TY - JOUR A1 - Resch-Genger, Ute ED - Kaiser, Martin ED - Würth, Christian ED - Kraft, Marco ED - Soukka, T. T1 - Explaining the influence of dopant concentration and excitation power density on the luminescence and brightness of β-NaYF4:Yb3+,Er3+ nanoparticles: Measurements and simulations N2 - We assessed the influence of Yb3+ and Er3+ dopant concentration on the relative spectral distribution, quantum yield (  UC), and decay kinetics of the upconversion luminescence (UCL) and particle brightness (BUC) for similarly sized (33 nm) oleate-capped -NaYF4:Yb3+,Er3+ upconversion (UC) nanoparticles (UCNPs) in toluene at broadly varied excitation power densities (P). This included an Yb3+ series where the Yb3+ concentration was varied between 11%–21% for a constant Er3+ concentration of 3%, and an Er3+ series, where the Er3+ concentration was varied between 1%–4% for a constant Yb3+ concentration of 14%. The results were fitted with a coupled rate equation model utilizing the UCL data and decay kinetics of the green and red Er3+ emission and the Yb3+ luminescence at 980 nm. An increasing Yb3+ concentration favors a pronounced triphotonic population of 4F9/2 at high P by an enhanced back energy transfer (BET) from the 4G11/2 level. Simultaneously, the Yb3+-controlled UCNPs absorption cross section overcompensates for the reduction in  UC with increasing Yb3+ concentration at high P, resulting in an increase in BUC. Additionally, our results show that an increase in Yb3+ and a decrease in Er3+ concentration enhance the color tuning range by P. These findings will pave the road to a deeper understanding of the energy transfer processes and their contribution to efficient UCL, as well as still debated trends in green-to-red intensity ratios of UCNPs at different P. KW - Nanoparticle KW - Lanthanide KW - Upconversion nanoparticle KW - Fluorescence KW - Integration sphere spectroscopy KW - Mechanism KW - Lifetime, synthesis KW - Surface chemistry KW - Yb(III) KW - Er(III) KW - Energy transfer KW - Absolute measurement KW - Quantum yield PY - 2019 DO - https://doi.org/10.1007/s12274-019-2450-4 SN - 1998-0124 SN - 1998-0000 VL - 12 IS - 8 SP - 1871 EP - 1879 PB - Springer AN - OPUS4-48880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Würth, Christian A1 - Frenzel, Florian A1 - Grauel, Bettina A1 - Weigert, Florian A1 - Wegner, Karl David T1 - Nanocrystals with Luminescence in the vis, NIR and SWIR – Photophysics and Applications N2 - Luminescent nanocrystals like core/shell semiconductor quantum dots and lanthanide doped nanophosphors as well as gold nanoclusters with emission in the visible (vis) and particularly in the near infrared (NIR) and short wavelength infrared (SWIR) region have been increasingly used as reporters in the life sciences and for bioimaging studies in the last years. This has led to sophisticated core-shell particle architectures of different chemical composition utilizing semiconductor quantum dots and lanthanide-based nanocrystals and initiated the design of gold nanoclusters with different ligands. In addition, this led to an increasing number of quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield to identify optimum particle structures. In the following, an overview of different classes of nanocrystalline emitters and their photophysics is provided and examples for the absolute characterization of the photoluminescence properties of these different vis/NIR/SWIR emitters are shown including excitation power density-dependent studies on the ensemble and single particle level. Also, the impact of such measurements on a profound mechanistic understanding of the underlying nonradiative deactivation pathways is highlighted as required for reporter design. T2 - MIMIT 2019 CY - Peking, People's Republic of China DA - 18.10.2019 KW - Fluorescence KW - Quantum yield KW - Integrating sphere spectroscopy KW - Dye KW - Nanocrystal KW - NIR KW - SWIR KW - Quantum dot KW - Lanthanide nanoparticle KW - Old nanocrystal KW - Imaging KW - Lifetime KW - Nanoparticle PY - 2019 AN - OPUS4-49361 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Pauli, Jutta A1 - Würth, Christian A1 - Güttler, Arne A1 - Richter, Maria A1 - Schneider, Thomas T1 - Determining