A dual-mode biosensing platform based on polydopamine-modified FeCoMOF/CoO nanoenzyme for sensitive detection of Escherichia coli O157:H7.

The sensitive and specific detection of Escherichia coli O157:H7 (E. coli O157:H7) plays a crucial role for human health in the food field. Here, polydopamine (PDA)-based FeCoMOF/CoO nanoenzymes (FeCoMOF/CoO@PDA) were successfully synthesized with three enzyme-like activities of catalase-like, superoxide dismutase-like and peroxidase-like. The PDA layer not only provided an adhesion surface for protein immobilization, but also significantly increased peroxidase-like activity of FeCoMOF/CoO@PDA. FeCoMOF/CoO@PDA could be directly coupled with antibody as probe for the E. coli O157:H7 detection. Accordingly, the improved Enzyme-Linked Immunosorbent Assay (ELISA) with a dual detection platform of colorimetric-intelligent sensing was developed. Its detection range was as wide as 10-10 CFU mL, and the detection limit was as low as 2 CFU mL. In addition, FeCoMOF/CoO@PDA-ELISA was further used for E. coli O157:H7 detection in actual samples. Thus, this work demonstrated that the proposed FeCoMOF/CoO@PDA-ELISA showed excellent potential for analytical testing of E. coli O157:H7.