Communication-Fast Electron Transfer Reaction of Azurin Fixed on the Modified Electrode in Hydrated Ionic Liquids

Structure of active site and redox reaction of azurin in a hydrated ionic liquid, cholinium dihydrogen phosphate ([ch][dhp]), was maintained after dissolution of azurin in hydrated [ch][dhp]. Cyclic voltammograms for azurin immobilized on a self-assembled monolayer (SAM) constructed on gold nanoparticle (AuNP) electrodes showed a reversible and stable redox response in hydrated [ch][dhp]. The electron transfer rate (ks) between azurin and the electrode in hydrated [ch][dhp] was 202 s−1, which is larger than that in 10 mM ammonium acetate buffer (ks = 44 s−1).