Functional Interface of Ferric Ion Immobilized on Phosphonic Acid Terminated Self-Assembled Monolayers on a Au Electrode for Detection of Hydrogen Peroxide

It is reported that inorganic ferric ion immobilized onto a phosphonic acid terminated functional interface can communicate an electron with the electrode and its electrochemistry is very similar to that of the enzymes (proteins) containing heme groups (such as microperoxidase, horseradish peroxidase, hemoglobin, and myoglobin). For example, its formal potential (E-0') is very close to that of the above-mentioned enzymes (proteins) in neutral solution; analogous to the direct electrochemistry of enzymes (proteins), the formal potential and electron-transfer rate of the immobilized inorganic ferric ion show a strong dependence on solution pH in cyclic voltammetry measurements. In comparison to the traditional enzyme (proteins)-based electrochemical biosensors, the ferric ion modified electrode shows more prominent electrocatalytic activity toward the reduction of hydrogen peroxide due to its high loading, fast electron-transfer rate, and excellent selection toward the reduction of hydrogen peroxide. Importantly, the iron ion, as an inorganic material, is very stable in high temperature and economical to produce. Therefore, the kind of iron ion modified electrode can be used to construct a new generation of biosensors with high performance, and it is very hopeful to substitute for enzyme-based biosensors for detection of hydrogen peroxide.