No abstract

No abstract

No abstract

We have constructed a new electrochemical biosensor by immobilization of hemoglobin (Hb) and ZnWO 4 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 ZnWO 4 nanorods.

In this paper NiMoO 4 nanorods were synthesized and used to accelerate the direct electron transfer of hemoglobin (Hb). By using an ionic liquid (IL) 1-butylpyridinium hexafluorophosphate (BPPF 6 ) modified carbon paste electrode (CILE) as the basic electrode, NiMoO 4 nanorods and Hb composite biomaterial was further cast on the surface of CILE and fixed by chitosan (CTS) to establish a modified electrode denoted as CTS/NiMoO 4 -Hb/CILE. UV-vis and FT-IR spectroscopic results showed that Hb in the film retained its native structures without any conformational changes. Electrochemical behaviors of Hb entrapped in the film were carefully investigated by cyclic voltammetry with a pair of well-defined and quasi-reversible redox voltammetric peaks appearing in phosphate buffer solution (PBS, pH 3.0), which was attributed to the direct electrochemistry of the electroactive center of Hb heme Fe(III)/Fe(II). The results were ascribed to the specific characteristic of NiMoO 4 nanorods, which accelerated the direct electron transfer rate of Hb with the underlying CILE. The electrochemical parameters of Hb in the composite film were further carefully calculated with the results of the electron transfer number (n) as 1.08, the charge transfer coefficient (a) as 0.39 and the electron-transfer rate constant (k s ) as 0.82 s À1. The Hb modified electrode showed good electrocatalytic ability toward the reduction of trichloroacetic acid (TCA) in the concentration range from 0.2 to 26.0 mmol/L with a detection limit of 0.072 mmol/L (3s), and H 2 O 2 in the concentration range from 0.1 to 426.0 mmol/L with a detection limit of 3.16 10 À8 mol/L (3s).