Detecting 5-morpholino-3-amino-2-oxazolidone residue in food with label-free electrochemical impedimetric immunosensor

This paper reported a novel label-free electrochemical impedimetric immunosensor for sensitive detection of metabolite of furaltadone, 5-morpholino-3-amino-2-oxazolidone (denoted as AMOZ), based on monoclonal antibody against AMOZ (denoted as AMOZ McAb) immobilized on gold electrode modified with 1,4-benzenedithiol and gold nanoparticle self-assembled layers. The sensitive steps of surface modification have been characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The immunoreaction between AMOZ and AMOZ McAb directly triggered a signal via electrochemical impedance spectroscopy measurement. Under the optimized conditions, the relative change in impedance was proportional to the logarithmic value of AMOZ concentrations in the range of 1.0 to 1.0 x 10(6) ng/mL (r = 0.9991) with the detection limit of 1.0 ng/mL The advantages of the immunosensor are exhibited in its high sensitivity, wide linear range and better stability. The proposed impedimetric immunosensor was successfully applied to the determination of AMOZ in animal derived food with excellent recoveries. (C) 2011 Elsevier Ltd. All rights reserved.