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Ultrasensitive photoelectrochemical immunosensor based on Cu-doped TiO2 and carbon nitride for detection of carcinoembryonic antigen

Wang, Yaoguang, Zhao, Guanhui, Zhang, Yong, Du, Bin, Wei, Qin
Carbon 2019 v.146 pp. 276-283
alkaline phosphatase, antigens, ascorbic acid, carbon nitride, copper, electric current, immunosensors, lighting, nanocomposites, neoplasms, photosensitizing agents, titanium dioxide, wavelengths
In this study, a sandwich-type photoelectrochemical (PEC) immunosensor was designed for ultrasensitive detection of carcinoembryonic antigen (CEA) by using Cu doped TiO2 compositing with carbon nitride (Cu:TiO2/g-C3N4). The strategy of signal enhancement was based on Cu:TiO2/g-C3N4 as photosensitizer and the employed alkaline phosphatase (ALP) could catalyze ascorbic acid 2-phosphate (AAP) to be ascorbic acid (AA) as electron donor. Thanks to the functionalized Cu:TiO2/g-C3N4 nanocomposites, large degree enhancement of photocurrent response could be obtained under illumination of 430 nm wavelength. Furthermore, the characterization and mechanism of the detection procedure were discussed in depth. This exquisite sandwich protocol was successfully constructed for CEA detection based on the photocurrent signals corresponding to the concentration of in situ generated electron donor, which was directly proportional to the amount of CEA. The current response of the fabricated PEC immunosensor was linear with CEA in the range of 0.005–1000 ng mL−1, together with low detection limit of 1 pg mL−1 (S/N = 3). And high selectivity, reproducibility and stability were acquired. In addition, the proposed method may find promising applications in detecting other tumor markers in clinical analysis.