ZnIn2S4/TiO2 NRs heterojunction-multifunctional hydrogel hybrid for ultrasensitive photoelectrochemical immunoassay

The prevalence of tobacco virus diseases has caused serious losses to the tobacco industry, making the development of efficient, sensitive, and convenient virus detection technologies increasingly important. Photoelectrochemical biosensors have been widely used in various fields due to their advantages, including low background signal, convenient operation, low cost, and fast response. However, few studies have explored the use of photoelectric sensing analysis technology for the detection of plant viruses. In this study, we propose a novel biosensor based on semiconductor heterojunction nanomaterials for the detection of plant virus tobacco mosaic virus (TMV). The sensor utilizes a ZnIn₂S₄/Titanium dioxide nanorod arrays (TiO₂ NRs) heterojunction nanocomposite, modified with fluorine-doped tin oxide (FTO), as a photoelectrode. This photoelectrode triggers a gelation reaction of the hydrogel by coupling the Ca²⁺ generated in the 96-well plate with TMV immune recognition events, thereby altering the interfacial mass transfer on the photoelectrode surface. This gelation significantly hinders the light absorption of the ZnIn₂S₄/TiO₂ NRs/FTO photoelectrodes, ultimately resulting in a corresponding change in the output current signal. The biosensor demonstrates excellent analytical performance, with a detection limit of 0.01 pg mL⁻¹ for TMV. This work provides a novel approach for the analysis and detection of plant viruses, holds significant potential for further development. It is expected to provide a general platform for detection and analysis of plant viruses, agricultural pollutants, food residues and other fields in the future.