Activated Au@Ag Nanoparticle-Based Platform for Synergistic Photodynamic/Ag ⁺ Antibacterial Therapy

Bacterial infections, aggravated by antibiotic misuse, contribute to the rise of drug-resistant strains and pose a major threat to human health. Therefore, developing infection microenvironment-responsive intelligent antimicrobial agents is critical for combating bacterial resistance and improving antimicrobial efficacy. This study presents an innovative reactive oxygen-species-activated Au@Ag nanoplatform for combined photodynamic therapy (PDT)-Ag antibacterial treatment. The Au@Ag@CM platform was synthesized by functionalizing Au@Ag with a positively charged chitosan (CS) layer and a hypochlorous-acid-responsive ligand (FDOCl-24). The CS coating enhanced interaction with negatively charged bacterial membranes, while ROS activation of Au@Ag@CM triggered the release of methylene blue photosensitizer from the nanoparticles, enabling PDT within the infection microenvironment. The Au@Ag nanoparticles not only amplified photodynamic effects through their surface plasmon resonance properties but also released silver ions at the infection site, facilitating a synergistic photodynamic-silver antibacterial response. In vitro experiments revealed significant antibacterial efficacy of the platform. In vivo data further demonstrated its effective wound infection healing capability in mice. This research offers a promising approach for developing responsive antibacterial nanoplatforms tailored to the unique conditions of infected microenvironments with the potential to advance precision medicine.