TY  - JOUR
A1  - Tasior, Mariusz
A1  - Bald, Ilko
A1  - Deperasinska, Irena
A1  - Cywinski, Piotr J.
A1  - Gryko, Daniel T.
T1  - An internal charge transfer-dependent solvent effect in V-shaped azacyanines
JF  - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry
Y1  - 2015
U6  - https://doi.org/10.1039/c5ob01633a
SN  - 1477-0520
SN  - 1477-0539
VL  - 13
IS  - 48
SP  - 11714
EP  - 11720
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Olejko, Lydia
A1  - Cywinski, Piotr J.
A1  - Bald, Ilko
T1  - Ion-Selective formation of a guanine quadruplex on DNA origami structures
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - DNA origami nanostructures are a versatile tool that can be used to arrange functionalities with high local control to study molecular processes at a single-molecule level. Here, we demonstrate that DNA origami substrates can be used to suppress the formation of specific guanine (G) quadruplex structures from telomeric DNA. The folding of telomeres into G-quadruplex structures in the presence of monovalent cations (e.g. Na+ and K+) is currently used for the detection of K+ ions, however, with insufficient selectivity towards Na+. By means of FRET between two suitable dyes attached to the 3- and 5-ends of telomeric DNA we demonstrate that the formation of G-quadruplexes on DNA origami templates in the presence of sodium ions is suppressed due to steric hindrance. Hence, telomeric DNA attached to DNA origami structures represents a highly sensitive and selective detection tool for potassium ions even in the presence of high concentrations of sodium ions.
KW  - DNA nanotechnology
KW  - FRET
KW  - G-quadruplexes
KW  - nanostructures
KW  - self-assembly
Y1  - 2015
U6  - https://doi.org/10.1002/anie.201409278
SN  - 1433-7851
SN  - 1521-3773
VL  - 54
IS  - 2
SP  - 673
EP  - 677
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Vogel, Stefanie
A1  - Rackwitz, Jenny
A1  - Schuerman, Robin
A1  - Prinz, Julia
A1  - Milosavljevic, Aleksandar R.
A1  - Refregiers, Matthieu
A1  - Giuliani, Alexandre
A1  - Bald, Ilko
T1  - Using DNA origami nanostructures to determine absolute cross sections for UV photon-induced DNA strand breakage
JF  - The journal of physical chemistry letters
N2  - We have characterized ultraviolet (UV) photon-induced DNA strand break processes by determination of absolute cross sections for photoabsorption and for sequence-specific DNA single strand breakage induced by photons in an energy range from 6.50 to 8.94 eV. These represent the lowest-energy photons able to induce DNA strand breaks. Oligonudeotide targets are immobilized on a UV transparent substrate in controlled quantities through attachment to DNA origami templates. Photon-induced dissociation of single DNA strands is visualized and quantified using atomic force microscopy. The obtained quantum yields for strand breakage vary between 0.06 and 0.5, indicating highly efficient DNA strand breakage by UV photons, which is clearly dependent on the photon energy. Above the ionization threshold strand breakage becomes clearly the dominant form of DNA radiation damage, which is then also dependent on the nucleotide sequence.
Y1  - 2015
U6  - https://doi.org/10.1021/acs.jpclett.5b02238
SN  - 1948-7185
VL  - 6
IS  - 22
SP  - 4589
EP  - 4593
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - GEN
A1  - Tasior, Mariusz
A1  - Bald, Ilko
A1  - Deperasińska, Irena
A1  - Cywiński, Piotr J.
A1  - Gryko, Daniel T.
T1  - An internal charge transfer-dependent solvent effect in V-shaped azacyanines
N2  - New V-shaped non-centrosymmetric dyes, possessing a strongly electron-deficient azacyanine core, have been synthesized based on a straightforward two-step approach. The key step in this synthesis involves palladium-catalysed cross-coupling of dibromo-N,N′-methylene-2,2′-azapyridinocyanines with arylacetylenes. The resulting strongly polarized π-expanded heterocycles exhibit green to orange fluorescence and they strongly respond to changes in solvent polarity. We demonstrate that differently electron-donating peripheral groups have a significant influence on the internal charge transfer, hence on the solvent effect and fluorescence quantum yield. TD-DFT calculations confirm that, in contrast to the previously studied bis(styryl)azacyanines, the proximity of S1 and T2 states calculated for compounds bearing two 4-N,N-dimethylaminophenylethynyl moieties establishes good conditions for efficient intersystem crossing and is responsible for its low fluorescence quantum yield. Non-linear properties have also been determined for new azacyanines and the results show that depending on peripheral groups, the synthesized dyes exhibit small to large two-photon absorption cross sections reaching 4000 GM.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 306 
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-102704
SP  - 11714
EP  - 11720
ER  -