Synergistic Effect of Thermal Energy on Bactericidal Action of Photolysis of H2O2 in Relation to Acceleration of Hydroxyl Radical Generation
Synergistic Effect of Thermal Energy on Bactericidal Action of Photolysis of H2O2 in Relation to Acceleration of Hydroxyl Radical Generation
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DOI：
10.1128/aac.05158-11
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发表时间：
2012-01-01
影响因子：
4.9
通讯作者：
Niwano, Yoshimi
中科院分区：
文献类型：
--
作者：
Shirato, Midori;Ikai, Hiroyo;Niwano, Yoshimi
本研究的目的是评估热能对过氧化氢（H₂O₂）光解产生的羟基自由基的产量及其杀菌作用的影响。在25℃下，用波长为400 ± 20 nm的发光二极管（LED）照射不同浓度的H₂O₂（250、500、750和1000 mM）以产生羟基自由基。在不同温度（25、35、45和55℃）下用LED照射500 mM的H₂O₂。电子自旋共振自旋捕集分析表明，羟基自由基的产量随温度以及H₂O₂浓度的升高而增加。在杀菌试验中使用了变形链球菌和粪肠球菌。在25℃下，用LED光照射500 mM H₂O₂中的细菌悬液，在3分钟内几乎无法杀死细菌，而随着温度升高，杀菌效果显著增强。例如，温度升高到55℃时，仅在1分钟内两种细菌的活菌数就减少了>99.999%。在55℃下500 mM H₂O₂的光解比在25℃下1000 mM H₂O₂的光解能更有效地减少细菌的活菌数，尽管在这两种条件下羟基自由基的产量几乎相同。这些发现表明，热能加速了H₂O₂光解产生羟基自由基的过程，进而导致羟基自由基和热能产生协同杀菌作用。
The purpose of the present study is to evaluate the effect of thermal energy on the yield of and the bactericidal action of hydroxyl radical generated by photolysis of H2O2. Different concentrations of H2O2 (250, 500, 750, and 1,000 mM) were irradiated with light-emitting diodes (LEDs) at a wavelength of 400 +/- 20 nm at 25 degrees C to generate hydroxyl radical. The 500 mM H2O2 was irradiated with the LEDs at different temperatures (25, 35, 45, and 55 degrees C). Electron spin resonance spin trapping analysis showed that the yield of hydroxyl radicals increased with the temperature, as well as the concentration of H2O2. Streptococcus mutans and Enterococcus faecalis were used in the bactericidal assay. The LED-light irradiation of the bacterial suspensions in 500 mM H2O2 at 25 degrees C could hardly kill the bacteria within 3 min, while the bactericidal effect was markedly enhanced with the temperature rise. For instance, a temperature increase to 55 degrees C resulted in >99.999% reduction of viable counts of both bacterial species only within 1 min. The photolysis of 500 mM H2O2 at 55 degrees C could reduce the viable counts of bacteria more efficiently than did the photolysis of 1,000 mM H2O2 at 25 degrees C, although the yields of hydroxyl radical were almost the same under the both conditions. These findings suggest that the thermal energy accelerates the generation of hydroxyl radical by photolysis of H2O2, which in turn results in a synergistic bactericidal effect of hydroxyl radical and thermal energy.