Evaluation of cold atmospheric pressure plasma irradiation of water as a method of singlet oxygen generation

摘要

We used cold atmospheric pressure plasma jet to examine in detail ~(1)O _(2) generation in water. ESR with 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide, a secondary amine probe, was used for the detection of ~(1)O _(2). Nitroxide radical formation was detected after cold atmospheric pressure plasma jet irradiation of a 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide solution. An ~(1)O _(2) scavenger/quencher inhibited the ESR signal intensity induced by cold atmospheric pressure plasma jet irradiation, but this inhibition was not 100%. As 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide reacts with oxidizing species other than ~(1)O _(2), it was assumed that the signal intensity inhibited by NaN _(3) corresponds to only the nitroxide radical generated by ~(1)O _(2). The concentration of ~(1)O _(2) produced by cold atmospheric pressure plasma jet irradiation for 60?s was estimated at 8?μM. When this ~(1)O _(2) generation was compared to methods of ~(1)O _(2) generation like rose bengal photoirradiation and 4-methyl-1,4-etheno-2,3-benzodioxin-1(4 H )-propanoic acid (endoperoxide) thermal decomposition, ~(1)O _(2) generation was found to be, in decreasing order, rose bengal photoirradiation ≥ cold atmospheric pressure plasma jet endoperoxide thermal decomposition. Cold atmospheric pressure plasma jet is presumed to not specifically generate ~(1)O _(2), but can be used to mimic states of oxidative stress involving multiple ROS.