An ultrasensitive photoelectrochemical immunosensor for carcinoembryonic antigen detection based on cobalt borate nanosheet array and Mn2O3@Au nanocube

Highly sensitive and selective method of determination for carcinoembryonic antigen (CEA) is of important significance for the effective early diagnosis and treatment of cancer. In this work, we report an ultrasensitive sandwich photoelectrochemical (PEC) immunosensor for CEA detection. To be precise, cobalt-borate nanosheet arrays (Co-Bi NSs) with the larger specific surface area are prepared by electrodeposition and used as the basal material to capture the primary antibody (Ab1) for the first time. And the other photoactive material Mn2O3@Au nanocube is exploited for labeling the secondary antibody (Ab2). The coulomb force of Mn2O3@Au nanocube and Co-Bi NSs photoelectrodes as the driving force effectively improves the photoelectric response. Under the light irradiation, charge separation occurs at the same time between AuNPs and Mn2O3, and the energy levels of Mn2O3@Au and Co-Bi NSs are effectively matched, achieving the high PEC performance of the biosensor. The synthesized nanomaterials are physically characterized by a series of characterization techniques. Besides, ascorbic acid (AA) is employed as an excellent electron donor, which can inhibit the recombination process of photogenerated electrons and holes, then obtaining enhanced and stable photocurrent signals. Under the optimal experimental conditions, the immunosensor shows a lower detection limit of 5.0 pg mL−1 (S/N = 3), a wider linear range of 0.1 ng mL−1 ∼ 1000 ng mL−1, as well as excellent specificity, stability and reproducibility. Additionally, as-constructed PEC immunosensor can be applied to detect CEA in human serum, this proposed strategy may afford a promising approach for the biomarker sensing and clinical applications.