An intelligent readable and capture-antibody-independent lateral flow immunoassay based on Cu 2- x Se nanocrystals for point-of-care detection of Escherichia coli O157:H7.

Escherichia coli ( E. coli ) O157:H7 is a common foodborne pathogen which can cause serious harm. It is particularly important to establish a simple and portable method to achieve on-site pathogen detection. In this study, a capture-antibody-independent lateral flow immunoassay (LFIA) was constructed based on Cu 2- x Se nanocrystals (Cu 2- x Se NCs) for rapid detection of E. coli O157:H7. Cu 2- x Se NCs can not only be regarded as the "nano-antibody" for the recognition of E. coli O157:H7 through electrostatic adsorption, but also as nanozymes that show good peroxidase-like catalytic activity. The formed compound of E. coli O157:H7 and Cu 2- x Se NCs would be captured by a detection antibody on the T line due to the specific recognition of the antibody and E. coli O157:H7. Then, Cu 2- x Se NCs could catalyze the oxidation of TMB by H 2 O 2 to generate oxTMB, thereby generating blue bands. Meanwhile, we developed a mobile app for rapid data analysis. Under the optimal reaction conditions, E. coli O157:H7 could be detected within 70 min. The detection limit of this method was 2.65 × 10 5 CFU mL -1 with good specificity and stability. Additionally, it could achieve on-site rapid detection of E. coli O157:H7 in environmental water samples, providing a promising biosensor for portable pathogen detection.