(562e) Microsensors for Electrocatalytic Quantification of Peroxynitrite

Peroxynitrite constitutes a major cytotoxic agent involved in an increasing number of pathophysiologic conditions, which stimulates a tremendous interest for its real-time in situ monitoring. The current detection methods including fluorescence spectroscopy, immunohistochemistry, or probe nitration, are inherently complex and difficult to apply in situ. We have investigated simple metallo-porphyrins electropolymerized into thin films on carbon macro- and micro-electrodes as a catalytic platform for peroxynitrite detection. The carbon electrodes were modified and characterized by surface analysis techniques, including field emission scanning electron microscopy with elemental analysis. The response of the modified electrodes in the presence the peroxynitrite was investigated by cyclic voltammetry, and showed typical electrocatalytic oxidation of this analyte. The modified electrodes were then used in amperometric determination of peroxynitrite in standing solutions, as well as in a flow-cell setting. Preliminary results show a detection limit in the high nanomolar range. More work is underway for improving the sensitivity, selectivity of these metalloporphyrin-modified microelectrodes towards peroxynitrite detection. The performance of these sensors is being assessed towards quantifying the potential uncoupling of electron transfer and NO biosynthesis by NOS enzymes on NOS-modified electrodes, which yields to peroxynitrite as a side product. This real-time quantification of peroxynitrite would bring a better understanding of the NOS catalytic reaction.