【作者】 姚思德； 王文锋； 林念芸；

【Author】 Yao Side, Wang Wenfeng, Lin Nianyun Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O.Box.800-204, Shanghai 201800

【机构】 中科院上海应用物理研究所；

【摘要】 上世纪八十年代初,当时的中科院上海原子核研究所辐射化学实验室,先后建立了纳秒级激光光解和脉冲辐解时间分辨吸收装置[1]。前后共进行了“七五”“八五”两个院重点项目,“八五”、“九五”“十五”三个国家自然科学基金重点项目,一个“九七三”攀登子项目的基础研究和几十个基金面上项目、自选项目的探索研究。设备于2002 年度末开始全面升级,2004 年将使现代化的纳秒、皮秒脉冲辐解和激光光解投入使用,条件许可将建立飞秒自由电子激光光解装置。现就二十年来应用时间分辨手段开展的辐射(光)化学和辐射生物学机理研究进行简略回顾。　　　　使用丙酮敏化与激光直接激发,系统获取双链和单链DNA 及其四个碱基、碱基核苷、碱基脱氧核苷酸的激发三重态的瞬态吸收谱,半衰寿命,与丙酮发生激发能转移的动力学常数,与丙酮激发态发生电子转移生成阳离子自由基及其脱质子中性自由基的瞬态吸收谱和动力学常数,极大地丰富了DNA 光物理和光化学研　究[2-3]。建立一整套脉冲辐解产生如:O2 ,　·OH,　1O2 ,　NO2·, CO2·,ROO·, N3·等氧化 ·- *性自由基的方法,系统研究了这些氧化性自由基损伤DNA 及其衍生物的机理和动力学[4-5],系统研究了几十种具有中国特色的天然抗氧化剂清除氧化性自由基的机理及其动力学,天然抗氧化剂修复为羟基损伤的DNA 及其衍生物氧化性自由基的机理及其动力学,探讨了天然抗氧化剂结构与性能的关系,阐明了中草药有效成分保护和修复基因辐射损伤及抗癌的机理。系统研究了醌类、黄素类内源性光敏剂,放线菌素、竹红菌素光敏剂的激发态、在可见光诱导下通过电子转移氧化性损伤DNA的机理及其动力学[6-7],获取该氧化性损伤定位于鸟嘌呤和DNA端粒的直接证据,为使用光动力治疗肿瘤开拓了新的思路。系统研究了黄素类内源性光敏剂在光诱导下产生氧化性自由基及其对溶菌酶为蛋白质模型的光敏损伤机理,抗氧化剂保护和修复蛋白质氧化性损伤的机理;电子沿蛋白质及芳香二肽转移与溶液pH 的关系,首次观察到磷酰化芳香二肽电子转移经由磷酸酯到酪氨酸向色氨酸阳离子的逆向转移[8]。系统研究了富勒烯的激发态,首次观察到经由空穴转移生成C60的阳离子自由基的特征瞬态吸收,从瞬态吸收谱和动力学两个方面证明了富勒烯与CCl3·, CCl3OO·生成长寿命自由基的机理[9-10],研究了水溶性富勒醇的辐射化学和光化学反应机理,丰富了富勒烯化学。此外,辐射增敏剂的单电子氧化还原电位测定,若干光致变色机理和动力学,类激素的环境变迁及其生物学效应,卤代烷烃、难降解有机物及印染废水辐射降解机理、纳米二氧化钛光敏化等研究都取得一些创新成果。　　　　　希望本所的时间分辩研究手段,为中国的辐射研究和辐射工艺科学事业作出更大的贡献。更多还原

【Abstract】 ion: The ns pulse radiolysis and laser flash photolysis system had been set up in the Laboratory of Radiation Chemistry of Shanghai Institute of Nuclear Research, Chinese Academy of Sciences at the beginning of eighty of last decade. By use of two apparatuses, several important projects and many fundamental projects supported by NSFC have been performed and a series of important results have been obtained. In this paper related mechanical studies in last twenty years will be reviewed though the ps pulse radiolysis and ns, ps laser flash photolysis equipped with new types of LINAC and lasers will be set up before the end of this year in our institute. With directed excitation and photo-sensitization of acetone, the transient absorption spectra, life-time, decay and quenched rate constants of excited triplet of DNA and its components including bases, nucleosides, nucleotides have been obtained. The rate constants of excited energy transfer and electron transfer from DNA and its components to acetone have also determined. It developed photo-physics and photochemistry of DNA greatly. The mechanism of DNA and its components damaged by active oxygen radicals such as O2 , ·OH, 1O2 , NO2·, CO2·, ROO·, N3·, etc, ·- * which may occurs involved in radiation damage has been studied in detail and related rate constants have been determined. Meanwhile, different mechanisms of active oxygen radicals scavenged by natural antioxidants containing in Chinese herbs and green tea have been studied and the relationship between molecular structure of natural antioxidants and their effects also have been explored. It has been confirmed that antioxidants can repair the oxidized damage of DNA adducted by OH radicals, which may be used to protect organism from tumours. The excited states of several photo-sensitizers existed in organism such as quinone and riboflavin derivatives have been studied and the photo sensitized damage of DNA via electron transfer reaction induced under irradiation of visible light have been confirmed. And the first direct evidence for oxidized damage of DNA involved in photosensitization located on guanine and telegrase has been obtained, which revealed that quinone and riboflavin derivatives may have some special action with telegrase. On other hand, the mechanism of lysozyme, as a model of protein, damaged by photo-oxidation of riboflavin, the mechanism repaired by antioxidants has been performed. It has been observed firstly that the reversing electron transfer from phosphorus to tyrosine and then to tryptophan residue occurs in phosphoryl peptide, which is very different from that with none-phosphoryl peptides. The radiation and photo chemistry of fullerene has been studied the transient radical cation of C60 produced via positive transfer have been observed firstly and both of transient absorption spectra and kinetics have been used to confirm the growing mechanism of adducted radicals of fullerene and transient species of fullerene solved in aqueous solution. In addition, the determination of single electron redox potential of radiation sensitizers, the photo-chromic mechanism, biological effect and environmental exchange of xenoestrogens, mechanism of radiation degradation of halogen alkyls and so on also has been explored. It can be expected that there will be a more development with the mechanical studies for radiation research and radiation processing by use of new apparatus in near future.更多还原