Determination of microcystin-LR with a glassy carbon impedimetric immunoelectrode modified with an ionic liquid and multiwalled carbon nanotubes

Abstract

We report on a sensitive, simple, label-free impedance-based immunoelectrode for the determination of microcystin-LR (MCLR). The surface of the electrode was modified with a composite made from multiwalled carbon nanotubes and an ionic liquid, and with immobilized polyclonal antibody against MCLR. Cyclic voltammetry and impedance spectroscopy were applied to characterize the modified electrode. It is found that the multi-walled carbon nanotubes act as excellent mediators for the electron transfer between the electrode and dissolved hexacyanoferrate redox pair, while the ionic liquid renders it biocompatible. The method exhibits a wide linear range (0.005 μg•L-1 to 1.0 μg•L-1), a low detection limit (1.7 ng•L-1) and a long-term stability of around 60 days. The ionic liquid 1-amyl-2,3-dimethylimidazolium hexafluorophosphate gave the best impedimetric response. The new immunoelectrode is sensitive, stable, and easily prepared. It has been successfully applied to the determination of MCLR in water samples.