@article{CywinskiHammannHuehnetal.2014, author = {Cywinski, Piotr J. and Hammann, Tommy and Huehn, Dominik and Parak, Wolfgang J. and Hildebrandt, Niko and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Europium-quantum dot nanobioconjugates as luminescent probes for time-gated biosensing}, series = {Journal of biomedical optics}, volume = {19}, journal = {Journal of biomedical optics}, number = {10}, publisher = {SPIE}, address = {Bellingham}, issn = {1083-3668}, doi = {10.1117/1.JBO.19.10.101506}, pages = {8}, year = {2014}, abstract = {Nanobioconjugates have been synthesized using cadmium selenide quantum dots (QDs), europium complexes (EuCs), and biotin. In those conjugates, long-lived photoluminescence (PL) is provided by the europium complexes, which efficiently transfer energy via Forster resonance energy transfer (FRET) to the QDs in close spatial proximity. As a result, the conjugates have a PL emission spectrum characteristic for QDs combined with the long PL decay time characteristic for EuCs. The nanobioconjugates synthesis strategy and photo-physical properties are described as well as their performance in a time-resolved streptavidin-biotin PL assay. In order to prepare the QD-EuC-biotin conjugates, first an amphiphilic polymer has been functionalized with the EuC and biotin. Then, the polymer has been brought onto the surface of the QDs (either QD655 or QD705) to provide functionality and to make the QDs water dispersible. Due to a short distance between EuC and QD, an efficient FRET can be observed. Additionally, the QD-EuC-biotin conjugates' functionality has been demonstrated in a PL assay yielding good signal discrimination, both from autofluorescence and directly excited QDs. These newly designed QD-EuC-biotin conjugates expand the class of highly sensitive tools for bioanalytical optical detection methods for diagnostic and imaging applications. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)}, language = {en} } @article{CywinskiMoroLoehmannsroeben2014, author = {Cywinski, Piotr J. and Moro, Artur J. and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Cyclic GMP recognition using ratiometric QD-fluorophore conjugate nanosensors}, series = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics}, volume = {52}, journal = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics}, publisher = {Elsevier}, address = {Oxford}, issn = {0956-5663}, doi = {10.1016/j.bios.2013.09.002}, pages = {288 -- 292}, year = {2014}, language = {en} } @misc{SuriyanarayananCywinskiMoroetal.2012, author = {Suriyanarayanan, Subramanian and Cywinski, Piotr J. and Moro, Artur J. and Mohr, Gerhard J. and Kutner, Wlodzimierz}, title = {Chemosensors based on molecularly imprinted polymers}, series = {Topics in current chemistry}, volume = {325}, journal = {Topics in current chemistry}, number = {4}, editor = {Haupt, K}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-642-28421-2}, issn = {0340-1022}, doi = {10.1007/128_2010_92}, pages = {165 -- 265}, year = {2012}, language = {en} } @article{IdzikCywinskiCranfieldetal.2011, author = {Idzik, Krzysztof Ryszard and Cywinski, Piotr J. and Cranfield, Charles G. and Mohr, Gerhard J. and Beckert, Rainer}, title = {Molecular recognition of the antiretroviral drug abacavir towards the development of a novel carbazole-based fluorosensor}, series = {Journal of fluorescence}, volume = {21}, journal = {Journal of fluorescence}, number = {3}, publisher = {Springer}, address = {New York}, issn = {1053-0509}, doi = {10.1007/s10895-010-0798-7}, pages = {1195 -- 1204}, year = {2011}, abstract = {Due to their optical and electro-conductive attributes, carbazole derivatives are interesting materials for a large range of biosensor applications. In this study, we present the synthesis routes and fluorescence evaluation of newly designed carbazole fluorosensors that, by modification with uracil, have a special affinity for antiretroviral drugs via either Watson-Crick or Hoogsteen base pairing. To an N-octylcarbazole-uracil compound, four different groups were attached, namely thiophene, furane, ethylenedioxythiophene, and