scispace - formally typeset
Search or ask a question
Journal Article•DOI•

Damage induced to DNA by low-energy (0-30 eV) electrons under vacuum and atmospheric conditions.

Emilie Brun1, Pierre Cloutier1, Cécile Sicard-Roselli1, Michel Fromm1, Léon Sanche1 •
University of Franche-Comté1
23 Jul 2009-Journal of Physical Chemistry B (American Chemical Society)-Vol. 113, Iss: 29, pp 10008-10013
TL;DR: It is shown that it is possible to obtain data on DNA damage induced by low-energy (0-30 eV) electrons under atmospheric conditions and the differences in damage yields recorded with the gold and glass substrates is essentially attributed to the interaction of low- energy electrons with DNA under vacuum and hydrated conditions.
Abstract: In this study, we show that it is possible to obtain data on DNA damage induced by low-energy (0-30 eV) electrons under atmospheric conditions. Five monolayer films of plasmid DNA (3197 base pairs) deposited on glass and gold substrates are irradiated with 1.5 keV X-rays in ultrahigh vacuum and under atmospheric conditions. The total damage is analyzed by agarose gel electrophoresis. The damage produced on the glass substrate is attributed to energy absorption from X-rays, whereas that produced on the gold substrate arises from energy absorption from both the X-ray beam and secondary electrons emitted from the gold surface. By analysis of the energy of these secondary electrons, 96% are found to have energies below 30 eV with a distribution peaking at 1.4 eV. The differences in damage yields recorded with the gold and glass substrates is therefore essentially attributed to the interaction of low-energy electrons with DNA under vacuum and hydrated conditions. From these results, the G values for low-energy electrons are determined to be four and six strand breaks per 100 eV, respectively.

Summary (2 min read)

Jump to: [Atmospheric Conditions] – [II. Experimental Methods] – [III. Results] – [IV. Discussion] and [V. Conclusion]

Atmospheric Conditions

  • Émilie Brun,† Pierre Cloutier,‡ Cécile Sicard-Roselli,† Michel Fromm,§ and Léon Sanche*,†,‡ Laboratoire de Chimie Physique, CNRS UMR 8000, UniVersité Paris-Sud 11, Bât.
  • The authors present knowledge of LEE-biomolecule interactions arises from both theoretical and experimental investigations.
  • Molecules that could be evaporated in a vacuum environment without decomposition have usually been studied as gases, but some studies have also been reported on solid molecular films.
  • 23,24 The apparatus is equipped with an Al KR X-ray source, but the metal target can be replaced for X-ray emission at other characteristic energies.
  • To delineate the portion of DNA damage caused by X-rays and that arising from LEE interactions, the authors performed experiments with films deposited on an insulator and the electron-emitting gold surface under different environmental conditions.

II. Experimental Methods

  • PGEM-3Zf(-) plasmid DNA (3197 base pairs, Promega) was extracted from Escherichia coli DH5R and purified with the QIAfilter Plasmid Giga Kit .
  • The stock solution concentration was approximatively 50 ng ·µL-1. DNA purity was checked by recording the ratio between absorbances at 260 and 280 nm.27-29 Sample Preparation.
  • The lyophilized samples were exposed to the Al KR X-rays produced, under atmospheric conditions, from a cold-cathode transmission target X-ray tube.
  • The discharge electron current is controlled by the stabilized circulation of the N2 gas with the leak valve.
  • The absorbed dose rate in water, according to the ionization chamber measurement, was 2.1 Gy ·min-1. A linear relationship between log10(I0/I) and the dose was obtained in the range 0-100 Gy.

III. Results

  • Within experimental error, the loss of the supercoiled form is a linear function of the photon fluence.
  • The enhancement factors (EF) derived from these values appear on the right.
  • As expected, the gold substrate enhances DNA damage.
  • The percentage yields derived from the slope of these curves are given in the second line of Table 1.
  • For 0-30 eV SE, the energy distribution η(Ek) was calculated using33 where ηs is a coefficient that normalizes the yield of SEs having kinetic energy of Ek and W is the work function of gold, that is, 4.8 eV.34 Ninety-six percent of these SEs have energies below 30 eV, and the average energy for these electrons is 5.9 eV.

