@article{RackwitzKopyraDabkowskaetal.2016, author = {Rackwitz, Jenny and Kopyra, Janina and Dabkowska, Iwona and Ebel, Kenny and Rankovic, MiloS Lj. and Milosavljevic, Aleksandar R. and Bald, Ilko}, title = {Sensitizing DNA Towards Low-Energy Electrons with 2-Fluoroadenine}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, volume = {55}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201603464}, pages = {10248 -- 10252}, year = {2016}, abstract = {2-Fluoroadenine ((2F)A) is a therapeutic agent, which is suggested for application in cancer radiotherapy. The molecular mechanism of DNA radiation damage can be ascribed to a significant extent to the action of low-energy (<20 eV) electrons (LEEs), which damage DNA by dissociative electron attachment. LEE induced reactions in (2F)A are characterized both isolated in the gas phase and in the condensed phase when it is incorporated into DNA. Information about negative ion resonances and anion-mediated fragmentation reactions is combined with an absolute quantification of DNA strand breaks in (2F)A-containing oligonucleotides upon irradiation with LEEs. The incorporation of (2F)A into DNA results in an enhanced strand breakage. The strand-break cross sections are clearly energy dependent, whereas the strand-break enhancements by (2F)A at 5.5, 10, and 15 eV are very similar. Thus, (2F)A can be considered an effective radiosensitizer operative at a wide range of electron energies.}, language = {en} } @article{RackwitzRankovićMilosavljevićetal.2017, author = {Rackwitz, Jenny and Ranković, Miloš Lj. and Milosavljević, Aleksandar R. and Bald, Ilko}, title = {A novel setup for the determination of absolute cross sections for low-energy electron induced strand breaks in oligonucleotides}, series = {The European physical journal : D, Atomic, molecular, optical and plasma physics}, volume = {71}, journal = {The European physical journal : D, Atomic, molecular, optical and plasma physics}, publisher = {Springer}, address = {New York}, issn = {1434-6060}, doi = {10.1140/epjd/e2016-70608-4}, pages = {9}, year = {2017}, abstract = {Low-energy electrons (LEEs) play an important role in DNA radiation damage. Here we present a method to quantify LEE induced strand breakage in well-defined oligonucleotide single strands in terms of absolute cross sections. An LEE irradiation setup covering electron energies <500 eV is constructed and optimized to irradiate DNA origami triangles carrying well-defined oligonucleotide target strands. Measurements are presented for 10.0 and 5.5 eV for different oligonucleotide targets. The determination of absolute strand break cross sections is performed by atomic force microscopy analysis. An accurate fluence determination ensures small margins of error of the determined absolute single strand break cross sections sigma SSB. In this way, the influence of sequence modification with the radiosensitive 5-Fluorouracil (U-5F) is studied using an absolute and relative data analysis. We demonstrate an increase in the strand break yields of U-5F containing oligonucleotides by a factor of 1.5 to 1.6 compared with non-modified oligonucleotide sequences when irradiated with 10 eV electrons.}, language = {en} }