An immunosensor based on hydrogen evolution signals of CoNiSe2/g-C3N4 for the detection of carcinoembryonic antigen

Electrochemical immunosensors are critical for biomarker detection, in which the enhancement of the electrochemical signal is beneficial to improve the sensitivity of the immunosensor. Recently, the hydrogen evolution reaction (HER) from water splitting has garnered significant attention because of its importance in the clean production of hydrogen energy; it also provides a novel way of constructing electrochemical immunosensors based on an electrocatalytic signal. Herein, we successfully fabricated a CoNiSe2/g-C3N4 composite using a hydrothermal reaction, and it exhibited outstanding HER activity in both acidic and neutral solutions. It was adopted as a novel electrocatalytic marker to capture carcinoembryonic antigen (CEA) secondary antibody (Ab2) because of its superior HER activity in neutral solution. Then, a glassy carbon electrode (GCE) decorated with gold nanoparticles (Au NPs) was applied to be the bridge immobilizing CEA major antibodies, after which the immunosensor with a sandwich structure was fabricated. The experimental results demonstrated that the immunosensor exhibits a linear range of 0.0001 to 100 ng mL-1 along with a detection limit for 0.18 pg mL-1 (S/N = 3). Additionally, it is exceedingly repeatable, specific, stable, and practical. Our study establishes a fresh strategy to detect CEA, further expanding the applications of the electrocatalytic HER process.