Electrochemical determination of dioxygen and hydrogen peroxide using Fe3O4@SiO2@hemin microparticles

Iron oxide microparticles were coated with 3-aminopropyltriethoxysilane and then coated with hemin via an amidation reaction. The resulting composite particles were characterized by transmission electron microscopy. FTIR spectroscopy revealed two bands (at 1,701 and 1,634 cm(-1)), which were assigned to the carboxy group and the amide linkage, respectively, resulting from the linkage between hemin and the amino-modified Fe3O4 particles. In addition, strong Fe-O vibrations can be observed at 563 cm(-1). An electrode was modified with these microparticles and then showed a well-defined redox behavior of the immobilized hemin, with a fast heterogeneous electron transfer process (14.5 s(-1)). The electrode is capable of sensing both O-2 and H2O2 and displays a wide linear range, high sensitivity, and fast response. The composites reported here also may serve as a support for the immobilization of proteins, which paves the way to potential applications in novel biosensors and bioelectronic devices.