Multiplex detection of foodborne pathogens using inductively coupled plasma mass spectrometry, magnetic separation and metal nanoclusters-mediated signal amplification

Drink or food is easy to be contaminated by multiple foodborne pathogens simultaneously. Demand for developing multiplex bioassay platforms is urgent and increasing. Here, we report a quantitative assay for the simultaneous detection of manifold foodborne pathogens by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), magnetic separation and metal nanoclusters-mediated signal amplification. In the first preconcentration step, the sample was mixed with magnetic nanoprobes and metal nanoclusters probes to form sandwich-type magnetic nanoprobes-targets-nanoclusters probes structures. The target bacteria were isolated and concentrated and then unbound metal nanoclusters probes were collected by magnetic separation. In the second step, free metal nanoclusters probes as element tags were etched in 5% HNO 3 for ICP-MS analysis and multiplex bacteria detection. The method was able to detect Staphylococcus aureus , Vibrio parahaemolyticus and Salmonella typhimurium simultaneously and successfully detected three targets as low as 10 CFU/mL in ∼30 min. Applications to the determination of target bacteria in food samples confirmed the feasibility of this multiplex assay. • By using rare element labels and ICP-MS analysis, impurity interference is greatly reduced. • This method can simultaneously analyze multiple bacteria at fast speed(< 30 min), high throughput and good sensitivity. • The method is easy-to-operate without nucleic acid extraction and purification.