SERS-Based Immunochromatographic Assay for Sensitive Detection of O157:H7 Using a Novel WS-Au Nanotag.

O157:H7 contamination in food and the environment poses a serious threat to human health. Rapid and sensitive identification of foodborne pathogens remains challenging. Here, we prepared tungsten disulfide (WS)-Au nanocomposites coupled with the Raman signal molecule 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB) and antibodies to replace the conventional colloidal gold nanoparticles and applied SERS-active nanotags in the SERS-ICA method for highly sensitive detection of O157:H7. The large surface area and numerous effective SERS hotspots of WS-Au nanotags provide superior SERS signals. Under optimized conditions, this ICA achieves the quantitative detection of O157:H7 in a broad linear range of 8 × 10-8 × 10 CFU/mL and at a low detection limit of 175 CFU/mL. In addition, the test strip indicates high specificity for O157:H7 identification, favorable reproducibility, and shows good accuracy in the detection of actual food samples, such as milk and pork. The proposed assay can be used for rapid qualitative and quantitative detection of O157:H7 and has great potential for field application.