A highly sensitive Aptamer–Antibody Birecognized ECL sensing platform based on the cascaded reaction between CeO2@mrGO and Co-SAC@NC for E.coli O157:H7 in untreated milk

Abstract

Rapid, sensitive and specific detection of foodborne pathogens is of great significance to the early warning and prevention of foodborne diseases and environmental pollution. Here, an electrochemiluminescent (ECL) biosensor with the cascaded reaction between two nanozymes was developed for the detection of E.coli O157:H7. Cobalt single-atom catalyst (Co-SAC@NC) with oxidase (OD) -like activity, as a co-reaction accelerator of O2, catalyzed oxygen to reactive oxygen species (ROSs) and boosted ECL of luminol-O2 system. Another nanozyme CeO2@mrGO with excellent phosphatase-like activity by the introduction of Fe was use to label Ab. CeO2@mrGO captured E.coli O157:H7, and then combined with Ap on the electrode surface through the affinity of aptamer and antibody to form a sandwich structure on the gold electrode (CeO2@mrGO-Ab/E.coli O157:H7/Ap-AuE). CeO2@mrGO converted AAP into AA, which consumed ROS and quenched ECL emission of luminol-O2 system. As a consequence, this ECL sensor had a linear response range of 17~1.7×105 CFU/mL with LOD of 2.78 CFU/mL. This aptamer-antibody birecognized system was able to be applied to assay E.coli O157:H7 in untreated contaminated milk samples with satisfactory results.