Dual-function of ZnS/Ag2S nanocages in ratiometric immunosensors for the discriminant analysis of ochratoxins: Photoelectrochemistry and electrochemistry

Abstract A ratiometric immunosensor was built to detect different ochratoxins in a mixture by combining broad-specific antibody and antigen, multidimensional signals, and computer programs. This immunosensor used MoS2 NFs/CdS as the photoelectrode to immobilize antigens and ZnS/Ag2S nanocages to capture the secondary antibody. During the immunoreaction recognition, the photoelectrochemical (PEC) current of MoS2 NFs/CdS and the square wave voltammetric (SWV) current of the dissolved Zn2+ from ZnS can be influenced by the deposition of the ZnS/Ag2S label. The results show that the ratio of PEC to SWV current decreased linearly with the logarithm of ochratoxin concentrations in a range from 1 ng/L to 1 μg/L. The present work provides a possible route to design broad-specific immunosensors and expands the scope of ratiometric biosensors in the detection of a mixture.