A procalcitonin photoelectrochemical immunosensor: NCQDs and Sb2S3 co-sensitized hydrangea-shaped WO3 as a matrix through a layer-by-layer assembly.

Using nitrogen-doped carbon quantum dots (NCQDs) and antimony trisulfide (Sb₂S₃) to co-sensitize hydrangea-shaped tungsten trioxide (WO₃), a novel photoelectrochemical (PEC) immunosensor was constructed to sensitively detect procalcitonin (PCT). WO₃ possessed a three-dimensional structure with uniform size and large surface area on the indium tin oxide (ITO) electrode. NCQDs with abundant carboxy groups and excitation-independent PEC behavior were modified on the surface of the WO₃ coating to enhance photochemical activity. Hence, the hydrangea-shaped WO₃/NCQDs/Sb₂S₃ composite was obtained by modifying NCQDs and well-crystallized Sb₂S₃ nanoparticles on WO₃ through a layer-by-layer assembly. It is worth noting that the photoelectric signal of WO₃/NCQDs/Sb₂S₃ was about 8 times that of pure WO₃ under visible light excitation. Moreover, the PEC immunosensor showed a large-scale response (0.001–100 ng mL⁻¹) and a low detection limit (0.42 pg mL⁻¹) under the best experimental conditions. This PEC immunosensor has advantages such as simplicity, facile fabrication, high sensitivity and strong stability, which have good research value in the analysis and detection of disease biomarkers. [ABSTRACT FROM AUTHOR]