Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-55132 Zeitschriftenartikel Zutta Villate, J. M.; Viviana Rojas, J.; Hahn, Marc Benjamin; Anselmo Puerta, J. Synthesis of 198Au nanoparticles sub 10 nm due optimization on local dose by Monte Carlo simulations for cancer treatment To enhance the biological effects of radiation damage in cancerous cells, we present an alternative approach to the use of gold nanoparticles (AuNP), focusing on the synthesis and characterization of highly monodisperse, spherical radioactive gold nanoparticles 198AuNP. The size of the AuNP size was optimized with the help of Geant4/TOPAS particle scattering simulations, and energy deposition per nm3 per decay for varying radii (2-10 nm) was evaluated. This work is the foundation for ongoing experimental work to evaluate cell death induced by 198AuNP which aims for the use of radioactive gold nanoparticles in cancer treatment. Springer Nature Akadémiai Kiadó, Budapest, Hungary 2022 Journal of Radioanalytical and Nuclear Chemistry 1 9 10.1007/s10967-022-08355-5 2022-06-29 OPUS4-56123 Vortrag Hahn, Marc Benjamin What can we learn from polymer degradation by radiation? 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. 2022 Material Strategy Beelitz, Germany 12.10.2022 2022-10-31 OPUS4-54775 Posterpräsentation Hahn, Marc Benjamin Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement by Monte-Carlo based particle scattering Simulations Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined.[1] Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. [2] These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for ongoing experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. 2022 NALS 2022 Santander, Spain 27.04.2022 29.04.2022 2022-05-09 OPUS4-53894 Vortrag Hahn, Marc Benjamin Importance of Radiation Damage to DNA-Protein Complexes 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. 2021 Scientific online presentations workshop Online meeting 03.12.2021 03.12.2021 2021-12-08 OPUS4-53611 Vortrag Hahn, Marc Benjamin Near-Ambient-Pressure XPS to investigate radiation damage to DNA 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. 2021 Physical and Chemical Analysis of Polymers seminar Online meeting 12.10.2021 12.10.2021 2021-10-26 OPUS4-52154 Vortrag Hahn, Marc Benjamin Data processing and nonlinear curve Fitting with fityk 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. 2021 AFM Data analysis seminar Online meeting 23.02.2021 23.02.2021 2021-02-24 OPUS4-55714 Zeitschriftenartikel Cordsmeier, Leo; Hahn, Marc Benjamin DNA Stability in Biodosimetry, Pharmacy and DNA Based Data-Storage: Optimal Storage and Handling Conditions DNA long-term stability and integrity is of importance for applications in DNA based bio-dosimetry, data-storage, pharmaceutical quality-control, donor insemination and DNA based functional nanomaterials. Standard protocols for these applications involve repeated freeze-thaw cycles of the DNA, which can cause detrimental damage to the nucleobases, as well as the sugar-phosphate backbone and therefore the whole molecule. Throughout the literature three hypotheses can be found about the underlying mechanisms occurring during freeze-thaw cycles. It is hypothesized that DNA single-strand breaks during freezing can be induced by mechanical stress leading to shearing of the DNA molecule, by acidic pH causing damage through depurination and beta elimination or by the presence of metal ions catalyzing oxidative damage via reactive oxygen species (ROS). Here we test these hypotheses under well defined conditions with plasmid DNA pUC19 in high-purity buffer (1xPBS) at physiological salt and pH 7.4 conditions, under pH 6 and in the presence of metal ions in combination with the radical scavengers DMSO and Ectoine. The results show for the 2686 bp long plasmid DNA, that neither mechanical stress, nor pH 6 lead to degradation during repeated freeze-thaw cycles. In contrast, the presence of metal ions (Fe2+) leads to degradation of DNA via the production of radical species. Wiley-VCH GmbH Chemistry Europe European Chemical Societies Publishing 2022 ChemBioChem 1 9 urn:nbn:de:kobv:b43-557148 10.1002/cbic.202200391 https://creativecommons.org/licenses/by/4.0/deed.de 2022-09-15 OPUS4-55751 Forschungsdatensatz Hahn, Marc Benjamin BioSAXS models for TOPAS/Geant4 Models for TOPAS/Geant4 to estimate the microscopic dose received by biomolecules during bioSAXS experiments. The C++ classes in this repository extend the functionality of the TOPAS (http://www.topasmc.org/) Monte-Carlo program, which is itself a wrapper of the Geant4 MCS Toolkit (http://geant4.org). Berlin Bundesanstalt für Materialforschung und -prüfung (BAM) 2022 10.26272/opus4-55751 https://creativecommons.org/publicdomain/zero/1.0/deed.de 2022-09-28 OPUS4-56811 Forschungsdatensatz Smales, Glen Jacob; Hahn, Marc Benjamin; Hallier, Dorothea C.; Seitz, H. X-ray scattering datasets and simulations associated with the publication "Bio-SAXS of single-stranded DNA-binding proteins: Radiation protection by the compatible solute ectoine" This dataset contains the processed and analysed small-angle X-ray scattering data associated with all samples from the publications "Bio-SAXS of Single-Stranded DNA-Binding Proteins: Radiation Protection by the Compatible Solute Ectoine" (https://doi.org/10.1039/D2CP05053F). Files associated with McSAS3 analyses are included, alongside the relevant SAXS data, with datasets labelled in accordance to the protein (G5P), its concentration (1, 2 or 4 mg/mL), and if Ectoine is present (Ect) or absent (Pure). PEPSIsaxs simulations of the GVP monomer (PDB structure: 1GV5 ) and dimer are also included. TOPAS-bioSAXS-dosimetry extension for TOPAS-nBio based particle scattering simulations can be obtained from https://github.com/MarcBHahn/TOPAS-bioSAXS-dosimetry which is further described in https://doi.org/10.26272/opus4-55751. This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under grant number 442240902 (HA 8528/2-1 and SE 2999/2-1). We acknowledge Diamond Light Source for time on Beamline B21 under Proposal SM29806. This work has been supported by iNEXT-Discovery, grant number 871037, funded by the Horizon 2020 program of the European Commission. Geneva Zenodo Bundesanstalt für Materialforschung und -prüfung (BAM) 2023 10.5281/zenodo.7515394 https://creativecommons.org/licenses/by/4.0/deed.de 2023-01-10 OPUS4-56813 Vortrag Hahn, Marc Benjamin Functionalized biopolymers - using nature's toolbox 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. 2022 Outreach talks Online meeting 24.11.2022 2023-01-10 OPUS4-57063 Posterpräsentation Hahn, Marc Benjamin The change of DNA radiation damage upon hydration: In-situ observations by near-ambient-pressure XPS 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. 2023 #RSCposter 2023 Online meeting 28.02.2023 01.03.2023 2023-03-02 OPUS4-57064 Posterpräsentation Hahn, Marc Benjamin Bio-SAXS of single-stranded DNA-binding proteins: Radiation protection by the compatible solute ectoine Small-angle X-ray scattering (SAXS) can be used for structural determination of biological macromolecules and polymers in their native states (e.g. liquid phase). This means that the structural changes of (bio-)polymers, such as proteins and DNA, can be monitored in situ to understand their sensitivity to changes in chemical environments. In an attempt to improve the reliability of such experiments, the reduction of radiation damage occurring from exposure to X-rays is required. One such method, is to use scavenger molecules to protect macromolecules against radicals produced during radiation exposure, such as reactive oxygen species (ROS). In this study we investigate the feasibility of applying the compatible solute, osmolyte and radiation protector Ectoine (THP(B)), as a scavenger molecule during SAXS measurements of the single-stranded DNA-binding protein Gene-V Protein (G5P/GVP). In this case, we monitor the radiation induced changes of G5P during bio-SAXS measurments and the resulting microscopic energy-damage relation was determined from microdosimetric calculations by Monte-Carlo based particle scattering simulations with TOPAS/Geant4 and a custom target-model. This resulted in a median-lethal energy deposit of pure G5P at 4 mg mL−1 of E1/2 = 7 ± 5 eV, whereas a threefold increase of energy-deposit was needed under the presence of Ectoine to reach the same level of damage. This indicates that Ectoine increases the possible exposure time before radiation-damage to G5P is observed. Furthermore, the dominant type of damage shifted from aggregation in pure solutions towards a fragmentation for solutions containing Ectoine as a cosolute. These results are interpreted in terms of indirect radiation damage by reactive secondary species, as well as post-irradiation effects, related to preferential-exclusion of the cosolute from the protein surface. Hence, Ectoine is shown to provide a non-disturbing way to improve structure-determination of proteins via bio-SAXS in future studies. 2023 #RSCposter 2023 Online meeting 28.02.2023 01.03.2023 2023-03-02 OPUS4-57134 misc Pauw, Brian Richard; Smales, Glen Jacob; Anker, A. S.; Balazs, D. M.; Beyer, F. L.; Bienert, Ralf; Bouwman, W. G.; Breßler, Ingo; Breternitz, J.; Brok, E. S.; Bryant, G.; Clulow, A. J.; Crater, E. R.; De Geuser, F.; Giudice, A. D.; Deumer, J.; Disch, S.; Dutt, S.; Frank, K.; Fratini, E.; Gilbert, E. P.; Hahn, Marc Benjamin; Hallett, J.; Hohenschutz, Max; Hollamby, M. J.; Huband, S.; Ilavsky, J.; Jochum, J. K.; Juelsholt, M.; Mansel, B. W.; Penttilä, P.; Pittkowski, R. K.; Portale, G.; Pozzo, L. D.; Ricardo de Abreu Furtado Garcia, P.; Rochels, L.; Rosalie, Julian M.; Saloga, P. E. J.; Seibt, S.; Smith, A. J.; Smith, G. N.; Annadurai, V.; Spiering, G. A.; Stawski, Tomasz; Taché, O.; Thünemann, Andreas; Toth, K.; Whitten, A. E.; Wuttke, J. The human factor: results of a small-angle scattering data analysis Round Robin A Round Robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions, and two from powders. Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5 % and half of the population width entries within 40 %, respectively. Due to the added complexity of the structure factor, much fewer people submitted answers on the powder datasets. For those that did, half of the entries for the means and widths were within 44 % and 86 % respectively. This Round Robin experiment highlights several causes for the discrepancies, for which solutions are proposed. New York Cornell University 2023 arXiv.org 1 23 urn:nbn:de:kobv:b43-571342 10.48550/arXiv.2303.03772 https://creativecommons.org/licenses/by/4.0/deed.de 2023-03-13 OPUS4-36372 Vortrag Hahn, Marc Benjamin Microdosimetric measurements for electron irradiation of DNA under physiological conditions: Low energy electrons vs. radicals 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. 2016 14th International Congress of the International Radiation Protection Association Cape Town, South Africa 09.05.2016 12.05.2016 2016-06-08 OPUS4-36399 Posterpräsentation Hahn, Marc Benjamin Electron irradiation of biomolecules under physiological conditions: Experimental realization and microdosimetric calculations In the last years, secondary low-energy electrons (LEE) emerged as important, if not predominant, reductive pathway in ionizing damage of biomolecules. These electrons are created in copious amount as result of inelastic scattering of high energy radiation at water. Until now, all experiments the quantification of the effects of LEEs on the biomolecular damage was either performed in vacuum with LEE sources or with DNA on surfaces in humid atmosphere. We present a new experimental setup to irradiate biomolecules with electrons under physiological conditions. In combination with monte carlo simulations this setup makes it possible to determine microdosimetric quantities for biomolecules in liquid environment under electron irradiation. This opens up new possibilities in radiation research to access the LEE damage under well defined physiological condition, for more complex systems, such as DNA-Protein complexes and even living cells. 2016 14th International Congress of the International Radiation Protection Association Cape Town, South Africa 09.05.2016 12.05.2016 2016-06-08 OPUS4-37676 Zeitschriftenartikel Hahn, Marc Benjamin; Uhlig, F.; Solomun, Tihomir; Smiatek, J.; Sturm, Heinz Combined influence of ectoine and salt: spectroscopic and numerical evidence for compensating effects of aqueous solutions Ectoine is an important osmolyte, which allows microorganisms to survive in extreme environmental salinity. The hygroscopic effects of ectoine in pure water can be explained by a strong water binding behavior whereas a study on the effects of ectoine in salty solution is yet missing. We provide Raman spectroscopic evidence that the influence of ectoine and NaCl are opposing and completely independent of each other. The effect can be explained by the formation of strongly hydrogen-bonded water molecules around ectoine which compensate the influence of the salt on the water dynamics. The mechanism is corroborated by first principles calculations and broadens our understanding of zwitterionic osmolytes in aqueous solution. Our findings allow us to provide a possible explanation for the relatively high osmolyte concentrations in halotolerant bacteria. UK Royal Society of Chemistry Royal Society of Chemistry 2016 Physical Chemistry Chemical Physics 18 41 28398 28402 urn:nbn:de:kobv:b43-376761 10.1039/c6cp05417j http://creativecommons.org/licenses/by/3.0/de/deed.de 2016-10-24 OPUS4-32905 Posterpräsentation Hahn, Marc Benjamin Water structuring induced by Ectoine as a possible explanation for its protection against radiation 2015 Annual Conference 2015 of the Association for General and Applied Microbiology Annual Conference 2015 of the Association for General and Applied Microbiology Marburg, Germany 2015-03-01 2015-03-04 2016-02-20 OPUS4-32906 Posterpräsentation Hahn, Marc Benjamin Ectoine induced water structuring as a possible explanation for its radiation protection properties 2015 Deutsche Physikalische Gesellschaft (DPG) 2015 Deutsche Physikalische Gesellschaft (DPG) 2015 Berlin, Germany 2015-03-15 2015-03-20 2016-02-20 OPUS4-38698 Zeitschriftenartikel Hahn, Marc Benjamin; Meyer, Susann; Schröter, Maria-Astrid; Seitz, H.; Kunte, Hans-Jörg; Solomun, Tihomir; Sturm, Heinz Direct electron irradiation of DNA in fully aqueous environment. Damage determination in combination with Monte Carlo simulations We report on a study in which plasmid DNA in water was irradiated with 30 keV electrons generated by a scanning electron microscope and passed through a 100 nm thick Si3N4 membrane. The corresponding Monte Carlo simulations suggest that the kinetic energy spectrum of the electrons throughout the water is dominated by low energy electrons (<100 eV). The DNA radiation damage, single-strand breaks (SSB) and double-strand breaks (DSB), was determined by electrophoresis. The median lethal dose of D1/2 = 1.7 ± 0.3 Gy was found to be much smaller compared to partially or fully hydrated DNA irradiated under vacuum conditions. The ratio of DSB to SSB was found to be (1:12) as compared to 1:88) found for hydrated DNA. Our method enables quantitative measurements of radiation damage to biomolecules (DNA, proteins) in solutions under varying conditions (pH, salinity, cosolutes) for an electron energy range which is difficult to probe by standard methods. Royal Society of Chemistry 2017 Physical Chemistry Chemical Physics 19 3 1798 1805 urn:nbn:de:kobv:b43-386981 10.1039/C6CP07707B http://creativecommons.org/licenses/by/3.0/de/deed.de 2017-01-19 OPUS4-44280 Vortrag Hahn, Marc Benjamin Quantifizierung der Schädigung von DNA in wässriger Lösung unter direkter Elektronenbestrahlung 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). 2018 Vortrag Freie Universität Berlin, Germany 14.02.2018 14.02.2018 2018-02-23 OPUS4-44510 Dissertation Hahn, Marc Benjamin Quantifizierung der Schädigung von DNA in wässriger Lösung unter direkter Elektronenbestrahlung Bei der Behandlung von Krebs wird Strahlentherapie zur Zerstörung von Tumorzellen eingesetzt. Der zugrunde liegende Wirkmechanismus ist die durch ionisierende Strahlung verursachte Schädigung an Biomolekülen. Dabei kommt den Schädigungsprozessen an DNA aufgrund ihrer zentralen Rolle in Mutation und Zelltod eine besondere Bedeutung zu. Durch den hohen Wasseranteil in menschlichen Zellen findet ein Großteil der inelastischen Streuprozesse an Wassermolekülen statt und führt zur deren Radiolyse. Die so entstehenden Radiolyseprodukte sind für einen Großteil des Schadens an DNA verantwortlich. Ein detailliertes Verständnis der zugrunde liegenden molekularen Interaktion ist die Voraussetzung um effizientere Therapien zu entwickeln. Ziel dieser Arbeit ist es, die Schädigung von DNA durch ionisierende Strahlung in Abhängigkeit der inelastischen Streuevents und des Energieeintrags innerhalb des biologisch relevanten mikroskopischen Treffervolumens zu quantifizieren. Die Bestrahlungen müssen dazu in Flüssigkeit, unter Berücksichtigung der chemischen Umgebung durchgeführt werden, welche die indirekten Schäden vermittelt. Deshalb wurde eine neuartige Kombination aus Experiment und Monte- Carlo-Simulationen entworfen und angewandt. Um Elektronenbestrahlung flüssiger Lösungen innerhalb eines Rasterelektronenmikroskops zu ermöglichen, wurde ein Probenhalter mit einer für Elektronen durchlässigen Nanomembran entwickelt. So können Bestrahlungen an DNA, Proteinen, und Zellen bei verschiedenen pH-Werten, Salzkonzentrationen oder in Anwesenheit von Kosoluten durchgeführt werden. Für ein Modellsystem aus Plasmid-DNA in Wasser wurde damit die mittlere letale Dosis aus der Kombination der experimentellen Daten, Partikelstreusimulationen (Geant4-DNA) und Diffusionsberechnungen zu D1/2 = 1.7 ± 0.3 Gy bestimmt. Aus der Konvolution der Plasmidpositionen mit dem durch Elektronenstreusimulationen bestimmten ortsaufgelösten Energieeintrag wurde dessen Häufigkeitsverteilung im Targetvolumen der Plasmide sowie der mittlere mikroskopische letale Energieeintrag berechnet als E1/2 = 6 ± 4 eV . Es wurde gefolgert, dass weniger als zwei Ionisationsprozesse im sensitiven Targetvolumen der DNA im Mittel zu einem Einzelstrangbruch führen. Das für mikrodosimetrische Modellierungen wichtige Verhältnis von Einzelstrangbrüchen (SSB) zu Doppelstrangbrüchen (DSB) wurde als SSB : DSB = 12 : 1 bestimmt. Die vorgestellte Methode zur Bestimmung mikroskopischer Schaden-Dosis Relationen wurde auf weitere Klassen von Bestrahlungsexperimenten verallgemeinert. Dadurch ist die Methode unabhängig von der verwandten Primärstrahlung, der Probengeometrie und den Diffusionseigenschaften der untersuchten Moleküle anwendbar. So wird eine Vergleichbarkeit experimenteller Systeme mit inhomogenen Energieverteilungen erreicht, die bei ausschließlicher Betrachtung makroskopischer, gemittelter Größen nicht gegeben ist. Des weiteren wurden die Strahlenschutzfunktionen des kompatiblen Soluts Ectoine und sein Einfluss auf Wasser und Biomoleküle untersucht. Mittels Ramanspektroskopie wurde ein kon-zentrationsabhängiger Anstieg des Anteils der Kollektivmoden des Wassers der OH-Streckschwingungen und dessen Unabhängigkeit von der Natriumchloridkonzentration beobachtet. Molekulardynamik-Simulationen zeigten, dass die zwitterionischen Eigenschaften zur Bildung einer half-chair Konformation Ectoines führen. Die Wasserstoffbrückenbindungen in der ersten Hydrationshülle sind signifikant stabiler und besitzen höhere Lebensdauern als das Bulk-Wasser. Bestrahlung von DNA in Anwesenheit von 1 M Ectoine führt zu einer Erhöhung der Überlebensrate um den Faktor 1,41. Die Schutzfunktion wurde auf die Erhöhung des Streuquerschnitts niederenergetischer Elektronen an den akustischen Vibrationsmoden des Wasser durch Ectoine und seine Wirkung als OH-Radikalfänger zurückgeführt. Dies wurde mittels Ramanspektroskopie und Elektronenspinresonanzmessungen (ESR) nachgewiesen. Berlin 2018 1 108 urn:nbn:de:kobv:188-fudissthesis000000106497-4 http://creativecommons.org/licenses/by/3.0/de/deed.de 2018-03-19 OPUS4-44564 Vortrag Hahn, Marc Benjamin Bestimmung des mikroskopischen Energiedeposits an DNA in komplexen Geometrien Mikrodosimetrie zum Einsatz in der Charakterisierung von per 3D Druck erstellen medizinischen Röntgenphantomen. 