Photoluminescence Quantum Yields of Molecular and Nanocrystal Emitters in the UV/vis/NIR/SWIR N2 - The comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters require accurate and quantitative photo-luminescence measurements. This is of special importance for all photoluminescence applications in the life and material sciences and nanobiophotonics. In the following, procedures for the determination of the spectroscopic key parameter photoluminescence quantum yield, i.e., the number of emitted per absorbed photons, in the UV/vis/NIR/SWIR are presented including pitfalls and achievable uncertainties and material-specific effects related to certain emitter classes are addressed. T2 - Kolloqium National Center for Nanoscience and Technology CY - Peking, People's Republic of China DA - 18.10.2019 KW - Fluorescence KW - Quantum yield KW - Integrating sphere spectroscopy KW - Dye KW - Nanocrystal KW - NIR KW - SWIR KW - Quantum dot KW - Fluorescence standard KW - Uncertainty KW - Calibration PY - 2019 AN - OPUS4-49362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schoder, S. A1 - Schröder, H. V. A1 - Cera, L. A1 - Puttreddy, R. A1 - Güttler, Arne A1 - Resch-Genger, Ute A1 - Rissanen, K. A1 - Schalley, C. A. T1 - Strong Emission Enhancement in pH-Responsive 2:2 Cucurbit[8]uril Complexes N2 - Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional conformational restriction of rotations around the aryl/aryl bonds. Because the cucurbituril complexes are pH switchable, this system represents an efficient supramolecular ON/OFF fluorescence switch. KW - Sensor KW - pH KW - Dye KW - Supramolecular chemistry KW - Synthesis KW - Host-guest interaction KW - Fluorescence KW - Enhancement KW - Curcubituril KW - Macrocyclus KW - Solid state PY - 2019 DO - https://doi.org/10.1002/chem.201806337 SN - 0947-6539 VL - 25 IS - 13 SP - 3257 EP - 3261 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-47599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tillo, Adam A1 - Bartelmeß, Jürgen A1 - Chauhan, Vraj P. A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Microfluidic Device for the Determination of Water Chlorination Levels Combining a Fluorescent meso-Enamine Boron Dipyrromethene Probe and a Microhydrocyclone for Gas Bubble Separation N2 - Chlorination procedures are commonly applied in swimming pool water and wastewater treatment, yet also in food, pharmaceutical, and paper production. The amount of chlorine in water needs to be strictly controlled to ensure efficient killing of pathogens but avoid the induction of negative health effects. Miniaturized microfluidic fluorescence sensors are an appealing approach here when aiming at online or at-site measurements. Two meso-enamine-substituted boron dipyrromethene (BODIPY) dyes were found to exhibit favorable indication properties, their reaction with hypochlorite leading to strong fluorescence enhancement. Real-time assays became possible after integration of these fluorescent probes with designed two-dimensional (2D) and three-dimensional (3D) microfluidic chips, incorporating a passive sinusoidal mixer and a microhydrocyclone, respectively. A comparison of the two microfluidic systems, including their abilities to prevent accumulation or circulation of microbubbles produced by the chemical indication reaction, showed excellent fluidic behavior for the microhydrocyclone-based device. After coupling to a miniaturized optical reader for fluorescence detection, the 2D microfluidic system showed a promising detection range of 0.04−0.5 mg L−1 while still being prone to bubble-induced fluctuations and suffering from considerably low signal gain. The microhydrocyclone-based system was distinctly more robust against gas bubbles, showed a higher signal gain, and allowed us to halve the limit of detection to 0.02 mg L−1. The use of the 3D system to quantify the chlorine content of swimming pool water samples for sensitive and quantitative chlorine monitoring was demonstrated. KW - Chlorine KW - BODIPY KW - Fluorescence KW - Micro-Hydrocyclone KW - Microfluidic Chip PY - 2019 DO - https://doi.org/10.1021/acs.analchem.9b03039 SN - 0003-2700 VL - 91 IS - 20 SP - 12980 EP - 12987 PB - American Chemical Society CY - Washington, DC