Direct Electron Transfer of Hemoglobin in a Hydrophilic Ionic Liquid/Gellan Gum Composite Film Modified Carbon Ionic Liquid Electrode

• Published in: Journal of the Chinese Chemical Society (Taipei) 2010-08, Vol.57 (4A), p.718-725
• Main Authors: Qiao, Li-Fang, Zheng, Jian-Bin, Gao, Rui-Fang, Sheng, Qing-Lin
• Format: Article
• Language: English
• Subjects: Carbon ionic liquid electrode; Direct electrochemistry; Gellan gum; Hemoglobin; Room temperature ionic liquids
• ISSN: 0009-4536; 2192-6549
• DOI: 10.1002/jccs.201000100

A gellan gum (GG)‐Hemoglobin (Hb)‐1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate ([BMIM] [BF4])/carbon ionic liquid electrode(CILE), GG‐Hb‐[BMIM][BF4]/CILE, was fabricated, and the direct electron transfer of hemoglobin and electrocatalytic reaction for electrocatalytic abilities were carefully investigated. Scanning electron microscopy images of the modified electrode showed that it had a dendritic structure. UV‐Vis spectra and FT‐IR spectra showed that Hb in the composite film retained its native structure. Cyclic voltammogram of the modified electrode showed that a pair of well‐defined redox peaks of Hb is observed with the formal potential (E0) of −0.278 V (vs. SCE). The electron transfer coefficient (a) and the apparent heterogeneous electron transfer rate constant (ks) was 0.44 and 2.0 s−1, respectively. The modified electrode also exhibited excellent electrocatalytic ability to the reduction of trichloroacetic acid and hydrogen peroxide with a detection limit of 6.8 μmol/L and 1.5 μmol/L (S/N = 3), respectively. The apparent Michaelis‐Menten constant (KMapp) was estimated to be 4.3 mmol/L and 0.13 mmol/L, respectively. The present study proved that the combination of GG‐[BMIM][BF4] film with CILE is able to open up new opportunities for the design of enzymatic biosensors with potential applications in practice. While a pair of well‐defined redox peaks was observed for GG‐Hb‐[BMIM][BF4]/CILE (Fig. 4b) with Epa of −0.227 V and Epc of −0.284 V. The E0′ was estimated to be −0.278V (vs. SCE) and ΔEp was 57 mV. Synergistic effects of GG and [BMIM][BF4] provided an excellent microenvironment for Hb to retain its high activity.