2018 Charite PhantomX Charite Campus Berlin, Germany 21.03.2018 21.03.2018 2018-03-27 OPUS4-44565 Posterpräsentation Hahn, Marc Benjamin Combination of Monte-Carlo simulations and experimental results to determine the microscopic energy depoit at DNA The quantification of radiation induced damage to DNA in aqueous en- vironment is of fundamental interest for dosimetry and its application in radiation-therapy and protection. We present a combined experi- mental and simulational approach to quantify and compare radiation induced damage to biomolecules in liquid environment for a wide range of primary radiation sources e. g. photons, electrons or ions and tar- gets, such as DNA, proteins or cells.[1] To show its viability, we will apply this method to an experimentally challenging systems, the di- rect irradiation of plasmid DNA (pUC19) in water with electrons as primary particles. Here we combine Geant4 electron-scattering simula- tions with calculations concerning the diffusion and convection induced movement of the biomolecules, within a coarse-grained model of the irradiated liquid. Additionally a microscopic target model for the plas- mid DNA based on the relation of lineal energy and radiation quality is used to calculate the effective target volume. 2018 DPG-Frühjahrstagung der Sektion Kondensierte Materie gemeinsam mit der EPS Berlin, Germany 11.03.2018 16.03.2018 2018-03-27 OPUS4-44566 Vortrag Hahn, Marc Benjamin DNA strand break yields by OH-radicals, low energy electrons and prehydrated electrons 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. 2018 DPG-Frühjahrstagung der Sektion Kondensierte Materie gemeinsam mit der EPS Berlin, Germany 11.03.2018 16.03.2018 2018-03-27 OPUS4-44620 Posterpräsentation Hahn, Marc Benjamin Ectoine protects biomolecules from ionizing radiation: Molecular mechanisms The compatible solute and osmolyte ectoine is an effective protectant of biomolecules and whole cells against heating, freezing and high salinity. The protection of cells (human Keratinocytes) by ectoine against ultraviolet radiation was also reported by various authors, although the underlying mechanism is not yet understood. We present results on the irradiation of biomolecules (DNA) with ionizing radiation (high energy electrons) in fully aqueous environment in the presence of ectoine and high salt concentrations. The results demonstrate an effective radiation protection of DNA by ectoine against the induction of single strand breaks by ionizing radiation. The effect is explained by an increased in low-energy electron scattering at the enhanced free-vibrational density of states of water due to ectoine, as well as the action of ectoine as an OH-radical scavenger. This was demonstrated by Raman spectroscopy, electron paramagnetic resonance (EPR) and Monte-Carlo simulations (Geant4). 2018 DPG-Frühjahrstagung der Sektion Kondensierte Materie gemeinsam mit der EPS Berlin, Germany 11.03.2018 16.03.2018 urn:nbn:de:kobv:b43-446202 http://creativecommons.org/licenses/by/3.0/de/deed.de 2018-04-04 OPUS4-44848 Beitrag zu einem Tagungsband Hahn, Marc Benjamin; Solomun, Tihomir; Sturm, Heinz Standard procedure for the irradiation of biomolecules with radiation of different linear energy transfer 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. IRPA 2018 Proceedings of International Radiation Protection Association Conference 2018 America 2018 XI International Radiation Protection Association Conference 2018 America Havanna, Cuba 16.04.2018 20.04.2018 1 5 2018-05-07 OPUS4-44820 Posterpräsentation Hahn, Marc Benjamin A standard procedure for the irradiation of biomolecules with radiation of varying linear energy transfer 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. 2018 IRPA 2018 Havanna, Cuba 16.04.2018 20.04.2018 2018-05-03 OPUS4-44821 Vortrag Hahn, Marc Benjamin Development of a standard procedure for the irradiation of biomolecules 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. 2018 IRPA 2018 Havanna, Cuba 16.04.2018 20.04.2018 2018-05-03 OPUS4-45103 Posterpräsentation Hahn, Marc Benjamin Irradiation of biomolecules in liquid with electrons of different linear energy transfer 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 particles 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. 2018 International workshop on radiation damage to DNA Aussois, France 27.05.2018 01.06.18 2018-06-05 OPUS4-48110 Vortrag Hahn, Marc Benjamin Simulational tools in nanoparticle research: Micromagnetics and particle scattering 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). 2019 NanoBioAp LLanes, Spain 23.05.2019 25.05.2019 2019-06-03 OPUS4-47964 Zeitschriftenartikel Zutta Villate, J. M.; Hahn, Marc Benjamin Radioactive gold nanoparticles for cancer treatment Dose enhancement by gold nanoparticles (AuNP) was shown to increase the biological effectiveness of radiation damage in biomolecules and tissue. Most of the current studies focus on external beam therapy on combination with AuNP. Here we present a Monte-Carlo study (Geant4) to characterise radioactive AuNP. Radioactive 198 Au emits beta and gamma rays and is considered for applications with solid tumours. To effectively apply 198 AuNP their energy deposit characteristics have to be determined in terms of intrinsic and extrinsic properties e.g. AuNP diameter, AuNP density, and their clustering behaviour. After each decay process, the energy deposit, inelastic scattering events, kinetic energy spectrum of secondary particles within the AuNP themselves and in a spherical target volume of water up to 1 μm radius were determined. Simulations were performed for AuNP radii ranging from 2.5 nm to 20 nm radius, different cluster sizes and densities. The results show an increase of the energy deposit in the vicinity of the AuNP up to 150 nm. This effect nearly vanishes for distances up to one micron. For the case of AuNP clusters and the same activity, the enhancement of the energy deposit increases with the relative gold mass percentage and therefore can be adjusted by changing AuNP radius or clustering behaviour. Berlin Springer Società Italiana di Fisica 2019 European physical journal D 73 95 1 7 10.1140/epjd/e2019-90707-x 2019-05-16 OPUS4-51150 Forschungsdatensatz Hahn, Marc Benjamin TOPAS cell model with nanoparticles These files contain cell models for TOPAS/Geant4 and the inclusion of nano particles in particle scattering simulations. A simple spherical cell with nanoparticles can be generated in a fast manner. The user has the option to include the following organelles: nucleus, mitochondria, cell membrane. Additionally nanoparticles can be included in the cytosol and at the surface of the nucleus and/or the mitochondria. The C++ classes in this repository extend the functionality of the TOPAS (http://www.topasmc.org/) Monte-Carlo program, which is itself a wrapper of the Geant4 MCS Toolkit (http://geant4.org). The sourcecode together with examples and scorers are provided. "If you use this extension please cite the following literature: Hahn, M.B., Zutta Villate, J.M. "Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement in cell organelles." Sci Rep 11, 6721 (2021). https://doi.org/10.1038/s41598-021-85964-2 " Berlin Bundesanstalt für Materialforschung und -prüfung (BAM) 2020 10.26272/opus4-51150 https://creativecommons.org/publicdomain/zero/1.0/deed.de 2020-10-20 OPUS4-51169 Forschungsdatensatz Hahn, Marc Benjamin Temperature effects in the Object Oriented Micromagnetic Framework (OOMMF) - OOMMF input parameter files for Tc determination To simulate the movement of the macroscopic magnetic moment in ferromagnetic systems under the influence of elevated temperatures, the stochastic version of the Landau-Lifshitz (LL) or the Landau-Lifshitz-Gilbert equation with a spin density of one per unit cell has to be used. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion has to be performed. OOMMF sample files MIF) are provided which can be used to determine the Curie temperature for the classical bulk magnets, iron, nickel and cobalt. Berlin Bundesanstalt für Materialforschung und -prüfung (BAM) 2020 10.26272/opus4-51169 https://creativecommons.org/publicdomain/zero/1.0/deed.de 2020-10-20 OPUS4-50985 Zeitschriftenartikel Solomun, Tihomir; Hahn, Marc Benjamin; Smiatek, J. Raman spectroscopic signature of ectoine conformations in bulk solution and crystalline state Recent crystallographic results revealed conformational changes of zwitterionic ectoine upon hydration. By means of confocal Raman spectroscopy and density functional theory calculations, we present a detailed study of this transformation process as part of a Fermi resonance analysis. The corresponding findings highlight that all resonant couplings are lifted upon exposure to water vapor as a consequence of molecular binding processes. The importance of the involved molecular groups for water binding and conformational changes upon hydration is discussed. Our approach further Shows that the underlying rapid process can be reversed by carbon dioxide saturated atmospheres. For the first time, we also confirm that the conformational state of ectoine in aqueous bulk solution coincides with crystalline ectoine in its dihydrate state, thereby highlighting the important role of a few bound water molecules. Weinheim Wiley-VCH 2020 ChemPhysChem 21 17 1945 1950 urn:nbn:de:kobv:b43-509855 10.1002/cphc.202000457 https://creativecommons.org/licenses/by/4.0/deed.de 2020-07-08 OPUS4-50779 Vortrag Hahn, Marc Benjamin DNA basierte Dosimetrie 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. 