Direct Electron Transfer of Horseradish Peroxidase in Gellan Gum–Hydrophilic Ionic Liquid Gel Film
✍ Scribed by Xiaodong Shangguan; Jianbin Zheng; Qinglin Sheng
- Book ID
- 102181685
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 198 KB
- Volume
- 21
- Category
- Article
- ISSN
- 1040-0397
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✦ Synopsis
Abstract
A new composite film of microbial exocellular polysaccharide‐gellan gum (GG) and hydrophilic room temperature ionic liquid 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate (BMIMBF~4~) was firstly used as an immobilization matrix to entrap horseradish peroxidase (HRP), and its properties were studied by UV/vis spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results showed that BMIMBF~4~ could promote the electron transfer between HRP and electrode surface, and the existence of GG could successfully immobilize BMIMBF~4~ on the electrode surface with improved stability. HRP–BMIMBF~4~–GG/GCE exhibited a pair of well‐defined and quasireversible cyclic voltammetric peaks in 0.1 M pH 7.0 phosphate buffer solutions at 1.8 V/s, which was the characteristic of HRP Fe(III)/Fe(II) redox couples. The formal potentials (E°′) was −0.368 V (vs. SCE) and the peak‐to‐peak potential separation (Δ__E__~P~) was 0.058 V. The peak currents were five times as large as those of HRP–GG/GCE. The average surface coverage (Γ*) and the apparent Michaelis‐Menten constant (K~m~) were 4.5×10^−9^ mol/cm^2^ and 0.67 μM, respectively. The electron transfer rate constant was estimated to be 15.8 s^−1^. The proposed electrode showed excellent electrocatalytic activity towards hydrogen peroxide (H~2~O~2~). The linear dynamic range for the detection of H~2~O~2~ was 0.05–0.5 μM with a correlation coefficient of 0.9945 and the detection limit was estimated at about 0.02 μM (S/N=3). BMIMBF~4~–GG composite film was promising to immobilize other redox enzymes or proteins and attain their direct electrochemistry.