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

Bacterial infections caused by pathogens like <i>Salmonella typhimurium</i> (<i>S. typhimurium</i>) 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 <i>S. typhimurium</i> 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.