A single-interface photoelectrochemical sensor based on branched TiO2 nanorods@strontium titanate for the detection of two biomarkers.

In this study, a single-interface photoelectrochemical (PEC) sensor for detecting two antigens, alpha fetoprotein (AFP) and cancer antigen 153 (CA 153), was achieved based on the heterostructure of branched titanium dioxide nanorods (B-TiO2 NRs)@strontium titanate (SrTiO3) heterostructures. The B-TiO2 NRs@SrTiO3 heterostructure, prepared by a facile hydrothermal method with the feature of enhanced photogenerated charge carrier separation properties, was first employed as a photoactive substrate for anchored analyst. In order to achieve the goal of successfully detecting two biomarkers at a single interface, the two specific enzyme tags β-galactosidase and acetylcholine esterase linked with a secondary detection antibody were utilized to catalytically hydrolyze p-aminophenyl galactopyranoside and acetylthiocholine to p-aminophenol and thiocholine, respectively. Based on the above enzyme-catalyzed reactions to produce sacrificial electron donors, the photocurrent signals generated from different analytes could be distinguished at a single interface. The results demonstrate that this single-interface PEC sensor not only provides a method for the early detection of AFP and CA 153 but also provides new insight into designing a novel PEC sensor for the detection of two biomarkers with high efficiency and a simple method of operation.