IV. Discussion

  • Given the mass absorption coefficient of DNA36 and the formula for transmitted photons (Xtrans in the Supporting Information), one can calculate that within a 5 ML film, 0.2% of 1.5 keV photons interact with DNA, while the rest pass through DNA.
  • Thus, DNA damage is induced by both X-ray photons and LEEs when DNA lies on a gold substrate.
  • In the presence of water, the G value of LEEs further increases by 50% whereas that of X-rays remains the same within instrumental error.
  • In dilute solution of DNA, the hydroxyl radical (OH) is considered to be the secondary species formed by water radiolysis that produces the largest amount of DNA damage.
  • The D(2S), O(3P2), and O(1D2) yields versus incident electron energy have an apparent threshold at ∼6.5 eV with a steadily increasing intensity.

V. Conclusion

  • The authors have shown that photoelectrons emitted from a gold substrate can be used as a source of low-energy electrons (LEEs) to irradiate DNA films under atmospheric conditions.
  • LEE damage to plasmid DNA with its hydratation shell was measured from comparison of results obtained with films deposited on gold and glass substrates.
  • The authors thank Ariane Dumont for providing us with the plasmid.
  • Details about of the calculations of the G values for photons and low-energy electrons, also known as Supporting Information Available.
  • This material is available free of charge via the Internet at http://pubs.acs.org.

Did you find this useful? Give us your feedback

Figures (5)

Content maybe subject to copyright    Report

Citations
More filters
Journal Article•DOI•
Low-energy electron-induced single strand breaks in 2'-deoxycytidine-3'-monophosphate using the local complex potential based time-dependent wave packet approach.

[...]

Renjith B1, Somnath Bhowmick1, Manoj Mishra2, Manabendra Sarma1•
Indian Institute of Technology Guwahati1, Indian Institute of Technology Bombay2
03 Nov 2011-Journal of Physical Chemistry A
TL;DR: Initial results obtained from the calculation in the gas phase provide a good agreement with experimental observation and show the plausibility of SSB at 0.75 eV, which is very close to the highest SSB yield reported from the experimental measurement (0.8 eV) on plasmid DNA in the condensed phase.
Abstract: Recent experimental and theoretical investigations on resonant electron scattering off DNA and DNA fragments using low-energy electrons (LEEs), to propose the mechanism for single strand breaks (SSBs) and double strand breaks (DSBs), have received considerable attention. It is our purpose here to understand theoretically the comprehensive route to SSB in a selected DNA fragment, namely, 2′-deoxycytidine-3′-monophosphate (3′-dCMPH), induced by LEE (0–3 eV) scattering using the local complex potential based time-dependent wave packet (LCP-TDWP) approach. To the best of our knowledge, there is no time-dependent quantum mechanical study that has been reported in the literature for this DNA fragment to date. Initial results obtained from our calculation in the gas phase provide a good agreement with experimental observation and show the plausibility of SSB at 0.75 eV, which is very close to the highest SSB yield reported from the experimental measurement (0.8 eV) on plasmid DNA in the condensed phase.

15 citations

Journal Article•DOI•
Electronic emission of radio-sensitizing gold nanoparticles under X-ray irradiation: experiment and simulations

[...]

Romain Casta1, Jean-Philippe Champeaux1, Martine Sence1, P Moretto-Capelle1, Pierre Cafarelli1, Angélique Amsellem1, Cécile Sicard-Roselli2 •
University of Toulouse1, University of Paris-Sud2
25 Mar 2014-Journal of Nanoparticle Research
TL;DR: In this paper, the electronic emission of Gold Nanoparticles (GNPs) using X-ray photoelectron spectroscopy (XPS) was compared to the gold bulk electron emission.
Abstract: In this paper, we present new results on electronic emission of Gold Nanoparticles (GNPs) using X-ray photoelectron spectroscopy (XPS) and compare them to the gold bulk electron emission. This subject has undergone new interest within the perspective of using GNPs as a radiotherapy enhancer. The experimental results were simulated using various models (Livermore and PENELOPE) of the Geant4 simulation toolkit dedicated to the calculation of the transportation of particles through the matter. Our results show that the GNPs coating is a key parameter to correctly construe the experimental GNPs electronic emission after X-ray irradiation and point out some limitations of the PENELOPE model. Using XPS spectra and Geant4 Livermore simulations, we propose a method to determine precisely the coating surface density of the GNPs. We also show that the expected intrinsic nano-scale electronic emission enhancement effect—suspected to contribute to the GNPs radio-sensitizing properties—participates at most for a few percent of the global electronic emission spectra of the GNPs compared to gold bulk.

