@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}
}
@article{MeilingCywinskiBald2016,
  author    = {Meiling, Till T. and Cywinski, Piotr J. and Bald, Ilko},
  title     = {White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis},
  series = {Scientific reports},
  volume    = {6},
  journal   = {Scientific reports},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/srep28557},
  pages     = {9},
  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}
}
@article{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},
  series = {Scientific reports},
  volume    = {6},
  journal   = {Scientific reports},
  publisher = {Nature Publishing Group},
  address   = {London},
  doi       = {10.1038/srep28557},
  pages     = {9},
  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}
}
@misc{CiuciuCywiński2014,
  author    = {Ciuciu, Adina I. and Cywiński, Piotr J.},
  title     = {Two-photon polymerization of hydrogels - versatile solutions to fabricate well-defined 3D structures},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-99450},
  year      = {2014},
  abstract  = {Hydrogels are cross-linked water-containing polymer networks that are formed by physical, ionic or covalent interactions. In recent years, they have attracted significant attention because of their unique physical properties, which make them promising materials for numerous applications in food and cosmetic processing, as well as in drug delivery and tissue engineering. Hydrogels are highly water-swellable materials, which can considerably increase in volume without losing cohesion, are biocompatible and possess excellent tissue-like physical properties, which can mimic in vivo conditions. When combined with highly precise manufacturing technologies, such as two-photon polymerization (2PP), well-defined three-dimensional structures can be obtained. These structures can become scaffolds for selective cell-entrapping, cell/drug delivery, sensing and prosthetic implants in regenerative medicine. 2PP has been distinguished from other rapid prototyping methods because it is a non-invasive and efficient approach for hydrogel cross-linking. This review discusses the 2PP-based fabrication of 3D hydrogel structures and their potential applications in biotechnology. A brief overview regarding the 2PP methodology and hydrogel properties relevant to biomedical applications is given together with a review of the most important recent achievements in the field.},
  language  = {en}
}
@article{MeilingCywinskiLoehmannsroeben2018,
  author    = {Meiling, Till Thomas and Cywinski, Piotr J. and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
  title     = {Two-Photon excitation fluorescence spectroscopy of quantum dots},
  series = {The journal of physical chemistry : C, Nanomaterials and interfaces},
  volume    = {122},
  journal   = {The journal of physical chemistry : C, Nanomaterials and interfaces},
  number    = {17},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1932-7447},
  doi       = {10.1021/acs.jpcc.7b12345},
  pages     = {9641 -- 9647},
  year      = {2018},
  abstract  = {The applications of quantum dots (QDs) in two-photon (2P) excitation applications demand reliable data about their 2P absorption (2PA) cross sections (sigma(2PA)). In the present study, sigma(2PA) values have been determined for a series of commercial colloidal CdSe/ZnS QDs and CdSeTe/ZnS QDs in aqueous media. For the first time for these QDs, the sigma(2PA) values have been determined over a wide spectral range, that is, between 720 and 900 nm, and are compared to the extinction coefficient (epsilon) values obtained under one-photon (1P) excitation. Furthermore, we present a QD in combination with an organic dye in a biotin-streptavidin Forster resonance energy transfer bioassay under 1P and 2P excitation. The results for the bioassay under 2P excitation are compared to those obtained under 1P excitation. The results demonstrate that in the case of the 2P excitation, higher sensitivity can be achieved because of an improved signal-to-noise ratio.},
  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}
}
@article{CywinskiIdzikCranfieldetal.2010,
  author    = {Cywinski, Piotr J. and Idzik, Krzysztof R. and Cranfield, Charles G. and Beckert, Rainer and Mohr, Gerhard J.},
  title     = {Synthesis and sensing properties of a new carbazole fluorosensor for detection of abacavir},
  issn      = {1061-0278},
  doi       = {10.1080/10610278.2010.506541},
  year      = {2010},
  abstract  = {An abacavir-targeted fluorosensor based on the carbazole moiety has been synthesised and characterised. Recognition of abacavir is by base pairing between a uracil moiety present in the fluorosensor and the guanine moiety of abacavir. The fluorosensor exhibits five-fold quenching in the presence of 50M abacavir. Its sensitivity to abacavir is superior to that of other reverse transcriptase inhibitors: zidovudine, lamivudine and didanosine. Due to its high sensitivity, this fluorosensor has the potential to be used in multi-analyte array-based detection platforms as well as in microfluidics systems.},
  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{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{HarmaPihlasaloCywinskietal.2013,
  author    = {Harma, Harri and Pihlasalo, Sari and Cywinski, Piotr J. and Mikkonen, Piia and Hammann, Tommy and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Hanninen, Pekka},
  title     = {Protein quantification using resonance energy transfer between donor nanoparticles and acceptor quantum dots},
  series = {Analytical chemistry},
  volume    = {85},
  journal   = {Analytical chemistry},
  number    = {5},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0003-2700},
  doi       = {10.1021/ac303586n},
  pages     = {2921 -- 2926},
  year      = {2013},
  abstract  = {A homogeneous time-resolved luminescence resonance energy transfer (TR-LRET) assay has been developed to quantify proteins. The competitive assay is based on resonance energy transfer (RET) between two luminescent nanosized particles. Polystyrene nanoparticles loaded with Eu3+ chelates (EuNPs) act as donors, while protein-coated quantum dots (QDs), either CdSe/ZnS emitting at 655 nm (QD655-strep) or CdSeTe/ZnS with emission wavelength at 705 nm (QD705-strep), are acceptors. In the absence of analyte protein, in our case bovine serum albumin (BSA), the protein-coated QDs bind nonspecifically to the EuNPs, leading to RET. In the presence of analyte proteins, the binding of the QDs to the EuNPs is prevented and the RET signal decreases. RET from the EuNPs to the QDs was confirmed and characterized with steady-state and time-resolved luminescence spectroscopy. In accordance with the Forster theory, the approximate average donor acceptor distance is around 15 nm at RET efficiencies, equal to 15\% for QD655 and 13\% for QD705 acceptor, respectively. The limits of detection are below 10 ng of BSA with less than a 10\% average coefficient of variation. The assay sensitivity is improved, when compared to the most sensitive commercial methods. The presented mix-and-measure method has potential to be implemented into routine protein quantification in biological laboratories.},
  language  = {en}
}