TY  - JOUR
A1  - Cywinski, Piotr J.
A1  - Olejko, Lydia
A1  - Löhmannsröben, Hans-Gerd
T1  - A time-resolved luminescent competitive assay to detect L-selectin using aptamers as recognition elements
JF  - Analytica chimica acta : an international journal devoted to all branches of analytical chemistry
N2  - L-selectin is a protein with potential importance for numerous diseases and clinical disorders. In this paper, we present a new aptamer-based luminescent assay developed to detect L-selectin. The sensing system working principle is based on Forster Resonance Energy Transfer (FRET) from a donor terbium complex (TbC) to an acceptor cyanine dye (Cy5). In the present approach, the biotinylated aptamer is combined with Cy5-labelled streptavidin (Cy5-Strep) to yield an aptamer-based acceptor construct (Apta-Cy5-Strep), while L-selectin is conjugated using luminescent TbC. Upon aptamer binding to the TbC-labelled L-selectin (L-selectin-TbC), permanent donor-acceptor proximity is established which allows for radiationless energy transfer to occur. However, when unlabelled L-selectin is added, it competes with the L-selectin-TbC and the FRET signal decreases as the L-selectin concentration increases. FRET from the TbC to Cy5 was observed with time-gated time-resolved luminescence spectroscopy. A significant change in the corrected luminescence signal was observed in the dynamic range of 10 -500 ng/mL L-selectin, the concentration range relevant for accelerated cognitive decline of Alzheimer's disease, with a limit of detection (LOD) equal to 10 ng/mL. The aptasensor-based assay is homogeneous and can be realized within one hour. Therefore, this method has the potential to become an alternative to tedious heterogeneous analytical methods, e.g. based on enzyme-linked immunosorbent assay (ELISA). (C) 2015 Elsevier B.V. All rights reserved.
KW  - Aptamer
KW  - FRET
KW  - L-selectin
KW  - Luminescence spectroscopy
KW  - Fluoroassay
KW  - Lanthanide
Y1  - 2015
U6  - https://doi.org/10.1016/j.aca.2015.06.045
SN  - 0003-2670
SN  - 1873-4324
VL  - 887
SP  - 209
EP  - 215
PB  - Elsevier
CY  - Amsterdam
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  -