2020 Zertkom Online meeting 13.05.2020 13.05.2020 2020-05-14 OPUS4-35800 Zeitschriftenartikel Hahn, Marc Benjamin; Solomun, Tihomir; Wellhausen, Robert; Herrmann, S; Seitz, H; Meyer, Susann; Kunte, Hans-Jörg; Zeman, J.; Uhlig, F; Smiatek, J; Sturm, Heinz Influence of the Compatible Solute Ectoine on the Local Water Structure: Implications for the Binding of the Protein G5P to DNA Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms. 2015 The journal of physical chemistry / B 119 49 15212 15220 10.1021/acs.jpcb.5b09506 2016-04-21 OPUS4-50577 Zeitschriftenartikel Hahn, Marc Benjamin; Smales, Glen Jacob; Seitz, H.; Solomun, Tihomir; Sturm, Heinz Ectoine interaction with DNA: Influence on ultraviolet radiation damage Ectoine is a small zwitterionic osmolyte and compatible solute, which does not interfere with cell metabolism even at molar concentrations. Plasmid DNA (pUC19) was irradiated with ultraviolet radiation (UV-C at 266 nm) under quasi physiological conditions (PBS) and in pure water in the presence and absence of ectoine (THP(B)) and hydroxyectoine (THP(A)). Different types of UV induced DNA damage were analysed: DNA single-strand breaks (SSBs), abasic sites and cyclobutane pyrimidine dimers (CPDs). A complex interplay between these factors was observed with respect to the nature and occurrence of DNA damage with 266 nm photons. In PBS, the cosolutes showed efficient protection against base damage, whilst in pure water, a dramatic shift from SSB damage to base damage was observed when cosolutes were added. To test whether these effects are caused by ectoine binding to DNA, further experiments were conducted: small-angle X-ray scattering (SAXS), surface-plasmon resonance (SPR) measurements and Raman spectroscopy. The results show, for the first time, a close interaction between ectoine and DNA. This is in stark contrast to the assumption made by preferential exclusion models, which are often used to interpret the behaviour of compatible solutes within cells and with biomolecules. It is tentatively proposed that the alterations of UV damage to DNA are attributed to ectoine influence on nucleobases through the direct interaction between ectoine and DNA. Cambridge Royal Society of Chemistry 2020 Physical Chemistry Chemical Physics 22 13 6984 6992 urn:nbn:de:kobv:b43-505772 10.1039/d0cp00092b https://creativecommons.org/licenses/by/4.0/deed.de 2020-03-23 OPUS4-50564 Vortrag Hahn, Marc Benjamin Simulaciónes de Montecarlo II: El scoring en las superficies 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. 2020 Seminar of the bioanalysis group Universidad Nacional de Colombia, Medellin, Colombia 16.03.2020 16.03.2020 2020-03-18 OPUS4-50366 Vortrag Hahn, Marc Benjamin Setup of a Particle Scattering Simulation environment A step by step introduction to the setup of a particle scattering simulation is given. Followed by an installation session. 2020 Seminar of the bioanalysis group Universidad Nacional de Colombia, Medellin, Columbia 12.02.2020 12.02.2020 2020-02-13 OPUS4-50472 Vortrag Hahn, Marc Benjamin Ejemplos de simulaciónes de Montecarlo La desintegración radioactiva A walkthrough how to setup radioactive sources in monte-carlo particle scattering simulations and perform different types of scorings. 2020 Seminar of the bioanalysis group Universidad Nacional de Colombia, Medellin, Columbia 27.02.2020 27.02.2020 2020-03-04 OPUS4-48762 Posterpräsentation Hahn, Marc Benjamin Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model. 2019 EUROMAT 2019 Stockholm, Sweden 01.09.2019 05.09.2019 2019-09-02 OPUS4-48763 Posterpräsentation Hahn, Marc Benjamin Radioactive gold nanoparticles for cancer treatment: Size and cluster dependent damage studied by Geant4 Monte-Carlo simulations Dose enhancement by gold nanoparticles (AuNP) was shown to increase the biological effectiveness of radiation damage in biomolecules and tissue. Most of the current studies focus on external beam therapy on combination with AuNP. Here we present a Monte-Carlo study (Geant4) to characterise radioactive AuNP. Radioactive ¹⁹⁸Au emits beta and gamma rays and is considered for applications with solid tumours. To effectively apply ¹⁹⁸AuNP their energy deposit characteristics have to be determined in terms of intrinsic and extrinsic properties e.g. AuNP diameter, AuNP density, and their clustering behaviour. After each decay process, the energy deposit, inelastic scattering events, kinetic energy spectrum of secondary particles within the AuNP themselves and in a spherical target volume of water up to 1 μm radius were determined. Simulations were performed for AuNP radii ranging from 2.5 nm to 20 nm radius, different cluster sizes and densities. The results show an increase of the energy deposit in the vicinity of the AuNP up to 150 nm. This effect nearly vanishes for distances up to one micron. For the case of AuNP clusters and the same activity, the enhancement of the energy deposit increases with the relative gold mass percentage and therefore can be adjusted by changing AuNP radius or clustering behaviour. 2019 EUROMAT 2019 Stockholm, Sweden 01.09.2019 05.09.2019 2019-09-02 OPUS4-48461 Zeitschriftenartikel Hahn, Marc Benjamin Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model. England IOPscience 2019 Journal of physics communications 3 7 075009-1 075009-8 urn:nbn:de:kobv:b43-484610 10.1088/2399-6528/ab31e6 http://creativecommons.org/licenses/by/3.0/de/deed.de 2019-07-15 OPUS4-47952 Zeitschriftenartikel Hahn, Marc Benjamin; Zutta Villate, Julian Mateo Radioactive gold nanoparticles for cancer treatment: Size and cluster dependent damage studied by Geant4 Monte-Carlo simulations Dose enhancement by gold nanoparticles (AuNP) was shown to increase the biological effectiveness of radiation damage in biomolecules and tissue. Most of the current studies focus on external beam therapy on combination with AuNP. Here we present a Monte-Carlo study (Geant4) to characterise radioactive AuNP. Radioactive ¹⁹⁸Au emits beta and gamma rays and is considered for applications with solid tumours. To effectively apply ¹⁹⁸AuNP their energy deposit characteristics have to be determined in terms of intrinsic and extrinsic properties e.g. AuNP diameter, AuNP density, and their clustering behaviour. After each decay process, the energy deposit, inelastic scattering events, kinetic energy spectrum of secondary particles within the AuNP themselves and in a spherical target volume of water up to 1 μm radius were determined. Simulations were performed for AuNP radii ranging from 2.5 nm to 20 nm radius, different cluster sizes and densities. The results show an increase of the energy deposit in the vicinity of the AuNP up to 150 nm. This effect nearly vanishes for distances up to one micron. For the case of AuNP clusters and the same activity, the enhancement of the energy deposit increases with the relative gold mass percentage and therefore can be adjusted by changing AuNP radius or clustering behaviour. Berlin Heidelberg Springer Società Italiana di Fisica 2019 Topical Issue: Dynamics of Systems on the Nanoscale (2018) 73 5 95, 1 7 10.1140/epjd/e2019-90707-x 2019-05-16 OPUS4-51831 misc Cano Murillo, Natalia; Ghasem Zadeh Khorasani, Media; Silbernagl, Dorothee; Hahn, Marc Benjamin; Hodoroaba, Vasile-Dan; Sturm, Heinz Cover image for the article "Nanomechanical study of polycarbonate/boehmite nanoparticles/epoxy ternary composite and their interphases" The image designed by Natalia Cano Murillo and colleagues shows the cross section of a ternary composite (boehmite/polycarbonate/epoxy, 80μm x 80μm). The surface was measured by AFM kelvin probe microscopy, yielding the surface potential which is shown as 3D-surface and contour lines. The sample was further subjected to AFM force spectroscopy with a lateral resolution of 1μm², yielding the local Young's modulus, projected in false colors on the 3D surface. The ternary system, containing boehmite nanoparticles, shows a broad distribution of modulus, desirable for optimized macroscopic mechanical properties, such as high stiffness as well as toughness. New York, NY Wiley 2020 Journal of applied polymer science 138 12 1 10.1002/app.50400 2020-12-16 OPUS4-51596 Zeitschriftenartikel Cano Murillo, Natalia; Ghasem Zadeh Khorasani, Media; Silbernagl, Dorothee; Hahn, Marc Benjamin; Hodoroaba, Vasile-Dan; Sturm, Heinz Nanomechanical study of polycarbonate/boehmite nanoparticles/epoxy ternary composite and their interphases Thermoplastic modified thermosets are of great interest especially due to their improved fracture toughness. Comparable enhancements have been achieved by adding different nanofillers including inorganic particles such as nanosized boehmite. Here, we present a nanomechanical study of two composite systems, the first comprising a polycarbonate (PC) layer in contact with epoxy resin (EP) and the second consisting of a PC layer containing boehmite nanoparticles (BNP) which is also in contact with an EP layer. The interaction between PC and EP monomer is tested by in situ Fourier transformed infrared (FT-IR) analysis, from which a reaction induced phase separation of the PC phase is inferred. Both systems are explored by atomic force microscopy (AFM) force spectroscopy. AFM force-distance curves (FDC) show no alteration of the mechanical properties of EP at the interface to PC. However, when a PC phase loaded with BNP is put in contact with an epoxy system during curing, a considerable mechanical improvement exceeding the rule of mixture was detected. The trend of BNP to agglomerate preferentially around EP dominated regions and the stiffening effect of BNP on EP shown by spatial resolved measurements of Young's modulus, suggest the effective presence of BNP within the EP phase. New York, NY Wiley 2021 Journal of applied polymer science 138 12 1 11 urn:nbn:de:kobv:b43-515965 10.1002/app.50231 https://creativecommons.org/licenses/by-nc/4.0/deed.de 2020-11-19 OPUS4-52060 Vortrag Hahn, Marc Benjamin Reference Materials at BAM A introduction into reference materials, the certification process and brief over current reference projects at BAM is given. 2021 AK-Postdoc seminar BAM Berlin, Germany 02.02.2021 02.02.2021 2021-02-03 OPUS4-50332 Vortrag Hahn, Marc Benjamin Particle Scattering Simulations with Geant4: An Overview A brief overview over the capabilities of Geant4 is provided together with some example applications 2020 Seminar of the bioanalysis group Universidad Nacional de Colombia, Bogotá, Columbia 03.02.2020 03.02.2020 2020-02-05 OPUS4-50333 Vortrag Hahn, Marc Benjamin Hands on: Particle scattering simulations A practical introduction A practical introduction is given for the necessary steps to start with particle scattering simulations based on Geant4/Topas. 