Detection of Superoxide Anion Radical Using Iron Porphyrin Complexes Bound to Electropolymerized Axial Ligands

Iron porphyrin complexes were applied for the electro- chemical detection of superoxide anion radical (O-2(-center dot)). An electropolymerizable axial ligand, 1-(4-(3-thienyl)benzyl)- imidazole was designed and synthesized for the application to a sensor for O-2(-center dot). The axial ligand was electro- polymerized onto a grassy carbon (GC) electrode. This electrode was immersed into the solution of iron porphyrin complexes. UV-visible absorption spectrum showed that iron porphyrin complexes were successfully bound to the axial ligand, and differential pulse voltammograms showed redox responses near 0 to -0.3 V vs. Ag/AgCl due to Fe2+/3+. These electrodes were applied to detect O-2(-center dot) produced by the xanthine oxidase (XOD)-catalyzed xanthine oxidation. These electrodes showed a linear relationship between the current and the O-2(-center dot) concentration.