Developing a novel immunochromatographic test strip with gold magnetic bifunctional nanobeads (GMBN) for efficient detection of Salmonella choleraesuis in milk

- GMBN was used as magnetic material for separation and probe for detection.
- A novel GMBN lateral flow assay for detecting S. choleraesuis was developed.
- The capture efficiency of GMBN was 82.4% for S. choleraesuis.
- Compared with colloidal gold-ICTS, GMBN-ICTS was more sensitive.
- GMBN-ICTS can be successfully applied in food sample (whole milk).

To date, immunochromatographic test strip has been widely applied in the rapid detection of foodborne pathogens. The label of an immunochromatographic test strip is the key factor for rapid detection. In this study, gold magnetic bifunctional nanobeads (GMBN) were selected as a novel label to prepare immunochromatographic test strip for detection of Salmonella choleraesuis. The strip was systematically developed and optimized. In the procedure of conjugation between GMBN and anti-S. choleraesuis monoclonal antibodies, the pH of system was 6 and 150 μg of antibody was added in 200 μL of GMBN (5 mg/mL). Twenty microliter of the antibody-GMBN complex was used to capture S. choleraesuis. The capture efficiency of S. choleraesuis was 82.4%. Furthermore, the S. choleraesuis-antibody-GMBN complex could be used to detect S. choleraesuis in immunochromatographic test strip. Results showed that the test strip was specific and rapid. The sensitivity of the strip was 5 × 105 CFU/mL. The immunochromatographic test strip could be applied in food samples (whole milk) and the entire detection time was 20 h.