Simultaneous detection of three foodborne pathogens based on immunomagnetic nanoparticles and fluorescent quantum dots

Abstract

This paper presents a peptide-mediated immunomagnetic separation technique and an immunofluorescence quantum dot technique for simultaneous and rapid detection of Escherichia coli O157:H7, Staphylococcus aureus, and Vibrio parahaemolyticus. First, three peptides that can specifically recognize the three foodborne pathogens were combined with magnetic nanoparticles to form an immunomagnetic nanoparticle probe for capturing three kinds of target bacteria and then added three quantum dot probes (quantum dots-aptamer), which formed a sandwich composite structure. When the three quantum dot probes specifically combined with the three pathogenic bacteria, the remaining fluorescent signal in the supernatant will be reduced by magnetic separation. Therefore, the remaining fluorescent signal in the supernatant can be measured with a fluorescence spectrophotometer to indirectly determine the three pathogens in the sample. The linear range of the method was 10-107 cfu/mL, and in the buffer, the detection limits of E. coli O157:H7, S. aureus, and V. parahaemolyticus were 2.460, 5.407, and 3.770 cfu/mL, respectively. In the tap water simulation, the detection limits of E. coli O157:H7, S. aureus, and V. parahaemolyticus were 2.730, 1.990 × 101, and 4.480 cfu/mL, respectively. In the milk simulation sample, the detection limits of E. coli O157:H7, S. aureus, and V. parahaemolyticus were 6.660, 1.070 × 101, and 2.236 × 101 cfu/mL, respectively. The method we presented can detect three kinds of foodborne pathogens at the same time, and the entire experimental process did not exceed 4 h. It has high sensitivity and low detection limit and may be used in the sample detection of other pathogens.