Fabrication of photothermal silver nanoparticles for accelerating MRSA-infected wound healing†

Recently, antibiotic-dependent strategies and photothermal therapy (PTT) have emerged as effective therapeutic approaches for treating bacterial infections. Currently, photothermal agents (PTAs) with bactericidal activities or antibiotics with photothermal effects are recognized as the most appropriate candidates for sterilization because of their enhanced bactericidal effects. In this study, we developed a novel strategy to fabricate photothermal silver nanoparticles (MP@AgNPs) via a green method using Mentha pulegium (MP) extract under UV radiation. By evaluating the biosynthesis parameters, small-sized MP@AgNPs mixed with small amounts of aggregates were obtained to enhance the absorption at NIR. This endowed MP@AgNPs with both PTA and antibiotic characteristics, which was confirmed by in vitro experiments. Apart from the outstanding antibacterial effect against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA), MP@AgNPs also exhibited multiple free radical scavenging activities. Benefiting from the superior photothermal effect, antioxidation activity and innate antimicrobial ability, MP@AgNPs embedded into the gelatin hydrogel network were used for treating MRSA-infected wounds. With the assistance of an 808 nm laser irradiation, MP@AgNPs significantly promoted the healing of infected skin injuries by killing the bacteria, eliminating inflammation cells and promoting collagen deposition. Thus, MP@AgNPs with photothermal and bactericidal functions offer great potential for the treatment of MRSA-infected wounds.