TY - JOUR A1 - Wang, P. A1 - Morales-Marquez, R. A1 - Cervas, G. A1 - Hernandez Medel, A. A1 - Ogayar, M. P. A1 - Jimenez de Aberasturi, D. A1 - de Isidro-Gomez, A. I. A1 - Torres-Padro, A. A1 - Palomares, F. J. A1 - Garcia-Orrit, S. A1 - Sousa, C. T. A1 - Espinosa, A. A1 - Telle, H. H. A1 - Ortgies, D. H. A1 - Vega-Mayoral, V. A1 - Cabanillas-Gonzalez, J. A1 - Rodriguez, E. M. A1 - Resch-Genger, Ute A1 - Wegner, Karl David A1 - Juarez, B. H. T1 - The role of temperature in the photoluminescence quantum yield (PLQY) of Ag2S-based nanocrystals N2 - Highly emissive Ag2S nanocrystals (NCs) passivated with a gradated shell incorporating Se and Zn were synthesized in air, and the temperature dependence of their photoluminescence quantum yield (PLQY) was quantified in both organic and aqueous media at B1200 nm. The relevance of this parameter, measured at physiological temperatures, is highlighted for applications that rely on the near infrared (NIR) photoluminescence of NCs, such as deep NIR imaging or luminescence nanothermometry. Hyperspectral NIR imaging shows that Ag2S-based NCs with a PLQY in organic media of about 10% are inefficient for imaging at 40 8C through 20 mm thick tissue with low laser irradiation power densities. In contrast, water-transferred Ag2S-based NCs with an initial PLQY of 2% in water exhibit improved robustness against temperature changes, enabling improved imaging performance. KW - Quantum dots KW - Ag2S KW - Fluorescence KW - Nanomaterial design KW - Advanced nanomaterials KW - Shortwave infrared (SWIR) KW - Temperature sensing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613877 DO - https://doi.org/10.1039/D4MH01016G SP - 1 EP - 11 PB - Royal Society of Chemistry (RSC) AN - OPUS4-61387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schlögl, Johanna A1 - Krappe, Alexander R. A1 - Fürstenwerth, Paul C. A1 - Brosius, Amelie L. A1 - Fasting, Carlo A1 - Hoffmann, Kurt F. A1 - Resch-Genger, Ute A1 - Eigler, Siegfried A1 - Steinhauer, Simon A1 - Riedel, Sebastian T1 - Luminescent Perhalofluoro Trityl Radicals N2 - In this proof-of-concept study, we show that polyfluorinated trityl radicals with the, to this date, highest fluorination grade can be accessed in quantitative yields in a straightforward manner starting from the perfluorinated trityl cation. The trityl skeleton is functionalized with trimethylsilyl halides to yield perhalofluoro trityl cations, which are subsequently reduced using commercial zinc powder. In this way, we prepare three perhalofluoro trityl radicals and analyze the impact of the fluorine ligands on their electro-optical properties, revealing some interesting trends. In comparison to literature-known polychlorinated trityl radicals, the new polyfluorinated derivatives exhibit substantially higher fluorescence quantum yields, longer luminescence lifetimes, and an expanded emission range that extends into the yellow spectral region. They further display enhanced photostability under light irradiation. In radical-stained polystyrene nanoparticles, an additional broad emission band in the red−NIR wavelength region is observed, which is attributed to excimer formation. Finally, the stability of the new radicals is investigated under ambient conditions, showing the slow conversion with atmospheric oxygen yielding the respective peroxides, which are characterized by single-crystal X-ray diffraction. All in all, our study extends the present scope of luminescent trityl radicals, as the functionalization of the perfluorinated cationic precursor unlocks the path toward a vast variety of polyfluorinated trityl radicals. KW - Dye KW - Fluorescence KW - Radical KW - Synthesis KW - Mechanism KW - Signal enhancement KW - Nano KW - Particle KW - Characterization KW - Quantum yield KW - Photophysics KW - Lifetime KW - Polarity KW - Polymer KW - Solvatchromism KW - Excimer PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647973 DO - https://doi.org/10.1021/jacs.5c16418 SN - 0002-7863 VL - 147 IS - 46 SP - 1 EP - 8 PB - American Chemical Society (ACS) AN - OPUS4-64797 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bertorelle, F. A1 - Wegner, Karl David A1 - Berkulic, M. P. A1 - Fakhouri, H. A1 - Comby-Zerbino, C. A1 - Sagar, A. A1 - Bernadó, P. A1 - Resch-Genger, Ute A1 - Bonacic-Koutecký, V. A1 - Le Guével, X. A1 - Antoine, R. T1 - Tailoring the NIR-II Photoluminescence of Single Thiolated Au25 Nanoclusters by Selective Binding to Proteins N2 - Atomically precise gold nanoclusters