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

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.