another uracil; yielding four different derivatives. Photophysical properties of these newly obtained derivatives are described, as are their interactions with the reverse transcriptase inhibitors such as abacavir, zidovudine, lamivudine and didanosine. The influence of each analyte on biosensor fluorescence was assessed on the basis of the Stern-Volmer equation and represented by Stern-Volmer constants. Consequently we have demonstrated that these structures based on carbazole, with a uracil group, may be successfully incorporated into alternative carbazole derivatives to form biosensors for the molecular recognition of antiretroviral drugs.}, language = {en} } @article{WeclawskiMeilingLeniaketal.2015, author = {Weclawski, Marek K. and Meiling, Till Thomas and Leniak, Arkadiusz and Cywinski, Piotr J. and Gryko, Daniel T.}, title = {Planar, Fluorescent Push-Pull System That Comprises Benzofuran and Iminocoumarin Moieties}, series = {Organic letters}, volume = {17}, journal = {Organic letters}, number = {17}, publisher = {American Chemical Society}, address = {Washington}, issn = {1523-7060}, doi = {10.1021/acs.orglett.5b02042}, pages = {4252 -- 4255}, year = {2015}, abstract = {Previously unknown, vertically linked heterocycles comprised of benzofuran and iminocoumarin moieties have been synthesized directly from 1,5-dibenzoyloxyanthraquinone and arylacetonitriles via double Knoevenagel condensation followed by formal HCN elimination. The structural assembly of fully conjugated, electron-rich benzofuran and electron-deficient iminocoumarin is responsible for the strongly polarized nature of these heterocycles which translates into their polarity-sensitive fluorescence.}, language = {en} } @article{NazirMeilingCywinskietal.2015, author = {Nazir, Rashid and Meiling, Till Thomas and Cywinski, Piotr J. and Gryko, Daniel T.}, title = {Synthesis and Optical Properties of alpha,beta-Unsaturated Ketones Bearing a Benzofuran Moiety}, series = {Asian journal of organic chemistry : an ACES journal}, volume = {4}, journal = {Asian journal of organic chemistry : an ACES journal}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2193-5807}, doi = {10.1002/ajoc.201500242}, pages = {929 -- 935}, year = {2015}, abstract = {Five pi-expanded alpha,beta-unsaturated ketones have been prepared from a strongly electron-rich benzofuran derivative via Knoevenagel reaction and aldol condensation. The incorporation of two 6-didodecylaminobenzofuran-2-yl groups at the periphery of D-pi-A and D-pi-A-pi-D molecules resulted in dyes with excellent solubility in the majority of organic solvents. In contrast to the majority of alpha,beta-unsaturated ketones, these dyes emit relatively strongly in the red region with a fluorescence quantum yield up to 40\%. They also display strong solvatofluorochromism with emission shifting from 570 nm in toluene to 670 nm in CHCl3. Depending on the chemical structure, they two-photon cross-sections (sigma(2)) are up to 1700 GM (1 GM=10(50) cm(4)s photon(-1)).}, language = {en} } @article{CywinskiOlejkoLoehmannsroeben2015, author = {Cywinski, Piotr J. and Olejko, Lydia and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {A time-resolved luminescent competitive assay to detect L-selectin using aptamers as recognition elements}, series = {Analytica chimica acta : an international journal devoted to all branches of analytical chemistry}, volume = {887}, journal = {Analytica chimica acta : an international journal devoted to all branches of analytical chemistry}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0003-2670}, doi = {10.1016/j.aca.2015.06.045}, pages = {209 -- 215}, year = {2015}, abstract = {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.}, language = {en} } @article{CywinskiMoroRitscheletal.2011, author = {Cywinski, Piotr J. and Moro, Artur J. and Ritschel, Thomas and Hildebrandt, Niko and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Sensitive and selective fluorescence detection of guanosine nucleotides by nanoparticles conjugated with a naphthyridine receptor}, series = {Analytical \& bioanalytical chemistry}, volume = {399}, journal = {Analytical \& bioanalytical chemistry}, number = {3}, publisher = {Springer}, address = {Heidelberg}, issn = {1618-2642}, doi = {10.1007/s00216-010-4420-2}, pages = {1215 -- 1222}, year = {2011}, abstract = {Novel fluorescent nanosensors, based on a naphthyridine receptor, have been developed for the detection of guanosine nucleotides, and both their sensitivity and selectivity to various nucleotides were evaluated. The nanosensors were constructed from polystyrene nanoparticles functionalized by (N-(7-((3-aminophenyl) ethynyl)-1,8-naphthyridin- 2-yl) acetamide) via carbodiimide ester activation. We show that this naphthyridine nanosensor binds guanosine nucleotides preferentially over adenine, cytosine, and thymidine nucleotides. Upon interaction with nucleotides, the fluorescence of the nanosensor is gradually quenched yielding Stern-Volmer constants in the range of 2.1 to 35.9mM(-1). For all the studied quenchers, limits of detection (LOD) and tolerance levels for the nanosensors were also determined. The lowest (3 sigma) LOD was found for guanosine 3',5'-cyclic monophosphate (cGMP) and it was as low as 150 ng/ml. In addition, we demonstrated that the spatial arrangement of bound analytes on the nanosensors' surfaces is what is responsible for their selectivity to different guanosine nucleotides. We found a correlation between the changes of the fluorescence signal and the number of phosphate groups of a nucleotide. Results of molecular modeling and zeta-potential measurements confirm that the arrangement of analytes on the surface provides for the selectivity of the nanosensors. These fluorescent nanosensors have the potential to be applied in multi-analyte, array-based detection platforms, as well as in multiplexed microfluidic systems.}, language = {en} } @article{CywinskiPietraszkiewiczMaciejczyketal.2016, author = {Cywinski, Piotr J. and Pietraszkiewicz, Marek and Maciejczyk, Michal and Gorski, Krzysztof and Hammann, Tommy and Liermann, Konstanze and Paulke, Bernd-Reiner and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Total protein concentration quantification using nanobeads with a new highly luminescent terbium(III) complex}, series = {RSC Advances}, volume = {6}, journal = {RSC Advances}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c6ra23207h}, pages = {115068 -- 115073}, year = {2016}, abstract = {Total protein concentration (TPC) is a key parameter in many biochemical experiments and its quantification is often necessary for isolation, separation, and analysis of proteins. A sensitive and rapid nanobead-based TPC quantification assay based on Forster Resonance Energy Transfer (FRET) has been developed. A new, highly luminescent Tb(III) complex has been synthesised and applied as donor in this FRET assay with an organic dye (Cy5) as acceptor. FRET-induced changes in luminescence have been investigated both at donor and acceptor emission wavelength using time-resolved luminescence spectroscopy with time-gated detection. In the assay, the Tb(III) complex and fine-tuned polyglycidyl methacrylate (PGMA) nanobeads ensure that an improvement in sensitivity and background reduction is achieved. Using 40 nm large PGMA nanobeads loaded with the Tb(III) complex, it is possible to determine TPC down to 50 ng mL(-1) in just 10 minutes. Through specific assay components the sensitivity has been improved when compared to existing nanobead-based assays and to currently known commercial methods. Additionally, the assay is relatively insensitive to the presence of contaminants, such as non-ionic detergents commonly found in biological samples. Due to no need for any centrifugal steps, this mix-and-measure bioassay can easily be implemented into routine TPC quantification protocols in biochemical laboratories.}, language = {en} } @misc{MeilingCywińskiBald2016, author = {Meiling, Till Thomas and Cywiński, Piotr J. and Bald, Ilko}, title = {White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-97087}, year = {2016}, abstract = {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.}, language = {en} }