The dual nucleic acid amplification with dynamic light scattering strategy for ultrasensitive detection of Salmonella in milk

Rapid detection of Salmonella in food has always been a research hotspot, which can contaminate milk. In this study, a novel method that combines streptavidin (SA)-modified gold nanoparticles (AuNPs) and dynamic light scattering (DLS) technology for ultrasensitive detection of Salmonella was proposed. First, dual nucleic acid amplification strategies, namely, polymerase chain reaction (PCR) and hybridization chain reaction (HCR), PCR was used to amplify the invA gene from Salmonella to produce the target single-stranded DNA to trigger HCR, whereas HCR was used to produce a long biotin-containing double-strand DNA. After adding the SA-AuNPs probe, the diameter change was measured by DLS. And different characterization methods were also used to verify the feasibility of the established PCR-HCR-DLS strategy. Moreover, under optimal experimental conditions, the developed method showed a limit of detection (LOD) at 100 CFU/mL in both pure culture and spiked skimmed milk. Therefore, the biosensor based on SA-AuNPs and PCR-HCR-DLS showed potential application in detecting Salmonella in milk.