Ultrasensitive Detection of Staphylococcus aureus and Listeria monocytogenes Genomic DNA by Nanoparticle-Enhanced Surface Plasmon Resonance Imaging

The rapid, sensitive and specific detection of pathogenic bacteria is key to the prevention of a variety of foodborne illnesses representing a significant threat to public health. Conventional methods for the detection and identification of pathogens may take up to a few days to yield an answer, and for this reason, efforts have been made to develop new biosensing platforms for the efficient detection of foodborne pathogens. Here we report the use of a nanoparticle-enhanced surface plasmon resonance (SPR) imaging biosensor for the rapid and femtomolar-attomolar detection of Staphylococcus aureus and Listeria monocytogenes genomic DNAs. We performed the nanoparticle enhanced SPR imaging detection of pathogen genomic DNAs with no need for the polymerase chain reaction (PCR) pre-amplification of the sequences to be detected. Here we show that peptide nucleic acid (PNA) probes can discriminate between two pathogenic genomic DNAs. We tested the selectivity of the detection method against control probe sequences or contaminating bovine genomic DNA and demonstrated, for the first time, the attomolar detection of Staphylococcus aureus genomic DNA in the presence of a 10-fold higher concentration of bovine genomic DNA.