在HI-13串列加速器加速的具有高LET值的^7Li离子辐照不同浓度的pUC19质粒DNA水溶液、加自由基清除剂(甘露醇)的DNA水溶液以及干状DNA样品,利用高分辨的原子力显微镜技术,研究^7Li致DNA损伤的直接作用和间接作用.结果显示,在相同剂量下,^7Li离子比低LET辐射能诱发更多的双链断裂,形成更多的集团损伤,使DSB的分布更局部和更密集.对于水溶液DNA,^7Li离子的水辐解产生的自由基的间接作用在DNA分子链断裂的产生方面发挥着重要作用,而且自由基清除剂甘露醇能有效地保护DNA分子.
n order to investigate the direct and indirect interaction of DNA damage induced by high LET heavy ions as well as the protective function of scavenger by means of atomic force microscopy, samples of pUC19 plasmid DNA aqueous solution, pUC19 plasmid DNA aqueous solution with scavenger (mannitol) and dry DNA are irradiated by ^7Li ions from the HI-13 Tandem accelerator in China Institute of Atomic Energy (CIAE). Results show that the indirect interaction of free radical plays an important role in DNA strand break induced by ^7Li ions and mannitol can protect the DNA molecules effectively.