are a fascinating class of nanomaterials that exhibit molecule-like properties and have outstanding photoluminescence (PL). Their ultrasmall size, molecular chemistry, and biocompatibility make them extremely appealing for selective biomolecule labeling in investigations of biological mechanisms at the cellular and anatomical levels. In this work, we report a simple route to incorporate a preformed Au25 nanocluster into a model bovine serum albumin (BSA) protein. A new approach combining small-angle X-ray scattering and molecular modeling provides a clear localization of a single Au25 within the protein to a cysteine residue on the gold nanocluster surface. Attaching Au25 to BSA strikingly modifies the PL properties with enhancement and a redshift in the second near-infrared (NIR-II) window. This study paves the way to conrol the design of selective sensitive probes in biomolecules through a ligand-based strategy to enable the optical detection of biomolecules in a cellular environment by live imaging. KW - Fluorescence KW - Aggregation KW - Signal enhancement KW - Cluster KW - Nano KW - Metal KW - NIRII KW - SWIR KW - Sensor KW - Quantum yield KW - Lifetime KW - Photophysics KW - Synthesis KW - Protein KW - Imaging KW - Bioimaging KW - Ligand KW - Gold PY - 2022 DO - https://doi.org/10.1002/chem.202200570 SN - 1521-3765 VL - 28 IS - 39 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim AN - OPUS4-55077 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Wang, Cui A1 - You, Y. A1 - Förster, C. A1 - Schubert, H. A1 - Heinze, K. A1 - Seitz, M. T1 - NIR-NIR-Aufkonvertierung in molekularen Chrom-Ytterbium-Salzen N2 - Photonen-Aufkonvertierung in hetero-oligonuklearen, Metallkomplex-Architekturen mit organischen Liganden ist ein interessantes, aber bisher selten beobachtetes Phänomen, trotz des großen Potentials sowohl aus Sicht der Grundlagenforschung als auch aus der Anwendungsperspektive. Nun wurde ein neues photonisches Material aus molekularen Chrom(III)- und Ytterbium(III)-Komplexionen entwickelt. Dieses zeigt im Festkörper bei Raumtemperatur abhängig von der Anregungsleistungsdichte nach Anregung des 2F7/2! 2F5/2-3berganges des Ytterbiums bei ca. 980 nm eine kooperative Sensibilisierung der Chrom(III)-zentrierten 2E/2T1-Phosphoreszenz bei ca. 775 nm. Der Aufkonvertierungsprozess ist unempfindlich gegenüber Luftsauerstoff und kann in Gegenwart von Wassermolekülen im Kristallgitter beobachtet werden. KW - Crystal KW - Sensor KW - NIR KW - Yb(III) complex KW - Cr(III) KW - Upconversion PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517217 DO - https://doi.org/10.1002/ange.202007200 VL - 132 IS - 42 SP - 18804 EP - 18808 PB - Angewandte Chemie AN - OPUS4-51721 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geißler, Daniel A1 - Wegner, Karl David A1 - Fischer, C. A1 - Resch-Genger, Ute T1 - Exploring Simple Particle-Based Signal Amplification Strategies in a Heterogeneous Sandwich Immunoassay with Optical Detection N2 - Heterogeneous sandwich immunoassays are widely used for biomarker detection in bioanalysis and medical diagnostics. The high analyte sensitivity of the current “gold standard” enzyme-linked immunosorbent assay (ELISA) originates from the signal-generating enzymatic amplification step, yielding a high number of optically detectable reporter molecules. For future point-of-care testing (POCT) and point-of-need applications, there is an increasing interest in more simple detection strategies that circumvent time-consuming and temperature-dependent enzymatic reactions. A common concept to aim for detection limits comparable to those of enzymatic amplification reactions is the usage of polymer nanoparticles (NP) stained with a large number of chromophores. We explored different simple NP-based signal amplification strategies for heterogeneous sandwich immunoassays that rely on an extraction-triggered release step of different types of optically detectable reporters. Therefore, streptavidinfunctionalized polystyrene particles (PSP) are utilized as carriers for (i) the fluorescent dye coumarin 153 (C153) and (ii) hemin (hem) molecules catalyzing the luminol reaction enabling chemiluminescence (CL) detection. Additionally, (iii) NP labeling with hemin-based microperoxidase MP11 was assessed. For each amplification approach, the PSP was first systematically optimized regarding size, loading concentration, and surface chemistry. Then, for an immunoassay for the inflammation marker C- eactive protein (CRP), the analyte sensitivity achievable with optimized PSP ystems was compared with the established ELISA concept for photometric and CL detection. Careful optimization led to a limit of detection (LOD) of 0.1 ng/mL for MP11-labeled PSP and CL detection, performing similarly well to a photometric ELISA (0.13 ng/mL), which demonstrates the huge potential of our novel assay concept. KW - Nanoparticle KW - Fluorescence KW - Immunoassay KW - Quality assurance KW - Antibody KW - Polymer KW - Dye KW - Signal enhancement KW - CRP KW - Biosensing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597853 DO - https://doi.org/10.1021/acs.analchem.3c03691 SN - 1520-6882 VL - 96 IS - 13 SP - 5078 EP - 5085 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-59785 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Fallisch, A. A1 - Petrov, E. P. A1 - Salhany, R. A1 - Forthman, C. A1 - Guttenberg, Z. A1 - Nitschke, R. T1 - Spectral fluorescence standards for the calibration and performance validation of fluorescence microscopes N2 - The standardization and calibration of fluorescence microscopy have become increasingly vital due to the wide-spread use of in life and materials sciences. As the demand for reliable and user-friendly methods to assess micro-scope performance grows, universal calibration tools accessible to both researchers and vendors are needed. To support the standardization of characterization methods in microscopy, it is crucial to provide calibration tools together with standardized operating procedures for their effective implementation. The public-funded project "FluMiKal"* develops calibration tools in the shape of typical microscopic slides to assess key parameters such as spatial resolution, point spread function, spectral sensitivity, linearity and sensitivity of the detection system. The focus is on creating calibration tools that are user-friendly, robust, and versatile in their application. This work addresses the critical parameter of wavelength-dependent spectral sensitivity, which affects the meas-ured signals from the instrument side, yielding instrument-specific data and instrument aging-induced changes over time. For this purpose, μ-slides from ibidi with six channels are used, allowing them to be filled with different solutions containing molecular or nanoscale fluorophores with well-characterized absorption and fluorescence properties. The certified spectral fluorescence standards BAM-F003, F004, F005, and F007 assessed provided as ethanolic solutions by the Federal Institute for Materials Research and Testing (BAM), cover a broad spectral range from the blue to the near-infrared [1], [2]. Dye-based slide prototypes have been used to determine the spectral sensitivity of confocal microscopes from different vendors with various detector types by acquiring the spectral data of the BAM dyes under standardized measurement conditions, demonstrating the applicability of this concept. Proof-of-concept experiments could demonstrate the proper sealing of the slides. Further experiments will explore long-term stability and their potential as standards for relative intensity calibrations. * FluMiKal is funded by the Federal Ministry for Economic Affairs and Climate Action, Germany (WIPANO FKZ 03TN0047B) [1] doi: 10.1007/4243_2008_028. [2] doi: 10.1007/s00216-024-05723-w. T2 - European Light Microscopy Initiative - ELMI 2025 CY - Heidelberg, Germany DA - 03.06.2025 KW - Fluorescence KW - Advanced material KW - Validation KW - Calibration KW - Method comparison KW - Reference material KW - Dye KW - Fluorescence standard KW - Microscopy KW - CLSM KW - Imaging PY - 2025 AN - OPUS4-64206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koshkina, Olga A1 - Bantz, C. A1 - Würth, Christian A1 - Lang, Thomas A1 - Resch-Genger, Ute A1 - Maskos, Michael T1 - Fluorophore-labeled siloxane-based nanoparticles for biomedical applications N2 - We present the synthesis and characterization of multifunctional fluorophore-labeled poly(organosiloxane) nanoparticles with core-shell architecture, where the fluorescent dye is incorporated into the core. Grafting of heterobifunctional poly(ethylene oxide) (PEO) onto the particle surface leads to water-soluble biocompatible nanoparticles. Two different strategies have been used for the synthesis: The encapsulation of dye-labeled monomers during the polycondensation with additional PEO coating and subsequent dye labeling by covalent attachment of the fluorescent dye rhodamine B