Dual-recognition fluorescent immunochromatographic strip based on IgG and antibiotic for smartphone-assisted detection of <i>Staphylococcus aureus</i> in food samples

<i>Staphylococcus aureus</i> (<i>S. aureus</i>), a bacterium ubiquitously distributed in natural environments and commonly colonizing human skin and mucous membranes, is a highly pathogenic agent that poses significant threats to human health. Consequently, the development of accurate and efficient detection methods for <i>S. aureus</i> is of utmost importance in clinical and public health contexts. Flow chromatography is widely used for the detection of <i>S. aureus</i> because of its short detection time and low demand for labor and material resources. Herein, we fabricated test strip sensors with dual recognition of IgG and cefradine (CE) for <i>S. aureus</i> detection, achieving a high degree of specificity and a low detection limit (10² CFU mL^-1). Meanwhile, by capturing images of the T-line with a smartphone to quantify its fluorescence intensity, this method enabled both qualitative and quantitative detection of <i>S. aureus</i>. The detection process was simple, which required no personnel training, and takes only 40 minutes, offering fast and convenient analysis. To prove the practicability, we applied the test strip sensors to orange juice, milk and beef, and they were highly sensitive (orange juice: 10² CFU mL^-1, milk: 10⁴ CFU mL^-1, beef: 10⁴ CFU mL^-1), reproducible (RSD < 5.4%). Therefore, we believe the test strip sensors have a bright application prospect in the field of rapid detection of <i>S. aureus</i>.