Direct electrochemistry of hemoglobin on an ionic liquid carbon electrode modified with zinc tungstate nanorods

We have constructed a new electrochemical biosensor by immobilization of hemoglobin (Hb) and ZnWO4 nanorods in a thin film of chitosan (CTS) on the surface of carbon ionic liquid electrode. UV–vis and FT-IR spectra reveal that Hb remains in its native conformation in the film. The modified electrode was characterized by scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. A pair of well-defined redox peaks appears which indicates direct electron transfer from the electrode. The presence of CTS also warrants biocompatibility. The electron transfer coefficient and the apparent heterogeneous electron transfer rate constant were calculated to be 0.35 and 0.757 s−1, respectively. The modified electrode displays good electrocatalytic activity for the reduction of trichloroacetic acid with the detection limit of 0.613 mmol L−1 (3σ). The results extend the protein electrochemistry based on the use of ZnWO4 nanorods.