to the (chloromethylphenyl)siloxane groups in the core after polymerization and grafting of PEO onto the surface. Comparison of the fluorescence quantum yields of the nanoparticles before and after PEO coating show a decrease in quantum yield after PEO coating. KW - Biocompatibility KW - Core-shell KW - Fluorescence KW - Fluorescence quantum yield KW - Nanoparticles KW - PEO PY - 2011 DO - https://doi.org/10.1002/masy.201100041 SN - 1022-1360 SN - 0258-0322 SN - 1521-3900 VL - 309/310 IS - 1 SP - 141 EP - 146 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Engel, A. A1 - Ottermann, C. A1 - Resch-Genger, Ute A1 - Hoffmann, Katrin A1 - Schweizer, S. A1 - Selling, J. A1 - Spaeth, J.-M. A1 - Rupertus, V. ED - Grzymala, R. ED - Haeberlé, O. T1 - Glass based fluorescence reference materials used for optical and biophotonic applications N2 - Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools and detection methods for product and process control, material sciences, environmental and biotechnical analysis, molecular genetics, cell biology, medical diagnostics, and drug screening. For routine measurements by fluorescence techniques the existence of an improved quality assurance is one of the basic needs. According to DIN/ISO 17025 certified standards are used for fluorescence diagnostics having the drawback of giving relative values only. Typical requirements onto fluorescence reference materials or standards deal with the verification of the instrument performance as well as the improvement of the data comparability. Especially for biomedical applications fluorescence labels are used for the detection of proteins. In particular these labels consist of nano crystalline materials like CdS and CdSe. The field of Non-Cadmium containing materials is under investigation. In order to evaluate whether glass based materials can be used as standards it is necessary to calculate absolute values like absorption/excitation cross sections or relative quantum yields. This can be done using different quantities of dopands in glass, glass ceramics or crystals. The investigated materials are based on different types of glass, silicate, phosphate and boron glass, which play a dominant role for the absorption and emission mechanism. Additional to the so-called elementary fluorescence properties induced by raw earth elements the formation of defects lead to higher cross sections additionally. The main investigations deal with wavelength accuracy and lifetime of doped glasses, glass ceramics and crystalline samples. Moreover intensity patterns, homogeneity aspects and photo stability will be discussed. KW - Fluorescence KW - Reference material KW - Glass KW - Glass ceramics KW - Biophotonic KW - Multiplexing PY - 2006 DO - https://doi.org/10.1117/12.663627 SN - 1605-7422 VL - 6191 SP - 619110-1-619110-10 AN - OPUS4-14429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Würth, Christian A1 - González, M.G. A1 - Niessner, R. A1 - Panne, Ulrich A1 - Haisch, C. A1 - Resch-Genger, Ute T1 - Determination of the absolute fluorescence quantum yield of rhodamine 6G with optical and photoacoustic methods - providing the basis for fluorescence quantum yield standards N2 - To establish the methodical basis for the development and certification of fluorescence quantum yield standards, we determined the fluorescence quantum yield Φf of rhodamine 6G (R6G) with two absolute methods with complementary measurement principles, here optical spectroscopy using an integrating sphere setup and pulsed laser photoacoustic spectroscopy (PAS). For the assessment of aggregation- and reabsorption-induced distortions of measured fluorescence quantum yields and procedures for the reliable consideration of such effects, this systematic comparison was performed in ethanol and in water employing different concentrations of R6G. In addition, the relative and absolute fluorescence quantum yields of these solutions were obtained with a calibrated spectrofluorometer and a commercialized integrating sphere setup. Based upon this systematic comparison, experimental advantages and systematic sources of variation were identified for both methods. KW - Fluorescence KW - Photoluminescence KW - Quantum yield KW - Photoacoustic spectroscopy KW - Absolute quantum yield KW - Integrating sphere KW - Rhodamine 6G KW - Aggregation KW - Reabsorption PY - 2012 DO - https://doi.org/10.1016/j.talanta.2011.12.051 SN - 0039-9140 VL - 90 SP - 30 EP - 37 PB - Elsevier CY - Amsterdam AN - OPUS4-25710 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heckmann, A. A1 - Dümmler, S. A1 - Pauli, Jutta A1 - Margraf, M. A1 - Köhler, J. A1 - Stich, D. A1 - Lambert, C. A1 - Fischer, I. A1 - Resch-Genger, Ute T1 - Highly fluorescent open-shell NIR dyes: the time-dependence of back electron transfer in triarylamine-perchlorotriphenylmethyl radicals KW - Triarylamine-perchlorotriphenylmethyl radical KW - Dono-acceptor compounds KW - CT state KW - Fluorescence quantum KW - Yield KW - Life time PY - 2009 DO - https://doi.org/10.1021/jp908425w SN - 1932-7447 SN - 1089-5639 VL - 113 SP - 20958 EP - 20966 PB - Soc. CY - Washington, DC AN - OPUS4-20757 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stroyuk, O. A1 - Raievska, O. A1 - Barabash, A. A1 - Batentschuk, M. A1 - Osvet, A. A1 - Fiedler, Saskia A1 - Resch-Genger, Ute A1 - Hauch, J. A1 - Brabec, C. J. T1 - "Green" synthesis of highly luminescent lead-free Cs2AgxNa1-xBiyIn1-yCl6 perovskites N2 - A new “green” and mild synthesis of highly stable microcrystalline Cs2AgxNa1-xBiyIn1-yCl6 (CANBIC) perovskites under ambient conditions was developed that is scalable to the multi-gram production. Under UV illumination, the CANBIC perovskites emit intense broadband photoluminescence (PL) with a quantum yield (QY) of 92% observed for x = 0.35 and y = 0.01-0.02. The combination of strong UV absorbance and broadband visible emission, high PL QY, and long PL lifetimes of up to 1.4 μs, along with an outstanding stability makes these CANBICs a promising material class for many optical applications. KW - Fluorescence KW - Perovskites KW - Solar cell KW - Automated synthesis KW - Green synthesis KW - Quantum yield KW - Integrating sphere spectroscopy KW - Absolute fluorescence KW - Quality assurance KW - Nano KW - Particle KW - Application KW - Semiconductor KW - Quantum dot KW - Renewable energy PY - 2022 DO - https://doi.org/10.1039/d2tc02055f SN - 2050-7526 VL - 10 IS - 27 SP - 9938 EP - 9944 PB - Royal Society of Chemistry AN - OPUS4-55453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, C. A1 - Schäferling, Michael A1 - Resch-Genger, Ute A1 - Gradzielski, M. T1 - Solvothermal Synthesis of Lanthanide-doped NaYF4 Upconversion N2 - Lanthanide-doped NaYF4 upconversion nano- and microcrystals were synthesized via a facile solvothermal approach. Thereby, the influence of volume ratios of ethylene glycol (EG)/H2O, molar ratios of NH4F/RE3+ (RE3+ represents the total amount of Y3+ and rare-earth dopant ions), Gd3+ ion contents, types of activator dopant ions, and different organic co-solvents on the crystal phase, size, and morphology of the resulting particles were studied systematically. A possible formation mechanism for the growth of crystals of different morphology is discussed. Our results show that the transition from the α- to the β-phase mainly depends on the volume ratio of EG/H2O and the molar ratio of NH4F/RE3+, while the morphology and size could be controlled by the type of organic co-solvent and Gd3+ dopant ions. Furthermore, the reaction time has to be long enough to convert α-NaYF4 into β-NaYF4 during the growth process to optimize the upconversion luminescence. The formation of larger β-NaYF4 crystals, which possess a higher upconversion luminescence than smaller particles, proceeds via intermediates of smaller crystals of cubic structure. In summary, our synthetic approach presents a facile route to tailor the size, Crystal phase, morphology, and luminescence features of upconversion materials. KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Photoluminescence KW - Lanthanide KW - Quantum yield KW - Photophysics KW - Lifetime KW - Surface chemistry KW - Single particle KW - Brightness KW - NIR KW - Synthesis PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520307 DO - https://doi.org/10.1002/cnma.202000564 VL - 7 IS - 2 SP - 174 EP - 183 PB - Wiley AN - OPUS4-52030 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Saleh, Maysoon I. A1 - Kembuan, C A1 - Rühle, Bastian A1 - Graf, C A1 - Resch-Genger, Ute T1 - Gold-shell coated NaYF4:Er3+, Yb3+ nanoparticles for the enhancement of fluorescence emission N2 - In the present work, we aim to explore how far the UCNP emission intensity can be enhanced by the aid of plasmonic interactions using a gold shell. The distance between the UCNP core and the gold shell is varied by adding a silica spacer of different thicknesses. The synthetic conditions for obtaining UCNP@SiO2@Au core-shell nanoparticles with precisely