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Probing DNA Radiation Damage by DNA Nanotechnology

利用 DNA 纳米技术探测 DNA 辐射损伤

基本信息

批准号：
230710387
负责人：
Professor Dr. Ilko Bald
金额：
--
依托单位：
Arbeitsgruppe Hybride Nanostrukturen
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/230710387?language=en
关键词：
Probing DNA Radiation Damage Nanotechnology

项目摘要

The damage of DNA by electromagnetic or particle radiation is a pivotal process occurring for instance during tumor radiation therapy. In radiotherapy radiosensitizers such as halogenated nucleosides are applied to sensitize the tumour tissue towards radiation. But the DNA is damaged only to a small extent by the primary high-energy radiation. Most of the damage occurs due to low-energy secondary particles such as electrons. In the meantime it is well-established that electrons with kinetic energy below 12 eV can damage DNA via the dissociative electron attachment mechanism. However, the underlying processes are only well-understood for simple model compounds such as single nucleobases. The influence of the DNA sequence on the DNA strand breakage and the effect of radiosensitizers was suggested within preliminary experiments, but could not be investigated systematically due to a lack of suitable analytical tools. In the previous project of the applicant a novel technique for the determination of DNA strand break yields in oligonucleotides of defined sequence was established. The key aspects of this technique are the arrangement of the target oligonucleotide sequences on DNA origami nanostructures and the detection of electron-induced strand breaks by atomic force microscopy (AFM). In this way, multiple DNA sequences can be compared within a single irradiation experiment, and absolute cross sections for strand breakage are directly accessible. In the present proposal cross sections for electron induced strand breakage will be determined for DNA sequences, which are modified with clinically established and potential radiosensitizers. By comparison with non-modified sequences enhancement factors will be determined at different electron energies. The molecular structure of the radiosensitizers will be modified systematically to reveal damage mechanisms and to be able to stimulate the development of novel radiosensitizers. Furthermore, the influence of an aqueous environment on the DNA damage will be studied. Gold nanoparticles are used as a source of photoelectrons, which can damage the DNA in solution. The influence of the solvent will on the one hand be studied by determination of strand break yields using the DNA origami technique and AFM and by comparison with vacuum experiments. On the other hand damage products can be detected using surface-enhanced Raman scattering. In this way complementary information about radiation induced chemical changes in aqueous environment will be obtained. This is a novel approach to explore damage mechanisms in increasingly complex systems and the final goal is to reveal the physico-chemical basis of DNA radiosensitization.

电磁或粒子辐射对DNA的损伤是例如在肿瘤放射治疗期间发生的关键过程。在放射疗法中，应用放射增敏剂如卤代核苷以使肿瘤组织对辐射敏感。但是DNA只在很小程度上被初级高能辐射破坏。大部分的破坏是由于低能次级粒子如电子造成的。与此同时，它是公认的动能低于12 eV的电子可以通过解离电子附着机制损伤DNA。然而，基本的过程仅对简单的模型化合物如单个核碱基有很好的理解。在初步实验中提出了DNA序列对DNA链断裂的影响和放射增敏剂的作用，但由于缺乏合适的分析工具，无法进行系统研究。在申请人的先前项目中，建立了一种用于测定确定序列的寡核苷酸中DNA链断裂产率的新技术。该技术的关键方面是DNA折纸纳米结构上的靶寡核苷酸序列的排列和通过原子力显微镜（AFM）检测电子诱导的链断裂。通过这种方式，可以在单个辐照实验中比较多个DNA序列，并且可以直接获得链断裂的绝对横截面。在本提案中，电子诱导的链断裂的横截面将被确定为DNA序列，这是修改与临床建立和潜在的放射增敏剂。通过与未修改的序列进行比较，将在不同的电子能量下确定增强因子。放射增敏剂的分子结构将被系统地修饰，以揭示损伤机制，并能够刺激新型放射增敏剂的开发。此外，将研究水性环境对DNA损伤的影响。金纳米颗粒被用作光电子的来源，这可能会破坏溶液中的DNA。溶剂的影响将一方面通过使用DNA折纸技术和AFM测定链断裂产率并通过与真空实验进行比较来研究。另一方面，可以使用表面增强拉曼散射检测损伤产物。通过这种方式，将获得关于辐射引起的水环境中的化学变化的补充信息。这是一种探索日益复杂的系统中损伤机制的新方法，最终目标是揭示DNA辐射增敏的物理化学基础。