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Abdoul-Carime H, Lys E, Gipouloux J, Rabilloud F. Experimental and Theoretical Investigations of the Fragmentation of Ethylenediamine Induced by Low-Energy (<10 eV) Electrons. Molecules 2023; 29:191. [PMID: 38202774 PMCID: PMC10780159 DOI: 10.3390/molecules29010191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/19/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024] Open
Abstract
Ethylenediamine is industrially used as an intermediate for the fabrication of many products. The development of new methodologies for synthesis compatible with the environment and sustainability, such as cold plasma processes, implicates reactions induced by nonthermal electrons. In this contribution, we study the interaction of low-energy (<10 eV) electrons with ethylenediamine. We show that electrons induce the fragmentation of the molecule into various anion fragments and associated neutral counterparts via dissociative electron attachment. The fragmentation mechanisms and energetics are discussed in the frame of DFT calculations. The fragmentation processes are quantified by the estimation of the cross sections and the branching ratios for competitive accessible dissociation routes.
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Affiliation(s)
- Hassan Abdoul-Carime
- Université Claude Bernard Lyon 1, Institut de Physique des 2 Infinis, CNRS/IN2P3, UMR5822, F-69003 Lyon, France
| | - Elena Lys
- Université Claude Bernard Lyon 1, Institut de Physique des 2 Infinis, CNRS/IN2P3, UMR5822, F-69003 Lyon, France
| | - Jeanne Gipouloux
- Université Claude Bernard Lyon 1, Institut Lumière Matière, CNRS/INP, UMR5306, F-69622 Villeurbanne, France (F.R.)
| | - Franck Rabilloud
- Université Claude Bernard Lyon 1, Institut Lumière Matière, CNRS/INP, UMR5306, F-69622 Villeurbanne, France (F.R.)
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2
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Kopyra J, Abdoul-Carime H. Fragmentation of metal(II) bis(acetylacetonate) complexes induced by slow electrons. Beilstein J Nanotechnol 2023; 14:980-987. [PMID: 37800122 PMCID: PMC10548254 DOI: 10.3762/bjnano.14.81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 09/14/2023] [Indexed: 10/07/2023]
Abstract
Nowadays, organometallic complexes receive particular attention because of their use in the design of pure nanoscale metal structures. In the present work, we present results obtained from a series of studies on the degradation of metal(II) bis(acetylacetonate)s induced by low-energy electrons. These slow particles induce the formation of the acetylacetonate anion, [acac]-, and the parent anion as the most dominant species at incident electron energies near 0 eV. They also fragment the organometallic compounds via various competitive reaction channels that occur at higher energies via dissociative electron attachment. The reported data may contribute to a better understanding of the physical chemistry underlying the electron-molecule interactions, which is crucial for potential applications of these molecular systems in the deposition of nanoscale structures.
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Affiliation(s)
- Janina Kopyra
- Siedlce University of Natural Sciences and Humanities, Faculty of Sciences, 3 Maja 54, 08-110 Siedlce, Poland
| | - Hassan Abdoul-Carime
- Universite de Lyon, Université Lyon 1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3, UMR5822, F-69003 Lyon, France
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3
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Lu QB. Formulation of the cosmic ray-driven electron-induced reaction mechanism for quantitative understanding of global ozone depletion. Proc Natl Acad Sci U S A 2023; 120:e2303048120. [PMID: 37364123 PMCID: PMC10319005 DOI: 10.1073/pnas.2303048120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 05/12/2023] [Indexed: 06/28/2023] Open
Abstract
This paper formulates the cosmic ray-driven electron-induced reaction as a universal mechanism to provide a quantitative understanding of global ozone depletion. Based on a proposed electrostatic bonding mechanism for charge-induced adsorption of molecules on surfaces and on the measured dissociative electron transfer (DET) cross sections of ozone-depleting substances (ODSs) adsorbed on ice, an analytical equation is derived to give atmospheric chlorine atom concentration: [Formula: see text] where Φe is the prehydrated electron (epre-) flux produced by cosmic ray ionization on atmospheric particle surfaces, [Formula: see text] is the surface coverage of an ODS, and ki is the ODS's effective DET coefficient that is the product of the DET cross section, the lifetimes of surface-trapped epre- and Cl-, and the particle surface area density. With concentrations of ODSs as the sole variable, our calculated results of time-series ozone depletion rates in global regions in the 1960s, 1980s, and 2000s show generally good agreement with observations, particularly with ground-based ozonesonde data and satellite-measured data over Antarctica and with satellite data in a narrow altitude band at 13 to 20 km of the tropics. Good agreements with satellite data in the Arctic and midlatitudes are also found. A previously unreported effect of denitrification on ozone loss is found and expressed quantitatively. But this equation overestimates tropospheric ozone loss at northern midlatitudes and the Arctic, likely due to increased ozone production by the halogen chemistry in polluted regions. The results render confidence in applying the equation to achieve a quantitative understanding of global ozone depletion.
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Affiliation(s)
- Qing-Bin Lu
- Department of Physics and Astronomy, University of Waterloo, Waterloo, ONN2L 3G1, Canada
- Department of Biology, University of Waterloo, Waterloo, ONN2L 3G1, Canada
- Department of Chemistry, University of Waterloo, Waterloo, ONN2L 3G1, Canada
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4
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Pintea M, Mason N, Peiró-Franch A, Clark E, Samanta K, Glessi C, Schmidtke IL, Luxford T. Dissociative electron attachment to gold(I)-based compounds: 4,5-dichloro-1,3-diethyl-imidazolylidene trifluoromethyl gold(I). Front Chem 2023; 11:1028008. [PMID: 37405247 PMCID: PMC10315492 DOI: 10.3389/fchem.2023.1028008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 06/01/2023] [Indexed: 07/06/2023] Open
Abstract
With the use of proton-NMR and powder XRD (XRPD) studies, the suitability of specific Au-focused electron beam induced deposition (FEBID) precursors has been investigated with low electron energy, structure, excited states and resonances, structural crystal modifications, flexibility, and vaporization level. 4,5-Dichloro-1,3-diethyl-imidazolylidene trifluoromethyl gold(I) is a compound that is a uniquely designed precursor to meet the needs of focused electron beam-induced deposition at the nanostructure level, which proves its capability in creating high purity structures, and its growing importance in other AuImx and AuClnB (where x and n are the number of radicals, B = CH, CH3, or Br) compounds in the radiation cancer therapy increases the efforts to design more suitable bonds in processes of SEM (scanning electron microscopy) deposition and in gas-phase studies. The investigation performed of its powder shape using the XRPD XPERT3 panalytical diffractometer based on CoKα lines shows changes to its structure with change in temperature, level of vacuum, and light; the sensitivity of this compound makes it highly interesting in particular to the radiation research. Used in FEBID, though its smaller number of C, H, and O atoms has lower levels of C contamination in the structures and on the surface, it replaces these bonds with C-Cl and C-N bonds that have lower bond-breaking energy. However, it still needs an extra purification step in the deposition process, either H2O, O2, or H jets.
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Affiliation(s)
- Maria Pintea
- School of Physical Sciences, University of Kent, Canterbury, United Kingdom
| | - Nigel Mason
- School of Physical Sciences, University of Kent, Canterbury, United Kingdom
| | - Anna Peiró-Franch
- School of Physical Sciences, University of Kent, Canterbury, United Kingdom
| | - Ewan Clark
- School of Physical Sciences, University of Kent, Canterbury, United Kingdom
| | - Kushal Samanta
- School of Physical Sciences, University of Kent, Canterbury, United Kingdom
| | | | | | - Thomas Luxford
- Department of Chemistry, J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
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5
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Zheng Y, Sanche L. Mechanisms of Nanoscale Radiation Enhancement by Metal Nanoparticles: Role of Low Energy Electrons. Int J Mol Sci 2023; 24. [PMID: 36902132 DOI: 10.3390/ijms24054697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/20/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
Metal nanoparticles are considered as highly promising radiosensitizers in cancer radiotherapy. Understanding their radiosensitization mechanisms is critical for future clinical applications. This review is focused on the initial energy deposition by short-range Auger electrons; when high energy radiation is absorbed by gold nanoparticles (GNPs) located near vital biomolecules; such as DNA. Auger electrons and the subsequent production of secondary low energy electrons (LEEs) are responsible for most the ensuing chemical damage near such molecules. We highlight recent progress on DNA damage induced by the LEEs produced abundantly within about 100 nanometers from irradiated GNPs; and by those emitted by high energy electrons and X-rays incident on metal surfaces under differing atmospheric environments. LEEs strongly react within cells; mainly via bound breaking processes due to transient anion formation and dissociative electron attachment. The enhancement of damages induced in plasmid DNA by LEEs; with or without the binding of chemotherapeutic drugs; are explained by the fundamental mechanisms of LEE interactions with simple molecules and specific sites on nucleotides. We address the major challenge of metal nanoparticle and GNP radiosensitization; i.e., to deliver the maximum local dose of radiation to the most sensitive target of cancer cells (i.e., DNA). To achieve this goal the emitted electrons from the absorbed high energy radiation must be short range, and produce a large local density of LEEs, and the initial radiation must have the highest possible absorption coefficient compared to that of soft tissue (e.g., 20-80 keV X-rays).
