Direct electron transfer of ferritin in dihexadecylphosphate on an Au film electrode and its catalytic oxidation toward ascorbic acid Original Research Article

Stable thin films were obtained by casting vesicle dispersion of dihexadecylphosphate (DHP) containing ferritin onto the nanometer Au film electrode. Ferritin in DHP films exhibited a well-defined current–potential curve. The voltammetric behavior of ferritin and the stability of the ferritin–DHP modified Au film electrode were investigated. UV–vis and reflctance absorbance infrared spectra indicated that ferritin retained near-native secondary structure in the DHP films. The loading and unloading of ferritin iron into the apoferritin shell were investigated by cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The results showed that iron exited the apoferritin shell when reduced, and entered into it when oxidized. Ferritin in DHP films exhibited a strong electrocatalytic activity toward the oxidation of ascorbic acid, which resulted in lowering 330 mV overpotential and greatly increasing the oxidation peak current. Based on this procedure, an amperometric method for the determination of ascorbic acid was proposed.