AN - OPUS4-49393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Valderrey, Virginia A1 - Kislenko, Evgeniia A1 - Kimani, Martha Wamaitha A1 - Rurack, Knut T1 - Fluorescent Molecularly Imprinted Polymers N2 - The development of new strategies for the sensing of phosphorylated and carboxylate-containing biomolecules such as phosphorylated tyrosine and histidine or sialic acid is currently of strong interest because those molecules are often involved in cancerous processes. Molecularly Imprinted Polymers (MIPs) are formed through the polymerization of a set of functional monomers and cross-linkers in the presence of a target molecule or an analogue of it. The target molecule is incorporated into the polymer network due to non-covalent interactions established with one or more functional monomers. Because those interactions are weak, the target molecule can be desorbed a posteriori from the polymer matrix, leaving imprinted cavities of complementary size, shape and electronic nature. Resembling the antigen-binding site of an antibody, MIPs can then be highly selective towards the target molecule. Besides these features, our approach involves also the use of functional fluorescent monomers which undergo fluorescence changes upon binding of the target molecule. This allows us to investigate the sensing process using fluorescence as a highly sensitive read-out. To that aim we present here the use of silica particles which contain a MIP shell formed by thiourea or guanidinium functionalized dyes for the recognition of phosphorylated and carboxylate-containing molecules of biological relevance in polar, protic solvents. T2 - ANAKON 2019 CY - Münster, Germany DA - 25.03.2019 KW - Molecularly Imprinted Polymers KW - Fluorophores KW - Fluorescence PY - 2019 AN - OPUS4-47919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wang, Cui A1 - Otto, S. A1 - Dorn, M. A1 - Heinze, K. A1 - Resch-Genger, Ute T1 - Ratiometric Nanosensors for Simultaneously “TOP” Measuring Temperature, Oxygen and pH at a Single Excitation Wavelength N2 - In summary, by combining the NIR-emissive [Cr(ddpd)2][BPh4]3 complex CrBPh4 with its extremely large energy gap between the longest wavelength absorption and emission maxima with a pH-responsive fluorescein derivative (FITC) and an inert reference dye like Nile Red (NR) and 5,10,15,20tetrakis(pentafluorophenyl) porphyrin (TFPP), we developed nanosensors for simultaneously sensing temperature, O2 partial pressure, and pH. These novel TOP nanosensors (temperature, oxygen, pH) cover the biologically and physiologically relevant concentration ranges of these parameters/analytes with single wavelength excitation in PBS buffer and in a cell culture medium containing bovine serum albumin (BSA). The response of both nanosensors to all parameters is fully reversible and only minimally affected by the presence of BSA, the most common serum albumin. Moreover, comparative studies with nanosensors containing only a single type of stimuli-responsive molecule and with the respective molecular systems revealed that the different sensor components do not interfere with each other. Future research will include the testing of these nanosensors in cellular uptake studies and, after surface modification with targeted bioligands, eventually in in vivo experiments as previously done by some of us with other polystyrene nanoparticle reporters and nanosensors.46,47 Moreover, this concept of multianalyte sensing will be expanded to nanosensors derived from differently sized premanufactured biocompatible polymer particles and different stimuli-responsive dyes like fluorescent indicators for biologically and bioanalytically relevant metal ions. T2 - ISPPCC 2019 CY - Hong Kong, China DA - 14.07.2019 KW - Medical diagnostics KW - Sensor KW - Nnanoparticle KW - Nanosensor KW - Fluorescence KW - Oxygen KW - Temperature KW - Ratiometric KW - PH KW - Lifetime KW - NIR KW - Cr(III) complex KW - FITC KW - Dye KW - Environment PY - 2019 AN - OPUS4-49698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wang, Cui A1 - Resch-Genger, Ute A1 - Otto, S. A1 - Dorn, M. A1 - Heinze, K. T1 - Ratiometric luminescent TOP nanosensors for simultaneously measuring temperature, oxygen, and pH at