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Adjei D, Reyes Y, Kumar A, Ward S, Denisov SA, Alahmadi M, Sevilla MD, Wnuk SF, Mostafavi M, Adhikary A. Pathways of the Dissociative Electron Attachment Observed in 5- and 6-Azidomethyluracil Nucleosides: Nitrogen (N 2) Elimination vs Azide Anion (N 3-) Elimination. J Phys Chem B 2023; 127:1563-1571. [PMID: 36780335 PMCID: PMC9984991 DOI: 10.1021/acs.jpcb.2c08257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
5-Azidomethyl-2'-deoxyuridine (5-AmdU, 1) has been successfully employed for the metabolic labeling of DNA and fluorescent imaging of live cells. 5-AmdU also demonstrated significant radiosensitization in breast cancer cells via site-specific nitrogen-centered radical (π-aminyl (U-5-CH2-NH•), 2, and σ-iminyl (U-5-CH═N•), 3) formation. This work shows that these nitrogen-centered radicals are not formed via the reduction of the azido group in 6-azidomethyluridine (6-AmU, 4). Radical assignments were performed using electron spin resonance (ESR) in supercooled solutions, pulse radiolysis in aqueous solutions, and theoretical (DFT) calculations. Radiation-produced electron addition to 4 leads to the facile N3- loss, forming a stable neutral C-centered allylic radical (U-6-CH2•, 5) through dissociative electron attachment (DEA) via the transient negative ion, TNI (U-6-CH2-N3•-), in agreement with DFT calculations. In contrast, TNI (U-5-CH2-N3•-) of 1, via facile N2 loss (DEA) and protonation from the surrounding water, forms radical 2. Subsequently, 2 undergoes rapid H-atom abstraction from 1 and produces the metastable intermediate α-azidoalkyl radical (U-5-CH•-N3). U-5-CH•-N3 converts facilely to radical 3. N3- loss from U-6-CH2-N3•- is thermodynamically controlled, whereas N2 loss from U-5-CH2-N3•- is dictated by protonation from the surrounding waters and resonance conjugation of the azidomethyl side chain at C5 with the pyrimidine ring.
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Affiliation(s)
- Daniel Adjei
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Yahaira Reyes
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Anil Kumar
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Samuel Ward
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Sergey A. Denisov
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Moaadh Alahmadi
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Michael D. Sevilla
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Stanislaw F. Wnuk
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Mehran Mostafavi
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Amitava Adhikary
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
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7
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Ameixa J, Arthur‐Baidoo E, Pereira‐da‐Silva J, Ruivo JC, T. do N. Varella M, Beyer MK, Ončák M, Ferreira da Silva F, Denifl S. Formation of Temporary Negative Ions and Their Subsequent Fragmentation upon Electron Attachment to CoQ 0 and CoQ 0 H 2. Chemphyschem 2022; 23:e202100834. [PMID: 35146888 PMCID: PMC9306667 DOI: 10.1002/cphc.202100834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/05/2022] [Indexed: 11/06/2022]
Abstract
Ubiquinone molecules have a high biological relevance due to their action as electron carriers in the mitochondrial electron transport chain. Here, we studied the dissociative interaction of free electrons with CoQ0 , the smallest ubiquinone derivative with no isoprenyl units, and its fully reduced form, 2,3-dimethoxy-5-methylhydroquinone (CoQ0 H2 ), an ubiquinol derivative. The anionic products produced upon dissociative electron attachment (DEA) were detected by quadrupole mass spectrometry and studied theoretically through quantum chemical and electron scattering calculations. Despite the structural similarity of the two studied molecules, remarkably only a few DEA reactions are present for both compounds, such as abstraction of a neutral hydrogen atom or the release of a negatively charged methyl group. While the loss of a neutral methyl group represents the most abundant reaction observed in DEA to CoQ0 , this pathway is not observed for CoQ0 H2 . Instead, the loss of a neutral OH radical from the CoQ0 H2 temporary negative ion is observed as the most abundant reaction channel. Overall, this study gives insights into electron attachment properties of simple derivatives of more complex molecules found in biochemical pathways.
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Affiliation(s)
- João Ameixa
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria,Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria,Centre of Physics and Technological ResearchDepartamento de FísicaFaculdade de Ciências e TecnologiaUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Eugene Arthur‐Baidoo
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria,Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - João Pereira‐da‐Silva
- Centre of Physics and Technological ResearchDepartamento de FísicaFaculdade de Ciências e TecnologiaUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Júlio C. Ruivo
- Instituto de FísicaUniversidade de São PauloRua do Matão 173105508-090São PauloBrazil
| | | | - Martin K. Beyer
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Filipe Ferreira da Silva
- Centre of Physics and Technological ResearchDepartamento de FísicaFaculdade de Ciências e TecnologiaUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria,Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
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8
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Cipriani M, Ingólfsson O. HF Formation through Dissociative Electron Attachment-A Combined Experimental and Theoretical Study on Pentafluorothiophenol and 2-Fluorothiophenol. Int J Mol Sci 2022; 23:2430. [PMID: 35269573 DOI: 10.3390/ijms23052430] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/18/2022] [Accepted: 02/22/2022] [Indexed: 02/05/2023] Open
Abstract
In chemoradiation therapy, dissociative electron attachment (DEA) may play an important role with respect to the efficiency of the radiosensitizers used. The rational tailoring of such radiosensitizers to be more susceptive to DEA may thus offer a path to increase their efficiency. Potentially, this may be achieved by tailoring rearrangement reactions into the DEA process such that these may proceed at low incident electron energies, where DEA is most effective. Favorably altering the orbital structure of the respective molecules through substitution is another path that may be taken to promote dissociation up on electron capture. Here we present a combined experimental and theoretical study on DEA in relation to pentafluorothiophenol (PFTP) and 2-fluorothiophenol (2-FTP). We investigate the thermochemistry and dynamics of neutral HF formation through DEA as means to lower the threshold for dissociation up on electron capture to these compounds, and we explore the influence of perfluorination on their orbital structure. Fragment ion yield curves are presented, and the thermochemical thresholds for the respective DEA processes are computed as well as the minimum energy paths for HF formation up on electron capture and the underlying orbital structure of the respective molecular anions. We show that perfluorination of the aromatic ring in these compounds plays an important role in enabling HF formation by further lowering the threshold for this process and through favorable influence on the orbital structure, such that DEA is promoted. We argue that this approach may offer a path for tailoring new and efficient radiosensitizers.
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Shih PY, Cipriani M, Hermanns CF, Oster J, Edinger K, Gölzhäuser A, Ingólfsson O. Low-energy electron interaction and focused electron beam-induced deposition of molybdenum hexacarbonyl (Mo(CO) 6). Beilstein J Nanotechnol 2022; 13:182-191. [PMID: 35186652 PMCID: PMC8822466 DOI: 10.3762/bjnano.13.13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/05/2022] [Indexed: 06/14/2023]
Abstract
Motivated by the potential role of molybdenum in semiconductor materials, we present a combined theoretical and experimental gas-phase study on dissociative electron attachment (DEA) and dissociative ionization (DI) of Mo(CO)6 in comparison to focused electron beam-induced deposition (FEBID) of this precursor. The DEA and DI experiments are compared to previous work, differences are addressed, and the nature of the underlying resonances leading to the observed DEA processes are discussed in relation to an earlier electron transmission study. Relative contributions of individual ionic species obtained through DEA and DI of Mo(CO)6 and the average CO loss per incident are calculated and compared to the composition of the FEBID deposits produced. These are also compared to gas phase, surface science and deposition studies on W(CO)6 and we hypothesize that reductive ligand loss through electron attachment may promote metal-metal bond formation in the deposition process, leading to further ligand loss and the high metal content observed in FEBID for both these compounds.
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Affiliation(s)
- Po-Yuan Shih
- Carl Zeiss SMT GmbH, Industriestraße 1, 64380 Roßdorf, Germany
- Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Maicol Cipriani
- Science Institute and Department of Chemistry, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
| | | | - Jens Oster
- Carl Zeiss SMT GmbH, Industriestraße 1, 64380 Roßdorf, Germany
| | - Klaus Edinger
- Carl Zeiss SMT GmbH, Industriestraße 1, 64380 Roßdorf, Germany
| | - Armin Gölzhäuser
- Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Oddur Ingólfsson
- Science Institute and Department of Chemistry, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
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Abstract
Substitution of the thymidine moiety in DNA by C5-substituted halogenated thymidine analogues causes significant augmentation of radiation damage in living cells. However, the molecular pathway involved in such radiosensitization process has not been clearly elucidated to date in solution at room temperature. So far, low-energy electrons (LEEs; 0-20 eV) under vacuum condition and solvated electrons (esol-) in solution are shown to produce the σ-type C5-centered pyrimidine base radical through dissociative electron attachment involving carbon-halogen bond breakage. Formation of this σ-type radical and its subsequent reactions are proposed to cause cellular radiosensitization. Here, we report time-resolved measurements at room temperature, showing that a radiation-produced quasi-free electron (eqf-) in solution promptly breaks the C5-halogen bond in halopyrimidines forming the σ-type C5 radical via an excited transient anion radical. These results demonstrate the importance of ultrafast reactions of eqf-, which are extremely important in chemistry, physics, and biology, including tumor radiochemotherapy.
