| Summary: | The convenient construction of carbon-based electrochemical immunosensors with high performance is highly desirable for the efficient detection of tumor biomarkers. In this work, an electrochemical immunosensor was fabricated by integrating a biofunctionalized mesoporous silica nanochannel film with a carbon-based electrode, which can enable the sensitive determination of carcinoembryonic antigen (CEA) in serum. The commonly used carbonaceous electrode, glassy carbon electrode (GCE), was employed as the supporting electrode and was pre-treated through electrochemical polarization to achieve the stable binding of a vertically ordered mesoporous silica film with amino groups (NH<sub>2</sub>-VMSF) without the use of any adhesive layer. To fabricate the immunorecognition interface, antibodies were covalently immobilized after the amino groups on the outer surface of NH<sub>2</sub>-VMSF was derivatized to aldehyde groups. The presence of amino sites within the high-density nanochannels of NH<sub>2</sub>-VMSF can facilitate the migration of negatively charged redox probes (Fe(CN)<sub>6</sub><sup>3-/4-</sup>) to the supporting electrode through electrostatic adsorption, leading to the generation of electrochemical signals. In the presence of CEA, the formation of immunocomplexes on the recognitive interface can reduce the electrochemical signal of Fe(CN)<sub>6</sub><sup>3-/4-</sup> on the supporting electrode. Based on this principle, the sensitive electrochemical detection of CEA was achieved. CEA can be determined to range from 0.01 ng mL<sup>−1</sup> to 100 ng mL<sup>−1</sup> with a limit of detection of 6.3 pg mL<sup>−1</sup>. The fabricated immunosensor exhibited high selectivity, and the detection of CEA in fetal bovine serum was achieved.
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