14 citations

Journal Article•DOI•
Low energy secondary electron induced damage of condensed nucleotides

[...]

Aaron D. McKee1, M. J. Schaible1, Richard A. Rosenberg2, Sramana Kundu1, Thomas M. Orlando1 •
Georgia Institute of Technology1, Argonne National Laboratory2
31 May 2019-Journal of Chemical Physics
TL;DR: Although x-ray induced reactions in nucleotides involve both direct ionization and excitation, the observed bonding changes were likely dominated by the inelastic energy-loss channels associated with secondary electron capture and transient negative ion decay.
Abstract: Radiation damage and stimulated desorption of nucleotides 2'-deoxyadenosine 5'-monophosphate (dAMP), adenosine 5'-monophosphate (rAMP), 2'-deoxycytidine 5'-monophosphate (dCMP), and cytidine 5'-monophosphate (rCMP) deposited on Au have been measured using x-rays as both the probe and source of low energy secondary electrons. The fluence dependent behavior of the O-1s, C-1s, and N-1s photoelectron transitions was analyzed to obtain phosphate, sugar, and nucleobase damage cross sections. Although x-ray induced reactions in nucleotides involve both direct ionization and excitation, the observed bonding changes were likely dominated by the inelastic energy-loss channels associated with secondary electron capture and transient negative ion decay. Growth of the integrated peak area for the O-1s component at 531.3 eV, corresponding to cleavage of the C-O-P phosphodiester bond, yielded effective damage cross sections of about 23 Mb and 32 Mb (1 Mb = 10-18 cm2) for AMP and CMP molecules, respectively. The cross sections for sugar damage, as determined from the decay of the C-1s component at 286.4 eV and the glycosidic carbon at 289.0 eV, were slightly lower (about 20 Mb) and statistically similar for the r- and d- forms of the nucleotides. The C-1s component at 287.6 eV, corresponding to carbons in the nucleobase ring, showed a small initial increase and then decayed slowly, yielding a low damage cross section (∼5 Mb). Although there is no statistical difference between the sugar forms, changing the nucleobase from adenine to cytidine has a slight effect on the damage cross section, possibly due to differing electron capture and transfer probabilities.

13 citations

Journal Article•DOI•
Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam.

[...]

J.-E. Groetz1, Nabil Ounoughi1, Christophe Mavon1, A. Belafrites2, Michel Fromm1 •
University of Franche-Comté1, University of Jijel2
20 Aug 2014-Review of Scientific Instruments
TL;DR: The developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.
Abstract: We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.

13 citations

Journal Article•DOI•
Photoionization of multishell fullerenes studied by ab initio and model approaches

[...]

Alexey V. Verkhovtsev, Andrei V. Korol, Andrey V. Solov’yov
25 Oct 2016-European Physical Journal D
TL;DR: In this article, the contribution of collective electron excitations arising in individual fullerenes is evaluated by means of plasmon resonance approximation (PRA) and an extension of the PRA formalism is presented, which allows for the study of collective electronsexcitations in multishell fullerene under photon impact.
Abstract: Photoionization of two buckyonions, C60@C240 and C20@C60, is investigated by means of time-dependent density-functional theory (TDDFT). The TDDFT-based photoabsorption spectrum of C60@C240, calculated in a broad photon energy range, resembles the sum of spectra of the two isolated fullerenes, thus illustrating the absence of strong plasmonic coupling between the fullerenes which was proposed earlier. The calculated spectrum of the smaller buckyonion, C20@C60, differs significantly from the sum of the cross sections of the individual fullerenes because of strong geometrical distortion of the system. The contribution of collective electron excitations arising in individual fullerenes is evaluated by means of plasmon resonance approximation (PRA). An extension of the PRA formalism is presented, which allows for the study of collective electron excitations in multishell fullerenes under photon impact. An advanced analysis of photoionization of buckyonions, performed using modern computational and analytical approaches, provides valuable information on the response of complex molecular systems to the external electromagnetic field.