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Affiliation(s)
- Jun Ma
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, P. R. China
| | - Teseer Bahry
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, P. R. China
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Sergey A. Denisov
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Amitava Adhikary
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI - 48309, United States
| | - Mehran Mostafavi
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
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Izadi F, Arthur‐Baidoo E, Strover LT, Yu L, Coote ML, Moad G, Denifl S. Selective Bond Cleavage in RAFT Agents Promoted by Low-Energy Electron Attachment. Angew Chem Int Ed Engl 2021; 60:19128-19132. [PMID: 34214239 PMCID: PMC8456798 DOI: 10.1002/anie.202107480] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Indexed: 11/08/2022]
Abstract
Radical polymerization with reversible addition-fragmentation chain transfer (RAFT polymerization) has been successfully applied to generate polymers of well-defined architecture. For RAFT polymerization a source of radicals is required. Recent work has demonstrated that for minimal side-reactions and high spatio-temporal control these should be formed directly from the RAFT agent or macroRAFT agent (usually carbonothiosulfanyl compounds) thermally, photochemically or by electrochemical reduction. In this work, we investigated low-energy electron attachment to a common RAFT agent (cyanomethyl benzodithioate), and, for comparison, a simple carbonothioylsulfanyl compound (dimethyl trithiocarbonate, DMTTC) in the gas phase by means of mass spectrometry as well as quantum chemical calculations. We observe for both compounds that specific cleavage of the C-S bond is induced upon low-energy electron attachment at electron energies close to zero eV. This applies even in the case of a poor homolytic leaving group (. CH3 in DMTTC). All other dissociation reactions found at higher electron energies are much less abundant. The present results show a high control of the chemical reactions induced by electron attachment.
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Affiliation(s)
- Farhad Izadi
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
| | - Eugene Arthur‐Baidoo
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
| | | | - Li‐Juan Yu
- Research School of ChemistryAustralian National UniversityCanberraACTAustralia
| | - Michelle L. Coote
- Research School of ChemistryAustralian National UniversityCanberraACTAustralia
| | | | - Stephan Denifl
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
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12
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Cipriani M, Svavarsson S, Ferreira da Silva F, Lu H, McElwee-White L, Ingólfsson O. The Role of Low-Energy Electron Interactions in cis-Pt(CO) 2Br 2 Fragmentation. Int J Mol Sci 2021; 22:8984. [PMID: 34445690 DOI: 10.3390/ijms22168984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 01/22/2023] Open
Abstract
Platinum coordination complexes have found wide applications as chemotherapeutic anticancer drugs in synchronous combination with radiation (chemoradiation) as well as precursors in focused electron beam induced deposition (FEBID) for nano-scale fabrication. In both applications, low-energy electrons (LEE) play an important role with regard to the fragmentation pathways. In the former case, the high-energy radiation applied creates an abundance of reactive photo- and secondary electrons that determine the reaction paths of the respective radiation sensitizers. In the latter case, low-energy secondary electrons determine the deposition chemistry. In this contribution, we present a combined experimental and theoretical study on the role of LEE interactions in the fragmentation of the Pt(II) coordination compound cis-PtBr2(CO)2. We discuss our results in conjunction with the widely used cancer therapeutic Pt(II) coordination compound cis-Pt(NH3)2Cl2 (cisplatin) and the carbonyl analog Pt(CO)2Cl2, and we show that efficient CO loss through dissociative electron attachment dominates the reactivity of these carbonyl complexes with low-energy electrons, while halogen loss through DEA dominates the reactivity of cis-Pt(NH3)2Cl2.
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Michalczuk B, Barszczewska W, Wysocki W, Matejčík Š. Low Energy Electron Attachment by Some Chlorosilanes. Molecules 2021; 26:molecules26164973. [PMID: 34443560 PMCID: PMC8400109 DOI: 10.3390/molecules26164973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/07/2021] [Accepted: 08/13/2021] [Indexed: 11/16/2022] Open
Abstract
In this paper, the rate coefficients (k) and activation energies (Ea) for SiCl4, SiHCl3, and Si(CH3)2(CH2Cl)Cl molecules in the gas phase were measured using the pulsed Townsend technique. The experiment was performed in the temperature range of 298-378 K, and carbon dioxide was used as a buffer gas. The obtained k depended on temperature in accordance with the Arrhenius equation. From the fit to the experimental data points with function described by the Arrhenius equation, the activation energies (Ea) were determined. The obtained k values at 298 K are equal to (5.18 ± 0.22) × 10-10 cm3·s-1, (3.98 ± 1.8) × 10-9 cm3·s-1 and (8.46 ± 0.23) × 10-11 cm3·s-1 and Ea values were equal to 0.25 ± 0.01 eV, 0.20 ± 0.01 eV, and 0.27 ± 0.01 eV for SiHCl3, SiCl4, and Si(CH3)2(CH2Cl)Cl, respectively. The linear relation between rate coefficients and activation energies for chlorosilanes was demonstrated. The DFT/B3LYP level coupled with the 6-31G(d) basis sets method was used for calculations of the geometry change associated with negative ion formation for simple chlorosilanes. The relationship between these changes and the polarizability of the attaching center (αcentre) was found. Additionally, the calculated adiabatic electron affinities (AEA) are related to the αcentre.
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Affiliation(s)
- Bartosz Michalczuk
- Faculty of Sciences, Siedlce University, 3 Maja 54, 08-110 Siedlce, Poland; (W.B.); (W.W.)
- Correspondence: ; Tel.: +48-256-431-005
| | - Wiesława Barszczewska
- Faculty of Sciences, Siedlce University, 3 Maja 54, 08-110 Siedlce, Poland; (W.B.); (W.W.)
| | - Waldemar Wysocki
- Faculty of Sciences, Siedlce University, 3 Maja 54, 08-110 Siedlce, Poland; (W.B.); (W.W.)
| | - Štefan Matejčík
- Department of Experimental Physics, Comenius University, Mlynská dolina F2, 84248 Bratislava, Slovakia;
- Department of Molecular Physics, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe sh. 31, 115409 Moscow, Russia
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Gao Y, Zheng Y, Sanche L. Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents. Int J Mol Sci 2021; 22:7879. [PMID: 34360644 PMCID: PMC8345953 DOI: 10.3390/ijms22157879] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 11/18/2022] Open
Abstract
The complex physical and chemical reactions between the large number of low-energy (0-30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.
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Affiliation(s)
- Yingxia Gao
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Yi Zheng
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Léon Sanche
- Département de Médecine Nucléaire et Radiobiologie et Centre de Recherche Clinique, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
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Kopyra J, Wierzbicka P, Tulwin A, Thiam G, Bald I, Rabilloud F, Abdoul-Carime H. Experimental and Theoretical Studies of Dissociative Electron Attachment to Metabolites Oxaloacetic and Citric Acids. Int J Mol Sci 2021; 22:ijms22147676. [PMID: 34299296 PMCID: PMC8303309 DOI: 10.3390/ijms22147676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/06/2021] [Accepted: 07/09/2021] [Indexed: 11/16/2022] Open
Abstract
In this contribution the dissociative electron attachment to metabolites found in aerobic organisms, namely oxaloacetic and citric acids, was studied both experimentally by means of a crossed-beam setup and theoretically through density functional theory calculations. Prominent negative ion resonances from both compounds are observed peaking below 0.5 eV resulting in intense formation of fragment anions associated with a decomposition of the carboxyl groups. In addition, resonances at higher energies (3-9 eV) are observed exclusively from the decomposition of the oxaloacetic acid. These fragments are generated with considerably smaller intensities. The striking findings of our calculations indicate the different mechanism by which the near 0 eV electron is trapped by the precursor molecule to form the transitory negative ion prior to dissociation. For the oxaloacetic acid, the transitory anion arises from the capture of the electron directly into some valence states, while, for the citric acid, dipole- or multipole-bound states mediate the transition into the valence states. What is also of high importance is that both compounds while undergoing DEA reactions generate highly reactive neutral species that can lead to severe cell damage in a biological environment.
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Affiliation(s)
- Janina Kopyra
- Faculty of Exact and Natural Sciences, Siedlce University of Natural Sciences and Humanities, 3 Maja 54, 08-110 Siedlce, Poland; (P.W.); (A.T.)
- Correspondence: (J.K.); (I.B.)
| | - Paulina Wierzbicka
- Faculty of Exact and Natural Sciences, Siedlce University of Natural Sciences and Humanities, 3 Maja 54, 08-110 Siedlce, Poland; (P.W.); (A.T.)
| | - Adrian Tulwin
- Faculty of Exact and Natural Sciences, Siedlce University of Natural Sciences and Humanities, 3 Maja 54, 08-110 Siedlce, Poland; (P.W.); (A.T.)
| | - Guillaume Thiam
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, UMR5306, F-69622 Villeurbanne, France; (G.T.); (F.R.)
| | - Ilko Bald
- Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
- Correspondence: (J.K.); (I.B.)
| | - Franck Rabilloud
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, UMR5306, F-69622 Villeurbanne, France; (G.T.); (F.R.)
| | - Hassan Abdoul-Carime
- Institut de Physique des 2 Infinis, Université Lyon 1, Université de Lyon, CNRS/IN2P3, UMR5822, F-69003 Lyon, France;
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16
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Arthur-Baidoo E, Ameixa J, Ončák M, Denifl S. Ring-Selective Fragmentation in the Tirapazamine Molecule upon Low-Energy Electron Attachment. Int J Mol Sci 2021; 22:ijms22063159. [PMID: 33808887 PMCID: PMC8003736 DOI: 10.3390/ijms22063159] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 01/08/2023] Open
Abstract
We investigate dissociative electron attachment to tirapazamine through a crossed electron-molecule beam experiment and quantum chemical calculations. After the electron is attached and the resulting anion reaches the first excited state, D1, we suggest a fast transition into the ground electronic state through a conical intersection with a distorted triazine ring that almost coincides with the minimum in the D1 state. Through analysis of all observed dissociative pathways producing heavier ions (90-161 u), we consider the predissociation of an OH radical with possible roaming mechanism to be the common first step. This destabilizes the triazine ring and leads to dissociation of highly stable nitrogen-containing species. The benzene ring is not altered during the process. Dissociation of small anionic fragments (NO2-, CN2-, CN-, NH2-, O-) cannot be conclusively linked to the OH predissociation mechanism; however, they again do not require dissociation of the benzene ring.
