Development of a label-free electrochemical immunosensor based on carbon nanotube for rapid determination of clenbuterol

Abstract

We have fabricated a label-free electrochemical immunosensor for the detection of clenbuterol, a kind of β-agonist. Clenbuterol was covalently linked to multi-wall carbon nanotubes (MWCNTs) through a two-step process using 1-(3-(dimethylamino)-propyl)-3-ethylcarbodiimide and N-hydroxysulfo-succinimide as crosslinkers. The clenbuterol-MWCNT conjugates were cast on a glassy carbon electrode. Cyclic voltammetry and differential pulse voltammetry were employed to monitor the fabrication steps of immunoreaction system using the redox probe of K 3Fe(CN) 6. In the presence of monoclonal antibody against clenbuterol, the redox peak current of [Fe(CN) 6] 3−/4− was decreased, presumably due to that antibody in solution could adsorb on the electrode surface modified clenbuterol-MWCNT conjugates. The selected monoclonal antibody showed very high sensitivity and specificity for clenbuterol, and was used for the detection and quantitative determination of clenbuterol in solution with a competitive mechanism. This approach provided a detection limit of 0.32 ng mL −1. Accurate detection of clenbuterol in spiked animal feeds was demonstrated by comparison with conventional ELISA assays and LC–MS method.