Theoretical studies of physical and chemical aspects of primary processes in fundamental radiobiology

基础放射生物学初级过程的物理和化学方面的理论研究

• 批准号: RGPIN-2015-06100
• 负责人: JayGerin, JeanPaul
• 金额: $ 3.35万
• 依托单位: Université de Sherbrooke
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613943
• 关键词: Theoretical; studies; physical; chemical; aspects

An understanding of radiation-induced processes in aqueous systems is vital to many areas of basic and applied radiobiological physics and chemistry, medicine, and in a variety of technological and industrial applications. If, nowadays, a general understanding of the phenomena that underline the radiation chemistry of water and aqueous solutions has been obtained in many cases, it appears that certain quantitative aspects of this radiolysis are not yet fully resolved. This is especially true forultrafast processes that link chemistry and physics in the first few picoseconds following energy deposition. Understanding this interface between radiation physics and radiation chemistry (i.e., "breaking the picosecond barrier") is of obvious relevance to fundamental radiobiology and related science as liquid water is by far the most abundant constituent of biological cells and tissue (living cells contain ~70-85% water by weight). Most importantly, it is central to a reliable description of the chemical nature and highly nonhomogeneous spatial distribution of all reactive species created on the (sub) picosecond time scale and involved as precursors of radiobiological damage. This understanding is also critical to creating reliable predictive models. Of a theoretical nature, the present project will focus on the characterization of the physicochemical stage of radiation action (<1 ps). In particular, one difficult problem that we wish to address in the next five years under an NSERC Discovery Grant is the physical behavior of the numerous low-energy (<30 eV) secondary electrons generated in the slowing of primary ionizing radiations and the pivotal role they can have, as precursors of hydrated electrons, on the transient ensuing chemistry in the radiation track development. Another aera of great importance that we wish to examine is the fact that the aqueous medium itself is not continuous on a molecular scale (all track physics programs have hitherto considered water as a continuum). We will attempt to generate a track in a manner that recognizes the molecular nature of the target medium. Using state-of-the-art stochastic Monte Carlo methods and molecular dynamics calculations in combination with the knowledge gained from current experimental efforts, the proposed research program aims to design experiment-and-theory based models to advance our knowledge of the radiolysis of (dilute and concentrated) aqueous systems for which, we feel, an early-time, molecular-level characterization of the underlying chemistry is essential to produce a complete, accurate picture of this radiolysis. It is, without doubt, part of a major challenge in fundamental radiobiology where our long-term goal is to achieve a global comprehension of the effects of radiation in biological systems and to apply this knowledge to enhance the therapeutic and diagnostic efficiency of radiation.

了解水系统中的辐射诱导过程对基础和应用放射生物物理和化学、医学以及各种技术和工业应用的许多领域至关重要。现在，如果对在许多情况下强调水和水溶液的辐射化学的现象有了一般的了解，那么这种辐射分解的某些定量方面似乎还没有完全解决。对于在能量沉积后的最初几皮秒内连接化学和物理的超快过程尤其如此。了解辐射物理学和辐射化学之间的这种界面（即“打破皮秒屏障”）与基础放射生物学和相关科学具有明显的相关性，因为液态水是迄今为止生物细胞和组织中最丰富的成分（活细胞按重量计含有70-85%的水）。最重要的是，它是可靠描述（亚）皮秒时间尺度上产生的所有反应物质的化学性质和高度非均匀空间分布的核心，这些反应物质是放射性生物损伤的前兆。这种理解对于创建可靠的预测模型也是至关重要的。从理论上讲，本项目将侧重于描述辐射作用（<1 ps）的物理化学阶段。特别是，在NSERC发现资助下，我们希望在未来五年内解决的一个难题是，在初级电离辐射减缓过程中产生的大量低能（<30 eV）次级电子的物理行为，以及它们作为水合电子的前体，在辐射轨道发展过程中瞬态后续化学反应中的关键作用。我们希望研究的另一个非常重要的领域是水介质本身在分子尺度上不是连续的（迄今为止所有的轨道物理程序都认为水是连续的）。我们将尝试以一种识别目标介质分子性质的方式生成轨迹。利用最先进的随机蒙特卡罗方法和分子动力学计算，结合从目前的实验努力中获得的知识，拟议的研究计划旨在设计基于实验和理论的模型，以提高我们对（稀和浓）水体系辐射分解的认识，我们认为，早期的、分子水平的潜在化学表征对于产生一个完整的、放射溶解的准确图片。毫无疑问，这是基础放射生物学的一个重大挑战，我们的长期目标是全面了解辐射对生物系统的影响，并应用这些知识来提高辐射的治疗和诊断效率。