a single excitation wavelength N2 - Two nanosensors for simultaneous optical measurements of temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with the near infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3 CrBPh4)[1][2] and an inert reference fluorescence dye (Nile Red NR or 5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin TFPP) and are covalently labeled with the pH-sensitive fluorophore fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal distinguishable emission spectra suitable for ratiometric intensity-based and time-resolved studies in the visible and near infrared spectral region. The core-shell nanostructure of these sensors reveals high colloidal stability in various aqueous media. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of the TOP nanosensors for optically detecting the three bioanalytically and biologically relevant analytes temperature, oxygen and pH simultaneously at the same position. T2 - 2nd European Biosensor Symposium CY - Florenz, Italy DA - 18.02.2019 KW - Sensor KW - Nanoparticle KW - Nanosensor KW - Fluorescence KW - Oxygen KW - Temperature KW - pH KW - Ratiometric KW - Lifetime KW - NIR KW - Cr(III) complex KW - FITC KW - Dye KW - Environment KW - Medical diagnostics PY - 2019 AN - OPUS4-47700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Cui A1 - Otto, S. A1 - Dorn, M. A1 - Heinze, K. A1 - Resch-Genger, Ute T1 - Luminescent TOP nanosensors for simultaneously measuring temperature, oxygen, and pH at a single excitation wavelength N2 - Two nanosensors for simultaneous optical measurements of the bioanalytically and biologically relevant analytes temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nmsized silica-coated polystyrene nanoparticles (PS-NPs) doped with a near-infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3, CrBPh4) and an inert reference dye (Nile Red, NR or 5,10,15,20tetrakis(pentafluorophenyl) porphyrin, TFPP) and are covalently labeled with pHsensitive fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal spectrally distinguishable emission bands, allowing for ratiometric intensity-based and time-resolved studies in the visible and near-infrared wavelength region. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of these nanosensors for the sensitive luminescence readout of TOP simultaneously at the same spatialposition. KW - Medical diagnostics KW - Sensor KW - Nanoparticle KW - Fluorescence KW - Nanosensor KW - Oxygen KW - Temperature KW - pH KW - Ratiometric KW - Lifetime KW - NIR KW - Cr(III) complex KW - Dye KW - FITC KW - Environment PY - 2019 DO - https://doi.org/10.1021/acs.analchem.8b05060 SN - 0003-2700 VL - 91 IS - 3 SP - 2337 EP - 2344 PB - ACS AN - OPUS4-47455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wang, Cui A1 - Resch-Genger, Ute A1 - Otto, S. A1 - Dorn, M. A1 - Heinze, K. T1 - Luminescent TOP nanosensors for simultaneously measuring temperature, oxygen, and pH at a single excitation wavelength N2 - Two nanosensors for simultaneous optical measurements of temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with the near infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3 CrBPh4)[1][2] and an inert reference fluorescence dye (Nile Red NR or 5,10,15,20tetrakis-(pentafluorophenyl) porphyrin TFPP) and are covalently labeled with the pHsensitive fluorophore fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal distinguishable emission spectra suitable for ratiometric intensity-based and time-resolved studies in the visible and near infrared spectral region. The core-shell nanostructure of these sensors reveals high colloidal stability in various aqueous media. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of the TOP nanosensors for optically detecting the three bioanalytically and biologically relevant analytes temperature, oxygen and pH simultaneously at the same position. T2 - ANAKON 2019 CY - Münster, Germany DA - 25.03.2019 KW - Sensor KW - Nanoparticle KW - Nanosensor KW - Fluorescence KW - Oxygen KW - Temperature KW - pH KW - Ratiometric KW - Lifetime KW - NIR KW - Cr(III) complex KW - FITC KW - Dye KW - Environment KW - Medical diagnostics PY - 2019 AN - OPUS4-47698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -