Impedimetric aflatoxin M1 immunosensor based on colloidal gold and silver electrodeposition

An impedimetric immunosensor based on colloidal gold and silver electrodeposition for the detection of aflatoxin M1 (AFM1) herein is reported. An indirect like competitive ELISA procedure was performed on screen-printed electrodes (SPEs) in presence of anti-AFM1 gold-labelled antibodies. Silver was chronoamperometrically electrodeposited at a fixed applied potential and for a determined period of time to amplify the signal. The calculated charge transfer resistance (Rct) was found to correlate well with the concentration of AFM1. The linear working range of the described AFM1 immunosensor ranged between 15 and 1000 ng/L with a limit of detection (LoD) equal to 15 ng/L (R.S.D. = 20%). Impedimetric results were confronted with linear sweep voltametry (LSV) and corresponded well to this technique.