Ultrafast electron - transfer reactions in radiation chemistry and radiation biology

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This renewal proposal describes a continuous research program to study ultrafast electron-transfer reactions in molecular systems of biological and environmental significance. Over the past several years, the applicant has built an innovative program to study ultrafast electron-transfer reactions of various molecular systems and to discover their importance for environmental and biological processes, ranging from atmospheric ozone depletion to the mechanisms of action of anticancer drugs for cancer treatment. The objectives of this proposal are to obtain real-time observations of ultrafast electron transfer reactions of organohalogen molecules, recognized as environmental pollutants, in biological and environmental systems under ionizing/UV radiation and to evaluate their biological effects. The applicant has built a high-sensitivity femtosecond (ultrafast) time-resolved laser spectroscopy, which is very powerful for real-time, direct observation of ultrafast electron-transfer reactions of organohalogen molecules in an aqueous environment. This is the remarkable opportunity afforded through the real-time observation of chemical reactions at the molecular level. The proposed research will utilize the novel ultrafast laser spectroscopic technique combined with biological analysis methods such as DNA damage and cell death assays. This project will have significance for understanding the molecular reaction mechanisms of organohalogen pollutants and their effects on Earth's environment and human health. Moreover, the reaction mechanism developed in this work may lead to the discovery of molecular agents for protection of humans exposed to organohalogens and radiation and the development of an efficient and economical technology for disposal of environmentally hazardous organohalogen materials.