Sensitive SERS Platform for the Detection of Staphylococcus aureus via Freezing SERS Tags and Core–Shell Aptamer-Au@Fe3O4 Nanoparticles

The detection of Staphylococcus aureus is crucial for the diagnosis and treatment of infectious diseases. However, developing a simple and sensitive method for S. aureus detection remains challenging. Herein, we propose a sensitive surface-enhanced Raman spectroscopy (SERS) platform for the detection of S. aureus using core-shell aptamer-Au@Fe₃O₄ nanoparticles (Fe₃O₄-Au@apt) and freezing SERS tags. Core-shell Au@Fe₃O₄ magnetic nanoparticles were modified with S. aureusspecific primary aptamers for precise and efficient capture of S. aureus, followed by modification with large amounts of secondary aptamers and tetramercaptobenzoic acid through freezing. The proposed SERS platform demonstrated significant sensitivity toward S. aureus, with a limit of detection of 6.91 CFU/mL, which demonstrates 99.25 times higher sensitivity than conventional SERS tags. Additionally, the proposed SERS platform achieved good recovery rates in human urine and serum samples, ranging from 97.7% to 104.0% and 90.5% to 104.7%. The findings of the study suggest that the proposed SERS platform holds promise for the rapid and efficient detection of pathogenic bacteria.