Low-energy electron-induced reactions in condensed matter

Arumainayagam, Christopher R.; Lee, Hsiao-Lu; Nelson, Rachel B.; Haines, David R.; Gunawardane, R. P.

doi:10.1016/j.surfrep.2009.09.001

Cited by 228 publications

(246 citation statements)

References 378 publications

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“…The results presented in Ref. [1] motivated a large amount of both experimental [11,30,31,32,33] and theoretical [34,35,36] work that aimed at elucidating the role played by LEE in DNA damage. In recent years, this research has moved on from idealized systems, e.g.…”

Section: Radiation Damage Of Dnamentioning

confidence: 95%

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

Kohanoff¹,

McAllister²,

Tribello³

et al. 2017

J. Phys.: Condens. Matter

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Abstract. DNA damage caused by irradiation has been studied for many decades. Such studies allow us to better assess the dangers posed by radiation, and to increase the efficiency of the radiotherapies that are used to combat cancer. A full description of the irradiation process involves multiple size and time scales. It starts from the interaction of radiation -either photons or swift ions -with the biological medium. Such interactions cause electronic excitation and ionisation. The two main products of ionising radiation are thus electrons and radicals. Both of these species can cause damage to biological molecules, in particular DNA. In the long run, this molecular level damage can prevent cells from replicating and can hence lead to cell death. For a long time it was assumed that the main actors in the damage process were the radicals. However, experiments in a seminal paper by the group of Leon Sanche in 2000 showed that low-energy electrons (LEE), such as those generated when ionising biological targets, can also cause bond breaks in biomolecules, in particular strand breaks in plasmid DNA [1]. These results prompted a significant amount of experimental and theoretical work aimed at elucidating the role played by LEE in DNA damage.In this Topical Review we provide a general overview of the problem. We discuss experimental findings and theoretical results hand in hand with the aim of describing the physics and chemistry that occurs during the process of radiation damage, from the initial stages of electronic excitation, through the inelastic propagation of electrons in the medium, the interaction of electrons with DNA, and the chemical end-point effects on DNA. A very important aspect of this discussion is the consideration of a realistic, physiological environment. The role played by the aqueous solution and the amino acids from the histones in chromatin must be considered. Moreover, thermal fluctuations must be incorporated when studying these phenomena. Hence, a special place in this Topical Review is occupied by our recent first-principles molecular dynamics simulations that address the issue of how the environment favours or prevents LEEs from causing damage to DNA. We finish by summarising the conclusions achieved so far, and by suggesting a number of possible directions for further study.

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Section: Radiation Damage Of Dnamentioning

confidence: 95%

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

Kohanoff¹,

McAllister²,

Tribello³

et al. 2017

J. Phys.: Condens. Matter

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“…37 A cisplatin-concentration calibration curve was recorded from the amount of Pt from cisplatin dissolved in ddH 2 O at known concentrations. The efficiency of cisplatin binding to DNA was found to be 33%.…”

Section: Analysis Of Platinum-dna Bindingmentioning

confidence: 99%

“…24 CRT (i.e., the combination of chemotherapy and radiotherapy) has been an important modality for the treatment of solid tumors for decades. 25 Cisplatin [Pt-(NH 3 ) 2 Cl 2 ], whose structure appears in Figure 1, was first introduced in chemotherapy in the 1970s. Since then, cisplatin and its analogues, oxaliplatin and carboplatin, have become the most frequently used agents in CRT.…”

Section: Introductionmentioning

confidence: 99%

Cisplatin Radiosensitization of DNA Irradiated with 2–20 eV Electrons: Role of Transient Anions