2020 Seminar of the bioanalysis group Universidad Nacional de Colombia, Bogotá, Columbia 04.02.2020 04.02.2020 2020-02-06 OPUS4-52461 misc Hahn, Marc Benjamin Behind the paper: Radiation, DNA and water: New techniques for deeper insights To gain deeper insights into the old questions about the influence of water on radiation interaction with DNA, new spectroscopic techniques had to be applied. London Springer Nature 2021 Nature Portfolio Chemistry Community 1 3 2021-04-23 OPUS4-52327 Zeitschriftenartikel Hahn, Marc Benjamin; Zutta Villate, J. M. Zutta Villate, J. M. Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement in cell organelles Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of Radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined. Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for future experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. Springer Nature 2021 Scientific Reports 11 1 6721 urn:nbn:de:kobv:b43-523276 10.1038/s41598-021-85964-2 https://creativecommons.org/licenses/by/4.0/deed.de 2021-03-25 OPUS4-52389 Forschungsbericht Hahn, Marc Benjamin; Sturm, Heinz; Bier, F; Solomun, Tihomir Biologische Konsequenzen einer nanoskaligen Energiedeposition: Fokussierung auf die Rolle niederenergetischer Elektronen Bei der Behandlung von Krebs mittels Strahlentherapie sollen Tumorzellen abgetötet werden ohne das umliegende gesunde Gewebe zu zerstören. Um Strahlentherapien für Patienten verträglicher zu machen, ist ein besseres Verständnis der zugrundeliegenden Prozesse auf der molekularen Ebene nötig. Dabei sind der Energieeintrag und die Streuprozesse der Strahlung in der Umgebung der DNA von besonderem Interesse. Durch Streuung von hochenergetischer Strahlung in Wasser werden besonders viele Sekundärelektronen mit niedriger Energie erzeugt. Zur Untersuchung der Schädigungseffizienz dieser Elektronen wurde ein Verfahren zur direkten Bestrahlung von Lösungen mittels Elektronen variabler Energien enwtickelt. Dies wurde durch einen neu entwickelten Probenhalter mit einer für Elektronen durchlässigen Nanomembran ermöglicht. Mit diesem können Bestrahlungen an DNA, Proteinen, und Zellen bei verschiedenen pH-Werten oder Salzkonzentrationen durchgeführt werden. Parallel dazu wurde der ortsabhängige Energieeintrag innerhalb des Wassers durch Elektronenstreusimulationen bestimmt. Diese neuartige Kombination von Experiment und Simulation ermöglicht die Bestimmung der Schaden-Dosis-Relation für Elektronenbestrahlung von biologischen Systemen unter realistischen physiologischen Bedingungen. So konnten für die genutzten Primärelektronen wie die mittlere letale Dosis, bei der 50 Prozent der DNA geschädigt sind, mit 1,7 Gy bestimmt. Ebenfalls wurde das für mikrodosimetrische Modellierungen und Betrachtungen der sogenannten Linear energy transfer (LET) Effekte, wichtige Verhältnis von DNA Einzelstrangbrüchen (SSB) zu Doppelstrangbrüchen (DSB) als SSB/DSB = 12/1 bestimmt. Mit Hilfe eines Modells für das Targetvolumen der DNA wurde der mittlere mikroskopische letale Energieeintrag berechnet als E1/2 = 6 ± 4 eV . Es wurde gefolgert, dass weniger als zwei Ionisationsprozesse im sensitiven Targetvolumen der DNA im Mittel zu einem Einzelstrangbruch führen. Diese Methode ist unabhängig von den Primärpartikel und geometrischen Bedingungen. Deshalb ermöglicht sie die Vergleichbarkeit experimenteller Systeme mit inhomogenen Energieverteilungen, welches sonst nicht gegeben ist. Des weiteren wurden die Strahlenschutzfunktionen des Zellschutzmoleküls Ectoines und sein Einfluss auf Wasser und Biomoleküle untersucht. Seine Schutzfunktion gegen ionisierende Strahlung wurde auf die Erhöhung des Streuquerschnitts niederenergetischer Elektronen und seine Eigenschaft als OH-Radikalfänger zurückgeführt. Aufbauend auf unseren Erkenntnissen finden in klinischen Arbeitsgruppen Untersuchungen zu Einsatzmöglichkeiten im Umfeld der Strahlentherapie statt. Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 245767821 2021 1 14 2021-04-07 OPUS4-52406 Zeitschriftenartikel Hahn, Marc Benjamin; Dietrich, P. M.; Radnik, Jörg In situ monitoring of the influence of water on DNA radiation damage by near-ambient pressure X-ray photoelectron spectroscopy 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 xperiments 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. London Springer Nature 2021 Communications Chemistry 4 1 50 urn:nbn:de:kobv:b43-524060 10.1038/s42004-021-00487-1 https://creativecommons.org/licenses/by/4.0/deed.de 2021-04-12 OPUS4-52361 Vortrag Hahn, Marc Benjamin DNA based Reference Materials: In Biodosimetry and Pharmaceutical Quality Control Applications of plasmid DNA base reference materials in dosimetry and pharmaceutical research. 2021 Physical and Chemical Analysis of Polymers seminar Online meeting 29.03.2021 29.03.2021 2021-03-31 OPUS4-40424 Zeitschriftenartikel Hahn, Marc Benjamin; Meyer, Susann; Kunte, Hans-Jörg; Solomun, Tihomir; Sturm, Heinz Measurements and simulations of microscopic damage to DNA in water by 30 keV electrons: A general approach applicable to other radiation sources and biological targets The determination of the microscopic dose-damage relationship for DNA in an aqueous environment is of a fundamental interest for dosimetry and applications in radiation therapy and protection. We combine geant4 particle-scattering simulations in water with calculations concerning the movement of biomolecules to obtain the energy deposit in the biologically relevant nanoscopic volume. We juxtaposition these results to the experimentally determined damage to obtain the dose-damage relationship at a molecular level. This approach is tested for an experimentally challenging system concerning the direct irradiation of plasmid DNA (pUC19) in water with electrons as primary particles. Here a microscopic target model for the plasmid DNA based on the relation of lineal energy and radiation quality is used to calculate the effective target volume. It was found that on average fewer than two ionizations within a 7.5-nm radius around the sugar-phosphate backbone are sufficient to cause a single strand break, with a corresponding median lethal energy deposit being E1/2=6±4 eV. The presented method is applicable for ionizing radiation (e.g., γ rays, x rays, and electrons) and a variety of targets, such as DNA, proteins, or cells. USA American Physical Society American Physical Society 2017 Physical Review E 95 5 052419-1 052419-8 urn:nbn:de:kobv:b43-404244 10.1103/PhysRevE.95.052419 http://creativecommons.org/licenses/by/3.0/de/deed.de 2017-05-31 OPUS4-40043 Posterpräsentation Hahn, Marc Benjamin Electron beam therapy: Microdosimetric calculations for the quantification of fundamental damaging processes Electron beam therpy is used to treat tumor cells by irradiation with high energy electrons (HEE). The irradiation is performed by medical linear accelerators. By interaction of the HEE with the irradiated tissue a broad spectra of secondary electrons and water dissoziation products is generated. These products interact with biomolecules, especially DNA, by various processes. The disentanglement of the resulting direct- and indirect damage to DNA and other cellular components is still under debate. To increase the efficiency of future therapies a better understanding of the microscopic damaging processes is highly important. Especially the various contributions of the secondary species produced, such as low energy electrons (LEE) and radicals is far from understood and quantified. To increase the understanding we present a combination of a microdosimetric simulations and experiments to quantify the damage by means of electron scattering and diffusion simulations within the Geant4-DNA framework. In combination with in-liquid irradiation of plasmid DNA it possible to determine microdosimetric quantities for biomolecules in liquid environment. The presented method was applied to the irradiation of plasmid DNA (pUC19) in water. This opens up new possibilities in radiation research to quantify the dosage-damage relationship for microscopic plasmid volumes under well defined physiological condition. 2017 IWBBIO17 Granada. Spain 25.04.2017 29.04.2017 2017-05-03 OPUS4-42617 Posterpräsentation Hahn, Marc Benjamin DNA strand break induction by secondary radiation products: damage yields of OH-radicals, low energy electrons and prehydrated electrons The damage caused by ionizing radiation to biomolecules, especially DNA, is the reason to treat cancer via radiation therapy. A better understanding of the molecular processes and the quantification of the various damaging mechanisms is the prerequisit to develope 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. Due to the high amount of water in biological tissue, most of the damage is caused by the secondary particles produced by the interaction of the IR 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 of the various species is of interest. Here we present an experimental approach to disentangle their relative DNA strand break yield. Plasmid DNA is irradiated in water with electrons under the presence of different scavengers. With the presented method it will be possible to reveal the relative contributions of OH-radicals, low energy electrons and prehydrated electrons to the DNA single and double strand break yield. 