A dual-target fluorescent assay for rapid detection of foodborne pathogens based on aptamer–magnetic bead technology

Abstract

This study presents a fluorescence-based detection method for Escherichia coli and Staphylococcus aureus using aptamers and magnetic nanobeads. Fluorescently labeled aptamers served as signal probes, while Fe₃O₄ magnetic nanoparticles immobilized with aptamers were used as capture probes. The signal probe specifically recognized and bound to the captured pathogen, forming a sandwich-type complex with the capture probe. Various parameters such as synthesis conditions of magnetic nanoparticles, amounts of capture probe, avidin, aptamer concentration, fluorescent probe dosage, capture time, incubation duration, and temperature were optimized. Under optimal conditions, both pathogens exhibited linear relationships between fluorescence intensity and concentrations in the range of 10²–10⁷ CFU mL⁻¹. The detection limits were 34.02 CFU mL⁻¹ for E. coli and 44.67 CFU mL⁻¹ for S. aureus. This method was successfully applied to real food samples, yielding results consistent with standard methods. Compared to existing techniques, this approach offers high sensitivity, rapidity, good specificity, and broad application prospects in the prevention and control of foodborne diseases.