One-step and DNA amplification-free detection of Listeria monocytogenes in ham samples: Combining magnetic relaxation switching and DNA hybridization reaction

Early screening of L. monocytogenes in ready-to-eat food can prevent and control its harmful effects. In this study, we propose a highly sensitive magnetic DNA sensor based on nucleic acid hybridization reaction and magnetic signal readout. We design the L. monocytogenes specific probe(1) and probe(2) and label them on the 30 and 250 nm magnetic nanoparticles, respectively. The hybridization reaction between the magnetic probes and DNA of L. monocytogenes could form a sandwich nanocomplex. After magnetic separation, the unbound MNP30-probe(2) can act as the transverse relaxation time (T-2) signal readout probe. This assay allows the one-step detection of L. monocytogenes as low as 50 CFU/mL within 2 h without DNA amplification, and the average recovery in the spiked ham sausage samples can reach 92.6%. This system integrates the high sensitivity of magnetic sensing and high efficiency of hybridization reaction, providing a promising detection platform for pathogens.

Automated summary

A highly sensitive magnetic DNA sensor based on nucleic acid hybridization reaction and magnetic signal readout was proposed for early screening of L. monocytogenes in ready-to-eat food. This assay allows one-step detection of L. monocytogenes within 2 hours without DNA amplification, showing high efficiency and sensitivity.