2017 Radiation Research Conference 2017 Cancun, Mexico 15.10.2017 18.10.2017 2017-10-24 OPUS4-42619 Posterpräsentation Hahn, Marc Benjamin From sensing to dosimetry: Immobilized single-stranded DNA on surfaces as versatile sensor for protein activity and irradiation damage We report on the design, preparation and application of immobilized Oligonucleotides as biological sensors for dosimetry and protein activity. Oligonucleotides can be custom tailored in terms of sequence and length to the needs of the specific application. The preparation can be scaled from small lab-scales to higher output via spotting technology on various surfaces such as glass, silicon-dioxide or gold. They can be applied for the sensing of DNA-protein interaction and surface-plasmon resonance to detect the influence of cosolutes on the protein activity. This can be applied in the testing of pharmaceutical or cosmsetic applications and incorporated in microfluidic devices. Other important use cases are the usage in dosimetric application where the oligonucleotides are subjected to ionizing radiation. They can directly act as a sensor for biological damage which is detected and quantified by the subsequent hybridization of complementary strands who carry a fluorescence dye. The quantification can be performed by an array scanner or fluorescence microscope. Investigation on a molecular level can be performed with the AFM-IR technique. Applications are calibration of radiation sources and the investigation of interaction of ionizing radiation with biomolecules. 2017 Euromat 2017 Thessaloniki, Greece 17.09.2017 22.09.2017 2017-10-24 OPUS4-42620 Vortrag Hahn, Marc Benjamin Direct electron irradiation of DNA in fully aqueous environment: Microscopic dose determination in combination with Monte-Carlo simulations 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 2017 Seminarvortrag im Joint Ultrafast Dynamics Laboratory in Solution and at Interfaces Helmholtz-Zentrum Berlin, Germany 14.06.2017 14.06.2017 2017-10-24 OPUS4-41313 Zeitschriftenartikel Meyer, Susann; Schröter, Maria-Astrid; Hahn, Marc Benjamin; Solumon, Tihomir; Strum, Heinz; Kunte, Hans-Jörg Ectoine can enhance structural changes in DNA in vitro Strand breaks and conformational changes of DNA have consequences for the physiological role of DNA. The natural protecting molecule ectoine is beneficial to entire bacterial cells and biomolecules such as proteins by mitigating detrimental effects of environmental stresses. It was postulated that ectoine-like molecules bind to negatively charged spheres that mimic DNA surfaces. We investigated the effect of ectoine on DNA and whether ectoine is able to protect DNA from damages caused by ultraviolet radiation (UV-A). In order to determine different isoforms of DNA, agarose gel electrophoresis and atomic force microscopy experiments were carried out with plasmid pUC19 DNA. Our quantitative results revealed that a prolonged incubation of DNA with ectoine leads to an increase in transitions from supercoiled (undamaged) to open circular (single-strand break) conformation at pH 6.6. The effect is pH dependent and no significant changes were observed at physiological pH of 7.5. After UV-A irradiation in ectoine solution, changes in DNA conformation were even more pronounced and this effect was pH dependent. We hypothesize that ectoine is attracted to the negatively charge surface of DNA at lower pH and therefore fails to act as a stabilizing agent for DNA in our in vitro experiments. 2017 Scientific Reports 7 1 Article 7170, 1 10 urn:nbn:de:kobv:b43-413139 10.1038/s41598-017-07441-z http://creativecommons.org/licenses/by/3.0/de/deed.de 2017-08-14 OPUS4-41933 Zeitschriftenartikel Hahn, Marc Benjamin; Susann, Meyer; Schröter, Maria-Astrid; Kunte, Hans-Jörg; Solomun, Tihomir; Sturm, Heinz DNA protection by ectoine from ionizing radiation: molecular mechanisms Ectoine, a compatible solute and osmolyte, is known to be an effective protectant of biomolecules and whole cells against heating, freezing and extreme salinity. Protection of cells (human keratinocytes) by ectoine against ultraviolet radiation has also been reported by various authors, although the underlying mechanism is not yet understood. We present the first electron irradiation of DNA in a fully aqueous environment in the presence of ectoine and at high salt concentrations. The results demonstrate effective protection of DNA by ectoine against the induction of single-strand breaks by ionizing radiation. The effect is explained by an increase in low-energy electron scattering at the enhanced free-vibrational density of states of water due to ectoine, as well as the use of ectoine as an ˙OH-radical scavenger. This was demonstrated by Raman spectroscopy and electron paramagnetic resonance (EPR). United Kingdom Royal Society of Chemistry 2017 Physical Chemistry Chemical Physics 19 37 25717 25722 urn:nbn:de:kobv:b43-419332 10.1039/C7CP02860A http://creativecommons.org/licenses/by/3.0/de/deed.de 2017-09-15 OPUS4-42828 Zeitschriftenartikel Schröter, Maria-Astrid; Meyer, Susann; Hahn, Marc Benjamin; Solomun, Tihomir; Sturm, Heinz; Kunte, Hans-Jörg Ectoine protects DNA from damage by ionizing radiation Ectoine plays an important role in protecting biomolecules and entire cells against environmental stressors such as salinity, freezing, drying and high temperatures. Recent studies revealed that ectoine also provides effective protection for human skin cells from damage caused by UV-A radiation. These protective properties make ectoine a valuable compound and it is applied as an active ingredient in numerous pharmaceutical devices and cosmetics. Interestingly, the underlying mechanism resulting in protecting cells from radiation is not yet fully understood. Here we present a study on ectoine and its protective influence on DNA during electron irradiation. Applying gel electrophoresis and atomic force microscopy, we demonstrate for the first time that ectoine prevents DNA strand breaks caused by ionizing electron radiation. The results presented here point to future applications of ectoine for instance in cancer radiation therapy. Nature 2017 Scientific Reports 7 1 15272, 1 15272, 7 urn:nbn:de:kobv:b43-428287 10.1038/s41598-017-15512-4 http://creativecommons.org/licenses/by/3.0/de/deed.de 2017-11-13 OPUS4-46383 Posterpräsentation Hahn, Marc Benjamin Determination of the Microscopic Dose-Damage Relation for Radiation of different Linear Energy Transfer The determination of the microscopic dose-damage relationship for DNA in an aqueous environment is of a fundamental interest for dosimetry and applications in radiation therapy and protection. We combine geant4 particle-scattering simulations in water with calculations concerning the movement of biomolecules to obtain the energy deposit in the biologically relevant nanoscopic volume.[1] We juxtaposition these results to the experimentally determined damage to obtain the microscopic dose-damage relationship at a molecular level. This approach is tested for an experimentally challenging system concerning the direct irradiation of plasmid DNA (pUC19) in water with electrons as primary particles.[2] Here a microscopic target model for the plasmid DNA based on the relation of lineal energy and radiation quality is used to calculate the effective target volume. It was found that on average fewer than two ionizations within a 7.5-nm radius around the sugar-phosphate backbone are sufficient to cause a single strand break, with a corresponding median lethal energy deposit being E1/2=6±4 eV.[1] The presented method is applicable for ionizing radiation (e.g., γ rays, x rays, and electrons) and a variety of targets, such as DNA, proteins, or cells. [1] Hahn, M. B., Meyer, S., Kunte, H.-J., Solomun, T. & Sturm, H. Measurements and simulations of microscopic damage to DNA in water by 30 keV electrons: A general approach applicable to other radiation sources and biological targets. Phys. Rev. E 95, 052419 (2017). [2] Hahn, M. B. et al. Direct electron irradiation of DNA in a fully aqueous environment. Damage determination in combination with Monte Carlo simulations. Phys. Chem. Chem. Phys. 19, 1798-1805 (2017). 2018 DYSON 2018 Potsdam, Germany 08.10.2018 12.10.2018 2018-10-29 OPUS4-41164 Beitrag zu einem Tagungsband Hahn, Marc Benjamin; Solomun, Tihomir; Meyer, Susann; Kunte, Hans-Jörg; Schröter, Maria-Astrid; Sturm, Heinz Development of a standard procedure for the irradiation of biomolecules In dosimetry the determination of the effectiveness of the damaging processes is standardized and accounted for by the radiation and tissue weighting factor. For the underlying constituents of the tissue, that is the various biomolecules, such a systematic approach doesn't exist. This makes it difficult to compare results obtained under different experimental conditions. In the following work, we will describe a method to obtain comparable values for the radiation-biomolecule interaction, measured under different conditions. This approach can lead to standardization of dosedamage relationship at the molecular level. Such approach is necessary for a better understanding of the relations between the damage of the single constituents of biological tissue and the whole - finally gaining a more complete picture of irradiation damage. International Raditation Protection Association 2017 Proceedings of the 14th IRPA International Congress 14 14th International Congress of the International Raditation Protection Association (IRPA) Cape Town, South Africa 09.05.2016 12.05.2016 1 5 2017-08-03 OPUS4-47810 Posterpräsentation Hahn, Marc Benjamin Measurement and Simulation of the Microscopic Energy Deposit: A general approach applicable to Ionizing Radiation Sources of varying Linear Energy Transfer The determination of microscopic dose-damage relations in aqueous environment is of fundamental interest for dosimetry and its application in radiation-therapy and protection. We present a combined experimental and simulational approach to quantify the microscopic energy deposit at biomolecules in liquid environment which is applicable to a wide range of primary radiation sources, e.g. photons, electrons or ions, and targets, such as DNA, proteins or cells.Therefore, we combine Geant4 particle-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 generalised damage model to determine the microscopic dose-damage relation at a molecular level. To show the viability of this approach, we apply this method to an experimentally challenging system, the direct irradiation of plasmid DNA (pUC19) in water with electrons as primary particles. Here we combine electron-scattering simulations with calculations concerning the diffusion and convection induced movement of the DNA, within a coarse-grained model of the irradiated liquid. Additionally a microscopic target model for DNA molecules based on the relation of lineal energy and radiation quality is used to calculate their effective target volume. It was found that on average fewer than two ionisations within a 7.5\,nm radius around the sugar-phosphate backbone are sufficient to cause a single strand break, with a corresponding median lethal energy deposit being E\textsubscript{1/2}=6+-4\,eV. The presented method is applicable for all types of ionising radiation and a broad variety of biological targets. 