High-Performance Photocathodic Bioanalysis Based on Core–Shell Structured Cu 2 O@TiO 2 Nanowire Arrays with Air–Liquid–Solid Joint Interfaces

Developing photoelectrochemical (PEC) bioassays based on the principle of a photocathodic measurement of enzymatic product H2O2 is highly attractive because it can naturally avoid interfering signals arising from reductive species inherent to biofluids. However, fluctuant oxygen levels in the analyte solution can compromise the accuracy of photocathodic bioanalysis and restrict its application because oxygen reduction potential is similar to H2O2. Herein, we addressed this restriction by constructing a triphase biophotocathode with air-liquid-solid joint interfaces by immobilizing an oxidase enzyme film on the tip part of superhydrophobic p-type semiconductor nanowire arrays. Such a triphase biophotocathode has a reaction zone with steady and air phasedependent oxygen concentration which stabilizes and increases the oxidase kinetics, and enables the photocathodic measurement principle in reliable PEC bioassay development with high selectivity, good accuracy, and a wide linear detection range. Moreover, the biophotocathode shows good stability during repeated testing under light illumination. This reliable PEC bioassay system has broad potential in the fields of disease diagnosis, medical research, and environmental monitoring. [GRAPHICS] .