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Affiliation(s)
- Eugene Arthur-Baidoo
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
| | - Joao Ameixa
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
- Atomic and Molecular Collisions Laboratory, Department of Physics, CEFITEC, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Milan Ončák
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Correspondence: (M.O.); (S.D.)
| | - Stephan Denifl
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
- Correspondence: (M.O.); (S.D.)
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Luxford TFM, Pshenichnyuk SA, Asfandiarov NL, Perečko T, Falk M, Kočišek J. 5-Nitro-2,4-Dichloropyrimidine as an Universal Model for Low-Energy Electron Processes Relevant for Radiosensitization. Int J Mol Sci 2020; 21:ijms21218173. [PMID: 33142925 PMCID: PMC7662275 DOI: 10.3390/ijms21218173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/27/2020] [Accepted: 10/27/2020] [Indexed: 01/18/2023] Open
Abstract
We report experimental results of low-energy electron interactions with.
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Affiliation(s)
- Thomas F. M. Luxford
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic;
| | - Stanislav A. Pshenichnyuk
- Institute of Molecule and Crystal Physics UFRC RAS, October Avenue 151, 450075 Ufa, Russia;
- Correspondence: (S.A.P.); (M.F.); (J.K.)
| | - Nail L. Asfandiarov
- Institute of Molecule and Crystal Physics UFRC RAS, October Avenue 151, 450075 Ufa, Russia;
| | - Tomáš Perečko
- Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, 612 65 Brno, Czech Republic;
| | - Martin Falk
- Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, 612 65 Brno, Czech Republic;
- Correspondence: (S.A.P.); (M.F.); (J.K.)
| | - Jaroslav Kočišek
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic;
- Correspondence: (S.A.P.); (M.F.); (J.K.)
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Arthur‐Baidoo E, Ameixa J, Ziegler P, Ferreira da Silva F, Ončák M, Denifl S. Reactions in Tirapazamine Induced by the Attachment of Low-Energy Electrons: Dissociation Versus Roaming of OH. Angew Chem Int Ed Engl 2020; 59:17177-17181. [PMID: 32543771 PMCID: PMC7540495 DOI: 10.1002/anie.202006675] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/09/2020] [Indexed: 11/27/2022]
Abstract
Tirapazamine (TPZ) has been tested in clinical trials on radio-chemotherapy due to its potential highly selective toxicity towards hypoxic tumor cells. It was suggested that either the hydroxyl radical or benzotriazinyl radical may form as bioactive radical after the initial reduction of TPZ in solution. In the present work, we studied low-energy electron attachment to TPZ in the gas phase and investigated the decomposition of the formed TPZ- anion by mass spectrometry. We observed the formation of the (TPZ-OH)- anion accompanied by the dissociation of the hydroxyl radical as by far the most abundant reaction pathway upon attachment of a low-energy electron. Quantum chemical calculations suggest that NH2 pyramidalization is the key reaction coordinate for the reaction dynamics upon electron attachment. We propose an OH roaming mechanism for other reaction channels observed, in competition with the OH dissociation.
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Affiliation(s)
- Eugene Arthur‐Baidoo
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
- Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
| | - João Ameixa
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
- Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
- Atomic and Molecular Collisions LaboratoryDepartment of PhysicsCEFITECUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Patrick Ziegler
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
- Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
| | - Filipe Ferreira da Silva
- Atomic and Molecular Collisions LaboratoryDepartment of PhysicsCEFITECUniversidade NOVA de Lisboa2829-516CaparicaPortugal
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte PhysikLeopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
- Center for Biomolecular Sciences Innsbruck (CMBI)Leopold-Franzens-Universität InnsbruckTechnikerstrasse 25A-6020InnsbruckAustria
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Ma J, Denisov S, Adhikary A, Mostafavi M. [How can an electron induce oxidative damage in DNA in solution]. Actual Chim 2020; 450:13-18. [PMID: 32747845 PMCID: PMC7397759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
DNA damage caused by the dissociative electron attachment (DEA) has been well-studied in the gas and solid phases. However, understanding of this process at the fundamental level in solution is still a challenge. The electrons, after losing their kinetic energy via ionization and excitation events, are thermalized and undergo a multistep hydration process with a time constant of ca. ≤1 ps, to becoming fully trapped as a hydrated or solvated electron (esol - or eaq -). Prior to the formation of esol -, the electron exists in its presolvated (or prehydrated) state (epre -) with no kinetic energy. We used picosecond pulse radiolysis to generate electrons in water or in liquid diethylene glycol (DEG) to observe the dynamics of capture of these electrons by DNA/RNA bases, nucleosides, and nucleotides. Contrary to the hypotheses in the literature that the presolvated electrons (epre -) are captured well by the DNA-nucleosides/tides and the transient negative ions (TNIs) cause strand breaks, we first show that the quasi-free electrons with kinetic energy (eqf -) or epre -cannot be captured by guanine and adenine at very long distances in aqueous solutions with concentrations lower than 50 mM. However, the observation of a substantial decrease in the initial yield of esol - as a function of nucleoside/nucleotide concentrations accompanied by the formation of the nucleotide anion radicals provides direct evidence of an ultrafast step involving radiation-produced electron-mediated DNA damage via DEA. Transient signal analysis suggests that the dissociation channel of TNIs in nucleotide solutions is not even probable up to 0.25 M. On the other hand, in diethylene glycol, we demonstrate that unlike esol - and epre -, eqf - effectively attaches itself to the RNA-nucleoside, ribothymidine, forming the TNI in the excited state (TNI*) that undergoes the N1-C1' glycosidic bond dissociation. Thanks to DEA, this process induced by eqf -, in fact, leads to an oxidation of the parent molecule similar to the hydroxyl radical (•OH) leading to the same glycosidic bond (N1-C1') cleavage.
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Affiliation(s)
- Jun Ma
- Professeur à l'Université de Nanjin en Chine (Aeronautics et Astronautics). Il a effectué sa thèse et une partie de son post-doctorat au Laboratoire de Chimie Physique
| | - Sergey Denisov
- Chargé de recherche au CNRS au Laboratoire de Chimie Physique (UMR 8000) à Orsay, développant les méthodes spectroscopiques sur ELYSE
| | - Amitava Adhikary
- Research Assistant Professor à l'Université d'Oakland aux Etats-Unis. Expert des dommages à l'ADN par le rayonnement ionisant
| | - Mehran Mostafavi
- Professeur à l'Université Paris-Sud, responsable de l'équipe « Actes chimiques élémentaires en phase condensée » du Laboratoire de Chimie Physique (UMR 8000) et directeur adjoint scientifique au CNRS en charge des grands instruments de recherche à l'institut de Chimie (INC). Distingué par le Prix Chercheur Confirmé 2019, de la Division de Chimie Physique de la SCF
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Ma J, Denisov SA, Adhikary A, Mostafavi M. Ultrafast Processes Occurring in Radiolysis of Highly Concentrated Solutions of Nucleosides/Tides. Int J Mol Sci 2019; 20:ijms20194963. [PMID: 31597345 PMCID: PMC6801490 DOI: 10.3390/ijms20194963] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 09/30/2019] [Accepted: 10/01/2019] [Indexed: 12/18/2022] Open
Abstract
Among the radicals (hydroxyl radical (•OH), hydrogen atom (H•), and solvated electron (esol−)) that are generated via water radiolysis, •OH has been shown to be the main transient species responsible for radiation damage to DNA via the indirect effect. Reactions of these radicals with DNA-model systems (bases, nucleosides, nucleotides, polynucleotides of defined sequences, single stranded (ss) and double stranded (ds) highly polymeric DNA, nucleohistones) were extensively investigated. The timescale of the reactions of these radicals with DNA-models range from nanoseconds (ns) to microseconds (µs) at ambient temperature and are controlled by diffusion or activation. However, those studies carried out in dilute solutions that model radiation damage to DNA via indirect action do not turn out to be valid in dense biological medium, where solute and water molecules are in close contact (e.g., in cellular environment). In that case, the initial species formed from water radiolysis are two radicals that are ultrashort-lived and charged: the water cation radical (H2O•+) and prethermalized electron. These species are captured by target biomolecules (e.g., DNA, proteins, etc.) in competition with their inherent pathways of proton transfer and relaxation occurring in less than 1 picosecond. In addition, the direct-type effects of radiation, i.e., ionization of macromolecule plus excitations proximate to ionizations, become important. The holes (i.e., unpaired spin or cation radical sites) created by ionization undergo fast spin transfer across DNA subunits. The exploration of the above-mentioned ultrafast processes is crucial to elucidate our understanding of the mechanisms that are involved in causing DNA damage via direct-type effects of radiation. Only recently, investigations of these ultrafast processes have been attempted by studying concentrated solutions of nucleosides/tides under ambient conditions. Recent advancements of laser-driven picosecond electron accelerators have provided an opportunity to address some long-term puzzling questions in the context of direct-type and indirect effects of DNA damage. In this review, we have presented key findings that are important to elucidate mechanisms of complex processes including excess electron-mediated bond breakage and hole transfer, occurring at the single nucleoside/tide level.
