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Mechanisms of Nanoscale Radiation Enhancement by Metal Nanoparticles: Role of Low Energy Electrons. Int J Mol Sci 2023; 24:ijms24054697. [PMID: 36902132 PMCID: PMC10003700 DOI: 10.3390/ijms24054697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/20/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
Metal nanoparticles are considered as highly promising radiosensitizers in cancer radiotherapy. Understanding their radiosensitization mechanisms is critical for future clinical applications. This review is focused on the initial energy deposition by short-range Auger electrons; when high energy radiation is absorbed by gold nanoparticles (GNPs) located near vital biomolecules; such as DNA. Auger electrons and the subsequent production of secondary low energy electrons (LEEs) are responsible for most the ensuing chemical damage near such molecules. We highlight recent progress on DNA damage induced by the LEEs produced abundantly within about 100 nanometers from irradiated GNPs; and by those emitted by high energy electrons and X-rays incident on metal surfaces under differing atmospheric environments. LEEs strongly react within cells; mainly via bound breaking processes due to transient anion formation and dissociative electron attachment. The enhancement of damages induced in plasmid DNA by LEEs; with or without the binding of chemotherapeutic drugs; are explained by the fundamental mechanisms of LEE interactions with simple molecules and specific sites on nucleotides. We address the major challenge of metal nanoparticle and GNP radiosensitization; i.e., to deliver the maximum local dose of radiation to the most sensitive target of cancer cells (i.e., DNA). To achieve this goal the emitted electrons from the absorbed high energy radiation must be short range, and produce a large local density of LEEs, and the initial radiation must have the highest possible absorption coefficient compared to that of soft tissue (e.g., 20-80 keV X-rays).
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Yu H, Kondo Y, Fujii K, Yokoya A, Yamashita S. Establishment of a Method for Investigating Direct and Indirect Actions of Ionizing Radiation Using Scavenger-free Plasmid DNA. Radiat Res 2022; 197:594-604. [PMID: 35363873 DOI: 10.1667/rade-21-00057.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 03/10/2022] [Indexed: 11/03/2022]
Abstract
In this study, an improved method using scavenger-free plasmid DNA was established to accurately determine yields of DNA damage induced by direct and indirect actions of ionizing radiation. The scavenger-free plasmid DNA was obtained by dialysis over 5-7 days, and the DNA solvent was replaced with phosphate buffer to completely remove impurities, which could be scavengers of radicals produced as a result of water radiolysis. DNA samples of films and dilute aqueous solutions were used to separately evaluate contributions of the direct and indirect actions of X rays (150-160 kVp). The irradiated DNA was analyzed by agarose gel electrophoresis to quantify strand-break yields. The yields of single-strand breaks (SSBs), n(SSB), were determined to be (6.5 ± 2.0) × 10-10 and (3.1 ± 0.9) × 10-7 SSBs/Gy/Da for the film and solution samples, respectively, showing a significant contribution of hydroxyl radicals (•OH) compared with direct energy depositions from ionizing radiation to DNA. As observed in SSBs, the yields of double-strand breaks (DSBs), n(DSB), were (5.6 ± 1.1) × 10-11 and (1.3 ± 0.2) × 10-8 DSBs/Gy/Da for the film and solution samples, respectively. The yield ratio of DSBs to SSBs, that is, n(DSB)/n(SSB), was 0.091 ± 0.026 for the film samples, while it was much lower for the solution samples (0.045 ± 0.010), indicating that direct actions result in more localized strand breaks relative to indirect actions. Base excision repair enzymes, namely, endonuclease III (Nth) and formamidopyrimidine-DNA glycosylase (Fpg), were utilized after irradiations to convert base lesions and apurinic/apyrimidinic (AP) sites into strand breaks. The amounts of Nth and Fpg for the conversion were optimized to a few units per μg of DNA, although the optimal concentrations can differ among conditions.
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Affiliation(s)
- Hao Yu
- Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188, Japan
| | - Yusuke Kondo
- Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kentaro Fujii
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology (QST), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1106, Japan
| | - Akinari Yokoya
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology (QST), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1106, Japan
| | - Shinichi Yamashita
- Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188, Japan.,Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Gao Y, Zheng Y, Sanche L. Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents. Int J Mol Sci 2021; 22:7879. [PMID: 34360644 PMCID: PMC8345953 DOI: 10.3390/ijms22157879] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 11/18/2022] Open
Abstract
The complex physical and chemical reactions between the large number of low-energy (0-30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.
