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

Abstract

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 × 10²-1.4 × 10⁷ 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.