DISPOSABLE ELECTROCHEMICAL SENSORS COUPLED TO MAGNETIC BEADS TO MAGNETIC BEADS FOR A RAPID AND SENSITIVE IMMUNODETECTION OF FOOD POLLUTANTS

In this work an electrochemical immunomagnetic sensor, based on a direct competitive assay, was developed using magnetic beads as solid phase and carbon screen-printed electrodes as transducers for the detection of sulfonamides. Magnetic beads coated with protein A were modified by immobilization of specific antibodies, then the competition between the target analyte and the corresponding analyte labeled with the enzyme was performed; after the immunosensing step, beads were captured by a magnet onto the working surface of a screen-printed electrode for the electrochemical detection. Screen-printed electrodes (SPEs) were chosen as transducers because they can be easily used in field and their technology allows mass-production at low cost, whereas the use of magnetic beads modified with antibody allowed the simultaneous concentration of the analytes and its separation from other matrix components. Alkaline Phosphatase (AP) was used as enzyme label and Differential Pulse Voltammetry (DPV) as fast electrochemical technique.

Calibration curves demonstrate that the developed immunomagnetic sensor was able to detect sulfonamide compounds in standard solutions at low concentrations (sub-ppb level). The fast incubation time (20 min) and electrochemical measurement (10 sec) make of this system a possible alternative to classic ELISA tests.