<scp>PathoSense</scp>: a rapid optical aptasensing platform for monitoring <i>Staphylococcus aureus</i> in milk

Abstract BACKGROUND Staphylococcus aureus presents a major public health and food safety challenge due to its ability to thrive in various environments. Conventional methods, such as polymerase chain reaction and enzyme‐linked immunosorbent assay, often suffer from limitations in sensitivity and specificity, highlighting the need for innovative detection strategies. RESULTS This study developed novel label‐free aptasensors for S. aureus detection using copper nanoparticles (CuNPs) as a platform. The CuNPs, characterized by a size of 40 nm, spherical morphology, and functional stability, served as the foundation for the biosensor. An iron‐regulated surface determinant protein A (IsdA)‐binding aptamer, specifically targeting the IsdA surface protein of S. aureus , was conjugated to CuNPs as the molecular recognition probe, while rhodamine 6G acted as the signal probe. In the absence of S. aureus , the aptamer kept the ‘gate’ on the CuNPs closed, preventing signal probe release. In the presence of S. aureus , specific binding between the aptamer and the pathogen triggered the ‘gate’ to open, releasing rhodamine 6G and generating a fluorescence signal. The aptasensors demonstrated a linear detection range of (10–10 6 ) CFU mL −1 , with a detection limit of 1 CFU mL −1 (correlation coefficient R 2 = 0.947). The biosensor demonstrated high stability and reproducibility, ensuring consistent detection performance. Furthermore, its application for S. aureus detection in milk samples highlighted its practical utility. CONCLUSION These findings establish the CuNP‐based aptasensor as a promising tool for sensitive and reliable S. aureus detection, with potential applications in food safety monitoring and public health. © 2025 Society of Chemical Industry (SCI).