The electrochemical immunosensor of the "signal on" strategy that activates MMoO4 (M = Co, Ni) peroxidase with Cu2+ to achieve ultrasensitive detection of CEA.

A new type of ultrasensitive electrochemical immunosensor with "signal on" strategy was designed for quantitative detection of CEA. The sensing strategy design is based on the following principles: We use HMSNs-Cu@HA as the signal probe, the structure of HA is destroyed under acidic conditions, and the released Cu activates the substrate material MMoO (M = Co, Ni) Peroxidase activity initiates the reaction of catalytic HO and realizes the "signal on" condition of electrical signals. This strategy has the following advantages: (1) HA coating of HMSNs-Cu can prevent Cu leakage, has good biocompatibility and can be connected with more antibodies. (2) The prepared sensor has the characteristics of high sensitivity and a low detection limit. When the electrode substrate was CoMoO, the detection range of the immunosensor was 0.01 pg/mL-40 ng/mL, and the detection limit was 0.0035 pg/mL (S/N = 3). This work innovatively applies the catalytic activity of metal ion-activated nanozymes in the detection of CEA, providing a new perspective for the monitoring and analysis of cancer markers.