Ultrasensitive “on-off-on” photoelectrochemical aptasensor for tumor biomarker using BiOI/α-Fe2O3 p-n heterojunction arrays by in-situ regulation of electron donor distance

Precise assay of carcinoembryonic antigen (CEA) is of paramount significance for the diagnosis, treatment, and prognosis of related cancers. Herein, an ultrasensitive “on-off-on” photoelectrochemical (PEC) aptasensor for CEA assay was proposed based on BiOI/α-Fe2O3 p-n heterojunction arrays by in-situ regulation of electron donor distance. The synthesized BiOI/α-Fe2O3 nanosheet arrays (BiOI/α-Fe2O3 NSAs) were served as photoactive materials, and the special structure facilitates considerably the immobilization of biomolecules. Ferrocene-modified hairpin DNA (Fc-hDNA), as the biorecognition elements and electron donor, was used to bond with CEA aptamer and offer electrons. The distance between Fc and BiOI/α-Fe2O3 NSAs interface can be effectively regulated through the specific recognition of Fc-hDNA and CEA aptamer, which also exhibited an “on-off-on” PEC sensoring model towards the detection of CEA. This method exhibited a wide linear range from 1.0 × 10−4 to 20 ng mL−1, with a low detection limit of 36.89 fg mL−1 for CEA detection. The developed PEC aptasensor has achieved satisfactory results in serum samples, also provide a novel perspective for other disease marker assay.