ionization and fragmentation of dna, rna componens induced by proton impact
DESCRIPTION
IONIZATION AND FRAGMENTATION OF DNA, RNA COMPONENS INDUCED BY PROTON IMPACT. P .Moretto-Capelle, A.Le Padellec, M.Richard-Viard, J.P.Champeaux and P.Cafarelli Laboratoire Collisions, Agregats, Reactivité (UMR5589 CNRS-Univ.Paul Sabatier Toulouse 3) IRSAMC 31062 Toulouse cedex 9, France. - PowerPoint PPT PresentationTRANSCRIPT
IONIZATION AND FRAGMENTATION OFIONIZATION AND FRAGMENTATION OF DNA, RNA COMPONENS INDUCED BY PROTON IMPACTDNA, RNA COMPONENS INDUCED BY PROTON IMPACT
P.Moretto-Capelle, A.Le Padellec, M.Richard-Viard, J.P.Champeaux and P.Cafarelli
Laboratoire Collisions, Agregats, Reactivité (UMR5589 CNRS-Univ.Paul Sabatier Toulouse 3) IRSAMC 31062 Toulouse cedex 9, France
Damages induced by ionizing radiation can directly be linked to alteration of the DNA molecule. In this work, we investigate interactions between protons and phase gas DNA/RNA bases and nucleoside
Energy loss by a proton in matter? Example of transport of 100 MeV proton in liquid water
Important dose deposition in a well defined spatial zone Bragg Peack (BP):
PROTONTHERAPY
Maximum dose: proton decellerated around 100keV: maximum LET
Corresponding DNA damages: evoluated Monte-Carlo codes (Nikjoo,O’Neill, Terrisol, Goodheart
Rad.Env.Biophys (1999)38), we used more simpler MCDS program whose coefficients are fitted on MC codes. (Semennenko, Steward Rad.Res. (2004) 161)
10 10010-21
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10-18
DD
CS
(cm
2 eV-1
sr-1
)
Electronic energy (eV)
100 keV 50 keV 25 keV
Thy
FROM BASES DAMAGES
EMISSION OF SECONDARY ELECTRONS
Damages induced by secondary electron depend on kinetic
energy:
Need to know energy spectrum of the emitted electrons
BUT also the absolute yield (cross section)
Low energy (<20eV): dissociative attachment
High energy(>20eV): ionization,fragmentation
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X mm
Dep
th (
mm
)
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Dep
th (m
m)
Proton Energy (keV)
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Proton Energy (keV)
LET
(keV
/m
)
Our accelerator energy range
100 1000 10000 100000
0.1
1
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% D
NA
dam
ages
Proton Energy (keV)
BD SSB SSBp 2SSD DSB DSBp DSBpp
Range around 100keV is interesting=> ultra thin target=> biomolecule in gaz phase
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TOWARDS ELEMENTARY STRAND BREAK: Irradiation of URIDINE
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Counts
Additivity?
Destruction of the sugar=> Strand Break
RADIOSENSITIZER? PHYSICAL MECHANISMS?
1-PHYSICAL Studies at molecular scale (… gaz phase)
fragmentation patterns, electronic emission, corresponding cross sections
Difference with ‘standart’ molecules?
2-IRRADIATION of DNA (plasmid) deposited SURFACE
without and with molecule
Carboplatine Cisplatine Halo-Uracil (F,Br,I)ANALYSIS OF STRAND BREAKS:LINKS?
Measurment of electron spectra: majority of low energy electrons
Caracterization by CTMC modeling:-Total cross sections-Yield in angle and energy
10
100
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S15S35
S55S75
S95S135
S155S175
DDCS (arb.unit)
ECC peack
Many small molecules are formed
PHYSICAL STAGE OF THE INTERACTION (fs): PRODUCTION OF DATA
Formation of numerous small fragments:- Identification and branching ratioCan interact with neighbouring structures
Number of molecule / base pair ?
SRIM 2006
Moretto-Capelle, Le Padellec, Phys.Rev.A (2006)