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

Abstract

Abstract A gellan gum (GG)‐Hemoglobin (Hb)‐1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate ([BMIM] [BF4])/carbon ionic liquid electrode(CILE), GG‐Hb‐[BMIM][BF 4 ]/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 ( E 0 ) of −0.278 V ( vs . SCE). The electron transfer coefficient (a) and the apparent heterogeneous electron transfer rate constant ( k s ) 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 ( K M app ) was estimated to be 4.3 mmol/L and 0.13 mmol/L, respectively. The present study proved that the combination of GG‐[BMIM][BF 4 ] film with CILE is able to open up new opportunities for the design of enzymatic biosensors with potential applications in practice.