Establishing of a Method Combined Immunomagnetic Separation with Colloidal Gold Lateral Flow Assay and Its Application in Rapid Detection of Escherichia coli O157:H7

In this study, immunomagnetic beads were prepared by coupling anti- Escherichia. coli O157:H7 monoclonal antibodies with magnetic beads. A colloidal gold test strip was composited with anti- E. coli O157:H7 monoclonal antibody marked by colloidal gold as the detection antibody, anti- E. coli O157:H7 polyclonal antibody as the test line, and donkey anti-mouse IgG secondary antibody as the control line. Immunomagnetic separation was coupled with colloidal gold lateral flow assay to detect E. coli O157:H7 rapidly. Results showed that 1 mL 7.6 × 10 3 colony-forming unit (CFU) mL 1 E. coli O157:H7 exhibited a positive outcome when colloidal gold lateral flow assay was performed after immunomagnetic separation. A food sample inoculated with 10 CFU/g E. coli O157:H7 after 6 h of enrichment could be detected within 72 min of immunomagnetic separation and colloidal gold lateral flow assay. The method proposed in this study could be used to on-site detect harmful substances in food significantly and rapidly.