Polydopamine nanocomposite-based aptasensor for rapid detection and effective killing of Staphylococcus aureus

Achieving accurate detection and early sterilization of Staphylococcus aureus ( S. aureus ) is one of the most important methods to prevent further contamination and spread of pathogenic bacteria. In this study, an aptasensor based on PDA/AuPt nanocomposites was prepared for specific binding, colorimetric detection, and photothermal inactivation of S. aureus . The aptamer (Apt) was immobilized on PDA/AuPt by gold-sulfur bonding (Au-S). Utilized the excellent peroxidase mimetic activity of PDA/AuPt as a colorimetric signal probe. The detection range in colorimetric mode was 1.4 × 10 2 -1.4 × 10 7  CFU/mL and the detection limit (LOD) was 44 CFU/mL. The comprehensive inspection procedure can be fully completed within a 45-min timeframe. Meanwhile, the aptasensor was successfully applied to the detection of S. aureus in real samples with the recoveries of 99.4%–110.8%. In addition, PDA/AuPt had a photothermal conversion efficiency of 22.2%, which made it an excellent photothermal agent. After incubation of 150 μg/mL apt-PDA/AuPt with S . aureus , the solution temperature rapidly increased to 62.9 °C after 5 min of near-infrared irradiation. The bacteria were killed by high temperature, and the inactivation rate was 95%.The results confirmed the application of PDA/AuPt for detecting and killing bacteria, contributing to the establishment of a food safety control system and protecting human health.