Ion-induced electron production in tissue-like media and DNA damage mechanisms

Surdutovich, Eugene; Obolensky, O. I.; Scifoni, E.; Pshenichnov, I.; Mishustin, I. N.; Solov’yov, Andrey V.; Greiner, Walter

doi:10.1140/epjd/e2008-00207-y

Cited by 68 publications

(118 citation statements)

References 32 publications

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“…As a consequence, if we try to describe the transport of all the electrons by diffusion (using the average energy W = 45 eV for all first generation electrons) the average energy transferred per collision ω, which should be ∼15 eV, has to be treated as an adjustable parameter that can be obtained from equation (6). This necessity to adjust ω when δ-electrons are not considered is exemplified by three different cases in Figures 2 and 3.…”

Section: The Contribution Of Sub-45-ev Electrons To the Radial Dose Dmentioning

confidence: 99%

“…Most of the ejected secondary electrons have relatively low energies, indeed more than 80% of them have energies below 50 eV [5]. This only slightly depends on ion type, its energy and on the biological target [6][7][8]. The number of secondary electrons is roughly proportional to the linear energy transfer (LET) and tens of them can be produced on each nm of ion trajectory in the Bragg peak.…”

Section: Introductionmentioning

confidence: 99%

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Radial doses around energetic ion tracks and the onset of shock waves on the nanoscale

et al. 2017

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Abstract. Energetic ions lose their energy in tissue mainly by ionising its molecules. This produces secondary electrons which transport this energy radially away from the ion path. The ranges of most of these electrons do not exceed a few nanometres, therefore large energy densities (radial doses) are produced within a narrow region around the ion trajectory. Large energy density gradients correspond to large pressure gradients and this brings about shock waves propagating away from the ion path. Previous works have studied these waves by molecular dynamics (MD) simulations investigating their damaging effects on DNA molecules. However, these simulations where performed assuming that all energy lost by ions is deposited uniformly in thin cylinders around their path. In the present work, the radial dose distributions, calculated by solving the diffusion equation for the low energy electrons and complemented with a semi-empirical inclusion of more energetic δ-electrons, are used to set up initial conditions for the shock wave simulation. The effect of these energy distributions vs. stepwise energy distributions in tracks on the strength of shock waves induced by carbon ions both in the Bragg peak region and out of it is studied by MD simulations.

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Section: The Contribution Of Sub-45-ev Electrons To the Radial Dose Dmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radial doses around energetic ion tracks and the onset of shock waves on the nanoscale

et al. 2017

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“…[18] and in a new parameterization here introduced for liquid. In our previous papers [15,16], we used a model based on a parameterization by Rudd [18], which yields an analytical formula for SDCS on a wide energy range combining the experimental data for water vapor, calculations within the plane-wave Born approximation, and other theoretical models. This model, original for protons, has been extended first to helium [12] and then to heavier ions by us [15,16] and a few other works [19].…”

Section: Slow Regimementioning

confidence: 99%

“…This parameterization is different from the original [18] in two respects: first, the expression for F 1 is modified so that it has the correct asymptotic behavior in the relativistic limit [16], and second, it contains an effective charge of the ion z ef f , which depends on the [18] and liquid [34] water (in eV). In the two approaches presented in this paper, the first and the second set are respectively used.…”

Section: Slow Regimementioning

confidence: 99%

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Spectra of secondary electrons generated in water by energetic ions

2010

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The energy distributions of secondary electrons produced by energetic carbon ions (in the energy range used, e.g., in hadron therapy) , incident on liquid water, are discussed. For low-energy ions, a new parameterization of the singly-differential ionization cross sections is introduced, based on tuning the position of the Bragg peak. The resulting parameterization allows a fast calculation of the energy spectra of secondary electrons at different depths along the ion's trajectory, especially near the Bragg peak. At the same time, this parameterization provides penetration depths for a broad range of initial-ion energies within the therapeutically-accepted error. For high-energy ions, the energy distribution is obtained with a use of the dielectric response function approach.Different models are compared and discussed. *

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Positive and negative ions of the amino acid histidine formed in low‐energy electron collisions

et al. 2019

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Histidine is an aromatic amino acid crucial for the biological functioning of proteins and enzymes. When biological matter is exposed to ionising radiation, highly energetic particles interact with the surrounding tissue which leads to efficient formation of low‐energy electrons. In the present study, the interaction of low‐energy electrons with gas‐phase histidine is studied at a molecular level in order to extend the knowledge of electron‐induced reactions with amino acids. We report both on the formation of positive ions formed by electron ionisation and negative ions induced by electron attachment. The experimental data were complemented by quantum chemical calculations. Specifically, the free energies for possible fragmentation reactions were derived for the τ and the π tautomer of histidine to get insight into the structures of the formed ions and the corresponding neutrals. We report the experimental ionisation energy of (8.48 ± 0.03) eV for histidine which is in good agreement with the calculated vertical ionisation energy. In the case of negative ions, the dehydrogenated parent anion is the anion with the highest mass observed upon dissociative electron attachment. The comparison of experimental and computational results was also performed in view of a possible thermal decomposition of histidine during the experiments, since the sample was sublimated in the experiment by resistive heating of an oven. Overall, the present study demonstrates the effects of electrons as secondary particles in the chemical degradation of histidine. The reactions induced by those electrons differ when comparing positive and negative ion formation. While for negative ions, simple bond cleav ages prevail, the observed fragment cations exhibit partly restructuring of the molecule during the dissociation process.

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Ion-induced electron production in tissue-like media and DNA damage mechanisms

Cited by 68 publications

References 32 publications

Radial doses around energetic ion tracks and the onset of shock waves on the nanoscale

Radial doses around energetic ion tracks and the onset of shock waves on the nanoscale

Spectra of secondary electrons generated in water by energetic ions

Positive and negative ions of the amino acid histidine formed in low‐energy electron collisions

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