Rapid And Sensitive Pathogen Detection Platform Based On A Lanthanide-Labeled Immunochromatographic Strip Test Combined With Immunomagnetic Separation

Sensitive point-of-care pathogen detection methods are urgently required as pathogens pose a significant threat to food safety and human health. Here, we reported a platform based on a lanthanide-labeled immunochmmatographic strip test combined with immunomagnetic separation for the detection of pathogens in food and clinical samples. First, immunomagnetic separation technology was employed as a pre-treatment to eliminate the effect of background in the samples. Then, the lanthanide chelate-loaded carboxyl-modified polystyrene nanoparticles, exhibiting bright luminescence, wide Stokes shift, and excellent stability, were prepared and used to label pathogens with antibody. Finally, an immunochmmatographic strip test, based on a sandwich format and supported by our custom-designed portable reader, was used to rapidly quantify the result. Using Salmonella typhimurium as a model pathogen, under optimal conditions, we achieved a detection limit of 10(3) CFU/mL and a linear range of 10(4) -10(6) CFU/mL in milk and human serum with good recovery, reproducibility, and specificity. Compared with the existing colloidal gold-based immunochromatographic strip test, our platform showed high sensitivity (100-fold improvement) and provided quantitative determination. Our detection platform was therefore demonstrated to be highly sensitive, rapid (within 1.5 h), and cost-effective, providing a promising platform for point-of-care pathogen detection in food and clinical fields.