Multifunctional Injectable Hydrogel Dressings for Effectively Accelerating Wound Healing: Enhancing Biomineralization Strategy

Designing wound dressing materials with outstanding therapeutic effects, self-healing, adhesiveness and suitable mechanical property has great practical significance in healthcare, especially for joints skin wound healing. Here, we designed a kind of self-healing injectable micelle/hydrogel composites with multi-functions as wound dressing for joint skin damage. By combining the dynamic Schiff base and copolymer micelle cross-linking in one system, a series of hydrogels were prepared by mixing quaternized chitosan (QCS) and benzaldehyde-terminated Pluronic®F127 (PF127-CHO) under physiological conditions. The inherent antibacterial property, pH-dependent biodegradation and release behavior were investigated to confirm multi-functions of wound dressing. The hydrogel dressings showed suitable stretchable and compressive property, comparable modulus with human skin, good adhesiveness and fast self-healing ability to bear deformation. The hydrogels exhibited efficient hemostatic performance and biocompatibility. Moreover, the curcumin loaded hydrogel showed good antioxidant ability and pH responsive release profiles. In vivo experiments indicated that curcumin loaded hydrogels significantly accelerated wound healing rate with higher granulation tissue thickness and collagen disposition and upregulated vascular endothelial growth factor (VEGF) in a full-thickness skin defect model. Taken together, the antibacterial adhesive hydrogels with self-healing and good mechanical property offer significant promise as dressing materials for joints skin wound healing.

The antibacterial effect and mechanism of action of a silver ion solution that was electrically generated were investigated for Staphylococcus aureus and Escherichia coli by analyzing the growth, morphology, and ultrastructure of the bacterial cells following treatment with the silver ion solution. Bacteria were exposed to the silver ion solution for various lengths of time, and the antibacterial effect of the solution was tested using the conventional plate count method and flow cytometric (FC) analysis. Reductions of more than 5 log(10) CFU/ml of both S. aureus and E. coli bacteria were confirmed after 90 min of treatment with the silver ion solution. Significant reduction of S. aureus and E. coli cells was also observed by FC analysis; however, the reduction rate determined by FC analysis was less than that determined by the conventional plate count method. These differences may be attributed to the presence of bacteria in an active but nonculturable (ABNC) state after treatment with the silver ion solution. Transmission electron microscopy showed considerable changes in the bacterial cell membranes upon silver ion treatment, which might be the cause or consequence of cell death. In conclusion, the results of the present study suggest that silver ions may cause S. aureus and E. coli bacteria to reach an ABNC state and eventually die.