEL DN hydrogel had better recovery and healing properties than those of the gamma-PGA single-network (SN) hydrogel. In addition, the gamma-PGA-GEL DN hydrogel exhibited good transparency, swelling and degradability. In vitro cell experiments demonstrated that the gamma-PGA-GEL DN hydrogel was beneficial to cell adhesion and proliferation. The evaluation of the full-thickness skin defects model in rats exhibited that the gamma-PGA-GEL DN hydrogel could significantly accelerate wound healing. These results indicated that the gamma-PGA-GEL DN hydrogel was an ideal candidate material for wound dressing.