12 citations

References
More filters
Journal Article•DOI•
Resonant Formation of DNA Strand Breaks by Low-Energy (3 to 20 eV) Electrons

[...]

Badia Boudaïffa1, Pierre Cloutier1, Darel J. Hunting1, Michael A. Huels1, Léon Sanche1 •
Université de Sherbrooke1
03 Mar 2000-Science
TL;DR: It is shown that reactions of such electrons, even at energies well below ionization thresholds, induce substantial yields of single- and double-strand breaks in DNA, which are caused by rapid decays of transient molecular resonances localized on the DNA's basic components.
Abstract: Most of the energy deposited in cells by ionizing radiation is channeled into the production of abundant free secondary electrons with ballistic energies between 1 and 20 electron volts. Here it is shown that reactions of such electrons, even at energies well below ionization thresholds, induce substantial yields of single- and double-strand breaks in DNA, which are caused by rapid decays of transient molecular resonances localized on the DNA's basic components. This finding presents a fundamental challenge to the traditional notion that genotoxic damage by secondary electrons can only occur at energies above the onset of ionization, or upon solvation when they become a slowly reacting chemical species.

1,891 citations

Journal Article•DOI•
Low energy electron-driven damage in biomolecules

[...]

Léon Sanche1•
Faculté de médecine – Université de Sherbrooke1
01 Aug 2005-European Physical Journal D
TL;DR: By comparing the results from different experiments and theory, it is possible to determine fundamental mechanisms that are involved in the dissociation of the biomolecules and the production of single- and double-strand breaks in DNA.
Abstract: The damage induced by the impact of low energy electrons (LEE) on biomolecules is reviewed from a radiobiological perspective with emphasis on transient anion formation. The major type of experiments, which measure the yields of fragments produced as a function of incident electron energy (0.1-30 eV), are briefly described. Theoretical advances are also summarized. Several examples are presented from the results of recent experiments performed in the gas-phase and on biomolecular films bombarded with LEE under ultra-high vacuum conditions. These include the results obtained from DNA films and those obtained from the fragmentation of elementary components of the DNA molecule (i.e., the bases, sugar and phosphate group analogs and oligonucleotides) and of proteins (e.g. amino acids). By comparing the results from different experiments and theory, it is possible to determine fundamental mechanisms that are involved in the dissociation of the biomolecules and the production of single- and double-strand breaks in DNA. Below 15 eV, electron resonances (i.e., the formation of transient anions) play a dominant role in the fragmentation of all biomolecules investigated. These transient anions fragment molecules by decaying into dissociative electronically excited states or by dissociating into a stable anion and a neutral radical. These fragments can initiate further reactions within large biomolecules or with nearby molecules and thus cause more complex chemical damage. Dissociation of a transient anion within DNA may occur by direct electron attachment at the location of dissociation or by electron transfer from another subunit. Damage to DNA is dependent on the molecular environment, topology, type of counter ion, sequence context and chemical modifications.

481 citations

Journal Article•DOI•
Effect of pH and ionic strength on the spectrophotometric assessment of nucleic acid purity

[...]

