A bifunctional catalyst based ECL immunosensor for a cardiac biomarker regulated by oxygen evolution reaction

Prostaglandin E1, a cardiac biomarker, is a pivotal member of the prostaglandin family which exerts diverse and powerful effects on cell function in many organ systems. In this study, a new approach for the ultrasensitive determination of prostaglandin E1 was proposed by using the ECL of peroxydisulfate with oxygen as coreactant. Compared to most peroxydisulfate ECL sensor, this proposed ECL strategy propounded employing oxygen evolution reaction to enhance the concentration of oxygen, which was unprecedented in ECL sensing platform. Herein, ultrathin NiCo2O4 nanosheets with large surface area and mesoporous structure were prepared by a facile method, and adamantane as enhancer was decorated on the surface of amino-modified NiCo2O4 to generate a bifunctional catalyst of NiCo2O4@AD(Prostaglandin E), which possessed excellent catalytic performance toward the oxygen evolution reaction. Accordingly, the sensitivity of ECL immunosensor was enhanced with the increasing concentration of oxygen by the bifunctional catalyst of NiCo2O4@AD. And the ECL response of the peroxydisulfate would decrease owing to the interaction between antibody and antigen on the modified electrode. Consequently, on the basis of the ECL intensity change of peroxydisulfate, the proposed immunosensor has realized ultrasensitive PGE1 assay with a wide linear detection range of 0.1 fg/ml to1 ng/ml and a detection limit of 0.1 fg/ml. The proposed ECL immunosensor was performed to analyze prostaglandin E1 in human serum, and satisfactory recoveries were obtained, indicating its potential applications in clinical diagnostics.