Electrochemical Aptasensor of Carcinoembryonic Antigen Based on Concanavalin A‑Functionalized Magnetic Copper Silicate Carbon Microtubes and Gold-Nanocluster-Assisted Signal Amplification.

An ultrasensitive electrochemical sensor was developed for the quantitative determination of carcinoembryonic antigen (CEA), which is often utilized as a tumor marker and a prognostic indicator. In the paper, first, copper silicate integrated with nitrogen-doped magnetic carbon microtubes (NCMTs@Fe₃O₄@Cusilicate) was synthesized and employed to enrich concanavalin A (ConA), which can be used as an affinity probe to selectively capture CEA. Through chemical chelation between a copper ion and Con A, the combination of Cusilicate/ConA was greatly improved. Furthermore, gold nanoclusters (AuNCs) immobilized with aptamers were provided for signal amplification. Thus, in the presence of the target protein, CEA, in a sandwich manner, was formed, and AuNCs were gathered on the electrode through a magnetic field. Electrochemical oxidation of AuNCs to AuCl₄^– was performed, and immediately differential pulse voltammetry was performed, resulting in an electrochemical response because of the reduction of AuCl₄^–. On the basis of these merits, the constructed sensing system provided a ultrasensitive detection scheme for CEA with a linear range from 0.03 to 6.00 ng·mL^–1 and a low detection limit of 5.38 pg·mL^–1. In addition, the proposed strategy was employed to detect CEA in serum, which showed excellent correlations with standard immunoassay. The excellent performance indicated that the proposed sensor has significant potential for clinical diagnosis. [ABSTRACT FROM AUTHOR]