Reactive oxygen species (ROS) have many vital functions including sterilizing function of white blood cell, carcinostatic function, aging, cell death, inflammation, and DNA damage. Among various ROS, superoxide anion radical (O2-•) has been attracting great attention as a cause of human disease. We have developed an O2-• sensor composed of a thin film of 1-methylimidazole (Im) coordinatied Bromoiron (III) meso-tetrathienyleporphyrin ([FeBr(ttp)]) for the electro-chemical detection. In this study, highly sensitive measurements of O2-• by potentiometry were conducted. The potentiometric response for O2-• was monitored in 10 mM phosphate buffer. The O2-• sensor displayed a high catalytic activity for oxidation of O2-• and showed a linear relationship between the sensor response and the logarithm of O2-• concentration. This O2-• sensor showed low interferences due to the electrochemical interferents H2O2 and uric acid. Measurement of O2 -• by potentiometry was able to detect the low concentrations of O2-• (7 × 10-7 M) that measurements of O2-• by amperometry could not easily detect.
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