tuneable silica shell thicknesses were investigated. A gold shell on the UCNP@SiO2 nanoparticles is expected to give rise to a noticeable enhancement of particle brightness and fluorescence, given that the thicknesses of the silica shell and the gold coating can be controlled and fine-tuned. First single particle studies revealing shortening of the Er3+ lifetimes suggest that plasmonic enhancement occurs. T2 - 2nd Conference and Spring School on Properties, Design and Applications of Upconversion Nanomaterials CY - Valencia, Spain DA - 02.04.2018 KW - Upconversion nanoparticles KW - Silica coating KW - Plasmonic enhancement PY - 2018 AN - OPUS4-44969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mathejczyk, J. A1 - Pauli, Jutta A1 - Dullin, C. A1 - Napp, J. A1 - Tietze, L.-F. A1 - Kessler, H. A1 - Resch-Genger, Ute A1 - Alves, F. T1 - Spectroscopically well-characterized RGD optical probe as a prerequisite for lifetime-gated tumor imaging N2 - Labeling of RGD peptides with near-infrared fluorophores yields optical probes for noninvasive imaging of tumors overexpressing ανβ3 integrins. An important prerequisite for optimum detection sensitivity in vivo is strongly absorbing and highly emissive probes with a known fluorescence lifetime. The RGD-Cy5.5 optical probe was derived by coupling Cy5.5 to a cyclic arginine–glycine–aspartic acid–D-phenylalanine–lysine (RGDfK) peptide via an aminohexanoic acid spacer. Spectroscopic properties of the probe were studied in different matrices in comparison to Cy5.5. For in vivo imaging, human glioblastoma cells were subcutaneously implanted into nude mice, and in vivo fluorescence intensity and lifetime were measured. The fluorescence quantum yield and lifetime of Cy5.5 were found to be barely affected on RGD conjugation but dramatically changed in the presence of proteins. By time domain fluorescence imaging, we demonstrated specific binding of RGD-Cy5.5 to glioblastoma xenografts in nude mice. Discrimination of unspecific fluorescence by lifetime-gated analysis further enhanced the detection sensitivity of RGD-Cy5.5-derived signals. We characterized RGD-Cy5.5 as a strongly emissive and stable probe adequate for selective targeting of ανβ3 integrins. The specificity and thus the overall detection sensitivity in vivo were optimized with lifetime gating, based on the previous determination of the probés fluorescence lifetime under application-relevant conditions. KW - Time domain near-infrared fluorescence (NIRF) imaging KW - Fluorescence KW - Lifetime KW - Quantum yield KW - RGD-Cy5.5 KW - Spectroscopic analysis PY - 2011 DO - https://doi.org/10.2310/7290.2011.00018 SN - 1535-3508 SN - 1536-0121 VL - 10 IS - 6 SP - 469 EP - 480 PB - Decker CY - Hamilton, Ont. AN - OPUS4-25711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Ramírez, A. A1 - Crasselt, C. A1 - Schmidt, W. A1 - Resch-Genger, Ute T1 - Utilizing optical spectroscopy and 2',7'-difluorofluorescein to characterize the early stages of cement hydration N2 - The increasingly sophisticated nature of modern, more environmentally friendly cementitious binders requires a better understanding and control particularly of the complex, dynamic processes involved in the early phase of cement hydration. In-situ monitoring of properties of a constantly changing system over a defined period of time calls for simple, sensitive, fast, and preferably also non-invasive methods like optical spectroscopy KW - Flourescence KW - Optical probe KW - Sensor KW - Dye KW - Flourescin KW - Photophysics KW - PH KW - Quantum yield KW - Quality assurance KW - Mechanism KW - Cement KW - Concrete KW - Building material KW - Hydration KW - Process monitoring PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537176 DO - https://doi.org/10.1088/2050-6120/ac2da0 SN - 2050-6120 VL - 10 IS - 1 SP - 2 EP - 13 PB - IOP Science AN - OPUS4-53717 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholtz, Lena A1 - Eckert, J. G. A1 - Elahi, T. A1 - Lübkemann, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Luminescence encoding of polymer microbeads with organic dyes and semiconductor quantum dots during polymerization N2 - Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5–2.5 μm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate. KW - Polymerization KW - Quantum dots KW - Microbeads KW - Fluorescence PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-553430 DO - https://doi.org/10.1038/s41598-022-16065-x SN - 2045-2322 VL - 12 SP - 1 EP - 16 