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

Abstract

Developing photoelectrochemical (PEC) bioassays based on the principle of a photocathodic measurement of enzymatic product H 2 O 2 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 H 2 O 2 . 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.

Review of TiO2-Based Heterojunction Coatings in Photocathodic Protection

“…93 Heterojunction coatings prepared by the ALD method have demonstrated enhanced photoelectrochemical performance. 94 Wang et al 95 results demonstrated the excellent stability of the prepared coating, which can be attributed to the TiO 2 coating formed by the ALD method. This coating effectively prevents direct contact between Cu 2 O and the electrolyte, thus enhancing the stability of the system.…”

Superhydrophobicity‐mediated enhanced enzymatic kinetics and high‐performance bioassays

“…However, the chemical stability of Cu 2 O is limited because of the hole‐induced anodic corrosion. To conquer this drawback, Wang et al 42 decorated Cu 2 O NWs with a thin layer of amorphous TiO 2 (Cu 2 O@TiO 2 ), and thus prevented the photo‐corrosion issue. After treating with low surface energy material trichloro(1H,1H,2H,2H‐perfluorooctyl)silane and covering a layer of hydrophilic oxidase, an integrated solid–liquid–air triphase bio‐photocathode was obtained and used for the PEC cathodic bioassay.…”

Three-Phase Interface Construction on Hydrophobic Carbonaceous Catalysts for Highly Active and Selective Photocatalytic CO2 Conversion

“…22 It was found that the three-phase interface could be regulated by simply tuning the hydrophobic property of the catalyst, substrate, or surface modifier. [16][17][18]23,24 For instance, a Ptloaded photocatalyst modified with a hydrophobic ligand exhibited significant CO 2 RR promotion and HER inhibition due to efficient three-phase contact of CO 2 , water, and catalyst. 17 Recently, fast delivery of CO 2 gas to the catalyst was reported by constructing a hydrophobic−hydrophilic abrupt interface on the hydrophobic substrate.…”

“…Recently, the gas (CO 2 )–liquid (aqueous solution)–solid (photocatalyst) three-phase reaction systems have been developed to address the limited CO 2 mass transfer issue in water. ,, The introduction of the gas layer to the liquid–solid boundary was found highly efficient in increasing the local concentration and diffusion rate of CO 2 while diluting the proton content near the catalyst surface, resulting in improved CO 2 RR activity and selectivity. , Iizuka et al reported a method to construct a three-phase interface by continuously bubbling CO 2 throughout the photoreactions, but the system required constant energy consumption to maintain . It was found that the three-phase interface could be regulated by simply tuning the hydrophobic property of the catalyst, substrate, or surface modifier. − ,, For instance, a Pt-loaded photocatalyst modified with a hydrophobic ligand exhibited significant CO 2 RR promotion and HER inhibition due to efficient three-phase contact of CO 2 , water, and catalyst . Recently, fast delivery of CO 2 gas to the catalyst was reported by constructing a hydrophobic–hydrophilic abrupt interface on the hydrophobic substrate .…”