Spirulina protein isolate/carboxymethyl chitosan based emulsion gel with pH/enzyme-responsive release of curcumin for enhanced infected wound healing.

In infected full-thickness skin injuries, deep wound exposure accompanying bacterial invasion and persistent inflammatory lead to prolonged wound healing, remaining a major challenge in clinical wound healing. In this work, an emulsion gel (SCEG) with pH/enzyme-responsive release for promoting infected wound repair was successfully constructed based on the Spirulina protein isolate/carboxymethyl chitosan (SPI/CMC) system. The SCEG was prepared by cross-linking the SPI/CMC emulsion with tetrakis (hydroxymethyl) phosphonium sulfate (THPS) through the Mitchell reaction. It effectively encapsulated the curcumin (Cur) with an encapsulation efficiency of 87.26 % and exhibited pH/enzyme-responsive release behavior. The SCEG showed excellent antibacterial activity against both S. aureus and E. coli. Additionally, it can evidently alleviate oxidative stress and maintain cell activity. Meanwhile, it could significantly reduce the secretion of pro-inflammatory cytokines TNF-α and IL-1β. Finally, a model of full-thickness skin damage infected with S. aureus was built to assess the wound healing effect of SCEG. The result showed that it can efficaciously inhibit bacterial infection of the wound, reduce inflammatory response, promote angiogenesis, accelerate tissue regeneration, and thus boost the healing process. Altogether, the emulsion gel dressing is expected to be a safe, efficient and promising candidate material for the field of infectious wound care.