Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005, India.
UM-DAE Centre for Excellence in Basic Science, Kalina Campus, Santa Cruz (East), Mumbai 400 098, India.
Phys Rev Lett. 2014 Apr 4;112(13):138105. doi: 10.1103/PhysRevLett.112.138105. Epub 2014 Apr 2.
We probe femtosecond laser induced damage to aqueous DNA, relying on strong-field interaction with water wherein electrons and free radicals are generated in situ; these, in turn, interact with DNA plasmids under physiological conditions, producing nicks. Exposure to intense femtosecond pulses of 1350 and 2200 nm light induces single strand breaks and double strand breaks (DSBs) in DNA. At the longer wavelength (and at higher intensities), rotationally hot OH radicals induce DSBs, producing linear DNA. Strand breaks occur due to single or multiple OH hits on DNA. With 2200 nm light, DSBs are formed mostly by the action of two OH radicals; use of OH scavengers establishes that the probability of a two-hit event reduces much faster than a one-hit event as scavenger concentration is increased. Thermal effects do not induce DSBs with 2200 nm light.
我们探究了飞秒激光诱导水相 DNA 损伤，这依赖于强场与水的相互作用，其中电子和自由基会就地生成；这些自由基继而在生理条件下与 DNA 质粒相互作用，产生缺口。暴露于 1350nm 和 2200nm 强飞秒脉冲光会导致 DNA 的单链断裂和双链断裂（DSBs）。在较长波长（和更高强度）下，旋转热 OH 自由基会诱导 DSBs，产生线性 DNA。由于 DNA 上单次或多次 OH 撞击而发生链断裂。对于 2200nm 光，DSBs 主要由两个 OH 自由基的作用形成；使用 OH 清除剂确定，随着清除剂浓度的增加，双击中的事件概率比单击中的事件概率下降得快得多。2200nm 光的热效应不会诱导 DSBs。