PB - Nature Publishing Group CY - London AN - OPUS4-55343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromer, C. A1 - Schwibbert, Karin A1 - Gadicherla, A. K. A1 - Thiele, Dorothea A1 - Nirmalananthan-Budau, Nithiya A1 - Laux, P. A1 - Resch-Genger, Ute A1 - Luch, A. A1 - Tschiche, H. R. T1 - Monitoring and imaging pH in biofilms utilizing a fluorescent polymeric nanosensor N2 - Biofilms are ubiquitous in nature and in the man-made environment. Given their harmful effects on human health, an in-depth understanding of biofilms and the monitoring of their formation and growth are important. Particularly relevant for many metabolic processes and survival strategies of biofilms is their extracellular pH. However, most conventional techniques are not suited for minimally invasive pH measurements of living biofilms. Here, a fluorescent nanosensor is presented for ratiometric measurements of pH in biofilms in the range of pH 4.5–9.5 using confocal laser scanning microscopy. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with pH-inert dye Nile Red and is surface functionalized with a pH-responsive fluorescein dye. Its performance was validated by fluorometrically monitoring the time-dependent changes in pH in E. coli biofilms after glucose inoculation at 37 °C and 4 °C. This revealed a temperature-dependent decrease in pH over a 4-h period caused by the acidifying glucose metabolism of E. coli. These studies demonstrate the applicability of this nanosensor to characterize the chemical microenvironment in biofilms with fluorescence methods. KW - Dye KW - Fluorescence KW - Signal enhancement KW - Sensor KW - Quantum yield KW - Synthesis KW - Nanoparticle KW - Nano KW - Polymer KW - Ph KW - Biofilm KW - MIC KW - Corrosion KW - Microorganism KW - Bacteria PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550751 DO - https://doi.org/10.1038/s41598-022-13518-1 SN - 2045-2322 VL - 12 IS - 1 SP - 1 EP - 10 PB - Nature Publishing Group CY - London AN - OPUS4-55075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stein, L. A1 - Wang, Cui A1 - Förster, C. A1 - Resch-Genger, Ute A1 - Heinze, K. T1 - Bulky ligands protect molecular ruby from oxygen quenching N2 - Chromium(III) complexes can show phosphorescence from the spin-flip excited doublet states 2E/2T1 in the near-infrared with high photoluminescence quantum yields and extremely long lifetimes in the absence of dioxygen. The prototype molecular ruby, [Cr(ddpd)2]3+ (ddpd = N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine), has a photoluminescence quantum yield and a luminescence lifetime of 13.7% and 1.1 ms in deaerated acetonitrile, respectively. However, its luminescence is strongly quenched by 3O2 via an efficient Dexter-type energy transfer process. To enable luminescence applications of molecular rubies in solution under aerobic conditions, we explored the potential of sterically demanding ddpd ligands to shield the chromium(III) center from O2 using steady state and time-resolved photoluminescence spectroscopy. The structures of the novel complexes with sterically demanding ligands were investigated by single crystal X-ray diffraction and quantum chemically by density functional theory calculations. The O2 sensitivity of the photoluminescence was derived from absolutely measured photoluminescence quantum yields and excited state lifetimes under inert and aerobic conditions and by Stern–Volmer analyses of these data. Optimal sterically shielded chromium(III) complexes revealed photoluminescence quantum yields of up to 5.1% and excited state lifetimes of 518 μs in air-saturated acetonitrile, underlining the large potential of this ligand design approach to broaden the applicability of highly emissive chromium(III) complexes. KW - Fluorescence KW - Synthesis KW - Production KW - Optical spectroscopy KW - Ligand KW - Photophysics KW - Cr(III) KW - Mechanism KW - NIR KW - Sensor KW - Oxygen PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570807 DO - https://doi.org/10.1039/d2dt02950b VL - 51 IS - 46 SP - 17664 EP - 17670 PB - The Royal Society of Chemistry CY - Berlin AN - OPUS4-57080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholtz, Lena A1 - Tavernaro, Isabella A1 - Eckert, J. G. A1 - Lutowski, Marc A1 - Geißler, Daniel A1 - Hertwig, Andreas A1 - Hidde, Gundula A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Influence of nanoparticle encapsulation and encoding on the surface chemistry of polymer carrier beads N2 - Surface-functionalized polymer beads encoded with molecular luminophores and nanocrystalline emitters such as semiconductor nanocrystals, often referred to as quantum dots (QDs), or magnetic nanoparticles are broadly used in the life sciences as reporters and carrier beads. Many of these applications require a profound knowledge of the chemical nature and total number of their surface functional groups (FGs), that control bead charge, colloidal stability, hydrophobicity, and the interaction with the environment and biological systems. For bioanalytical applications, also the number of groups accessible for the subsequent functionalization with, e.g., biomolecules or targeting ligands is relevant. In this study, we explore the influence of QD encoding on the amount of carboxylic acid (COOH) surface FGs of 2 μm polystyrene microparticles (PSMPs). This is done for frequently employed oleic acid and oleylamine stabilized, luminescent core/shell CdSe QDs and two commonly used encoding procedures. This included QD addition during bead formation by a thermally induced polymerization reaction and a post synthetic swelling procedure. The accessible number of COOH groups on the surface of QD-encoded and pristine beads was quantified by two colorimetric assays, utilizing differently sized reporters and electrostatic and covalent interactions. The results were compared to the total number of FGs obtained by a conductometric titration and Fourier transform infrared spectroscopy (FTIR). In addition, a comparison of the impact of QD and dye encoding on the bead surface chemistry was performed. Our results demonstrate the influence of QD encoding and the QD-encoding strategy on the number of surface FG that is ascribed to an interaction of the QDs with the carboxylic acid groups on the bead surface. These findings are of considerable relevance for applications of nanoparticle-encoded beads and safe-by-design concepts for nanomaterials. KW - Optical spectroscopy KW - Particle KW - Optical assay KW - IR spectroscopy KW - Fluorescence KW - Quantum yield KW - Quality assurance KW - Nano KW - Synthesis KW - Surface chemistry KW - Quantification KW - Method KW - Conductometry PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581502 DO - https://doi.org/10.1038/s41598-023-38518-7 SN - 2045-2322 VL - 13 IS - 1 SP - 1 EP - 15 PB - Springer Nature CY - London AN - OPUS4-58150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reiber, T. A1 - Hübner, Oskar A1 - Dose, C. A1 - Yushchenko, D. A. A1 - Resch-Genger, Ute T1 - Fluorophore multimerization on a PEG backbone as a concept for signal amplification and lifetime modulation N2 - Fluorescent labels have strongly contributed to many advancements in bioanalysis, molecular biology, molecular imaging, and medical diagnostics. Despite a large toolbox of molecular and nanoscale fluorophores to choose from, there is still a need for brighter labels, e.g., for flow cytometry and fluorescence microscopy, that are preferably of molecular nature. This requires versatile concepts for fluorophore multimerization, which involves the shielding of dyes from other chromophores and possible quenchers in their neighborhood. In addition, to increase the number of readout parameters for fluorescence microscopy and eventually also flow cytometry, control and tuning of the labels’ fluorescence lifetimes is desired. Searching for bright multi-chromophoric or multimeric labels, we developed PEGylated dyes bearing functional groups for their bioconjugation and explored their spectroscopic properties and photostability in comparison to those of the respective monomeric dyes for two exemplarily chosen fluorophores excitable at 488 nm. Subsequently, these dyes were conjugated with anti-CD4 and anti-CD8 immunoglobulins to obtain fluorescent conjugates suitable for the labeling of cells and beads. Finally, the suitability of these novel labels for fluorescence lifetime imaging and target discrimination based upon lifetime measurements was assessed. Based upon the results of our spectroscopic studies including measurements of fluorescence quantum yields (QY) and fluorescence decay kinetics we could demonstrate the absence of significant dye-dye interactions and self-quenching in these multimeric labels. Moreover, in a first fluorescence lifetime imaging (FLIM) study, we could show the future potential of this multimerization concept for lifetime discrimination and multiplexing. KW - Imaging KW - Quantum yield KW - Quality assurance KW - Antibody KW - