Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations

Fromm, M.; Boulanouar, Omar

doi:10.1016/j.radphyschem.2016.05.025

Cited by 7 publications

(20 citation statements)

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“…In this particular case, it may be likely that the radicals produced on the glycerol molecules further to hydroxyl radical scavenging at their turn attack the plasmids as well. It was shown recently that this type of side effects arise when arginine is used as an • OH scavenger . We also observe lower agreement with the data presented by others, stemming from proton track simulations that were carried out in small micrometric volumes representing small DNA containments using an adapted DBSAN algorithm.…”

Section: Discussioncontrasting

confidence: 53%

“…It was shown recently that this type of side effects arise when arginine is used as an • OH scavenger. 39 We also observe lower agreement with the data presented by others, 40 stemming from proton track simulations that were carried out in small micrometric volumes representing small DNA containments using an adapted DBSAN algorithm. In these studies, proton energies ranged from 500 keV to 50 MeV and SSB and DSB yields at 500 keV are typically 10-fold higher than those in ours.…”

Section: ■ Discussioncontrasting

confidence: 45%

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Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies

et al. 2017

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Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 μm thick polyester films and exposed to proton Bragg-peak energies (90-3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a maximum in the 150-200 keV energy range; as for LET, it peaks at 90 keV. We also show that fragmentation starts to be significant for proton fluences greater than 1 × 10 cm at the Bragg-peak energies. Finally, we determine the average proton track radial extension, r, corresponding to an occupation probability of 100% DSB in the Bragg-peak region. The r values determined are in excellent agreement with the radial extensions of proton tracks determined by simulation approaches in water. When plotted as a function of LET, both SSB and DSB cross sections bend back at high LETs.

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Section: Discussioncontrasting

confidence: 53%

Section: ■ Discussioncontrasting

confidence: 45%

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies

et al. 2017

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“…12). From there, a successful irradiation of DNA films both under vacuum and atmospheric conditions was conducted [87,88]. …”

Section: And (B) -20mentioning

confidence: 99%

Evaluating experimental molecular physics studies of radiation damage in DNA*

Śmiałek

2016

Eur. Phys. J. D

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Abstract. The field of Atomic and Molecular Physics (AMP) is a mature field exploring the spectroscopy, excitation, ionisation of atoms and molecules in all three phases. Understanding of the spectroscopy and collisional dynamics of AMP has been fundamental to the development and application of quantum mechanics and is applied across a broad range of disparate disciplines including atmospheric sciences, astrochemistry, combustion and environmental science, and in central to core technologies such as semiconductor fabrications, nanotechnology and plasma processing. In recent years the molecular physics also started significantly contributing to the area of the radiation damage at molecular level and thus cancer therapy improvement through both experimental and theoretical advances, developing new damage measurement and analysis techniques. It is therefore worth to summarise and highlight the most prominent findings from the AMP community that contribute towards better understanding of the fundamental processes in biologically-relevant systems as well as to comment on the experimental challenges that were met for more complex investigation targets.

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“…The thin films are usually prepared by lyophilization or evaporation of a droplet of a plasmid solution. To maximize product formation, while minimizing the effects of film charging and those of the substrate, multilayer DNA films are usually prepared with a maximum average thickness, limited to the thermalization distance of LEEs in DNA, which is of the order of 10 to 16 nm. ,, Excessive charge buildup is also reduced by deposition on a conductive substrate under a controlled atmosphere, before introduction into UHV and LEE irradiation. , …”

Section: Introductionmentioning

confidence: 99%

“…Since the discovery of LEE-induced damage to plasmid DNA via the formation and decay of transient anions, laboratories have investigated the parameters involved in the formation of plasmid films, including the presence of stabilizer molecules [e.g., TE (Tris and EDTA) buffer] in evaporated solutions ,, and the effect of the substrate, environment, and temperature . Many of these studies were accompanied by visualization of the deposit on various substrates ,,, and measurements of the yields of single-and double-strand breaks (SSBs and DSBs) resulting from LEE impact on DNA in the supercoiled configuration. ,,,,,− ,, So far, the best method to produce uniform films of plasmids has been developed by Fromm and co-workers. ,,− The technique enables self-assembly of the DNA molecules by the intercalation of 1,3-diaminopropane (Dap) or amino acids between the plasmids on highly oriented pyrolytic graphite (HOPG). Recently, Dap-DNA films of comparable uniformity were deposited on tantalum (Ta) substrates by the same technique, at lower cost .…”

Section: Introductionmentioning

confidence: 99%

Low-Energy Electron Damage to Plasmid DNA in Thin Films: Dependence on Substrates, Surface Density, Charging, Environment, and Uniformity

et al. 2022

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The interaction of low-energy electrons (LEEs) with DNA plays a significant role in the mechanisms leading to biological damage induced by ionizing radiation, particularly in radiotherapy, and its sensitization by chemotherapeutic drugs and nanoparticles. Plasmids constitute the form of DNA found in mitochondria and appear as a suitable model of genomic DNA. In a search for the best LEE targets, damage was induced to plasmids, in thin films in vacuum, by 6, 10, and 100 eV electrons under single collision conditions. The yields of single-and double-strand breaks, other cluster damage, isolated base lesions, and crosslinks were measured by electrophoresis and enzyme treatment. The films were deposited on oriented graphite or polycrystalline tantalum, with or without DNA autoassembly via diaminopropane (Dap) intercalation. Yields were correlated with the influence of vacuum, film uniformity, surface density, substrates, and the DNA environment. Aided by surface potential measurements and scanning electron microscopy and atomic force microscopy images, the lyophilized Dap-DNA films were found to be the most practical high-quality targets. These studies pave the way to the fabrication of LEE targetfilms composed of plasmids intercalated with biomolecules that could mimic the cellular environment; for example, as a first step, by replacing Dap with an amino acid.

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Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations

Cited by 7 publications

References 53 publications

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies

Evaluating experimental molecular physics studies of radiation damage in DNA*

Low-Energy Electron Damage to Plasmid DNA in Thin Films: Dependence on Substrates, Surface Density, Charging, Environment, and Uniformity

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