Photoelectrochemical aptasensor based on flower-like Z-scheme WO₃/CdIn₂S₄ heterostructure for sub-picomolar detection...

Staphylococcal enterotoxin B (SEB) is a major causative agent of foodborne illnesses in humans. Its presence in drinking water or food processing water sources poses significant public health risks. Therefore, a simple and sensitive detection method for SEB is highly significant for food safety assurance and protecting public health. In our study, a photoelectrochemical (PEC) sensing platform was constructed for the detection of SEB using WO₃/CdIn₂S₄ as the signal source. Z-scheme WO₃/CdIn₂S₄ heterostructure was fabricated via a solvothermal approach, and their morphology, structure, and optical properties were systematically characterized using a combination of analytical techniques. The photocurrent intensity of WO₃/CdIn₂S₄ was 3.8 and 3.7 times as high as that of WO₃ and CdIn₂S₄, respectively. Moreover, the interfacial charge transfer mechanism was comprehensively elucidated through detailed experimental and theoretical analyses. Further coupling of the aptamer can enable the SEB to be specifically captured at the sensing interface, which resulted in elevated interface resistance, consequently suppressing the photocurrent, thereby achieving sensitive detection of the SEB. The developed PEC aptasensor exhibited good sensing performance for detection of SEB. Specifically, within the range of 1.0 × 10^-17-1.0 × 10^-12 mol/L, the logarithm of SEB concentration was linearly related to the photocurrent, with a detection limit of 1.26 × 10^-18 mol/L. The real water sample were evaluated and satisfactory results were obtained. The proposed PEC sensing platform demonstrates significant potential for bioanalytical applications and the trace level detection of target analytes.