Nonreleasing AgNP Colloids Composite Hydrogel with Potent Hemostatic, Photodynamic Bactericidal and Wound Healing-Promoting Properties

Reactive oxygen species (ROS) produced by noble metallic nanoparticles under visible light is an effective way to combat drug-resistant bacteria colonized on the wound. However, the photocatalytic efficiency of noble metallic nanoparticles is limited by its self-aggregation in water media. Moreover, the fast release of noble metallic ions from nanoparticles might engender cellular toxicity and hazardous environmental issues. Herein, we chose AgNPs, the most common plasmonic noble metallic nanoparticles, as an example, modifying the surface of AgNPs with oleic acid and n-butylamine and imbedded them into calcium alginate (CA) hydrogel that holds tissue adhesion, rapid hemostatic, sunlight-sensitive antibacterial and anti-inflammatory abilities, and thus effectively promotes the healing of wounds. Unlike conventional AgNP-based materials, the constrain of colloids and hydrogel networks hinders the leach of Ag+. Nonetheless, the CA/Ag hydrogels exhibit on-demand photodynamic antibacterial efficacy due to the generation of ROS under visible light. In addition, the CA/Ag hydrogel can effectively stop the hemorrhage in a mouse liver bleeding model due to their skin-adaptive flexibility and tissue adhesiveness. The potent sunlight-responsive antibacterial activity of the CA/Ag hydrogel can effectively kill multidrug-resistant bacteria both in vitro (>99.999%) and in vivo (>99.9%), while the diminished Ag+ release guarantees its biocompatibility. The CA/Ag hydrogel significantly promotes the wound healing process by the downregulation of proinflammatory cytokines (TNF-α and IL-6) in a rodent full-thickness cutaneous wound model. Overall, the proposed multifunctional CA/Ag nanocomposite hydrogel has excellent prospects as an advanced wound dressing.