2019 CCQM Workshop Paris, France 09.04.2019 10.04.2019 2019-04-17 OPUS4-47819 Vortrag Hahn, Marc Benjamin Geant4: A universal Monte-Carlo toolkit for Particle scattering simulations 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. 2019 Department 6 Seminar Berlin, Germany 04.04.2019 04.04.2019 2019-04-17 OPUS4-58761 Vortrag Hahn, Marc Benjamin The change of dna and protein radiation damage upon hydration: in-situ observations by near-ambient-pressure xps 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. 2023 AVS69 Portland, USA 05.11.2023 10.11.2023 2023-11-07 OPUS4-58877 Zeitschriftenartikel Tavasolyzadeh, Zeynab; Tang, Peng; Hahn, Marc Benjamin; Hweidi, Gada; Nordholt, Niclas; Haag, Rainer; Sturm, Heinz; Topolniak, Ievgeniia 2D and 3D Micropatterning of Mussel-Inspired Functional Materials by Direct Laser Writing AbstractThis work addresses the critical need for multifunctional materials and substrate-independent high-precision surface modification techniques that are essential for advancing microdevices and sensing elements. To overcome existing limitations, the versatility of mussel-inspired materials (MIMs) is combined with state-of-the-art multiphoton direct laser writing (DLW) microfabrication. In this way, 2D and 3D MIM microstructures of complex designs are demonstrated with sub-micron to micron resolution and extensive post-functionalization capabilities. This study includes polydopamine (PDA), mussel-inspired linear, and dendritic polyglycerols (MI-lPG and MI-dPG), allowing their direct microstructure on the substrate of choice with the option to tailor the patterned topography and morphology in a controllable manner. The functionality potential of MIMs is demonstrated by successfully immobilizing and detecting single-stranded DNA on MIM micropattern and nanoarray surfaces. In addition, easy modification of MIM microstructure with silver nanoparticles without the need of any reducing agent is shown. The methodology developed here enables the integration of MIMs in advanced applications where precise surface functionalization is essential. Weinheim Wiley-VCH 2023 Small : nano micro 1 12 urn:nbn:de:kobv:b43-588778 10.1002/smll.202309394 https://creativecommons.org/licenses/by/4.0/deed.de 2023-11-22 OPUS4-57060 Posterpräsentation Hahn, Marc Benjamin Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement by Monte-Carlo based particle scattering Simulations Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined.[1] Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. [2] These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for ongoing experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. 2023 #RSCposter 2023 Online meeting 28.02.2023 01.03.2023 2023-03-02 OPUS4-57061 Posterpräsentation Hahn, Marc Benjamin Ectoine protects biomolecules from ionizing radiation: Molecular mechanisms The compatible solute and osmolyte ectoine is an effective protectant of biomolecules and whole cells against heating, freezing and high salinity. The protection of cells (human Keratinocytes) by ectoine against ultraviolet radiation was also reported by various authors, although the underlying mechanism is not yet understood. We present results on the irradiation of biomolecules (DNA) with ionizing radiation (high energy electrons) in fully aqueous environment in the presence of ectoine and high salt concentrations. The results demonstrate an effective radiation protection of DNA by ectoine against the induction of single strand breaks by ionizing radiation. The effect is explained by an increased in low-energy electron scattering at the enhanced free-vibrational density of states of water due to ectoine, as well as the action of ectoine as an OH-radical scavenger. This was demonstrated by Raman spectroscopy, electron paramagnetic resonance (EPR) and Monte-Carlo simulations (Geant4). 2023 #RSCposter 2023 Online meeting 28.02.2023 01.03.2023 2023-03-02 OPUS4-57062 Posterpräsentation Hahn, Marc Benjamin Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model. 2023 #RSCposter 2023 Online meeting 28.02.2023 01.03.2023 2023-03-02 OPUS4-57006 Zeitschriftenartikel Hallier, Dorothea C.; Smales, Glen Jacob; Seitz, H.; Hahn, Marc Benjamin Inside back cover for the article "Bio-SAXS of single-stranded DNA-binding proteins: Radiation protection by the compatible solute ectoine" Showcasing research from the Federal Institute for Material Research and Testing Berlin and Fraunhofer Institute for Celltherapy and Immunology Branch Bioanalytics and Bioprocesses Potsdam. Bio-SAXS of single-stranded DNA-binding proteins: Radiation protection by the compatible solute ectoine. We aimed to increase the possible undisturbed exposure time during bio-SAXS measurements of single-stranded DNA-binding proteins. Therefore small angle X-ray scattering was performed on Gene-V Protein (G5P/GVP), which is involved in DNA repair processes. To achieve this, irradiations were performed in presence and absence of the hydroxyl-radical scavenger and osmolyte Ectoine, which showed efficient radiation protection and prevented protein aggregation, thus allows for a non-disturbing way to improve structure-determination of biomolecules. Cambridge Royal Society of Chemistry 2023 Physical chemistry chemical physics (PCCP) 25 7 5889 10.1039/D3CP90056H 2023-02-21 OPUS4-57782 Posterpräsentation Hahn, Marc Benjamin Near-ambient-pressure Xray photoelectron spectroscopy (XPS) to monitor DNA radiation damage directly in water 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. 2023 RADeleven Herceg Novi, Montenegro 19.06.2023 23.06.2023 2023-06-28 OPUS4-56890 Zeitschriftenartikel Hallier, Dorothea C.; Smales, Glen Jacob; Seitz, H.; Hahn, Marc Benjamin Bio-SAXS of single-stranded DNA-binding proteins: Radiation protection by the compatible solute ectoine Small-angle X-ray scattering (SAXS) can be used for structural determination of biological macromolecules and polymers in their native states (e.g. liquid phase). This means that the structural changes of (bio-)polymers, such as proteins and DNA, can be monitored in situ to understand their sensitivity to changes in chemical environments. In an attempt to improve the reliability of such experiments, the reduction of radiation damage occurring from exposure to X-rays is required. One such method, is to use scavenger molecules to protect macromolecules against radicals produced during radiation exposure, such as reactive oxygen species (ROS). In this study we investigate the feasibility of applying the compatible solute, osmolyte and radiation protector Ectoine (THP(B)), as a scavenger molecule during SAXS measurements of the single-stranded DNA-binding protein Gene-V Protein (G5P/GVP). In this case, we monitor the radiation induced changes of G5P during bio-SAXS measurments and the resulting microscopic energy-damage relation was determined from microdosimetric calculations by Monte-Carlo based particle scattering simulations with TOPAS/Geant4 and a custom target-model. This resulted in a median-lethal energy deposit of pure G5P at 4 mg mL−1 of E1/2 = 7 ± 5 eV, whereas a threefold increase of energy-deposit was needed under the presence of Ectoine to reach the same level of damage. This indicates that Ectoine increases the possible exposure time before radiation-damage to G5P is observed. Furthermore, the dominant type of damage shifted from aggregation in pure solutions towards a fragmentation for solutions containing Ectoine as a cosolute. These results are interpreted in terms of indirect radiation damage by reactive secondary species, as well as post-irradiation effects, related to preferential-exclusion of the cosolute from the protein surface. Hence, Ectoine is shown to provide a non-disturbing way to improve structure-determination of proteins via bio-SAXS in future studies. Cambridge Royal Society of Chemistry 2023 Physical chemistry chemical physics (PCCP) 25 7 5372 5382 urn:nbn:de:kobv:b43-568909 10.1039/d2cp05053f https://creativecommons.org/licenses/by/4.0/deed.de 2023-01-25 OPUS4-58709 Zeitschriftenartikel Pauw, Brian Richard; Smales, Glen Jacob; Anker, A. S.; Annadurai, V.; Balazs, D. M.; Bienert, Ralf; Bouwman, W. G.; Breßler, Ingo; Breternitz, J.; Brok, E. S.; Bryant, G.; Clulow, A. J.; Crater, E. R.; De Geuser, F.; Del Giudice, A.; Deumer, J.; Disch, S.; Dutt, S.; Frank, K.; Fratini, E.; Garcia, P. R. A. F.; Gilbert, E. P.; Hahn, Marc Benjamin; Hallett, J.; Hohenschutz, M.; Hollamby, M.; Huband, S.; Ilavsky, J.; Jochum, J. K.; Juelsholt, M.; Mansel, B. W.; Penttilä, P.; Pittkowski, R. K.; Portale, G.; Pozzo, L. D.; Rochels, L.; Rosalie, Julian M.; Saloga, Patrick E. J.; Seibt, S.; Smith, A. J.; Smith, G. N.; Spiering, G. A.; Stawski, Tomasz M.; Taché, O.; Thünemann, Andreas; Toth, K.; Whitten, A. E.; Wuttke, J. The human factor: results of a small-angle scattering data analysis round robin A round-robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions and two from powders. Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5% and half of the population width entries within 40%. Due to the added complexity of the structure factor, far fewer people submitted answers on the powder datasets. For those that did, half of the entries for the means and widths were within 44 and 86%, respectively. This round-robin experiment highlights several causes for the discrepancies, for which solutions are proposed. International Union of Crystallography (IUCr) 2023 Journal of Applied Crystallography 56 6 1618 1629 urn:nbn:de:kobv:b43-587091 10.1107/S1600576723008324 https://creativecommons.org/licenses/by/4.0/deed.de 2023-11-02 OPUS4-58742 Vortrag Hahn, Marc Benjamin Radiation biophysics 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. 