TY  - JOUR
A1  - Meiling, Till Thomas
A1  - Cywiński, Piotr J.
A1  - Bald, Ilko
T1  - White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis
JF  - Scientific reports
N2  - In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification. The CNDs are stable over a long period of time (>1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst.
KW  - Fluorescence spectroscopy
KW  - Nanoparticles
KW  - Synthesis and processing
Y1  - 2016
U6  - https://doi.org/10.1038/srep28557
VL  - 6
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Morgner, Frank
A1  - Bennemann, Mark
A1  - Cywiński, Piotr J.
A1  - Kollosche, Matthias
A1  - Górski, Krzysztof
A1  - Pietraszkiewicz, Marek
A1  - Geßner, André
A1  - Löhmannsröben, Hans-Gerd
T1  - Elastic FRET sensors for contactless pressure measurement
JF  - RSC Advances : an international journal to further the chemical sciences
N2  - Contactless pressure monitoring based on Forster resonance energy transfer between donor/acceptor pairs immobilized within elastomers is demonstrated. The donor/acceptor energy transfer is employed by dispersing terbium(III) tris[(2-hydroxybenzoyl)-2-aminoethyl] amine complex (LLC, donor) and CdSe/ZnS quantum dots (QD655, acceptor) in styrene-ethylene/buthylene-styrene (SEBS) and poly(dimethylsiloxane) (PDMS). The continuous monitoring of QD luminescence showed a reversible intensity change as the pressure signal is alternated between two stable states indicating a pressure sensitivity of 6350 cps kPa(-1). Time-resolved measurements show the pressure impact on the FRET signal due to an increase of decay time (270 ms up to 420 ms) for the donor signal and parallel drop of decay time (170 mu s to 155 mu s) for the acceptor signal as the net pressure applied. The LLC/QD655 sensors enable a contactless readout as well as space resolved monitoring to enable miniaturization towards smaller integrated stretchable opto-electronics. Elastic FRET sensors can potentially lead to developing profitable analysis systems capable to outdo conventional wired electronic systems (inductive, capacitive, ultrasonic and photoelectric sensors) especially for point-of-care diagnostics, biological monitoring required for wearable electronics.
Y1  - 2017
U6  - https://doi.org/10.1039/c7ra06379b
SN  - 2046-2069
VL  - 7
SP  - 50578
EP  - 50583
PB  - RSC Publishing
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Olejko, Lydia
A1  - Cywiński, Piotr J.
A1  - Bald, Ilko
T1  - An ion-controlled four-color fluorescent telomeric switch on DNA origami structures
JF  - Nanoscale
N2  - The folding of single-stranded telomeric DNA into guanine (G) quadruplexes is a conformational change that plays a major role in sensing and drug targeting. The telomeric DNA can be placed on DNA origami nanostructures to make the folding process extremely selective for K+ ions even in the presence of high Na+ concentrations. Here, we demonstrate that the K+-selective G-quadruplex formation is reversible when using a cryptand to remove K+ from the G-quadruplex. We present a full characterization of the reversible switching between single-stranded telomeric DNA and G-quadruplex structures using Förster resonance energy transfer (FRET) between the dyes fluorescein (FAM) and cyanine3 (Cy3). When attached to the DNA origami platform, the G-quadruplex switch can be incorporated into more complex photonic networks, which is demonstrated for a three-color and a four-color FRET cascade from FAM over Cy3 and Cy5 to IRDye700 with G-quadruplex-Cy3 acting as a switchable transmitter.
KW  - resonance energy-transfer
KW  - g-quadruplex
KW  - quantum dots
KW  - strand breakage
KW  - photonic wires
KW  - 3-color fret
KW  - nanostructures
KW  - recognition
KW  - sensitivity
KW  - assemblies
Y1  - 2016
U6  - https://doi.org/10.1039/C6NR00119J
SN  - 2040-3372
SN  - 2040-3364
VL  - 8
SP  - 10339
EP  - 10347
PB  - RSC Publ.
CY  - Cambridge
ER  -