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Affiliation(s)
- Jun Ma
- Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China.
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215000, China.
| | - Sergey A Denisov
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, 91405 Orsay, CEDEX, France.
| | - Amitava Adhikary
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309, USA.
| | - Mehran Mostafavi
- Laboratoire de Chimie Physique, UMR 8000 CNRS/Université Paris-Sud, Bât. 349, 91405 Orsay, CEDEX, France.
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Ferreira da Silva F, do N Varella MT, Jones NC, Vrønning Hoffmann S, Denifl S, Bald I, Kopyra J. Electron-Induced Reactions in 3-Bromopyruvic Acid. Chemistry 2019; 25:5498-5506. [PMID: 30706547 DOI: 10.1002/chem.201806132] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/22/2019] [Indexed: 01/20/2023]
Abstract
3-Bromopyruvic acid (3BP) is a potential anti-cancer drug, the action of which on cellular metabolism is not yet entirely clear. The presence of a bromine atom suggests that it is also reactive towards low-energy electrons, which are produced in large quantities during tumour radiation therapy. Detailed knowledge of the interaction of 3BP with secondary electrons is a prerequisite to gain a complete picture of the effects of 3BP in different forms of cancer therapy. Herein, dissociative electron attachment (DEA) to 3BP in the gas phase has been studied both experimentally by using a crossed-beam setup and theoretically through scattering and quantum chemical calculations. These results are complemented by a vacuum ultraviolet absorption spectrum. The main fragmentation channel is the formation of Br- close to 0 eV and within several resonant features at 1.9 and 3-8 eV. At low electron energies, Br- formation proceeds through σ* and π* shape resonances, and at higher energies through core-excited resonances. It is found that the electron-capture cross-section is clearly increased compared with that of non-brominated pyruvic acid, but, at the same time, fragmentation reactions through DEA are significantly altered as well. The 3BP transient negative ion is subject to a lower number of fragmentation reactions than those of pyruvic acid, which indicates that 3BP could indeed act by modifying the electron-transport chains within oxidative phosphorylation. It could also act as a radio-sensitiser.
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Affiliation(s)
- Filipe Ferreira da Silva
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal
| | - Márcio T do N Varella
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, 05508-090, São Paulo, Brazil
| | - Nykola C Jones
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000, Aarhus, Denmark
| | - Søren Vrønning Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000, Aarhus, Denmark
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Ilko Bald
- Department of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam-Golm, Germany
- Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Strasse 11, 12489, Berlin, Germany
| | - Janina Kopyra
- Faculty of Sciences, Siedlce University, 3 Maja 54, 08-110, Siedlce, Poland
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22
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Pietanza LD, Colonna G, Capitelli M. Dissociative Electron Attachment From Vibrationally Excited Molecules in Nanosecond Repetitively Pulsed CO Discharges and Afterglows. Front Chem 2019; 7:163. [PMID: 30984736 PMCID: PMC6450140 DOI: 10.3389/fchem.2019.00163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 03/04/2019] [Indexed: 11/23/2022] Open
Abstract
Non-equilibrium vibrational distributions and electron energy distributions of CO in nanosecond repetitively pulsed (NRP) discharges and afterglows have been determined from a coupled solution of the time dependent Boltzmann equation for the electron energy distribution function (eedf) of free electrons and the master equations for the vibrational distribution function (vdf) of CO and the electronic excited states of CO and O and C atoms. Emphasis is given to the role of dissociative electron attachment (DEA) from vibrationally excited states in affecting the eedf and vdf under extreme conditions, i.e., an optically thick plasma with quenching processes involving the electronic excited states, populated by a sequence of discharge pulses and corresponding afterglows. In particular, the quenching process of the a3Π electronic state of CO determines a pumping of vibrational quanta in the ground state, which in turn largely modifies the CO vdf promoting the activation of DEA process. DEA rate coefficients have been obtained by using a complete set of vibrational (v) dependent cross sections through the CO -(X 2Π) channel and by using the experimental v = 0 cross section of Rapp and Briglia, which should include the contribution of other CO - resonant states. The importance of the last contribution has been also estimated by using a scaling law to extend the v = 0 cross section over all the vibrational ladder of CO. In particular, this mechanism becomes competitive with the other reactive channels for very short inter-pulse delay times, i.e., the t id = 1 μs, being less important for longer inter-pulse delay times, i.e., the t id = 25 μs.
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Abstract
High-energy radiation is used in combination with radiosensitizing therapeutics to treat cancer. The most common radiosensitizers are halogenated nucleosides and cisplatin derivatives, and recently also metal nanoparticles have been suggested as potential radiosensitizing agents. The radiosensitizing action of these compounds can at least partly be ascribed to an enhanced reactivity towards secondary low-energy electrons generated along the radiation track of the high-energy primary radiation, or to an additional emission of secondary reactive electrons close to the tumor tissue. This is referred to as physico-chemical radiosensitization. In this Concept article we present current experimental methods used to study fundamental processes of physico-chemical radiosensitization and discuss the most relevant classes of radiosensitizers. Open questions in the current discussions are identified and future directions outlined, which can lead to optimized treatment protocols or even novel therapeutic concepts.
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Affiliation(s)
- Robin Schürmann
- Institute of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.,Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Str. 11, 12489, Berlin, Germany
| | - Stefanie Vogel
- Institute of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.,Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Str. 11, 12489, Berlin, Germany.,School of Analytical Sciences Adlershof, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099, Berlin, Germany
| | - Kenny Ebel
- Institute of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.,Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Str. 11, 12489, Berlin, Germany
| | - Ilko Bald
- Institute of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.,Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Str. 11, 12489, Berlin, Germany
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24
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P RKT, Weirich P, Hrachowina L, Hanefeld M, Bjornsson R, Hrodmarsson HR, Barth S, Fairbrother DH, Huth M, Ingólfsson O. Electron interactions with the heteronuclear carbonyl precursor H 2FeRu 3(CO) 13 and comparison with HFeCo 3(CO) 12: from fundamental gas phase and surface science studies to focused electron beam induced deposition. Beilstein J Nanotechnol 2018; 9:555-579. [PMID: 29527432 PMCID: PMC5827713 DOI: 10.3762/bjnano.9.53] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 12/20/2017] [Indexed: 05/11/2023]
Abstract
In the current contribution we present a comprehensive study on the heteronuclear carbonyl complex H2FeRu3(CO)13 covering its low energy electron induced fragmentation in the gas phase through dissociative electron attachment (DEA) and dissociative ionization (DI), its decomposition when adsorbed on a surface under controlled ultrahigh vacuum (UHV) conditions and exposed to irradiation with 500 eV electrons, and its performance in focused electron beam induced deposition (FEBID) at room temperature under HV conditions. The performance of this precursor in FEBID is poor, resulting in maximum metal content of 26 atom % under optimized conditions. Furthermore, the Ru/Fe ratio in the FEBID deposit (≈3.5) is higher than the 3:1 ratio predicted. This is somewhat surprising as in recent FEBID studies on a structurally similar bimetallic precursor, HFeCo3(CO)12, metal contents of about 80 atom % is achievable on a routine basis and the deposits are found to maintain the initial Co/Fe ratio. Low temperature (≈213 K) surface science studies on thin films of H2FeRu3(CO)13 demonstrate that electron stimulated decomposition leads to significant CO desorption (average of 8-9 CO groups per molecule) to form partially decarbonylated intermediates. However, once formed these intermediates are largely unaffected by either further electron irradiation or annealing to room temperature, with a predicted metal content similar to what is observed in FEBID. Furthermore, gas phase experiments indicate formation of Fe(CO)4 from H2FeRu3(CO)13 upon low energy electron interaction. This fragment could desorb at room temperature under high vacuum conditions, which may explain the slight increase in the Ru/Fe ratio of deposits in FEBID. With the combination of gas phase experiments, surface science studies and actual FEBID experiments, we can offer new insights into the low energy electron induced decomposition of this precursor and how this is reflected in the relatively poor performance of H2FeRu3(CO)13 as compared to the structurally similar HFeCo3(CO)12.