2023 Project overview Berlin, Germany 27.09.2023 2023-11-06 OPUS4-58744 Vortrag Hahn, Marc Benjamin Radiation biophysics: a journey 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. 2023 Project update Online meeting 09.10.2023 2023-11-06 OPUS4-58295 Zeitschriftenartikel Solomun, Tihomir; Cordsmeier, Leo; Hallier, Dorothea C.; Seitz, Harald; Hahn, Marc Benjamin Interaction of a Dimeric Single-Stranded DNA-Binding Protein (G5P) with DNA Hairpins. A Molecular Beacon Study Gene-V protein (G5P/GVP) is a single-stranded (ss)DNA-binding protein (SBP) of bacteriophage f1 that is required for DNA synthesis and repair. In solution, it exists as a dimer that binds two antiparallel ssDNA strands with high affinity in a cooperative manner, forming a left-handed helical protein-DNA filament. Here, we report on fluorescence studies of the interaction of G5P with different DNA oligonucleotides having a hairpin structure (molecular beacon, MB) with a seven base-pair stem (dT24-stem7, dT18-stem7), as well as with DNA oligonucleotides (dT38, dT24) without a defined secondary structure. All oligonucleotides were end-labeled with a Cy3-fluorophore and a BHQ2-quencher. In the case of DNA oligonucleotides without a secondary structure, an almost complete quenching of their strong fluorescence (with about 5% residual intensity) was observed upon the binding of G5P. This implies an exact alignment of the ends of the DNA strand(s) in the saturated complex. The interaction of the DNA hairpins with G5P led to the unzipping of the base-paired stem, as revealed by fluorescence measurements, fluorescence microfluidic mixing experiments, and electrophoretic mobility shift assay data. Importantly, the disruption of ssDNA's secondary structure agrees with the behavior of other single-stranded DNA-binding proteins (SBPs). In addition, substantial protein-induced fluorescence enhancement (PIFE) of the Cy3-fluorescence was observed. ACS Publications 2023 The Journal of Physical Chemistry B 127 38 8131 8138 10.1021/acs.jpcb.3c03669 2023-09-18 OPUS4-57324 Zeitschriftenartikel Hahn, Marc Benjamin Accessing radiation damage to biomolecules on the nanoscale by particle-scattering simulations Radiation damage to DNA plays a central role in radiation therapy to cure cancer. The physico-chemical and biological processes involved encompass huge time and spatial scales. To obtain a comprehensive understanding on the nano and the macro scale is a very challenging tasks for experimental techniques alone. Therefore particle-scattering simulations are often applied to complement measurements and aide their interpretation, to help in the planning of experiments, to predict their outcome and to test damage models. In the last years, powerful multipurpose particle-scattering framework based on the Monte-Carlo simulation (MCS) method, such as Geant4 and Geant4-DNA, were extended by user friendly interfaces such as TOPAS and TOPAS-nBio. This shifts their applicability from the realm of dedicated specialists to a broader range of scientists. In the present review we aim to give an overview over MCS based approaches to understand radiation interaction on a broad scale, ranging from cancerous tissue, cells and their organelles including the nucleus, mitochondria and membranes, over radiosensitizer such as metallic nanoparticles, and water with additional radical scavenger, down to isolated biomolecules in the form of DNA, RNA, proteins and DNA-protein complexes. Hereby the degradation of biomolecules by direct damage from inelastic scattering processes during the physical stage, and the indirect damage caused by radicals during the chemical stage as well as some parts of the early biological response is covered. Due to their high abundance the action of hydroxyl radicals (•OH) and secondary low energy electrons (LEE) as well as prehydrated electrons are covered in additional detail. Applications in the prediction of DNA damage, DNA repair processes, cell survival and apoptosis, influence of radiosensitizer on the dose distribution within cells and their organelles, the study of linear energy transfer (LET), the relative biological effectiveness (RBE), ion beam cancer therapy, microbeam radiation therapy (MRT), the FLASH effect, and the radiation induced bystander effect are reviewed. London Institute of Physics (IOP) Publishing 2023 Journal of Physics Communications 7 4 042001 urn:nbn:de:kobv:b43-573240 10.1088/2399-6528/accb3f https://creativecommons.org/licenses/by/4.0/deed.de 2023-04-19 OPUS4-57253 Posterpräsentation Hahn, Marc Benjamin BP150: Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement by Monte-Carlo based particle scattering Simulations Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined. Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. We apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. 2023 DPG Frühjahrstagung Dresden, Germany 26.03.2023 31.03.2023 2023-04-03 OPUS4-57254 Posterpräsentation Hahn, Marc Benjamin BP150: Bio-SAXS of single-stranded DNA-binding proteins: Radiation protection by the compatible solute ectoine Small-angle X-ray scattering (SAXS) can be used for structural determination of biological macromolecules and polymers in their native states (e.g. liquid phase). This means that the structural changes of (bio-)polymers, such as proteins and DNA, can be monitored in situ to understand their sensitivity to changes in chemical environments. In an attempt to improve the reliability of such experiments, the reduction of radiation damage occurring from exposure to X-rays is required. One such method, is to use scavenger molecules to protect macromolecules against radicals produced during radiation exposure, such as reactive oxygen species (ROS). In this study we investigate the feasibility of applying the compatible solute, osmolyte and radiation protector Ectoine (THP(B)), as a scavenger molecule during SAXS measurements of the single-stranded DNA-binding protein Gene-V Protein (G5P/GVP). In this case, we monitor the radiation induced changes of G5P during bio-SAXS measurments and the resulting microscopic energy-damage relation was determined from microdosimetric calculations by Monte-Carlo based particle scattering simulations with TOPAS/Geant4 and a custom target-model. This resulted in a median-lethal energy deposit of pure G5P at 4 mg mL−1 of E1/2 = 7 ± 5 eV, whereas a threefold increase of energy-deposit was needed under the presence of Ectoine to reach the same level of damage. This indicates that Ectoine increases the possible exposure time before radiation-damage to G5P is observed. Furthermore, the dominant type of damage shifted from aggregation in pure solutions towards a fragmentation for solutions containing Ectoine as a cosolute. These results are interpreted in terms of indirect radiation damage by reactive secondary species, as well as post-irradiation effects, related to preferential-exclusion of the cosolute from the protein surface. Hence, Ectoine is shown to provide a non-disturbing way to improve structure-determination of proteins via bio-SAXS in future studies. 2023 DPG Frühjahrstagung Dresden, Germany 26.03.2023 31.03.2023 2023-04-03 OPUS4-57255 Posterpräsentation Hahn, Marc Benjamin BP153: The change of DNA radiation damage upon hydration: In-situ observation by near-ambient pressure XPS 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. 2023 DPG Frühjahrstagung Dresden, Germany 26.03.2023 31.03.2023 2023-04-03 OPUS4-57406 Vortrag Hahn, Marc Benjamin The change of DNA AND PROTEIN radiation damage upon hydration: In-situ observations by near-ambient-pressure XPS 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. 2023 Dyson Conference 2023 Prague, Czech Republic 24.04.2023 26.04.2023 2023-05-03 OPUS4-57407 Posterpräsentation Hahn, Marc Benjamin Extending Bio-SAXS measurements of Single-Stranded DNA-Binding Proteins: Radiation Protection of G5P by Cosolutes Small-angle X-ray scattering (SAXS) can be used for structural de- termination of biological macromolecules and polymers in their na- tive states. To improve the reliability of such experiments, the re- duction of radiation damage occurring from exposure to X-rays is needed.One method, is the use of scavenger molecules that protect macromolecules against radicals produced by radiation exposure.In this study we investigate the feasibility to apply the compatible solute, osmolyte and radiation protector Ectoine (THP(B)) as a scavenger throughout SAXS measurements of single-stranded DNA-binding protein Gene-V Protein (G5P/GVP). Therefore we monitor the radiation induced changes of G5P during bio-SAXS. The resulting microscopic energy-damage relation was determined by particle scattering simu- lations with TOPAS/Geant4. The results are interpreted in terms of radical scavenging as well as post-irradiation effects, related to preferential-exclusion from the protein surface. Thus, Ectoine provides an non-disturbing way to improve structure-determination of proteins via bio-SAXS in future studies. 2023 MultiChem Conference 2023 Prague, Czech Republic 26.04.2023 28.04.2023 2023-05-04 OPUS4-57645 Vortrag Hahn, Marc Benjamin Combined experimental and simulational approaches to access radiation damage to DNA-Protein complexes 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. 2023 High performance computing workshop Allan, Jordan 26.06.2023 02.07.2023 2023-06-13 OPUS4-57646 Posterpräsentation Hahn, Marc Benjamin Near-ambient-pressure XPS as as tool to monitor DNA radiation damage directly in water 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. 2023 Miller Conference Furiani, France 03.06.2023 08.06.2023 2023-06-13 OPUS4-58214 Posterpräsentation Hahn, Marc Benjamin In-situ monitoring of water dependent DNA and protein radiation damage by near-ambient-pressure XPS 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. 2023 ICRR 2023 Montreal, Canada 26.08.2023 31.08.2023 2023-09-12