NIR-Activated Ag2S Quantum Dots for Efficient Broad-Spectrum Antibacterial and Biofilm Disruption

Abstract

Bacterial biofilms, encased in a protective extracellular polymeric substance (EPS) matrix and harboring metabolically dormant persister cells, pose a critical challenge in antimicrobial therapy due to their inherent resistance to conventional antibiotics. To overcome this, we present a near-infrared (NIR)-activated nanoplatform based on silver sulfide quantum dots (Ag₂S QDs) that synergistically integrates photothermal therapy (PTT) and photodynamic therapy (PDT). Under NIR irradiation, Ag₂S QDs rapidly generate localized hyperthermia and reactive oxygen species (ROS). This leads to complete eradication (99.99%) of planktonic bacteria within 10 min, as well as significant disruption of pre-established biofilms (69–84% removal). The mechanism involves photothermal-mediated degradation of the EPS barrier to facilitate deep penetration, and ROS-induced oxidative damage to bacterial membranes and intracellular components. This strategy exhibits a physical barrier-disruption paradigm that circumvents conventional antibiotic resistance mechanisms, demonstrating broad-spectrum activity, a well-defined therapeutic index, and spatiotemporally controllable biosafety for the precision treatment of biofilm-associated infections.