An injectable, adhesive, and self-healable composite hydrogel wound dressing with excellent antibacterial activity

• A hydrogel developed with fusiform-like ZnO(brZnO) and carboxymethyl chitosan. • The brZnO works both as crosslinker and nano-fillers in the construction of hydrogel. • The hydrogel displays bidirectional sol-gel conversions at 42 °C and 26 °C. • The hydrogel possesses excellent injectability, self-healing, antibacterial activity. • The hydrogel creates a sterilized micro-environment that promotes wound tissue repair. Hydrogels have attracted extensive attention as wound dressing because they can provide a moist microenvironment to accelerate wound healing. However, simple physical coverage of wound cannot satisfy the complicated process of wound repair. Here, we report an injectable multifunctional hydrogel (CMCS-brZnO) synthesized by incorporating fusiform-like zinc oxide nanorods (brZnO) into carboxymethyl chitosan (CMCS), in which the brZnO works dually as crosslinker and nano-filler. The hydrogel possesses controllable gelation time, quick self-healing, good tissue adhesion and fast hemostasis capability. Further, the CMCS-brZnO hydrogel presents excellent antibacterial properties with minimal inhibitory concentration (MIC) for E.coli and S.aureus of 0.0125 and 0.025 mg mL -1 , respectively. The hydrogel could be injected directly into the irregular-shaped wounds in a full-thickness skin defect experiment, and the good fitting of the gel to the wound geometries together with the slow and sustainable release of antibacterial Zn 2+ significantly promoted wound healing and reduced the inflammatory response. This study illustrates that the CMCS-brZnO hydrogels with an organic-inorganic micro-structure have great potential in accelerating wound healing.