Electrically addressable deposition of diazonium-functionalized antibodies on boron-doped diamond microcells for the detection of ochratoxin A

This work reports the manufacturing procedure for an impedimetric immunosensor for sensitive detection of the mycotoxin, ochratoxin A (OTA), through electroaddressing of diazonium functionalized antibodies on the working electrode of a planar Boron Doped Diamond (BDD) electrochemical microcell. The immunosensor elaboration and the immunochemical reaction between ochratoxin A and the surface-bound antibody were monitored using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The impedance variation due to the specific antibody–OTA interaction was correlated with the OTA concentration in the samples. The increase in electron-transfer resistance values presents a sigmoidal shape versus log concentration of OTA, with a dynamic range between 7 pg mL−1 and 25 ng mL−1. A limit of detection (LOD) of 7 pg mL−1 and a IC50 of 1.2 ng mL−1 were obtained. The immunosensor thus fabricated exhibited high sensitivity, good reproducibility, long-term stability, and was used for the detection of OTA in real coffee samples with a good recovery rate. The reported validated manufacturing procedure is compatible with the production of microarrays for multidetection.