TY - GEN A1 - Hahn, Marc Benjamin T1 - Near-ambient-pressure XPS as as tool to monitor DNA radiation damage directly in water N2 - Ionizing radiation damage to DNA plays a fundamental role in cancer therapy. X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. The results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further. T2 - Miller Conference CY - Furiani, France DA - 03.06.2023 KW - Base damage KW - Base loss KW - Cancer treatment KW - DNA KW - DNA radiation damage KW - Direct damage KW - Dissociative electron attachment (DEA) KW - Dissociative electron transfer (DET) KW - Dosimetry KW - Double-strand break (DSB) KW - ESCA KW - Energy deposit KW - G5P KW - Geant4 KW - Geant4-DNA KW - Hydrated DNA KW - Hydrated electron KW - Hydroxyl radical KW - Indirect damage KW - Ionisation KW - Ionization KW - LEE KW - Low energy electrons KW - MCS KW - Microdosimetry KW - NAP-XPS KW - Near ambient pressure xray photo electron spectroscopy KW - Net-ionization reaction KW - OH radical KW - PES KW - Particle scattering KW - Prehydrated electron KW - Presolvated electron KW - Protein KW - Quasi-direct damage KW - ROS KW - Radiation damage KW - Radiation therapy KW - Radical KW - Radiolysis KW - Radiotherapy KW - Reactive oxygen species KW - Simulation KW - Single-strand break (SSB) KW - Single-stranded DNA-binding proteins KW - TOPAS KW - TOPAS-nbio KW - XPS KW - Xray KW - Xray photo electron spectrocopy KW - Hydration shell PY - 2023 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/57646 AN - OPUS4-57646 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany