TY - CONF A1 - Hahn, Marc Benjamin T1 - Radiation biophysics N2 - We give an overview about our work related to radiation damage to DNA, proteins, and DNA-protiren complexes damage. Hereby the focus lies on the combination of experiments and Geant4 particle scattering simulations to understand effects in plasmid DNA pUC19, Oligos, and G5P protein. T2 - Project overview CY - Berlin, Germany DA - 27.09.2023 KW - DNA KW - Dosimetry KW - Proteins KW - Radiation damage KW - G5P KW - Microdosimetry KW - Ionizing radiation KW - Geant4 KW - TOPAS KW - TOPAS-nBio KW - Geant4-DNA KW - LEE KW - OH KW - Hydroxyl radical PY - 2023 AN - OPUS4-58742 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Dietrich, P. M. A1 - Radnik, Jörg A1 - Solomun, Tihomir A1 - Hallier, Dorothea C. A1 - Seitz, H. T1 - The change of dna and protein radiation damage upon hydration: in-situ observations by near-ambient-pressure xps N2 - 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. Our 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. Furthermore, first data about the degradation of single-stranded DNA binding-proteins (G5P / GV5 and hmtSSB) under vacuum and NAP-XPS conditions are presented. T2 - AVS69 CY - Portland, USA DA - 05.11.2023 KW - Base damage KW - Base loss KW - Cancer treatment KW - DNA KW - Protein KW - Proteins KW - Geant4 KW - Dosimetry KW - Microdosimetry KW - NAP-XPS KW - Xray photo electron spectrocopy KW - Radiation damage KW - Geant4-DNA KW - G5P KW - GVP KW - Hydroxyl radical KW - LEE KW - DEA KW - DET KW - ROS KW - Prehydrated electron KW - TOPAS KW - Near ambient pressure xray photo electron spectroscopy KW - SSB KW - DSB KW - Single-strand break (SSB) KW - ESCA KW - Single-stranded DNA-binding proteins KW - Reactive oxygen species PY - 2023 AN - OPUS4-58761 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Radiation biophysics: a journey N2 - We give an overview about recent work concerning ionizing radiation damage to Oligonucleotides, plasmid DNA, DNA binding proteins (G5P), and DNA-protein complexes. We focus on combining new experimental setups with Geant4/TOPAS particle scattering simulations to understand the effets of ionizing radiation. T2 - Project update CY - Online meeting DA - 09.10.2023 KW - DNA KW - Proteins KW - G5P KW - Geant4 KW - Geant4-DNA KW - TOPAS KW - TOPAS-nBio KW - LEE KW - Dosimetry KW - Microdosimetry KW - Magnetism KW - Protein PY - 2023 AN - OPUS4-58744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Hahn, Marc Benjamin A1 - Meyer, Susann A1 - Solomun, Tihomir A1 - Kunte, Hans-Jörg A1 - Sturm, Heinz T1 - Microdosimetric measurements for electron irradiation of DNA under physiological conditions: Low energy electrons vs. radicals N2 - Radiation damage to DNA is one of the main causes for cancer and likewise a major tool in its treatment. One of the dogma of the classical radiochemistry and physics involves the opinion that radicals such as OH° produced by ionizing radiation are the most lethal agents. This scenario is increasingly disputed as secondary low-energy electrons are emerging [1] as important, if not predominant, reductive pathway in ionizing damage of biomolecules. These electrons are generated in copious amount in aqueous environment as secondary scattering products. But until now all research concerning the quantification of the effects of low energy electrons on the biomolecular damage was either performed in vacuum with low energy electron sources or with DNA plasmids on metallic surfaces in humid environment. In this work we present detailed experimental and simulation microdosimetry data on electron damage to plasmid DNA in liquid environment: Well-defined electron energy and dosage irradiation was achieve by using an EM and the irradiation through a nanomembrane. The results are analyzed in terms of single- and double-strand break probabilities in the dependence of dose, energy, number of primary and secondary electrons. The results are important not only from the basic scientific point of view but also for the development of effective radiosensitizers, either as protecting or enhancing (radiotherapy) cofactors. T2 - 14th International Congress of the International Radiation Protection Association CY - Cape Town, South Africa DA - 09.05.2016 KW - geant4 KW - DNA KW - radiation Damage KW - low energy electrons KW - radicals KW - dosimetry PY - 2016 AN - OPUS4-36372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Geant4: A universal Monte-Carlo toolkit for Particle scattering simulations N2 - Particle scattering simulations are an useful tool to plan experiments, design detectors, estimate doses in irradiated materials and medical treatment planning. Geant4 is a Monte-Carlo toolkit for the simulation of of particles scattering in matter. Photons, electrons, ions etc can be simulated with energies in the eV to GeV range. Their interactions with matter in arbitrary scattering geometries be studied. Scattering models, cross sections and material parameters can be set to cover interactions in gas, liquid and solid state. The import of geometries from computer aided design files or the protein data base is possible. It is currently being applied in high energy and nuclear physics, accelerator and detector design, space application, dosimetry and medical sciences. In this first part of the talk a brief overview over the structure, functionality and possible applications of Geant4 will be given. In the second part an example application will be presented: The determination of the microscopic dose-damage relations in aqueous environment for electron irradiated plasmid DNA will be explained. Therefore, we combine electron scattering simulations in water with calculations concerning the movement of biomolecules to obtain the energy deposit in the biologically relevant nanoscopic volume. We present, how to combine these simulational results and experimental data via a generalized damage model to determine the microscopic dose-damage relation at a molecular level. T2 - Department 6 Seminar CY - Berlin, Germany DA - 04.04.2019 KW - Geant4 KW - Dosimetry KW - Microdosimetry KW - Radiation damage KW - Electron irradiation KW - Monte-Carlo Simulation KW - Monte-Carlo Simulations KW - DNA KW - Computer simulation KW - Geant4-DNA PY - 2019 AN - OPUS4-47819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - DNA based Reference Materials: In Biodosimetry and Pharmaceutical Quality Control N2 - Applications of plasmid DNA base reference materials in dosimetry and pharmaceutical research. T2 - Physical and Chemical Analysis of Polymers seminar CY - Online meeting DA - 29.03.2021 KW - Analytic KW - Certification KW - DNA KW - Dosimetry KW - Homogeneity KW - Quality testing KW - Reference material KW - Referenzmaterialien KW - Stability KW - Dose KW - Radiation KW - Pharmacy KW - Electrohpresis PY - 2021 AN - OPUS4-52361 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Reference Materials at BAM N2 - A introduction into reference materials, the certification process and brief over current reference projects at BAM is given. T2 - AK-Postdoc seminar CY - BAM Berlin, Germany DA - 02.02.2021 KW - Referenzmaterialien KW - Reference material KW - Homogeneity KW - Stability KW - Quality testing KW - Analytic KW - DNA KW - Dosimetry KW - Certification PY - 2021 AN - OPUS4-52060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Data processing and nonlinear curve Fitting with fityk N2 - A brief introduction into fityk is given. The introduction is followed by a pratical session. Fityk is a versatile data processing tool for nonlinear curve fitting. T2 - AFM Data analysis seminar CY - Online meeting DA - 23.02.2021 KW - Fityk KW - Curve fitting KW - Analysis KW - Raman KW - IR KW - XPS PY - 2021 AN - OPUS4-52154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Direct electron irradiation of DNA in fully aqueous environment: Microscopic dose determination in combination with Monte-Carlo simulations N2 - Introduction: Ionizing radiation & DNA damage Experimental setup: Direct electron irradiation of DNA in liquid Monte-Carlo simulations: Electron scattering & diffusion Application: Radiation protection by compatible solutes T2 - Seminarvortrag im Joint Ultrafast Dynamics Laboratory in Solution and at Interfaces CY - Helmholtz-Zentrum Berlin, Germany DA - 14.06.2017 KW - DNA KW - Ectoine KW - Microdosimetry KW - Dosimetry KW - Radiation damage KW - Compatible solutes KW - Low energy electrons KW - Ionizing radiation KW - OH radical KW - Hydroxyl radicals KW - Prehydrated electrons KW - Radiation therapy KW - Cancer KW - Cancer therapy KW - Radiation protection KW - Proteins KW - Monte carlo simulations KW - Geant4 KW - Electron scattering PY - 2017 AN - OPUS4-42620 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - What can we learn from polymer degradation by radiation? N2 - It is discussed what can be learned from polymer degradation, especially of biopolymers such as DNA and proteins. Synergetci effects of combining methods for structural and chemical analysis as well as Monte-Carlo simulations are presented. T2 - Material Strategy CY - Beelitz, Germany DA - 12.10.2022 KW - Polymer KW - Polymer degradation KW - DNA KW - Protein KW - XPS KW - ESEM KW - Raman KW - MCS KW - Monte-Carlo Simulations PY - 2022 AN - OPUS4-56123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Combined experimental and simulational approaches to access radiation damage to DNA-Protein complexes N2 - We combine irradiation experiments at DNA, proteins and their complexes with Geant4 based particle-scattering simulations to understand the degradation mechanisms on a molecular level. T2 - High performance computing workshop CY - Allan, Jordan DA - 26.06.2023 KW - DNA KW - Protein KW - Radiadion damage KW - Geant4 KW - Geant4-DNA KW - MCS KW - Particle scattering simulations KW - gold nanoparticles PY - 2023 AN - OPUS4-57645 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Simulational tools in nanoparticle research: Micromagnetics and particle scattering N2 - Simulational tools are applied to investigate the physical properties of nanoparticles. For the description of radioactive gold nanoparticles, particles scattering simulations are performed with the Geant4 monte carlo simulation toolkit. The temperature dependent behaviour of the magnetization dynamics of different magnetic nanoparticles are simulated with the object oriented micormagnetic framework (OOMMF). T2 - NanoBioAp CY - LLanes, Spain DA - 23.05.2019 KW - Monte Carlo KW - Monte-Carlo simulation KW - MCS KW - Nanoparticle KW - AuNP KW - Dosimetry KW - Radioactive NP KW - Microdosimetry KW - Geant4 KW - OOMMF KW - Micromagnetism KW - Simulation KW - Magnetic nanoparticle KW - LLG PY - 2019 AN - OPUS4-48110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Zutta Villate, J. M. T1 - Ejemplos de simulaciónes de Montecarlo La desintegración radioactiva N2 - A walkthrough how to setup radioactive sources in monte-carlo particle scattering simulations and perform different types of scorings. N2 - En esta presentación desarrollaremos un ejemplo de aplicación para la dispersión de partículas utilizando el método de simulación de Monte- Carlo. Se discutirá el caso de las nanopartículas de oro radiactivo y los diferentes tipos del scoring. T2 - Seminar of the bioanalysis group CY - Universidad Nacional de Colombia, Medellin, Columbia DA - 27.02.2020 KW - MCS KW - Geant4-DNA KW - Geant4 KW - Radioactive nanoparticle KW - Radioactive decay KW - Particle scattering simulations KW - Particle scattering simulation KW - Topas KW - Monte-Carlo simulations KW - Desintegracion radioactiva KW - Método de Montecarlo KW - Geant4 KW - nanoparticula PY - 2020 AN - OPUS4-50472 LA - spa AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Simulaciónes de Montecarlo II: El scoring en las superficies N2 - En esta presentación desarrollaremos un ejemplo de aplicación para la dispersión de partículas utilizando el método de simulación de Monte- Carlo. Se discutirá el caso de las nanopartículas de oro radiactivo y como obtener informacions sobre diferente tipos de particulas pasando las superfices. T2 - Seminar of the bioanalysis group CY - Universidad Nacional de Colombia, Medellin, Colombia DA - 16.03.2020 KW - Geant4 KW - Geant4-DNA KW - MCS KW - Particle scattering simulation KW - Particle scattering simulations KW - Radioactive decay KW - Radioactive nanoparticle KW - Desintegracion radioactiva KW - Geant4 KW - Monte-Carlo simulations KW - Método de Montecarlo KW - Topas KW - nanoparticula PY - 2020 AN - OPUS4-50564 LA - spa AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Hands on: Particle scattering simulations A practical introduction N2 - A practical introduction is given for the necessary steps to start with particle scattering simulations based on Geant4/Topas. T2 - Seminar of the bioanalysis group CY - Universidad Nacional de Colombia, Bogotá, Columbia DA - 04.02.2020 KW - Geant4 KW - Geant4-DNA KW - MCS KW - Monte-Carlo simulations KW - Simulations KW - Particle scattering simulation KW - Scattering KW - Topas PY - 2020 AN - OPUS4-50333 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Setup of a Particle Scattering Simulation environment N2 - A step by step introduction to the setup of a particle scattering simulation is given. Followed by an installation session. T2 - Seminar of the bioanalysis group CY - Universidad Nacional de Colombia, Medellin, Columbia DA - 12.02.2020 KW - Geant4 KW - Geant4-DNA KW - MCS KW - Monte-Carlo simulations KW - Particle scattering simulations KW - Scattering KW - Simulations KW - Debian KW - Linux KW - Topas KW - C++ KW - Topas-nbio KW - Git KW - Cmake PY - 2020 AN - OPUS4-50366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - DNA basierte Dosimetrie N2 - We propose the development of a standardized DNA based dosimeter. This dosimeter will improve the comparability between the results of different laboratories in radiation research. Compared to conventional methods in dosimetry, this Approach provides direct access to the relation between radiation interaction and biological damage. Moreover, it enables the systematic investigation of the relation between the microscopic characteristics of radiation and DNA damage over a wide dose range. T2 - Zertkom CY - Online meeting DA - 13.05.2020 KW - DNA KW - Dosimetrie KW - Dosimetry KW - Effective dose KW - Energy dose KW - Energiedosis KW - Equivalent dose KW - Absorbed dose PY - 2020 AN - OPUS4-50779 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Radnik, Jörg A1 - Dietrich, P. M. T1 - Near-Ambient-Pressure XPS to investigate radiation damage to DNA N2 - 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. Our 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 - Physical and Chemical Analysis of Polymers seminar CY - Online meeting DA - 12.10.2021 KW - Base damage KW - Base loss KW - Cancer therapy 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 KW - DSB KW - Dry DNA KW - Geant4 KW - Geant4-DNA KW - Hydrated DNA KW - Hydrated electron KW - Hydration shell KW - Hydroxyl radical KW - Indirect damage KW - Ionization KW - LEE KW - Low energy electrons KW - Microdosimetry KW - NAP-XPS KW - Near ambient pressure xray photo electron spectroscopy KW - Net-ionization reaction KW - OH radical KW - PES KW - Prehydrated electron KW - Quasi-direct damage KW - ROS KW - Radiation damage KW - Radiation therapy KW - Radical KW - Reactive oxygen species KW - Single-strand break KW - SSB KW - TOPAS KW - TOPAS-nbio KW - XPS KW - Xray KW - Xray photo electron spectrocopy PY - 2021 AN - OPUS4-53611 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Particle Scattering Simulations with Geant4: An Overview N2 - A brief overview over the capabilities of Geant4 is provided together with some example applications T2 - Seminar of the bioanalysis group CY - Universidad Nacional de Colombia, Bogotá, Columbia DA - 03.02.2020 KW - Geant4 KW - Geant4-DNA KW - MCS KW - Simulation KW - Monte-Carlo simulation KW - Particle scattering simulation KW - Dosimetry KW - Xrays KW - Electrons KW - Radiation PY - 2020 AN - OPUS4-50332 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Functionalized biopolymers - using nature’s toolbox N2 - Biopolymers are the building blocks of life. Their properties are exploited for material functionalization on the nanoscale in a flexible manner. An overview over current research activities in the field of sensing, nanostrcuturing, radiation damage measurements on DNA and proteins and microfluidics is given. T2 - Outreach talks CY - Online meeting DA - 24.11.2022 KW - DNA KW - Proteins KW - Biopolymers KW - Sensing KW - MPL KW - Nanostructuring KW - G5P KW - Functionalization KW - Polymers PY - 2022 AN - OPUS4-56813 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Development of a standard procedure for the irradiation of biomolecules N2 - The damage caused by ionizing radiation to DNA and proteins is the reason to treat cancer by radiation therapy. A better understanding of the molecular processes and quantification of the different damaging mechanisms is the prerequisite to develop more efficient therapies. Hereby the understanding of the processes involved in the damage to DNA are of key interest due to its central role in reproduction and mutation. For radiation with low linear energy transfer (LET), most of the damage is caused by the secondary particles produced by scattering of the ionizing radiation with water. Thereby a multitude of species are produced, whereby especially kinetic low energy electrons, prehydrated electrons, OH-radicals and ions are of importance. With higher LET the relative amount of the direct damaging effects increases. This is especially important considering the increased usage of high LET nucleons in radiation therapy. Therefore, the quantification of the contribution to DNA damage of direct and indirect effects and the different secondary species is of high interest due to the increase of radio biological efficiency when applying high LET radiation. Here we present an approach to investigate the relative contributions to DNA strand break yield for radiation of different LET within a single electron microscope in combination with electron scattering simulations. T2 - IRPA 2018 CY - Havanna, Cuba DA - 16.04.2018 KW - DNA KW - Radiation damage KW - Ionizing radiation KW - Linear energy transfer KW - IRPA KW - LET KW - Electrons KW - SEM KW - Cancer therapy KW - OH radicals KW - LEE KW - Geant4 PY - 2018 AN - OPUS4-44821 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - DNA strand break yields by OH-radicals, low energy electrons and prehydrated electrons N2 - Universität Berlin Radiation damage to biomolecules such as DNA, is the reason to treat cancer via radiation therapy. The understanding of the molecular processes and the quantification of the underlying damaging mechanisms is necessary to develope more efficient irradiation protocols for cancer therapy. Thereby damage to DNA is of key interest due to its central role in reproduction and mutation. Due to the high amount of water in biological tissue, most of the damage is caused by the secondary particles which are produced by the interaction of ionizing radiation with water. Thereby a multitude of species are produced, e.g. kinetic low energy electrons, prehydrated electrons, OH-radicals and ions. The quantification of the contribution to DNA damage by the various species is of interest. Here we present an experimental approach to disentangle their relative DNA strand break yields. Plasmid DNA (pUC19 ) is irradiated in water with electrons under the presence of different scavengers. The presented preliminary results reveal the relative contributions of OH-radicals, low energy electrons and prehydrated electrons and their DNA single and double strand break yields. T2 - DPG-Frühjahrstagung der Sektion Kondensierte Materie gemeinsam mit der EPS CY - Berlin, Germany DA - 11.03.2018 KW - DNA KW - Radiation damage KW - Dosimetry KW - Low energy electrons KW - Hydroxyl radicals KW - Geant4 KW - Prehydrated electrons KW - Scavenger KW - Radiation damage to DNA KW - Plasmid DNA KW - Strand breaks KW - Double strand breaks KW - Single strand breaks PY - 2018 AN - OPUS4-44566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Importance of Radiation Damage to DNA-Protein Complexes N2 - The formation of DNA-protein complexes ocurrs during replication and repair within cells. They are assumed to modify the damage caused by ionization radiation during radaition therapy. Hereby the assumption is, that the underlying damaging channels in DNA and proteins are modified, especially when compared to single molecules. T2 - Scientific online presentations workshop CY - Online meeting DA - 03.12.2021 KW - DNA KW - Proteins KW - Radiation damage KW - Ionizing radiation KW - Hydroxyl radicals PY - 2021 AN - OPUS4-53894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Dietrich, Paul M. A1 - Radnik, Jörg T1 - The change of DNA AND PROTEIN radiation damage upon hydration: In-situ observations by near-ambient-pressure XPS N2 - 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. Our 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 - Dyson Conference 2023 CY - Prague, Czech Republic DA - 24.04.2023 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 - Geant4 KW - Geant4-DNA KW - Hydrated DNA KW - Hydrated electron KW - Hydration shell KW - Hydroxyl radical KW - Indirect damage KW - Ionization KW - Ionisation 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 - 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 - TOPAS KW - TOPAS-nbio KW - XPS KW - Xray KW - Xray photo electron spectrocopy KW - G5P KW - Protein KW - Single-stranded DNA-binding proteins PY - 2023 AN - OPUS4-57406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Quantifizierung der Schädigung von DNA in wässriger Lösung unter direkter Elektronenbestrahlung N2 - To cure cancer radiation therapy is used to kill tumor cells. It is based on radiation induced damage to biomolecules. Especially DNA damage is of key interest due to its central role in apoptosis and mutation. Because of the high amount of water in biological tissue, most of the damage is caused by the secondary particles produced by the inelastic scattering of ionizing radiation and water. A detailed understanding of the underlying molecular processes under physiological conditions is the prerequisite to develop more efficient therapies. Goal of this work is to quantify the DNA damage caused by ionizing radiation in dependence of the inelastic scattering events and the energy deposit within the microscopic target volume of biological relevance. The irradiations have to be performed in liquid, under consideration of the chemical environment. Therefore, a new combination of experiment and Monte-Carlo simulations was developed and tested. To make it possible to irradiate liquids with electrons within scanning electron microscopes a new sample holder was constructed incorporating an electron transparent nanomembrane. It makes it possible to irradiate DNA, proteins or cells at different pH, salinity and in the presence of cosolutes. %The most important results of this work are as follows: The median lethal dose for a model system of plasmid DNA and water was determined by the combination of experimental data, particle scattering simulations (Geant4-DNA) and diffusion calculations as D0.5=(1.7+-0.3) Gy. From the convolution of plasmid positions and the spatially resolved energy deposit, as determined by electron scattering simulations, the histogram of the energy deposit within the target volume of the plasmids and the microscopic median lethal energy deposit was calculated as E0.5=6+-4eV. It could be deduced that on average less than two ionization events are sufficient to cause a single-strand-break. The relation of single-strand-breaks (SSB) to double-strand-breaks (DSB), which is of importance for microdosimetric modeling, was determined as SSB:DSB = 12:1. The presented method for the determination of microscopic dose-damage relations was further extended to be applicable for general irradiation experiments. It becomes independent of the type of primary radiation used, the experimental geometry, and the diffusional properties of the molecules under investigation. This way different experimental systems with varying, inhomogeneous energy deposit characteristics become comparable with each other, which is not possible when only macroscopic averaged values are taken into account. In addition, the radiation protection properties of the compatible solute ectoine, as well as its influence on the water properties and biomolecules were investigated. %In addition, the influence of the compatible solute ectoine on water, biomolecules and its radiation protection properties were investigated. Raman spectroscopy revealed a concentration dependent increase of the collective water modes in the OH-stretching region, which was found to be independent of the sodium chloride concentration. Molecular dynamic simulations showed that the zwitterionic properties of ectoine lead to its half-chair conformation. The hydrogen bonds in the first hydration shell are more stable and have an increased lifetime compared to the bulk water. Irradiation experiments with DNA in the presence of 1M ectoine revealed an increase of the survival rate by a factor of 1.41 as compared to the absence of ectoine. The protective properties of ectoine result from the increase of the inelastic scattering probabilities of low energy electrons at the acoustic vibrational modes of water and its properties as OH-radical scavenger. This was shown by Raman spectroscopy and electron paramagnetic resonance measurements (EPR). T2 - Vortrag CY - Freie Universität Berlin, Germany DA - 14.02.2018 KW - DNA KW - Radiation damage KW - Ionizing radiation KW - DNA strand break KW - Dosimetry KW - Microdosimetry KW - Ectoine KW - Ectoine radiation protection KW - Salt KW - Water PY - 2018 AN - OPUS4-44280 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Sturm, Heinz A1 - Solomun, Tihomir T1 - Bestimmung des mikroskopischen Energiedeposits an DNA in komplexen Geometrien N2 - Mikrodosimetrie zum Einsatz in der Charakterisierung von per 3D Druck erstellen medizinischen Röntgenphantomen. T2 - Charite PhantomX CY - Charite Campus Berlin, Germany DA - 21.03.2018 KW - Dosimetrie KW - Phantome KW - Strahlentherapie KW - Computertomographie KW - Medizintechnik KW - Geant4 KW - Monte-Carlo Simulationen PY - 2018 AN - OPUS4-44564 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -