A voltammetric immunoassay for the carcinoembryonic antigen using silver(I)-terephthalate metal-organic frameworks containing gold nanoparticles as a signal probe.

A voltammetric immunoassay for the carcinoembryonic antigen (CEA) was developed using silver metal-organic frameworks (Ag-MOFs) as a signal probe. The Ag-MOFs contained a substantial amount of Ag(I) whose electrochemical signal was relatively stable. Therefore, the Ag-MOFs were viable signal probes. The signal can be detected without previous acid dissolution and preconcentration steps. This simplifies the detection steps and reduces the detection time. If CEA binds to its antibody on the modified electrode, the signal for Ag(I) becomes reduced. Measurements were best performed at a potential as low as 0.07 V (vs. SCE) which made the electrode hardly sensitive to potential electroactive interferents. Under optimized conditions, the method included a wide linear response range (0.05 to 120 ng mL) and a low detection limit of 8.0 fg mL (S/N = 3). The synthesis of Ag-MOFs is relatively simple, and Ag-MOFs are not only used as nanocarriers for immobilizing anti-CEA but also acted as electroactive materials for a signal probe. The voltammetric immunoassay is stable, inexpensive, sensitive, and selective. Based on these advantages, the method holds great promise for applications in the point-of-care disease and environmental monitoring. Graphical abstract Schematic presentation of a novel electrochemical immunoassay for the carcinoembryonic antigen (CEA) using silver metal-organic frameworks (Ag-MOFs) as a signal probe.