Dual-Functional Aptasensor for the Detection and Inactivation of <i>Salmonella</i> Based on Cascade Signal Amplification Coupled with Ag–Pt Nanozymes

The establishment of a pathogen monitoring platform that integrates detection and disinfection can effectively reduce the risk of secondary pollution. Herein, we report a dual-functional aptasensor for ultrasensitive detection and efficient inactivation of <i>Salmonella</i> based on cascade signal amplification and nucleic-acid-templated silver-platinum (Ag-Pt) nanozymes. Specifically, in the presence of <i>Salmonella</i>, the method promotes an exponential amplification reaction (EXPAR) and automatic assembly circuit (AAC) reaction by aptamer targeting bacteria, accompanied by an exponentially magnified "turn-on" fluorescence. Concurrently, guided by an aptamer, Ag-Pt nanozymes attached to the surface of <i>Salmonella</i> can catalyze H₂O₂ to produce reactive oxygen species and effectively inactivate <i>Salmonella</i>. The aptasensor shows good specificity and sensitivity, with a linear range of 2 × 10⁰-2 × 10⁵ CFU/mL and a detection limit of 2 × 10⁰ CFU/mL. Besides, it was applied in the detection of milk, and satisfactory results were obtained. The strategy offers a robust solution for early pathogen detection and control in food safety.