Generation of Localized Highly Concentrated Hydrogen Peroxide Clusters in Water by X-Rays.

Generation of Localized Highly Concentrated Hydrogen Peroxide Clusters in Water by X-Rays. Free Radic Res. 2020 May 25;:1-45 Authors: Ueno M, Nakanishi I, Matsumoto KI Abstract The formation of highly concentrated hydrogen peroxide (H2O2) clusters (localized circumstance) in an aqueous solution during X-ray irradiation was demonstrated. The relationship between H2O2 concentration and hydrogen donor-independent reduction of nitroxyl radicals was examined. The method to measure the distance between the clusters (localized circumstance) was assessed by comparing the simulation and the experimental results. Reaction mixtures containing a nitroxyl redox probe, 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) and 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CmP) at 0.1 mM were prepared containing several different concentrations (1.0 mM‒9.8 M) of H2O2. The reaction mixture was irradiated by 12000 μW/cm2 UVB for 2 min, and reduction of the electron paramagnetic resonance (EPR) signal of the nitroxyl radicals was measured. An aliquot (2 µL) of 200 mM K3[Fe(CN)6] or FeCl3 solution was added to 200 µL of the reaction mixture, and the time course of the EPR signal of the nitroxyl radicals was measured. To estimate the distance between the H2O2 clusters, a series of nitroxyl radical solutions with several different concentrations (0.06 μM‒2.28 mM) was irradiated with X-rays, and the degree of reduction of nitr...
Source: Free Radical Research - Category: Research Tags: Free Radic Res Source Type: research