Potential Use of Biosensors for the Rapid and Specific Isolation of Listeria monocytogenes from Ready-to-Eat (RTE) Foods

<i>Listeria monocytogenes</i> is a major foodborne pathogen associated with increasing global public health concern due to numerous outbreaks. Rapid pathogen detection is critical for reducing both the incidence and severity of foodborne illnesses. Recent advances in nanotechnology are transforming analytical methods, particularly for detecting foodborne pathogens. Magnetic nanoparticles (MNPs) and gold nanoparticles (GNPs) are among the most widely used nanomaterials in this field. This study investigated the potential use of MNPs and GNPs for the rapid and specific isolation of <i>L. monocytogenes</i> from fresh salad, deli meat, and frozen vegetables. <i>L. monocytogenes</i> (ATCC 19117) served as the model organism for biosensing and target capture. Results showed that the limits of detection (LoDs) for the GNP-based plasmonic/colorimetric biosensor and the MNP-based biosensor were 2.5 ng/µL DNA and 1.5 CFU/mL, respectively. Both GNPs and MNPs specifically detected <i>L. monocytogenes</i> even in the presence of closely related pathogens. Integration of MNPs and GNPs significantly enhanced the sensitivity of <i>L. monocytogenes</i> detection. Within one hour, naturally contaminated pre-packaged salad samples demonstrated clear evidence of effective direct capture by MNPs and specific identification by GNPs. This combined approach enables rapid and accurate on-site detection of <i>L. monocytogenes</i>, facilitating timely intervention and reducing the risk of contaminated foods reaching consumers.