TY - JOUR A1 - Prinz, J. A1 - Schreiber, B. A1 - Olejko, L. A1 - Oertel, J. A1 - Rackwitz, J. A1 - Keller, A. A1 - Bald, Ilko T1 - DNA origami substrates for highly sensitive surface-enhanced Raman scattering N2 - DNA nanotechnology holds great promise for the fabrication of novel plasmonic nanostructures and the potential to carry out single-molecule measurements using optical spectroscopy. Here, we demonstrate for the first time that DNA origami nanostructures can be exploited as substrates for surface-enhanced Raman scattering (SERS). Gold nanoparticles (AuNPs) have been arranged into dimers to create intense Raman scattering hot spots in the interparticle gaps. AuNPs (15 nm) covered with TAMRA-modified DNA have been placed at a nominal distance of 25 nm to demonstrate the formation of Raman hot spots. To control the plasmonic coupling between the nanoparticles and thus the field enhancement in the hot spot, the size of AuNPs has been varied from 5 to 28 nm by electroless Au deposition. By the precise positioning of a specific number of TAMRA molecules in these hot spots, SERS with the highest sensitivity down to the few-molecule level is obtained. KW - DANN Origami KW - Surface-enhanced Raman scattering KW - Nanoparticles KW - TAMRA PY - 2013 DO - https://doi.org/10.1021/jz402076b SN - 1948-7185 VL - 4 IS - 23 SP - 4140 EP - 4145 PB - ACS CY - Washington, DC AN - OPUS4-29907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rackwitz, J. A1 - Kopyra, J. A1 - Dabkowska, I. A1 - Ebel, K. A1 - Rankovic, M. A1 - Milosavljevic, A. R. A1 - Bald, Ilko T1 - Sensitizing DNAtowards low-energy electrons with 2-fluoroadenine N2 - 2-Fluoroadenine (2FA) 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 2FA 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 2FA-containing oligonucleotides upon irradiation with LEEs. The incorporation of 2FA into DNA results in an enhanced strand breakage. The strand-break cross sections are clearly energy dependent, whereas the strand-break enhancements by 2FA at 5.5, 10, and 15 eV are very similar. Thus, 2FA can be considered an effective radiosensitizer operative at a wide range of electron energies. KW - Ab initio calculations KW - Dissociative electron attachment KW - DNA origami KW - DNA radiation damage KW - Fludarabine PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/anie.201603464/full DO - https://doi.org/10.1002/anie.201603464 SN - 1433-7851 SN - 1521-3773 VL - 55 IS - 35 SP - 10248 EP - 10252 AN - OPUS4-37372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rackwitz, J. A1 - Rankovic, M. A1 - Milosavljevic, A. A1 - Bald, Ilko T1 - A novel setup for the determination of absolute cross sections for low-energy electron induced strand breaks in oligonucleotides – The effect of the radiosensitizer 5-fluorouracil N2 - 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 σSSB. In this way, the influence of sequence modification with the radiosensitive 5-Fluorouracil (5FU) is studied using an absolute and relative data analysis. We demonstrate an increase in the strand break yields of 5FU containing oligonucleotides by a factor of 1.5 to 1.6 compared with non-modified oligonucleotide sequences when irradiated with 10 eV electrons. KW - DNA origami KW - DNA radiation damage KW - Radiosensitizer KW - AFM KW - Fluorouracil PY - 2017 UR - http://epjd.epj.org/articles/epjd/abs/2017/02/d160608/d160608.html DO - https://doi.org/10.1140/epjd/e2016-70608-4 VL - 71 SP - 32 PB - Springer CY - New York, NY, USA AN - OPUS4-39643 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -