Development of Zn-Based Tower-like Photoelectrochemical Sensor Array for Sandwich-Type Immunosensing Analysis of Tau

A novel tower-like photoelectrochemical (PEC) sensor array, incorporating a self-calibration strategy, has been developed. In this study, Zn foil was folded into a quadrangular prism, upon which ZnO nanorods were grown in situ via a hydrothermal process. Subsequently, these ZnO nanorods were sensitized with narrow bandgap CdSe nanospheres. The resultant Zn/ZnO/CdSe have a stepped bandgap structure, effectively minimizing electron-hole pair recombination, enhancing electron transfer, and boosting PEC efficiency. The quadrangular structure is partitioned into four layers by light shields, creating a tower-like electrode equipped with 16 detection points. Furthermore, ZnFe₂O₄ is used as a detection antibody label for signal amplification. By rotating and moving the tower-like electrode, continuous multiple points detections are achieved, which reduces the operation time and helps to minimize the batch-to-batch variability. Additionally, the integration of a self-calibration strategy allows for selecting a point on the working electrode as a reference for calibration, thereby enhancing detection accuracy and sensitivity. In addition, the PEC immunosensor demonstrates a good linear correlation with microtubule-associated protein tau (Tau) within a measurement range of 0.01-50 ng·mL^-1, with a detection limit of 1.1 pg·mL^-1. This immunosensor is portable, highly stable, repeatable, and has strong specificity, with good storage stability.