Electrochemistry and Electrocatalysis of a Nafion/Nano‐CaCO 3 /Hb Film Modified Carbon Ionic Liquid Electrode Using BMIMPF 6 as Binder

• Published in: Electroanalysis (New York, N.Y.) N.Y.), 2007-07, Vol.19 (13), p.1368-1374
• Main Authors: Sun, Wei, Gao, Rui‐fang, Jiao, Kui
• Format: Article
• Language: English
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/elan.200703859

In this paper a room temperature ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF 6 ) was used as binder for the construction of carbon ionic liquid electrode (CILE) and a new electrochemical biosensor was developed for determination of H 2 O 2 by immobilization of hemoglobin (Hb) in the composite film of Nafion/nano‐CaCO 3 on the surface of CILE. The Hb modified electrode showed a pair of well‐defined, quasi‐reversible redox peaks with E pa and E pc as −0.265 V and −0.470 V (vs. SCE). The formal potential ( E °′) was got by the midpoint of E pa and E pc as −0.368 V, which was the characteristic of Hb Fe(III)/Fe(II) redox couples. The peak to peak separation was 205 mV in pH 7.0 Britton–Robinson (B–R) buffer solution at the scan rate of 100 mV/s. The direct electrochemistry of Hb in the film was carefully investigated and the electrochemical parameters of Hb on the modified electrode were calculated as α =0.487 and k s =0.128 s −1 . The Nafion/nano‐CaCO 3 /Hb film electrode showed good electrocatalysis to the reduction of H 2 O 2 in the linear range from 8.0 to 240.0 μmol/L and the detection limit as 5.0 μmol/L (3 σ ). The apparent Michaelis–Menten constant ( K M app ) was estimated to be 65.7 μmol/L. UV‐vis absorption spectroscopy and FT‐IR spectroscopy showed that Hb in the Nafion/nano‐CaCO 3 composite film could retain its native structure.