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ABSTRACT: A stable composite film composed of the ionomer Nafion, the ZnO nanoparticle and the protein hemoglobin was cast on the surface of an ionic liquid modified carbon paste electrode (CILE) to establish a modified electrode denoted as Nafion/nano-ZnO/Hb/CILE. UV-vis and FT-IR spectrum showed that hemoglobin in the film retained its native conformation. The electrochemical behaviors of hemoglobin entrapped in the film were carefully investigated with cyclic voltammetry. A pair of well-defined and quasi-reversible redox voltammetric peaks for Hb Fe(III)/Fe(II) was obtained with the standard potential (E(0)') located at -0.344 V (vs. SCE) in phosphate buffer solution (PBS, pH 7.0), which was attributed to the direct electron transfer of Hb with electrode in the microenvironments of ZnO nanoparticle and ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF(6)). The electrochemical parameters of Hb in the composite film were further carefully calculated with the results of the electron-transfer rate constant (k(s)) as 0.139 s(-1), the charge transfer coefficient (alpha) as 0.413 and the number of electron transferred (n) as 0.95. The Hb modified electrode showed good electrocatalytic ability toward the reduction of trichloroacetic acid (TCA).
Bioelectrochemistry (Amsterdam, Netherlands) 12/2008; 74(2):295-300. · 2.65 Impact Factor
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ABSTRACT: A novel biocompatible composite film containing sodium alginate (SA), room temperature ionic liquid 1-butyl-3-methylimidazolium
hexafluorophosphate (BMIMPF6), SiO2 nanoparticle, and hemoglobin (Hb) was fabricated and covered on the surface of a traditional carbon paste elecrode (CPE).
The immobilized Hb on the electrode surface showed good direct electrochemical behaviors, and a pair of quasi-reversible redox
peaks of Hb was obtained, which indicated that the direct electron transfer of Hb with the electrode surface had been achieved.
The SA/nano-SiO2/BMIMPF6/Hb/CPE showed dramatically electrocatalytic activity to the reduction of trichloroacetic acid, hydrogen peroxide (H2O2), and oxygen (O2). The kinetic parameters for the electrocatalytic reactions were evaluated. The composite film showed the potential to the
biosensor and biocatalysis.
Journal of Solid State Electrochemistry 05/2008; 12(6):655-661. · 2.13 Impact Factor
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ABSTRACT: A new hemoglobin (Hb) and room temperature ionic liquid modified carbon paste electrode was constructed by mixing Hb with 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) and graphite powder together. The Hb modified carbon ionic liquid electrode (Hb-CILE) was further characterized by FT-IR spectra, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Hb in the carbon ionic liquid electrode remained its natural structure and showed good direct electrochemical behaviors. A pair of well-defined quasireversible redox peaks appeared with the apparent standard potential (E′) as −0.334 (vs. SCE) in pH 7.0 phosphate buffer solution (PBS). The electrochemical parameters such as the electron transfer number (n), the electron transfer coefficient (α) and the heterogeneous electron transfer kinetic constant (ks) of the electrode reaction were calculated with the results as 1.2, 0.465 and 0.434 s−1, respectively. The fabricated Hb-CILE exhibited excellent electrocatalytic activity to the reduction of H2O2. The calibration range for H2O2 quantitation was between 8.0×10−6 mol/L and 2.8×10−4 mol/L with the linear regression equation as Iss (μA)=0.12 C (μmol/L)+0.73 (n=18, γ=0.997) and the detection limit as 1.0×10−6 mol/L (3σ). The apparent Michaelis–Menten constant (KMapp) of Hb in the modified electrode was estimated to be 1.103 mmol/L. The surface of this electrochemical sensor can be renewed by a simple polishing step and showed good reproducibility.
Electroanalysis 04/2008; 20(10):1048 - 1054. · 2.87 Impact Factor
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ABSTRACT: In this paper the direct electron transfer of hemoglobin (Hb) was carefully investigated by using a room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) modified carbon paste electrode (CILE) as the basal working electrode. Hb was immobilized on the surface of CILE with the nanocomposite film composed of Nafion and CdS nanorods by a step-by-step method. UV–vis and FT-IR spectra showed that Hb in the composite film remained its native structure. The direct electrochemical behaviors of Hb in the composite film were further studied in a pH 7.0 phosphate buffer solution (PBS). A pair of well-defined and quasi-reversible cyclic voltammetric peaks of Hb was obtained with the formal potential (E0′) at −0.295 V (vs. SCE), which was the characteristic of heme Fe(III)/Fe(II) redox couples. The direct electrochemistry of Hb was achieved on the modified electrode and the apparent heterogeneous electron transfer rate constant (ks) was calculated to be 0.291 s−1. The formal potentials of Hb Fe(III)/Fe(II) couple shifted negatively with the increase of buffer pH and a slope value of −45.1 mV/pH was got, which indicated that one electron transfer accompanied with one proton transportation. The fabricated Hb sensor showed good electrocatalytic manner to the reduction of trichloroacetic acid (TCA).
Electrochimica Acta.
