Abstract：
We investigated the deoxyribonucleic acid (DNA) damage induced by laser filamentation, which was generated by focusing femtosecond near-infrared Ti:Sapphire laser light in water at several repetition rates ranging from 1000 Hz to 10 Hz. Using plasmid DNA (pUC19), the single-strand break, double-strand break, nucleobase lesions, and the fragmented DNA were analyzed and quantified by agarose gel electrophoresis. Additionally, the H2O2 concentration after irradiation was determined. We observed that (1) the DNA damage per laser shot and (2) the enzyme-sensitive base lesions per total DNA damage decreased as the laser repetition rate increased. Furthermore, (3) extraordinarily short DNA fragments were likely to be produced, compared with those produced using X-rays, and (4) most OH radicals could be eliminated by recombination to generate H2O2, preventing them from damaging the DNA. The Monte-Carlo simulation of the strand break formation implies that the observed dependency of strand break efficiency on the laser repetition rate is mainly due to diffusion of DNA molecules. These findings quantitatively and qualitatively revealed that an intense laser pulse induces a specific DNA damage profile that is not induced by X-rays, a sparsely ionizing radiation source.
摘要：
我们研究了激光成丝诱导的脱氧核糖核酸（DNA）损伤，它是通过以1000Hz至10Hz的多个重复频率在水中聚焦飞秒近红外Ti：Sapphire激光而产生的。使用质粒DNA（pUC19），单链断裂，双股断裂,核碱基损伤,和片段化的DNA通过琼脂糖凝胶电泳进行分析和定量。此外,测定辐照后的H2O2浓度。我们观察到（1）每次激光发射的DNA损伤和（2）每次总DNA损伤的酶敏感碱基损伤随着激光重复率的增加而减少。此外，(3)很可能产生非常短的DNA片段，与使用X射线产生的相比，和（4）大多数OH自由基可以通过重组消除以产生H2O2，防止它们破坏DNA。链断裂形成的蒙特卡罗模拟表明，观察到的链断裂效率对激光重复率的依赖性主要是由于DNA分子的扩散。这些发现定量和定性地揭示了强激光脉冲诱导的特定DNA损伤谱不是由X射线诱导的，稀疏的电离辐射源。
