NIR-induced photothermal hydrogel with silver ions boosts antibiotic-resistant bacterial elimination and infectious wound healing.

Skin wound infection is a key factor that hinders the healing process and repair outcome of wounds, especially when it involves drug-resistant bacteria, which is extremely difficult to eliminate. Therefore, developing wound dressings with the ability to kill drug-resistant bacteria holds great value. Herein, carboxymethyl chitosan (CMCS) and 2,4,6-trihydroxybenzaldehyde (THBA)@silver ion chelates were assembled into a triple dynamically cross-linked hydrogel (CTA) through imine bonds, hydrogen bonds, and polyphenol metal chelate bonds. The CTA0.15 hydrogel exhibits sensitive near-infrared response properties. When exposed to 808 nm near-infrared light with a power density of 0.3 W/cm2, the temperature can easily rise to between 45 °C and 50 °C, enabling photothermal sterilization. Combined with the strong antibacterial activity of silver ions and the photothermal effect of the hydrogel, it can quickly (15 min) and completely eliminate common pathogenic bacteria (E. coli and S. aureus) and drug-resistant bacteria (MRSA) in vitro. In addition, this hydrogel also possesses injectability, tissue adhesiveness, self-healing property, shape adaptability, antioxidant capability, catalase (CAT)-like activity, and biocompatibility. The in vivo experiments and transcriptome analysis demonstrated that the combination of CTA hydrogel and NIR treatment significantly accelerated the healing process of MRSA-infected wounds by eliminating antibiotic-resistant bacterial infections, regulating inflammatory responses, promoting collagen deposition and angiogenesis.