Highly Sensitive Colorimetric Detection of Listeria monocytogenes by Using Gold Nanoparticles Based on Magnetic Metal-Organic Framework Separation

In this study, magnetic metal organic framework composites as capture probe and immunofunctionalized gold nanoparticles as signal probe were used to develop a rapid colorimetric method for the detection of Listeria monocytogenes. Under optimal conditions, the visual detection limit for L. monocytogenes was 1.2 × 10³ CFU/mL. The results of ultraviolet spectroscopy showed a good linear relationship in the range of 1.2 × 10¹-1.2 × 10⁸ CFU/mL (Y = 0.519 - 0.043X, R² = 0.978), the detection limit was as low as 0.45 CFU/mL, and the intra-batch coefficient of variation of all concentration gradients was between 0.31% and 1.30%. The recoveries for spiked chicken breast were 91.1%-108.7% with coefficient of variation less than 7.4%, and the result was consistent with that of the plate counting method. In conclusion, the proposed assay is rapid, accurate sensitive, and highly applicable to the detection of foodborne pathogens.