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MO: Fachverband Molekülphysik

MO 16: Biomoleküle

MO 16.4: Poster

Tuesday, March 11, 2008, 14:00–19:00, Poster C1

Ion-induced radiation damage to DNA-building blocks — Fresia Alvarado, Jos Postma, Sadia Bari, Przemek Sobocinski, Ronnie Hoekstra, and •Thomas Schlathölter — KVI Atomic Physics, University of Groningen, The Netherlands

The interaction of keV protons and heavy ions with DNA building blocks is of particular biological relevance in view of the increasing number of facilities employing MeV proton/heavy-ion irradiation for tumor treatment. When these ions traverse tissue and are decelerated to sub MeV energies, the so-called Bragg-peak is reached where the induced damage is highest due to maximum linear energy transfer (LET) and relative biological effectiveness (RBE) at these energies. Biological consequences of irradiation with energetic protons and heavy ions from galactic cosmic rays (GCR) and solar particle events (SPE) are also a limiting factor for human space exploration.

We investigate the response of isolated DNA building blocks and their clusters upon keV singly and multiply charged ion impact using high resolution coincidence time-of-flight mass spectrometry. Fragment ion energies exceeding several 10 eV are observed which have the potential to induce subsequent damage in a biological environment. Deoxyribose molecules from the DNA backbone are found to be most sensitive to keV ion impact and thus represent the weakest link in the DNA structure. Comparative studies on isolated molecules and molecules embedded in clusters reveal that intermolecular hydrogen bonds strongly affect the fragmentation dynamics of the DNA building blocks under study.