Development of an Electrochemical Immunoassay Based on the Use of an Eight-Electrodes Screen-Printed Array Coupled with Magnetic Beads for the Detection of Antimicrobial Sulfonamides in Honey

In this work an electrochemical immunoassay, based on a direct competitive assay, was developed using magnetic beads as solid phase and carbon screen-printed arrays as transducers for the detection of sulfonamides in food matrices such as honey. Magnetic beads coated with protein A were modified by immobilisation of specific antibodies and then the competition between the target analyte and the corresponding analyte-labelled with an enzyme was carried out: after the immunosensing step, beads were captured by a magnet onto the working surfaces of a screen-printed eight-electrodes array for a multiple electrochemical detection. Screen-printed eight-electrodes arrays were chosen as transducers due to the possibility to repeat multiple analysis and to test different samples simultaneously. Alkaline Phosphatase (AP) was used as enzyme label and Differential Pulse Voltammetry (DPV) as fast electrochemical technique. Calibration curves demonstrate that the developed electrochemical immunoassay was able to detect this class of drugs in standard solutions at low concentrations (ng/mL levels). The short incubation times (25 min) and the fast electrochemical measurement (10 sec) make of these systems a possible alternative to classic ELISA tests. The developed electrochemical immunoassay was coupled to Solid Phase Extraction (SPE) for the analysis of these compounds in a food matrix such as honey.