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Affiliation(s)
- Yingxia Gao
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Yi Zheng
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Léon Sanche
- Département de Médecine Nucléaire et Radiobiologie et Centre de Recherche Clinique, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
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Vyšín L, Burian T, Ukraintsev E, Davídková M, Grisham ME, Heinbuch S, Rocca JJ, Juha L. Dose-Rate Effects in Breaking DNA Strands by Short Pulses of Extreme Ultraviolet Radiation. Radiat Res 2018; 189:466-476. [PMID: 29505347 DOI: 10.1667/rr14825.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In this study, we examined dose-rate effects on strand break formation in plasmid DNA induced by pulsed extreme ultraviolet (XUV) radiation. Dose delivered to the target molecule was controlled by attenuating the incident photon flux using aluminum filters as well as by changing the DNA/buffer-salt ratio in the irradiated sample. Irradiated samples were examined using agarose gel electrophoresis. Yields of single- and double-strand breaks (SSBs and DSBs) were determined as a function of the incident photon fluence. In addition, electrophoresis also revealed DNA cross-linking. Damaged DNA was inspected by means of atomic force microscopy (AFM). Both SSB and DSB yields decreased with dose rate increase. Quantum yields of SSBs at the highest photon fluence were comparable to yields of DSBs found after synchrotron irradiation. The average SSB/DSB ratio decreased only slightly at elevated dose rates. In conclusion, complex and/or clustered damages other than cross-links do not appear to be induced under the radiation conditions applied in this study.
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Affiliation(s)
- Luděk Vyšín
- a Institute of Physics.,e Department of Nuclear Chemistry, Czech Technical University in Prague, Prague, Czech Republic
| | - Tomáš Burian
- a Institute of Physics.,c Institute of Plasma Physics.,d J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | | | | | - Michael E Grisham
- f Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado
| | - Scott Heinbuch
- f Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado
| | - Jorge J Rocca
- f Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado
| | - Libor Juha
- a Institute of Physics.,c Institute of Plasma Physics
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Choofong S, Cloutier P, Sanche L, Wagner JR. Base Release and Modification in Solid-Phase DNA Exposed to Low-Energy Electrons. Radiat Res 2016; 186:520-530. [PMID: 27802110 DOI: 10.1667/rr14476.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ionization generates a large number of secondary low-energy electrons (LEEs) with a most probable energy of approximately 10 eV, which can break DNA bonds by dissociative electron attachment (DEA) and lead to DNA damage. In this study, we investigated radiation damage to dry DNA induced by X rays (1.5 keV) alone on a glass substrate or X rays combined with extra LEEs (average energy of 5.8 eV) emitted from a tantalum (Ta) substrate under an atmosphere of N2 and standard ambient conditions of temperature and pressure. The targets included calf-thymus DNA and double-stranded synthetic oligonucleotides. We developed analytical methods to measure the release of non-modified DNA bases from DNA and the formation of several base modifications by LC-MS/MS with isotopic dilution for precise quantification. The results show that the yield of non-modified bases as well as base modifications increase by 20-30% when DNA is deposited on a Ta substrate compared to that on a glass substrate. The order of base release (Gua > Ade > Thy ∼ Cyt) agrees well with several theoretical studies indicating that Gua is the most susceptible site toward sugar-phosphate cleavage. The formation of DNA damage by LEEs is explained by DEA leading to the release of non-modified bases involving the initial cleavage of N1-C1', C3'-O3' or C5'-O5' bonds. The yield of base modifications was lower than the release of non-modified bases. The main LEE-induced base modifications include 5,6-dihydrothymine (5,6-dHT), 5,6-dihydrouracil (5-dHU), 5-hydroxymethyluracil (5-HmU) and 5-formyluracil (5-ForU). The formation of base modifications by LEEs can be explained by DEA and cleavage of the C-H bond of the methyl group of Thy (giving 5-HmU and 5-ForU) and by secondary reactions of H atoms and hydride anions that are generated by primary LEE reactions followed by subsequent reaction with Cyt and Thy (giving 5,6-dHU and 5,6-dHT).
