Development of an ultrasensitive label-free immunosensor for fungal aflatoxin B1 detection

In this work, we developed and characterized a homemade electrochemical immunosensor for the detection of fungal B1 aflatoxin (AFB1), one of the most dangerous toxins ma in food production chains, for which highly specific, rapid, easy to use and low-cost detection tools are still required. Our sensor is based on screen-printed electrodes, the working one being submitted to a cleaning procedure, before being functionalized using three different protocols by a supramolecular architecture made of a streptavidin layer immobilizing biotinylated anti-AFB1 antibodies. Each step of the sensor design was studied using complementary methods (atomic force microscopy, contact angle measurement, electrochemical impedance spectroscopy, Fourier-Transform InfraRed spectroscopy and cyclic voltammetry), leading to the choice of one of the three functionalization protocols combining reproducibility and simplicity of execution for the elaboration of the final sensor. This optimized sensor allows the detection of AFB1 in a large linear range from 50 fg/ml to 5 ng/ml with a limit of detection of about 50 fg/ml, showing, therefore, a significant enhancement of sensitivity as compared to other sensors described in the literature for the detection of this toxin.