Sandwich-type photoelectrochemical immunosensor for procalcitonin detection based on Mn2+ doped CdS sensitized Bi2WO6 and signal amplification of NaYF4:Yb, Tm upconversion nanomaterial

In this paper, we constructed a sandwich-type photoelectrochemical (PEC) immunosensor for the quantitative detection of procalcitonin (PCT) based on the sensitization of Mn2+ doped CdS (CdS:Mn) nanocomposites to Bi2WO6 and the signal amplification effect of an upconversion material NaYF4:Yb,Tm. Bi2WO6 was synthesized with a three-dimensional flowered structure. CdS:Mn reduced the recombination of photogenerated carriers, and significantly improved photocurrent response. Lanthanide-doped upconversion nanomaterials were used as the label of secondary antibody. NaYF4:Yb,Tm have two functions, not only connected with the secondary antibody, but also can further amplify the photocurrent response. The proposed immunosensor for detecting PCT provided a desired linear range of 0.5 pg mL-1-100 ng mL-1 and a detection limit of 0.13 pg mL-1 under optimal experimental conditions. Besides, the PEC immunosensor demonstrated good reproducibility, specificity and stability. The results of determination of PCT in real human serum samples were satisfactory. Thus, the immunosensor may be applied in the clinical diagnosis of PCT and other biomarkers.