Effective cross sections for production of single-strand breaks in plasmid DNA by 0.1 to 4.7 eV electrons.

Effective cross sections for production of single-strand breaks in plasmid DNA by 0.1 to 4.7 eV electrons.

Radiation research (2006-04-04)

Radmila Panajotovic, Frédéric Martin, Pierre Cloutier, Darel Hunting, Léon Sanche

ABSTRACT

We determined effective cross sections for production of single-strand breaks (SSBs) in plasmid DNA [pGEM 3Zf(-)] by electrons of 10 eV and energies between 0.1 and 4.7 eV. After purification and lyophilization on a chemically clean tantalum foil, dry plasmid DNA samples were transferred into a high-vacuum chamber and bombarded by a monoenergetic electron beam. The amount of the circular relaxed DNA in the samples was separated from undamaged molecules and quantified using agarose gel electrophoresis. The effective cross sections were derived from the slope of the yield as a function of exposure and had values in the range of 10(-15)- 10(-14) cm2, giving an effective cross section of the order of 10(-18) cm2 per nucleotide. Their strong variation with incident electron energy and the resonant enhancement at 1 eV suggest that considerable damage is inflicted by very low-energy electrons to DNA, and it indicates the important role of pi* shape resonances in the bond-breaking process. Furthermore, the fact that the energy threshold for SSB production is practically zero implies that the sensitivity of DNA to electron impact is universal and is not limited to any particular energy range.

MATERIALS

Product Number

Brand

Product Description

GF98666230

Tantalum, foil, light tested, 150x150mm, thickness 0.03mm, as rolled, 99.9%

GF52742099

Tantalum, foil, light tested, 100x100mm, thickness 0.034mm, as rolled, 99.9%

GF33704142

Tantalum, foil, not light tested, 100x100mm, thickness 0.009mm, 99.9%

GF19254472

Tantalum, foil, not light tested, 25x25mm, thickness 0.0005mm, 99.9%

GF83507238

Tantalum, foil, light tested, 100x100mm, thickness 0.03mm, as rolled, 99.9%

GF98156144

Tantalum, foil, not light tested, 25x25mm, thickness 0.0015mm, 99.9%

GF15979494

Tantalum, foil, light tested, 50x50mm, thickness 0.075mm, annealed, 99.9%

GF55545149

Tantalum, foil, light tested, 25x25mm, thickness 0.02mm, 99.9%

GF65369324

Tantalum, foil, light tested, 100x100mm, thickness 0.05mm, annealed, 99.9%

GF15129817

Tantalum, foil, not light tested, 50x50mm, thickness 0.01mm, 99.9%

GF90076989

Tantalum, foil, not light tested, 50x50mm, thickness 0.0015mm, 99.9%

GF64866202

Tantalum, foil, not light tested, 82x100mm, thickness 0.006mm, 99.9%

GF84327510

Tantalum, foil, not light tested, 25x25mm, thickness 0.01mm, 99.9%

GF00815958

Tantalum, foil, not light tested, 25x25mm, thickness 0.001mm, 99.9%

GF11923589

Tantalum, foil, light tested, 25x25mm, thickness 0.006mm, 99.9%

GF40402572

Tantalum, foil, 6mm disks, thickness 0.009mm, 99.9%

GF51719317

Tantalum, foil, 25mm disks, thickness 0.15mm, annealed, 99.9%

GF87367405

Tantalum, foil, 4mm disks, thickness 0.75mm, annealed, 99.9%

GF27272167

Tantalum, foil, 8mm disks, thickness 0.025mm, as rolled, 99.9%

GF68866060

Tantalum, foil, 6mm disks, thickness 0.100mm, annealed, 99.9%

GF23523229

Tantalum, foil, 4mm disks, thickness 0.009mm, 99.9%

GF62916318

Tantalum, foil, 10mm disks, thickness 0.75mm, annealed, 99.9%

GF35443672

Tantalum, foil, 6mm disks, thickness 0.0125mm, 99.9%

GF99539667

Tantalum, foil, 2m coil, thickness 0.025mm, coil width 0.75mm, annealed, 99.9%

GF53856186

Tantalum, foil, 1m coil, thickness 0.03mm, coil width 1.2mm, annealed, 99.9%

GF85320907

Tantalum, foil, 15mm disks, thickness 0.03mm, as rolled, 99.9%

GF24472616

Tantalum, foil, 50mm disks, thickness 0.075mm, annealed, 99.9%

GF89833854

Tantalum, foil, 4mm disks, thickness 0.5mm, annealed, 99.9%

GF23496756

Tantalum, foil, 50mm disks, thickness 0.03mm, as rolled, 99.9%

GF64539872

Tantalum, foil, 15mm disks, thickness 0.75mm, annealed, 99.9%