Direct electrochemistry of hemoglobin immobilized on gold electrode by Langmuir-Blodgett technique

In this research, we reported a novel method of forming hemoglobin (Hb)-linoleic acid (LA) Langmuir-Blodgett (LB) monolayer by spreading Hb solution directly onto the subphase covered with a layer of LA. This method is suitable for preparing electrochemical devices with protein-lipid LB film because almost no protein adsorbed on electrode surface before protein-lipid film transferred from air-water interface to electrode, which ensured better electrode activity. The compressibility of Hb-LA monolayer was used to character the phase transition during compression process. Optimal experimental conditions were obtained by analyzing pressure-time, pressure-area and pressure-compressibility curves. The direct electrochemistry of Hb, which was immobilized on Au electrode surface incorporated with LA layer by LB method, was investigated using cyclic voltammetry for the first time. The electrode modified with Hb-LA LB film holds high electrochemical activity and shows a fast direct electron transfer of Hb. Redox peak currents increased linearly with the increase of scan rate, indicating a surface-controlled electrode process. The electron transfer rate constant was 2.68+/-0.45 s-1. As a target of this research, this work provides a new way to prepare biomimetic film and biosensor.