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Affiliation(s)
- Ragesh Kumar T P
- Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland
| | - Paul Weirich
- Physikalisches Institut, Max-von-Laue-Str. 1, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | | | - Marc Hanefeld
- Physikalisches Institut, Max-von-Laue-Str. 1, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - Ragnar Bjornsson
- Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland
| | - Helgi Rafn Hrodmarsson
- Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland
| | - Sven Barth
- Institute of Materials Chemistry, TU Wien, 1060 Vienna, Austria
| | | | - Michael Huth
- Physikalisches Institut, Max-von-Laue-Str. 1, Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - Oddur Ingólfsson
- Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland
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25
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Lacko M, Papp P, Szymańska IB, Szłyk E, Matejčík Š. Electron interaction with copper(II) carboxylate compounds. Beilstein J Nanotechnol 2018; 9:384-398. [PMID: 29515952 PMCID: PMC5815308 DOI: 10.3762/bjnano.9.38] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 01/02/2018] [Indexed: 06/08/2023]
Abstract
In the present study we have performed electron collision experiments with copper carboxylate complexes: [Cu2(t-BuNH2)2(µ-O2CC2F5)4], [Cu2(s-BuNH2)2(µ-O2CC2F5)4], [Cu2(EtNH2)2(µ-O2CC2F5)4], and [Cu2(µ-O2CC2F5)4]. Mass spectrometry was used to identify the fragmentation pattern of the coordination compounds produced in crossed electron - molecular beam experiments and to measure the dependence of ion yields of positive and negative ions on the electron energy. The dissociation pattern of positive ions contains a sequential loss of both the carboxylate ligands and/or the amine ligands from the complexes. Moreover, the fragmentation of the ligands themselves is visible in the mass spectrum below m/z 140. For the studied complexes the metallated ions containing both ligands, e.g., Cu2(O2CC2F5)(RNH2)+, Cu2(O2CC2F5)3(RNH2)2+ confirm the evaporation of whole complex molecules. A significant production of Cu+ ion was observed only for [Cu2(µ-O2CC2F5)4], a weak yield was detected for [Cu2(EtNH2)2(µ-O2CC2F5)4] as well. The dissociative electron attachment processes leading to formation of negative ions are similar for all investigated molecules as the highest unoccupied molecular orbital of the studied complexes has Cu-N and Cu-O antibonding character. For all complexes, formation of the Cu2(O2CC2F5)4-• anion is observed together with mononuclear DEA fragments Cu(O2CC2F5)3-, Cu(O2CC2F5)2- and Cu(O2CC2F5)-•. All dominant DEA fragments of these complexes are formed through single particle resonant processes close to 0 eV.
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Affiliation(s)
- Michal Lacko
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina F2, 842 48 Bratislava, Slovakia
| | - Peter Papp
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina F2, 842 48 Bratislava, Slovakia
| | - Iwona B Szymańska
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
| | - Edward Szłyk
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
| | - Štefan Matejčík
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina F2, 842 48 Bratislava, Slovakia
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26
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Koch S, Kaiser CD, Penner P, Barclay M, Frommeyer L, Emmrich D, Stohmann P, Abu-Husein T, Terfort A, Fairbrother DH, Ingólfsson O, Gölzhäuser A. Amplified cross-linking efficiency of self-assembled monolayers through targeted dissociative electron attachment for the production of carbon nanomembranes. Beilstein J Nanotechnol 2017; 8:2562-2571. [PMID: 29259871 PMCID: PMC5727824 DOI: 10.3762/bjnano.8.256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/01/2017] [Indexed: 06/07/2023]
Abstract
The determination of the negative ion yield of 2'-chloro-1,1'-biphenyl (2-Cl-BP), 2'-bromo-1,1'-biphenyl (2-Br-BP) and 2'-iodo-1,1'-biphenyl (2-I-BP) upon dissociative electron attachment (DEA) at an electron energy of 0 eV revealed cross section values that were more than ten times higher for iodide loss from 2-I-BP than for the other halogenides from the respective biphenyls (BPs). Comparison with dissociative ionization mass spectra shows that the ratio of the efficiency of electron impact ionization induced fragmentation of 2-I-BP, 2-Br-BP, and 2-Cl-BP amounts to approximately 1:0.7:0.6. Inspired by these results, self-assembled monolayers (SAMs) of the respective biphenyl-4-thiols, 2-Cl-BPT, 2-Br-BPT, 2-I-BPT as well as BPT, were grown on a Au(111) substrate and exposed to 50 eV electrons. The effect of electron irradiation was investigated by X-ray photoelectron spectroscopy (XPS), to determine whether the high relative DEA cross section for iodide loss from 2-I-BPT as compared to 2-Br-BP and 2-Cl-BP is reflected in the cross-linking efficiency of SAMs made from these materials. Such sensitization could reduce the electron dose needed for the cross-linking process and may thus lead to a significantly faster conversion of the respective SAMs into carbon nanomembranes (CNMs) without the need for an increased current density. XPS data support the notation that DEA sensitization may be used to achieve more efficient electron-induced cross-linking of SAMs, revealing more than ten times faster cross-linking of 2-I-BPT SAMs compared to those made from the other halogenated biphenyls or from native BPT at the same current density. Furthermore, the transfer of a freestanding membrane onto a TEM grid and the subsequent investigation by helium ion microscopy (HIM) verified the existence of a mechanically stable CNM created from 2-I-BPT after exposure to an electron dose as low as 1.8 mC/cm2. In contrast, SAMs made from BPT, 2-Cl-BPT and 2-Br-BPT did not form stable CNMs after a significantly higher electron dose of 9 mC/cm2.
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Affiliation(s)
- Sascha Koch
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33613 Bielefeld, Germany
| | - Christopher D Kaiser
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33613 Bielefeld, Germany
| | - Paul Penner
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33613 Bielefeld, Germany
| | - Michael Barclay
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Lena Frommeyer
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33613 Bielefeld, Germany
| | - Daniel Emmrich
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33613 Bielefeld, Germany
| | - Patrick Stohmann
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33613 Bielefeld, Germany
| | - Tarek Abu-Husein
- Department of Chemistry, Institute of Inorganic and Analytical Chemistry, Goethe-University, 60438 Frankfurt, Germany
| | - Andreas Terfort
- Department of Chemistry, Institute of Inorganic and Analytical Chemistry, Goethe-University, 60438 Frankfurt, Germany
| | - D Howard Fairbrother
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Oddur Ingólfsson
- Department of Chemistry and Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
| | - Armin Gölzhäuser
- Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33613 Bielefeld, Germany
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27
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P RKT, Hari S, Damodaran KK, Ingólfsson O, Hagen CW. Electron beam induced deposition of silacyclohexane and dichlorosilacyclohexane: the role of dissociative ionization and dissociative electron attachment in the deposition process. Beilstein J Nanotechnol 2017; 8:2376-2388. [PMID: 29181294 PMCID: PMC5687010 DOI: 10.3762/bjnano.8.237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 10/09/2017] [Indexed: 06/07/2023]
Abstract
We present first experiments on electron beam induced deposition of silacyclohexane (SCH) and dichlorosilacyclohexane (DCSCH) under a focused high-energy electron beam (FEBID). We compare the deposition dynamics observed when growing pillars of high aspect ratio from these compounds and we compare the proximity effect observed for these compounds. The two precursors show similar behaviour with regards to fragmentation through dissociative ionization in the gas phase under single-collision conditions. However, while DCSCH shows appreciable cross sections with regards to dissociative electron attachment, SCH is inert with respect to this process. We discuss our deposition experiments in context of the efficiency of these different electron-induced fragmentation processes. With regards to the deposition dynamics, we observe a substantially faster growth from DCSCH and a higher saturation diameter when growing pillars with high aspect ratio. However, both compounds show similar behaviour with regards to the proximity effect. With regards to the composition of the deposits, we observe that the C/Si ratio is similar for both compounds and in both cases close to the initial molecular stoichiometry. The oxygen content in the DCSCH deposits is about double that of the SCH deposits. Only marginal chlorine is observed in the deposits of from DCSCH. We discuss these observations in context of potential approaches for Si deposition.
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Affiliation(s)
- Ragesh Kumar T P
- Department of Chemistry and Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
| | - Sangeetha Hari
- Department of ImPhys, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, Netherlands
| | - Krishna K Damodaran
- Department of Chemistry and Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
| | - Oddur Ingólfsson
- Department of Chemistry and Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
| | - Cornelis W Hagen
- Department of ImPhys, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, Netherlands
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28
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Lengyel J, Papp P, Matejčík Š, Kočišek J, Fárník M, Fedor J. Suppression of low-energy dissociative electron attachment in Fe(CO) 5 upon clustering. Beilstein J Nanotechnol 2017; 8:2200-2207. [PMID: 29114446 PMCID: PMC5669234 DOI: 10.3762/bjnano.8.219] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/19/2017] [Indexed: 06/07/2023]
Abstract
In this work, we probe anion production upon electron interaction with Fe(CO)5 clusters using two complementary cluster-beam setups. We have identified two mechanisms that lead to synthesis of complex anions with mixed Fe/CO composition. These two mechanisms are operative in distinct electron energy ranges. It is shown that the elementary decomposition mechanism that has received perhaps the most attention in recent years (i.e., dissociative electron attachment at energies close to 0 eV) becomes suppressed upon increasing aggregation of iron pentacarbonyl. We attribute this suppression to the electrostatic shielding of a long-range interaction that strongly enhances the dissociative electron attachment in isolated Fe(CO)5.
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Affiliation(s)
- Jozef Lengyel
- J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Peter Papp
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina F2, 84215 Bratislava, Slovakia
| | - Štefan Matejčík
- Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina F2, 84215 Bratislava, Slovakia
| | - Jaroslav Kočišek
- J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Michal Fárník
- J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Juraj Fedor
- J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
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29
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Schürmann R, Tsering T, Tanzer K, Denifl S, Kumar SVK, Bald I. Resonant Formation of Strand Breaks in Sensitized Oligonucleotides Induced by Low-Energy Electrons (0.5-9 eV). Angew Chem Int Ed Engl 2017; 56:10952-10955. [PMID: 28670830 DOI: 10.1002/anie.201705504] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Indexed: 12/20/2022]
Abstract
Halogenated nucleobases are used as radiosensitizers in cancer radiation therapy, enhancing the reactivity of DNA to secondary low-energy electrons (LEEs). LEEs induce DNA strand breaks at specific energies (resonances) by dissociative electron attachment (DEA). Although halogenated nucleobases show intense DEA resonances at various electron energies in the gas phase, it is inherently difficult to investigate the influence of halogenated nucleobases on the actual DNA strand breakage over the broad range of electron energies at which DEA can take place (<12 eV). By using DNA origami nanostructures, we determined the energy dependence of the strand break cross-section for oligonucleotides modified with 8-bromoadenine (8Br A). These results were evaluated against DEA measurements with isolated 8Br A in the gas phase. Contrary to expectations, the major contribution to strand breaks is from resonances at around 7 eV while resonances at very low energy (<2 eV) have little influence on strand breaks.
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Affiliation(s)
- Robin Schürmann
- Department of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam-Golm, Germany.,Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Strasse 11, 12489, Berlin, Germany
| | - Thupten Tsering
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba Mumbai, 400 005, India
| | - Katrin Tanzer
- Institute of Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25, A-6020, Innsbruck, Austria
| | - Stephan Denifl
- Institute of Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25, A-6020, Innsbruck, Austria
| | - S V K Kumar
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba Mumbai, 400 005, India
| | - Ilko Bald
- Department of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam-Golm, Germany.,Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Strasse 11, 12489, Berlin, Germany
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30
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Khreis JM, Ameixa J, Ferreira da Silva F, Denifl S. Interactions of low-energy electrons with the FEBID precursor chromium hexacarbonyl (Cr(CO) 6). Beilstein J Nanotechnol 2017; 8:2583-2590. [PMID: 29259873 PMCID: PMC5727870 DOI: 10.3762/bjnano.8.258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/08/2017] [Indexed: 05/11/2023]
Abstract
Interactions of low-energy electrons with the FEBID precursor Cr(CO)6 have been investigated in a crossed electron-molecular beam setup coupled with a double focusing mass spectrometer with reverse geometry. Dissociative electron attachment leads to the formation of a series of anions by the loss of CO ligand units. The bare chromium anion is formed by electron capture at an electron energy of about 9 eV. Metastable decays of Cr(CO)5- into Cr(CO)4-, Cr(CO)4- into Cr(CO)3- and Cr(CO)3- into Cr(CO)2- are discussed. Electron-induced dissociation at 70 eV impact energy was found to be in agreement with previous studies. A series of Cr(CO) n C+ (0 ≤ n ≤ 3) cations formed by C-O cleavage is described for the first time. The metastable decay of Cr(CO)6+ into Cr(CO)5+ and collision-induced dissociation leading to bare Cr+, are discussed. In addition, doubly charged cations were identified and the ration between doubly and singly charged fragments was determined and compared with previous studies, showing considerable differences.
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Affiliation(s)
- Jusuf M Khreis
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - João Ameixa
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal
| | - Filipe Ferreira da Silva
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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31
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Kopyra J, Maciejewska P, Maljković J. Dissociative electron attachment to coordination complexes of chromium: chromium(0) hexacarbonyl and benzene-chromium(0) tricarbonyl. Beilstein J Nanotechnol 2017; 8:2257-2263. [PMID: 29423353 PMCID: PMC5784315 DOI: 10.3762/bjnano.8.225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 09/28/2017] [Indexed: 05/11/2023]
Abstract
Here we report the results of dissociative electron attachment (DEA) to gas-phase chromium(0) hexacarbonyl (Cr(CO)6) and benzene-chromium(0) tricarbonyl ((η6-C6H6)Cr(CO)3) in the energy range of 0-12 eV. Measurements have been performed utilizing an electron-molecular crossed beam setup. It was found that DEA to Cr(CO)6 results (under the given experimental conditions) in the formation of three fragment anions, namely [Cr(CO)5]-, [Cr(CO)4]-, and [Cr(CO)3]-. The predominant reaction channel is the formation of [Cr(CO)5]- due to the loss of one CO ligand from the transient negative ion. The [Cr(CO)5]- channel is visible via two overlapping resonant structures appearing in the energy range below 1.5 eV with a dominant structure peaking at around 0 eV. The peak maxima of the fragments generated by the loss of two or three CO ligands are blue-shifted and the most intense peaks within the ion yield curves appear at 1.4 eV and 4.7 eV, respectively. (η6-C6H6)Cr(CO)3 shows a very rich fragmentation pattern with decomposition leading to the formation of seven fragment anions. Three of them are generated from the cleavage of one, two or three CO ligand(s). The energy of the peak maxima of the [(C6H6)Cr(CO)2]-, [(C6H6)Cr(CO)]-, and [(C6H6)Cr]- fragments is shifted towards higher energy with respect to the position of the respective fragments generated from Cr(CO)6. This phenomenon is most likely caused by the fact that chromium-carbonyl bonds are stronger in the heteroleptic complex (η6-C6H6)Cr(CO)3 than in homoleptic Cr(CO)6. Besides, we have observed the formation of anions due to the loss of C6H6 and one or more CO units. Finally, we found that Cr-, when stripped of all ligands, is generated through a high-energy resonance, peaking at 8 eV.
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Affiliation(s)
- Janina Kopyra
- Faculty of Sciences, Siedlce University, 3 Maja 54, 08-110 Siedlce, Poland
| | | | - Jelena Maljković
- Laboratory for Atomic Collision Processes, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
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32
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Rackwitz J, Kopyra J, Dąbkowska I, Ebel K, Ranković ML, Milosavljević AR, Bald I. Sensitizing DNA Towards Low-Energy Electrons with 2-Fluoroadenine. Angew Chem Int Ed Engl 2016; 55:10248-52. [PMID: 27481662 DOI: 10.1002/anie.201603464] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/16/2016] [Indexed: 11/09/2022]
Abstract
2-Fluoroadenine ((2F) A) is a therapeutic agent, which is suggested for application in cancer radiotherapy. The molecular mechanism of DNA radiation damage can be ascribed to a significant extent to the action of low-energy (<20 eV) electrons (LEEs), which damage DNA by dissociative electron attachment. LEE induced reactions in (2F) A are characterized both isolated in the gas phase and in the condensed phase when it is incorporated into DNA. Information about negative ion resonances and anion-mediated fragmentation reactions is combined with an absolute quantification of DNA strand breaks in (2F) A-containing oligonucleotides upon irradiation with LEEs. The incorporation of (2F) A into DNA results in an enhanced strand breakage. The strand-break cross sections are clearly energy dependent, whereas the strand-break enhancements by (2F) A at 5.5, 10, and 15 eV are very similar. Thus, (2F) A can be considered an effective radiosensitizer operative at a wide range of electron energies.
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Affiliation(s)
- Jenny Rackwitz
- Institute of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Janina Kopyra
- Faculty of Sciences, Siedlce University, 3 Maja 54, 08-110, Siedlce, Poland
| | - Iwona Dąbkowska
- Department of Chemistry, University of Gdańsk, 80-952, Gdańsk, Poland
| | - Kenny Ebel
- Institute of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - MiloŠ Lj Ranković
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080, Belgrade, Serbia
| | - Aleksandar R Milosavljević
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080, Belgrade, Serbia.,SOLEIL, l'Orme des Merisiers, St. Aubin, BP48, 91192, Gif sur Yvette Cedex, France
| | - Ilko Bald
- Institute of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany. .,Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Str. 11, 12489, Berlin, Germany.
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Makurat S, Chomicz-Mańka L, Rak J. Electrophilic 5-Substituted Uracils as Potential Radiosensitizers: A Density Functional Theory Study. Chemphyschem 2016; 17:2572-8. [PMID: 27156191 DOI: 10.1002/cphc.201600240] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Indexed: 12/13/2022]
Abstract
Although 5-bromo-2'-deoxyuridine (5BrdU) possesses significant radiosensitizing power in vitro, clinical studies do not confirm any advantages of radiotherapy employing 5BrdU. This situation calls for a continuous search for efficient radiosensitizers. Using the proposed mechanism of radiosensitization by 5BrdU, we propose a series of 5-substituted uracils, XYU, that should undergo efficient dissociative electron attachment. The DFT-calculated thermodynamic and kinetic data concerning the XYU degradations induced by electron addition suggests that some of the scrutinized derivatives have much better characteristics than 5BrdU itself. Synthesis of these promising candidates for radiosensitizers, followed by studies of their radiosensitizing properties in DNA context, and ultimately in cancer cells, are further steps to confirm their potential applicability in anticancer treatment.
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Affiliation(s)
- Samanta Makurat
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Lidia Chomicz-Mańka
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland.
| | - Janusz Rak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland.
