Hybridization chain reaction-based aptasensor for sensitive detection of Staphylococcus aureus in milk

FRET-based aptasensor with HCR amplification for S. aureus detection. • Integrated magnetic beads and HCR for cascaded signal amplification. • Achieved detection limit of 53 CFU/mL. • Obtained recoveries of 94–110% and RSDs of 1.07–3.89% in spiked milk. • Showed excellent specificity against non-target bacteria up to 10 6  CFU/mL. Staphylococcus aureus ( S. aureus ) is recognized as a high-risk pathogen responsible for severe food safety incidents. To address this concern, this study developed a fluorescent aptasensor based on fluorescence resonance energy transfer (FRET) for the rapid detection of S. aureus in milk. The proposed strategy employed high-specificity aptamers as recognition elements. Target bacteria were specifically captured, enriched, and isolated using aptamer-functionalized magnetic beads (MBs), thereby converting the concentration of S. aureus into a measurable fluorescence signal. To further enhance analytical sensitivity, a hybridization chain reaction (HCR)-based nucleic acid amplification strategy was integrated to achieve cascaded signal amplification. Under optimal conditions, the developed method achieved a limit of detection as low as 5.3 × 10 1  CFU/mL for S. aureus . This work provides a valuable reference for the development of biosensors with significant potential for diverse target detection in food safety and environmental monitoring.