William W. Wilfinger, Karol Mackey, Piotr Chomczynski1•
University of Cincinnati1
01 Mar 1997-BioTechniques
TL;DR: RNA A260/280 ratios are found to be more reliable and reproducible when these spectrophotometric measurements were performed at pH 8.0-8.5 and the ability to detect protein contamination was significantly improved when RNA wasSpectrophotometrically analyzed in an alkaline solution.
Abstract: The ratio of absorbance at 260 and 280 nm (the A260/280 ratio) is frequently used to assess the purity of RNA and DNA preparations. Data presented in this report demonstrate significant variability in the RNA A260/280 ratio when different sources of water were used to perform the spectrophotometric determinations. Adjusting the pH of water used for spectrophotometric analysis from approximately 5.4 to a slightly alkaline pH of 7.5-8.5 significantly increased RNA A260/280 ratios from approximately 1.5 to 2.0. Our studies revealed that changes in both the pH and ionic strength of the spectrophotometric solution influenced the A260/280 ratios. In addition, the ability to detect protein contamination was significantly improved when RNA was spectrophotometrically analyzed in an alkaline solution. UV spectral scans showed that the 260-nm RNA absorbance maximum observed in water was shifted by 2 nm to a lower wavelength when determinations were carried out in Na2HPO4 buffer at a pH of 8.5. We found RNA A260/280 ratios to be more reliable and reproducible when these spectrophotometric measurements were performed at pH 8.0-8.5 in 1-3 mM Na2HPO4 buffer.

450 citations

Journal Article•DOI•
DNA strand breaks induced by 0-4 eV electrons: the role of shape resonances.

[...]

Frédéric Martin1, Paul Burrow2, Zhongli Cai1, Pierre Cloutier1, Darel J. Hunting1, Léon Sanche1 •
Université de Sherbrooke1, University of Nebraska–Lincoln2
03 Aug 2004-Physical Review Letters
TL;DR: Collisions of 0-4 eV electrons with thin DNA films are shown to produce single strand breaks, which support aspects of a theoretical study by Barrios et al. indicating that such a mechanism could produce strand breaks in DNA.
Abstract: Collisions of 0--4 eV electrons with thin DNA films are shown to produce single strand breaks. The yield is sharply structured as a function of electron energy and indicates the involvement of ${\ensuremath{\pi}}^{*}$ shape resonances in the bond breaking process. The cross sections are comparable in magnitude to those observed in other compounds in the gas phase in which ${\ensuremath{\pi}}^{*}$ electrons are transferred through the molecule to break a remote bond. The results therefore support aspects of a theoretical study by Barrios et al. [J. Phys. B 106, 7991 (2002)] indicating that such a mechanism could produce strand breaks in DNA.

415 citations

Book•
The biochemistry of the nucleic acids

[...]

J. N. Davidson
01 Jan 1969
TL;DR: The biochemistry of the nucleic acids is studied in detail in order to establish a clear picture of the role of phosphorous and nitrogen in the structure of DNA.
Abstract: The biochemistry of the nucleic acids , The biochemistry of the nucleic acids , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

389 citations

Related Papers (5)
Resonant Formation of DNA Strand Breaks by Low-Energy (3 to 20 eV) Electrons

[...]

03 Mar 2000-Science
Badia Boudaïffa, Pierre Cloutier, Darel J. Hunting, Michael A. Huels, Léon Sanche 
Production of low-energy electrons by ionizing radiation

[...]

01 Aug 2007-Radiation Physics and Chemistry
Simon M. Pimblott, Simon M. Pimblott, Jay A. LaVerne
Single, double, and multiple double strand breaks induced in DNA by 3-100 eV electrons.

[...]

22 Mar 2003-Journal of the American Chemical Society
Michael A Huels, Badia Boudaïffa, Pierre Cloutier, Darel Hunting, Léon Sanche 
DNA strand breaks induced by 0-4 eV electrons: the role of shape resonances.

[...]

03 Aug 2004-Physical Review Letters
Frédéric Martin, Paul Burrow, Zhongli Cai, Pierre Cloutier, Darel J. Hunting, Léon Sanche 
Precursors of solvated electrons in radiobiological physics and chemistry.

[...]

22 Jun 2012-Chemical Reviews
Elahe Alizadeh, Léon Sanche
Frequently Asked Questions (1)
Q1. What are the contributions in "Damage induced to dna by low-energy (0-30 ev) electrons under vacuum and atmospheric conditions" ?

Brun et al. this paper showed that photoelectrons emitted from a gold substrate can be used as a source of low-energy electrons ( LEEs ) to irradiate DNA films under atmospheric conditions.