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Thorman RM, Kumar T. P. R, Fairbrother DH, Ingólfsson O. The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors. Beilstein J Nanotechnol 2015; 6:1904-26. [PMID: 26665061 PMCID: PMC4660900 DOI: 10.3762/bjnano.6.194] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/12/2015] [Indexed: 05/25/2023]
Abstract
Focused electron beam induced deposition (FEBID) is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (<100 eV) secondary electrons generated by interactions of the primary beam with the substrate. These low-energy electrons are abundant both inside and outside the area of the primary electron beam and are associated with reactions causing incomplete ligand dissociation from FEBID precursors. As it is not possible to directly study the effects of secondary electrons in situ in FEBID, other means must be used to elucidate their role. In this context, gas phase studies can obtain well-resolved information on low-energy electron-induced reactions with FEBID precursors by studying isolated molecules interacting with single electrons of well-defined energy. In contrast, ultra-high vacuum surface studies on adsorbed precursor molecules can provide information on surface speciation and identify species desorbing from a substrate during electron irradiation under conditions more representative of FEBID. Comparing gas phase and surface science studies allows for insight into the primary deposition mechanisms for individual precursors; ideally, this information can be used to design future FEBID precursors and optimize deposition conditions. In this review, we give a summary of different low-energy electron-induced fragmentation processes that can be initiated by the secondary electrons generated in FEBID, specifically, dissociative electron attachment, dissociative ionization, neutral dissociation, and dipolar dissociation, emphasizing the different nature and energy dependence of each process. We then explore the value of studying these processes through comparative gas phase and surface studies for four commonly-used FEBID precursors: MeCpPtMe3, Pt(PF3)4, Co(CO)3NO, and W(CO)6. Through these case studies, it is evident that this combination of studies can provide valuable insight into potential mechanisms governing deposit formation in FEBID. Although further experiments and new approaches are needed, these studies are an important stepping-stone toward better understanding the fundamental physics behind the deposition process and establishing design criteria for optimized FEBID precursors.
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Affiliation(s)
- Rachel M Thorman
- Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, USA
| | - Ragesh Kumar T. P.
- Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland
| | | | - Oddur Ingólfsson
- Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland
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Abstract
Many experimental and theoretical advances have recently allowed the study of direct and indirect effects of low-energy electrons (LEEs) on DNA damage. In an effort to explain how LEEs damage the human genome, researchers have focused efforts on LEE interactions with bacterial plasmids, DNA bases, sugar analogs, phosphate groups, and longer DNA moieties. Here, we summarize the current understanding of the fundamental mechanisms involved in LEE-induced damage of DNA and complex biomolecule films. Results obtained by several laboratories on films prepared and analyzed by different methods and irradiated with different electron-beam current densities and fluencies are presented. Despite varied conditions (e.g., film thicknesses and morphologies, intrinsic water content, substrate interactions, and extrinsic atmospheric compositions), comparisons show a striking resemblance in the types of damage produced and their yield functions. The potential of controlling this damage using molecular and nanoparticle targets with high LEE yields in targeted radiation-based cancer therapies is also discussed.
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Affiliation(s)
- Elahe Alizadeh
- Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, J1H 5N4 Sherbrooke, Canada
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Zhang X, Vieker H, Beyer A, Gölzhäuser A. Fabrication of carbon nanomembranes by helium ion beam lithography. Beilstein J Nanotechnol 2014; 5:188-94. [PMID: 24605285 PMCID: PMC3943867 DOI: 10.3762/bjnano.5.20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 01/22/2014] [Indexed: 06/01/2023]
Abstract
The irradiation-induced cross-linking of aromatic self-assembled monolayers (SAMs) is a universal method for the fabrication of ultrathin carbon nanomembranes (CNMs). Here we demonstrate the cross-linking of aromatic SAMs due to exposure to helium ions. The distinction of cross-linked from non-cross-linked regions in the SAM was facilitated by transferring the irradiated SAM to a new substrate, which allowed for an ex situ observation of the cross-linking process by helium ion microscopy (HIM). In this way, three growth regimes of cross-linked areas were identified: formation of nuclei, one-dimensional (1D) and two-dimensional (2D) growth. The evaluation of the corresponding HIM images revealed the dose-dependent coverage, i.e., the relative monolayer area, whose density of cross-links surpassed a certain threshold value, as a function of the exposure dose. A complete cross-linking of aromatic SAMs by He(+) ion irradiation requires an exposure dose of about 850 µC/cm(2), which is roughly 60 times smaller than the corresponding electron irradiation dose. Most likely, this is due to the energy distribution of secondary electrons shifted to lower energies, which results in a more efficient dissociative electron attachment (DEA) process.
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Affiliation(s)
- Xianghui Zhang
- Department of Physics, Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany
| | - Henning Vieker
- Department of Physics, Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany
| | - André Beyer
- Department of Physics, Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany
| | - Armin Gölzhäuser
- Department of Physics, Physics of Supramolecular Systems and Surfaces, Bielefeld University, 33615 Bielefeld, Germany
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Park Y, Peoples AR, Madugundu GS, Sanche L, Wagner JR. Side-by-side comparison of DNA damage induced by low-energy electrons and high-energy photons with solid TpTpT trinucleotide. J Phys Chem B 2013; 117:10122-31. [PMID: 23909580 PMCID: PMC3817083 DOI: 10.1021/jp405397m] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The genotoxic effects of high-energy ionizing radiation have been largely attributed to the ionization of H2O leading to hydroxyl radicals and the ionization of DNA leading mostly to damage through base radical cations. However, the contribution of low-energy electrons (LEEs; ≤ 10 eV), which involves subionization events, has been considered to be less important than that of hydroxyl radicals and base radical cations. Here, we compare the ability of LEEs and high-energy X-ray photons to induce DNA damage using dried thin films of TpTpT trinucleotide as a simple and representative model for DNA damage. The main radiation-induced damage of TpTpT as measured by high-performance liquid chromatography (HPLC) with UV detection and HPLC coupled to tandem mass spectrometry analyses included thymine release (-Thy), strand breaks (pT, Tp, pTpT, TpTp, and TpT), and the formation of base modifications [5,6-dihydrothymine (5,6-dhT), 5-hydroxymethyluracil (5-hmU), and 5-formyluracil (5-fU)]. The global profile of products was very similar for both types of radiation indicating converging pathways of formation. The percent damage of thymine release, fragmentation, and base modification was 20, 19, and 61 for high-energy X-rays, respectively, compared to 35, 13, and 51 for LEEs (10 eV). Base release was significantly lower for X-rays. In both cases, phosphodiester bond cleavage gave mononucleotides (pT and Tp) and dinucleotides (pTpT and TpTp) containing a terminal phosphate as the major fragments. For base modifications, the ratio of reductive (5,6-dhT) to oxidative products (5-hmU plus 5-fU) was 0.9 for high-energy X-rays compared to 1.7 for LEEs. These results indicate that LEEs give a similar profile of products compared to ionizing radiation.
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Affiliation(s)
- Yeunsoo Park
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Heath Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4
- Fundamental Technology Division, Plasma Technology Research Center, National Fusion Research Institute, Gunsan, Jeollabuk-do, South Korea 573-540
| | - Anita R. Peoples
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Guru S. Madugundu
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Heath Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4
| | - Léon Sanche
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Heath Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4
| | - J. Richard Wagner
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Heath Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4
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Mitterdorfer C, Edtbauer A, Karolczak S, Postler J, Gschliesser D, Denifl S, Illenberger E, Scheier P. Strong fragmentation processes driven by low energy electron attachment to various small perfluoroether molecules. Int J Mass Spectrom 2011; 306:63-69. [PMID: 21977005 PMCID: PMC3161377 DOI: 10.1016/j.ijms.2011.06.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 06/03/2011] [Accepted: 06/24/2011] [Indexed: 05/13/2023]
Abstract
Negative ion formation in the three perfluoroethers (PFEs) diglyme (C(6)F(14)O(3)), triglyme (C(8)F(18)O(4)) and crownether (C(10)F(20)O(5)) is studied following electron attachment in the range from ∼0 to 15 eV. All three compounds show intense low energy resonances at subexcitation energies (<3 eV) decomposing into a variety of negatively charged fragments. These fragment ions are generated via dissociative electron attachment (DEA), partly originating from sequential decompositions on the metastable (μs) time scale as observed from the MIKE (metastable induced kinetic energy) scans. Only in perfluorocrownether a signal due to the non-decomposed parent anion is observed. Additional and comparatively weaker resonances are located in the energy range between ∼10 and 17 eV which preferentially decompose into lighter ions. It is suggested that specific features of perfluoropolyethers (PFPEs) relevant in applications, e.g., the strong bonding to surfaces induced by UV radiation of the substrate or degradation of PFPE films in computer hard disc drives can be explained by their pronounced sensitivity towards low energy electrons.
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Affiliation(s)
- C. Mitterdorfer
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - A. Edtbauer
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - S. Karolczak
- Institute of Applied Radiation Chemistry (IARC) Technical University of Lodz, ul. Wroblewskiego 15, 93-590 Lodz, Poland
| | - J. Postler
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - D. Gschliesser
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - S. Denifl
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Corresponding author. Tel.: +43 0 512 507 6416; fax: +43 0 512 507 2932.
| | - E. Illenberger
- Institut für Chemie und Biochemie-Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany
| | - P. Scheier
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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