Bacteria-Activated AuNP Plasmonic Coupling: One-Step Photothermal Platform for Pathogen Detection and Sterilization

Bacterial infections caused by pathogens like Salmonella typhimurium (S. typhimurium) demand rapid, accurate detection and destruction to mitigate public health risks. Conventional culture-based methods are time-consuming, while existing nanomaterial biosensors often lack clinical validation. Here, we present a novel aptamer-stabilized gold nanoparticles (AuNPs)-based photothermal approach for integrated bacterial identification, detection, and destruction. The system exploits the localized surface plasmon resonance of AuNPs, whose aggregation-triggered by aptamer detachment in the presence of target bacteria─induces a redshift to the near-infrared (NIR) region, amplifying NIR photothermal conversion efficiency. This aggregation mechanism enables rapid (<1 h), instrument-free detection using a digital thermometer, achieving a sensitivity of 49 CFU/mL and a linear range of 10²-10⁷ CFU/mL. This method exhibits high specificity for S. typhimurium over other pathogens and demonstrates robust performance in clinical samples (feces, serum, wound exudates), showing 86.67% diagnostic accuracy and strong agreement with gold-standard bacterial culture method. By replacing aptamers, this approach extends to diverse pathogens, underscoring its universality. Crucially, the localized photothermal effect generated during detection achieves >90% bacterial destruction, preventing secondary contamination. This work bridges rapid diagnostics with therapeutic functionality, offering a cost-effective, clinically translatable solution for bacterial infection assay and infection control.