Electrochemical immunoassay based on an atomically Cu-dispersed nitrogen-doped carbon electrode for screening carcinoembryonic antigen

Abstract

This research put forward an electrochemical immunoassay based on an atomically Cu dispersed nitrogen-doped carbon (Cu-CN) modified disposable screen-printed carbon electrode (Cu-CN/SPCE) for sensitive screening of carcinoembryonic antigen (CEA) with a split-type strategy. Atomic-level Cu–CN can be obtained after pyrolysis of a metal–organic skeleton encapsulated with copper acetylacetone, which can realize significant electrochemical signal amplification of ascorbic acid. Using alkaline phosphatase (ALP) catalytic chemistry to in situ generate ascorbic acid from a sandwich immunoassay, an exquisite protocol was successfully constructed for the CEA bioassay due to the dependence of differential pulse voltammetry (DPV) peak current signals of the Cu–CN/SPCE on the concentration of ascorbic acid. Under optimal conditions, this electrochemical immunoassay is capable of assaying the CEA biomarker sensitively, from which a linear range of 0.01 to 50 ng mL⁻¹ was derived along with a low limit of detection (LOD) of 2.4 pg mL⁻¹. In addition, this method shows good stability and high specificity in the detection process. Compared with the commercial ELISA detection method, the proposed sensing mode exhibits satisfactory accuracy in actual detection samples. Such enhanced analytical performance through atomic level dispersed metals provides a path for the future development of electrochemical immunoassay in the field of tumor biomarkers.