Construction of an electrochemical immunosensor based on the OER signal of Au@CoFe-(oxy)hydroxide for ultrasensitive detection of CEA

Based on the OER signal of Au@CoFe-(oxy)hydroxide, a novel electrochemical immunosensor was constructed for detection of carcinoembryonic antigen (CEA). The proposed electrochemical immunosensor exhibited a good linear response from 0.0001 to 200 ng mL−1 and a low detection limit of 0.0534 pg mL−1. [Display omitted] •Immunosensor based on electrocatalytic signal has been constructed for CEA detection with a satisfied linear range and detection limit.•Au@CeO2 combined with Ab1 through the formation of Au-S bonds and ester-like bonds.•Au@CoFe-(oxy)hydroxide with a large specific surface area and an excellent OER signal. Carcinoembryonic antigen (CEA) is a group of glycoproteins highly associated with cell adhesion and is an important antigen as a tumor biomarker commonly used in clinical diagnosis. Therefore, CEA detection plays a significant role in early clinical tumor diagnosis. In this study, an electrocatalytic signal labeled immunosensor was constructed for CEA ultrasensitive detection. We use a core–shell Au@CeO2 modified glassy carbon electrode (GCE) to capture more primary antibody (Ab1). The core–shell structure captures Ab1 through Au-S and OC–O bonds, providing more binding sites and a more stable binding force for Ab1. Because of the large specific surface area of the Au@CoFe-(oxy)hydroxide nanosheets and its outstanding oxygen evolution reaction (OER) signal under neutral medium, Au@CoFe-(oxy)hydroxide combined with secondary antibody (Ab2) as the signal tag and signal amplifier of the sensor. The proposed electrochemical immunosensor exhibited a good linear response from 0.0001 ng mL−1 to 200 ng mL−1 and a low detection limit of 0.0534 pg mL−1. The effectiveness of the sensor is verified by the standard addition method. This work provides a novel research approach for the clinical detection of tumor markers.