et al. 2014

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Platinum chemotherapeutic agents, such as cisplatin (cis-diamminedichloroplatinum(II)), can act as radiosensitizers when bound covalently to nuclear DNA in cancer cells. This radiosensitization is largely due to an increase in DNA damage induced by low-energy secondary electrons, produced in large quantities by high-energy radiation. We report the yields of single-and doublestrand breaks (SSB and DSB) and interduplex cross-links (CL) induced by electrons of 1.6-19.6 eV (i.e., the yield functions) incident on 5 monolayer (ML) films of cisplatin-DNA complexes. These yield functions are compared with those previously recorded with 5 ML films of unmodified plasmid DNA. Binding of five cisplatin molecules to plasmid DNA (3197 base pairs) enhances SSB, DSB, and CL by factors varying, from 1.2 to 2.8, 1.4 to 3.5, and 1.2 to 2.7, respectively, depending on electron energy. All yield functions exhibit structures around 5 and 10 eV that can be attributed to enhancement of bond scission, via the initial formation of core-excited resonances associated with π → π* transitions of the bases. This increase in damage is interpreted as arising from a modification of the parameters of the corresponding transient anions already present in nonmodified DNA, particularly those influencing molecular dissociation. Two additional resonances, specific to cisplatin-modified DNA, are formed at 13.6 and 17.6 eV in the yield function of SSB. Furthermore, cisplatin binding causes the induction of DSB by electrons of 1.6-3.6 eV, i.e., in an energy region where a DSB cannot be produced by a single electron in pure DNA. Breaking two bonds with a subexcitation-energy electron is tentatively explained by a charge delocalization mechanism, where a single electron occupies simultaneously two σ* bonds linking the Pt atom to guanine bases on opposite strands.

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“…At 10 eV, electrons break DNA strands essentially via core-excited resonances, i.e., the formation of a transient anion consisting of the incoming electron trapped by the positive electron affinity of an electronically excited state of a basic unit of DNA. 6,62,64 In our previous work, we evaluated the contribution of different lesions induced by γ-radiation to the loss of pGEM-3Zf (-) plasmid DNA functionality. 42 We found that frank DSBs, which can induce cell lethality if not repaired, make a relatively minor contribution to the loss of DNA functionality induced by γ-radiation.…”

Section: Discussionmentioning

confidence: 99%

Loss of Cellular Transformation Efficiency Induced by DNA Irradiation with Low-Energy (10 eV) Electrons

et al. 2014

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Low energy electrons (LEEs) of energies less than 20 eV are generated in large quantities by ionizing radiation in biological matter. While LEEs are known to induce single (SSBs) and double strand breaks (DSBs) in DNA, their ability to inactivate cells by inducing nonreparable lethal damage has not yet been demonstrated. Here we observe the effect of LEEs on the functionality of DNA, by measuring the efficiency of transforming Escherichia coli with a [pGEM-3Zf (-)] plasmid irradiated with 10 eV electrons. Highly ordered DNA films were prepared on pyrolitic graphite by molecular self-assembly using 1,3-diaminopropane ions (Dap 2+ ). The uniformity of these films permits the inactivation of approximately 50% of the plasmids compared to <10% using previous methods, which is sufficient for the subsequent determination of their functionality. Upon LEE irradiation, the fraction of functional plasmids decreased exponentially with increasing electron fluence, while LEE-induced isolated base damage, frank DSB, and non DSB-cluster damage increased linearly with fluence. While DSBs can be toxic, their levels were too low to explain the loss of plasmid functionality observed upon LEE irradiation. Similarly, non-DSB cluster damage, revealed by transforming cluster damage into DSBs by digestion with repair enzymes, also occurred relatively infrequently. The exact nature of the lethal damage remains unknown, but it is probably a form of compact cluster damage in which the lesions are too close to be revealed by purified repair enzymes. In addition, this damage is either not repaired or is misrepaired by E. coli, since it results in plasmid inactivation, when they contain an average of three lesions. Comparison with previous results from a similar experiment performed with γ-irradiated plasmids indicates that the type of clustered DNA lesions, created directly on cellular DNA by LEEs, may be more difficult to repair than those produced by other species from radiolysis.

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Low-energy electron-induced reactions in condensed matter

Cited by 228 publications

References 378 publications

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

Cisplatin Radiosensitization of DNA Irradiated with 2–20 eV Electrons: Role of Transient Anions

Loss of Cellular Transformation Efficiency Induced by DNA Irradiation with Low-Energy (10 eV) Electrons

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