Dynamically self-degradable, injectable and self-healing 6-deoxy-6-arginine grafted chitosan hydrogels for wounds healing

6-Deoxy-6-arginine grafted chitosan (DAC) is cross-linked with dibenzaldehyde-functionalized polyethylene glycol (DF-PEG) via the acylhydrazone (–N=CH–) bonds, which can be utilized for the encapsulation of metformin (MET). The resultant injectable DAC/DF-PEG/MET (DDM) hydrogels highlight well-behaved antibacterial and anti-inflammatory activity as well as self-healing capability. More interestingly, the DDM hydrogels exhibit appealing dynamic self-degradability. The electrostatic attraction between DAC and DF-PEG is significantly weakened at slightly alkaline surface (pH 7.0–8.0) that is the characteristic of skin wounds, resulting in the swelling of the hydrogels and the release of MET. As the wounds gradually get healed, the skin tissue turns to be weakly acidic (pH 4.0–6.0), leading to the hydrolysis of the –N=CH– bonds between DAC and DF-PEG. Therefore, the DDM hydrogels can be dynamically self-degraded during the wound healing process. Owing to the injectability and self-healing properties, the DDM hydrogels are suitable for use as the wound dressing for the wounds in any shape. The developed DDM hydrogels also display excellent hemocompatibility and cytocompatibility, indicating that they might be a potential wound dressing for skin wounds.