Negative Ions

Massey, H. S. W.

doi:10.1016/s0065-2199(08)60293-6

Cited by 71 publications

(43 citation statements)

References 108 publications

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“…Additionally, the rest of the absorbed radiation energy produces excited molecules which may dissociate to produce ionized or neutral atoms via reactions N 2 * → (N + + N − , N + N) and O 2 * → (O + + O − , O + O). 59 Another process well-described in the literature 59,60 that may occur in the surrounding atmosphere is electron attachment of the low energy SEs produced by the fact electrons. These LEEs arises from transient anions in gas-phase N 2 .…”

Section: Discussionmentioning

confidence: 99%

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

et al. 2011

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DNA damage induced by low energy electrons (LEEs) and soft X-rays is measured under dry nitrogen and oxygen at atmospheric pressure and temperature. Five-monolayer plasmid DNA films deposited on tantalum and glass substrates are exposed to Al K α X-rays of 1.5 keV in the two different environments. From the damage yields for DNA, G-values are extracted for X-rays and LEEs. The G values for LEEs are 3.5 and 3.4 higher than those for X-ray photons under N 2 and O 2 atmospheres, respectively. Since most of the measured damage is in the form of single strand breaks (SSB), this result indicates a much higher effectiveness for LEEs relative to X-rays in causing SSB in both environments. The results indicate that the oxygen fixation mechanism, which is highly effective in increasing radiobiological effectiveness, under aerobic conditions, is operative on the type of damage created at the early stage of DNA radiolysis by LEEs.

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Section: Discussionmentioning

confidence: 99%

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

et al. 2011

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“…The formation of TMAs is well described and reviewed in the literature [15][16][17][18][19][20][21]. There are two major types of TMAs or "resonances" [15][16][17].…”

Section: Decay Of Gaseous Transient Anions Into Dissociative Electronmentioning

confidence: 99%

Transient Anions in Radiobiology and Radiotherapy: From Gaseous Biomolecules to Condensed Organic and Biomolecular Solids

Alizadeh¹,

Ptasińska²,

Sanche³

2016

Radiation Effects in Materials

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This chapter focuses on the fundamental processes that govern interactions of lowenergy (1-30 eV) electrons with biological systems. These interactions have been investigated in the gas phase and within complex arrangements in the condensed phase. They often lead to the formation of transient molecular anions (TMAs), and their decay by autoionization or dissociation accompanied by bond dissociation. The damage caused to biomolecules via TMAs is emphasized in all sections. Such damage, which depends on a large number of factors, including electron energy, molecular environment, and type of biomolecule, and its physical and chemical interactions with radiosensitizing agents are extensively discussed. A majority of recent findings resulting from experimental and theoretical endeavors are presented. They encompass broad research areas to elucidate important roles of TMAs in irradiated biological systems, from the molecular level to nanoscale cellular dimensions. Fundamental aspects of TMA formation are stressed in this chapter, but many practical applications in a variety of radiation-related fields such as radiobiology and radiotherapy are addressed.

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“…Curve crossing between the ground state of the C-O moiety and the TNI state is also reduced to the value R c′ , as well as the time available for autoionization of the σ* electron. The probability of autodetachment depends exponentially on R c , 53,54 so that the probability of anion survival without electron autodetachment is considerably increased, as well as that of DEA at the 3′-and 5′-positions of the backbone. Since in the 0.5-15 eV range the yields of SSB arise via rupture of the C-O σ* bond in the DNA chain, this mechanism may lie at the basis of the observed enhancement of SSB in cisplatin-DNA complexes below 13 eV and could very well play a role in increasing direct DEA to the bases or other subunits, in the presence of cisplatin, so as to produce additional radicals causing cross-linking.…”

Section: B Increasing Ssb and CL Yields With Cisplatinmentioning

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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Negative Ions

Cited by 71 publications

References 108 publications

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

Transient Anions in Radiobiology and Radiotherapy: From Gaseous Biomolecules to Condensed Organic and Biomolecular Solids

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

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Negative Ions

Cited by 71 publications

References 108 publications

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N2 and O2 Atmospheres

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N2 and O2 Atmospheres

Transient Anions in Radiobiology and Radiotherapy: From Gaseous Biomolecules to Condensed Organic and Biomolecular Solids

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

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Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres