Photogenerated Hole-Induced Chemical–Chemical Redox Cycling Strategy on a Direct Z-Scheme Bi₂S₃/Bi₂MoO₆ Heterostructure Photoelectrode: Toward an Ultrasensitive Photoelectrochemical Immunoassay

Abstract

To achieve high sensitivity for biomolecule detection in photoelectrochemical (PEC) bioanalysis, the ideal photoelectrode and ingenious signaling mechanism play crucial roles. Herein, the feasibility of the photogenerated hole-induced chemical–chemical redox cycling amplification strategy on a Z-scheme heterostructure photoelectrode was validated, and the strategy toward enhanced multiple signal amplification for advanced PEC immunoassay application was developed. Specifically, a direct Z-scheme Bi2S3/Bi2MoO6 heterostructure was synthesized via a classic hydrothermal method and served as a photoelectrode for the signal response. Under the illumination, the PEC chemical–chemical redox cycling (PECCC) among 4-aminophenol generated by the enzymatic catalysis from a sandwich immunoassay, ferrocene as a mediator, and tris (2-carboxyethyl) phosphine as a reducing agent was run on the Z-scheme Bi2S3/Bi2MoO6 heterostructure photoelectrode. Exemplified by interleukin-6 (IL-6) as the target, the applicability of the strategy was studied in a PEC immunoassay. Thanks to the multiple signal amplification originating from the high efficiency of the PECCC redox cycling system, the enzymatic amplification, and the fine performance of the Z-scheme Bi2S3/Bi2MoO6 heterostructure photoelectrode, the assay for IL-6 exhibits a very low detection limit of 2.0 × 10–14 g/mL with a linear range from 5.0 × 10–14 to 1.0 × 10–8 g/mL. This work first validates the feasibility of the PECCC redox cycling on the Z-scheme heterostructure photoelectrode and the good performance of the strategy in PEC bioanalysis. We envision that it would provide a new prospective for highly sensitive PEC bioanalysis on the basis of a Z-scheme heterostructure.

Novel Photoelectrochemical Biosensing Platform Based on a Double Type II CdLa2S4/SnIn4S8/Sb2S3 Ternary Heterojunction as Photoactive Materials and NiCo2O4 Nanospheres as a Photoquencher for CA19-9 Detection

“…To obtain the best performance of PEC biosensing, all external conditions that might affect the experimental results were screened. , As displayed in Figure S5A,B, the pH of PBS and the number of electron donors contained in the buffer solution were selected. When the concentrations of AA and pH of PBS were 0.1 and 7.4 mol/L, respectively, the photocurrent response reached the peak value.…”

Recent advances on portable photoelectrochemical biosensors for diagnostics

“…To improve the separation of electron-hole pairs can also be considered by design to form heterojunction and structurally defective heterojunction structures [133,134]. Heterojunctions are interfacial region formed by the contact of two different semiconductor phases [135,136]. Heterojunctions can be categorized into three types based on the semiconductor bandgap and the VB and CB potentials, type I (trans-energy-gap), type II (interleaved-gap), and type III (broken-gap) heterojunctions [137] (Figure 3).…”

Liposome-Mediated In Situ Formation of Ag3PO4/AgBr/Br-CN Ternary Nanostructures on Photoanodes for Photoelectrochemical Immunoassay

“…1 Traditional PEC sensors always operated by driving the sensing progress with an external electrical power supply, which may complicate the configuration and raise the cost. 2 To fulfill the increasing demand for the analytical device with the characteristics of miniaturization, portability, and low cost, self-powered PEC sensors driving the sensing system by light irradiation have attracted extensive attention. Up to now, self-powered PEC sensors with different configurations such as the combination of photoanodes and cathodes have been developed for detecting ions, 3 proteins, 4 small molecules, 5,6 and so on.…”

“…Photoelectrochemical (PEC) analysis with the superiority of simple instrumentation and high sensitivity has been explored in biological, medical, and other fields . Traditional PEC sensors always operated by driving the sensing progress with an external electrical power supply, which may complicate the configuration and raise the cost . To fulfill the increasing demand for the analytical device with the characteristics of miniaturization, portability, and low cost, self-powered PEC sensors driving the sensing system by light irradiation have attracted extensive attention.…”