Vacuum-UV and Low-Energy Electron-Induced DNA Strand Breaks - Influence of the DNA Sequence and Substrate.
Vacuum-UV and Low-Energy Electron-Induced DNA Strand Breaks - Influence of the DNA Sequence and Substrate.
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DOI：
10.1002/cphc.201801152
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发表时间：
2019-03
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影响因子：
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通讯作者：
Stefanie Vogel;Kenny Ebel;R. Schürmann;C. Heck;T. Meiling;A. Milosavljević;A. Giuliani;I. Bald
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文献类型：
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作者：
Stefanie Vogel;Kenny Ebel;R. Schürmann;C. Heck;T. Meiling;A. Milosavljević;A. Giuliani;I. Bald
DNA被辐射有效地破坏，这一方面可以导致癌症，另一方面直接用于治疗肿瘤组织。能量低于DNA电离能的光子已经诱导DNA链断裂。在高光子能量下，大多数DNA链断裂是由低能二次电子引起的。在本研究中，我们定量的光子和电子诱导的DNA链断裂在四个不同的12聚体寡核苷酸。它们被8.44 eV的真空紫外（VUV）光子和8.8 eV的低能电子（LEE）直接照射。通过使用Si代替VUV透明CaF 2作为基底，VUV暴露会导致LEE的额外释放，LEE的最大能量为3.6 eV，可以显着增强链断裂横截面。原子力显微镜用于观察DNA折纸平台上的链断裂，并确定链断裂横截面的绝对值。在用8.44 eV光子照射时，所有研究的序列显示出非常相似的链断裂截面，范围为1.7-2.3×10-16 cm 2。在8.8 eV的LEE照射的链断裂截面比真空紫外光子的大一到两个数量级，并观察到轻微的序列依赖性。对于能量<3.6 eV的LEE，序列依赖性甚至更明显。目前的结果有助于评估DNA损伤的光子和电子接近电离阈值。
DNA is effectively damaged by radiation, which can on the one hand lead to cancer and is on the other hand directly exploited in the treatment of tumor tissue. DNA strand breaks are already induced by photons having an energy below the ionization energy of DNA. At high photon energies, most of the DNA strand breaks are induced by low-energy secondary electrons. In the present study we quantified photon and electron induced DNA strand breaks in four different 12mer oligonucleotides. They are irradiated directly with 8.44 eV vacuum ultraviolet (VUV) photons and 8.8 eV low energy electrons (LEE). By using Si instead of VUV transparent CaF2 as a substrate the VUV exposure leads to an additional release of LEEs, which have a maximum energy of 3.6 eV and can significantly enhance strand break cross sections. Atomic force microscopy is used to visualize strand breaks on DNA origami platforms and to determine absolute values for the strand break cross sections. Upon irradiation with 8.44 eV photons all the investigated sequences show very similar strand break cross sections in the range of 1.7-2.3×10-16 cm2 . The strand break cross sections for LEE irradiation at 8.8 eV are one to two orders of magnitude larger than the ones for VUV photons, and a slight sequence dependence is observed. The sequence dependence is even more pronounced for LEEs with energies <3.6 eV. The present results help to assess DNA damage by photons and electrons close to the ionization threshold.