Enhanced wound healing and antimicrobial efficacy of PHMB-loaded injectable chitosan/quaternary chitosan/NaHCO3/β-glycerophosphate hydrogels for seawater-infected wounds.

Bacterial infection is often linked to delayed wound healing. Seawater immersion further increases the risk of wound infection from bacteria in the water. A suitable wound environment is important for healing. In this study, to promote the healing of seawater immersion wounds, an injectable thermosensitive chitosan /quaternary chitosan/NaHCO3/β-glycerophosphate hydrogel wound dressings loaded with polyhexamethylene biguanide (PHMB) was developed. The physicochemical properties of the hydrogel were characterized, and antimicrobial and wound-healing capabilities were assessed. The hydrogel showed rapid gelling (2 min) at physiological temperature (35.15 °C), exhibiting adequate mechanical properties and enhanced network. The hydrogel demonstrates the ability to release 79.9 % of PHMB within 6 h. It also exhibits favorable adhesion and biocompatibility profile, characterized by a hemolysis ratio that remains below the 2 % threshold. In addition, the hydrogel loaded with 1 mg/mL PHMB demonstrated excellent antimicrobial properties both in vivo and in vitro. Furthermore, the hydrogel can reduce inflammatory cells, increase collagen fibre deposition and promote angiogenesis, demonstrating a high healing rate (95.03 % after 14 days) for wounds immersed in seawater. In summary, this injectable thermosensitive hydrogel shows great potential as a multifunctional dressing for treating complex bacterial wound infections and seawater-immersed wounds.