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Affiliation(s)
- Surakarn Choofong
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Pierre Cloutier
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Léon Sanche
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - J Richard Wagner
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Billik P. Simple radiosensitizing of hypoxic tumor tissues by N2O/Br(-) mixture. Med Hypotheses 2015; 85:37-40. [PMID: 25812437 DOI: 10.1016/j.mehy.2015.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/20/2015] [Accepted: 03/12/2015] [Indexed: 11/27/2022]
Abstract
The radiosensitization model of hypoxic tumor tissues based on the N2O/Br(-) mixture is described. The well-documented radiolysis of water in the presence of N2O and Br(-) ions at a low concentration supports this model. An aqueous solution saturated with N2O gas during the radiolysis generates OH radicals in a large extent. In N2O/Br- media at pH<9, Br2 is formed. Br2 hydrolyzes in an aqueous solution to form a very reactive hypobromous (HOBr) acid. Such process is described by the following chemical reaction: H2O + Br(-) + N2O + ionizing radiation (IR) --> HOBr + OH(-). In vivo formed HOBr as a long-lived product with a high biological activity induces the hypoxic tumor cell damage via many unique mechanisms. A local application or inhalation of an N2O-O2 mixture before or during the radiotherapy to enhance the saturation of tissues with N2O is a key prerequisite. Since the extracellular concentration of Br(-) ions is very low (0.02-0.05 mM), an oral or local application of NaBr should be used to shift the extracellular concentration of Br(-) ions to the mM region.
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Affiliation(s)
- P Billik
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská Dolina, SK-842 15 Bratislava, Slovakia; Department of Magnetometry, Institute of Measurement Science, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.
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Simulation of the chemical stage in water radiolysis with the help of Continuous Petri nets. Radiat Phys Chem Oxf Engl 1993 2014. [DOI: 10.1016/j.radphyschem.2013.12.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Alizadeh E, Sanche L. Absolute measurements of radiation damage in nanometer-thick films. RADIATION PROTECTION DOSIMETRY 2012; 151:591-9. [PMID: 22562941 PMCID: PMC3846537 DOI: 10.1093/rpd/ncs036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The problem of absolute measurements of radiation damage in films of nanometer thicknesses is addressed. Thin films of DNA (∼2-160 nm) are deposited onto glass substrates and irradiated with varying doses of 1.5-keV X-rays under dry N(2) at atmospheric pressure and room temperature. For each different thickness, the damage is assessed by measuring the loss of the supercoiled configuration as a function of incident photon fluence. From the exposure curves, the G-values are deduced, assuming that X-ray photons interacting with DNA deposit all of their energy in the film. The results show that the G-value (i.e. damage per unit of deposited energy) increases with film thickness and reaches a plateau at 30±5 nm. This thickness dependence provides a correction factor to estimate the actual G-value for films with thicknesses <30 nm thickness. Thus, the absolute values of the damage can be compared with that of films of any thickness under different experimental conditions.
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Affiliation(s)
- Elahe Alizadeh
- Groupe en Science des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la santé, Université de Sherbrooke, Sherbrooke, Canada J1H 5N4.
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Alizadeh E, Sanche L. Precursors of solvated electrons in radiobiological physics and chemistry. Chem Rev 2012; 112:5578-602. [PMID: 22724633 DOI: 10.1021/cr300063r] [Citation(s) in RCA: 225] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Elahe Alizadeh
- Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
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Alizadeh E, Sanche L. Measurements of G values for DNA damage induced by low-energy electrons. J Phys Chem B 2011; 115:14852-8. [PMID: 22035128 DOI: 10.1021/jp207922n] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We address the problem of measuring G values (damage per unit of deposited energy) for low-energy electrons (LEEs) below 30 eV. Such values (G(LEE)) usually have to be derived from damage yields in nanometer- (~10-nm-) thick films, which are too thin to allow complete absorption of the energy of LEEs. In this work, we determine optimum corrections to obtain reliable G(LEE) values in 2-80-nm-thick films of plasmid DNA that are not uniform. G(LEE) was found to increase with average film thickness and reach a plateau at 260 ± 50 nmol/J around 20 nm, which corresponds to the most reliable value. The previously measured G(LEE) values for films thinner than 20 nm that were underestimated can be corrected using a factor derived from the present results. This method could be used to obtain reliable G(LEE) values for other biomolecules so as to enable the comparison of LEE-induced damage to that produced by other types of radiation under various experimental conditions.
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Affiliation(s)
- Elahe Alizadeh
- Département de médecine nucléaire et radiobiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Canada.
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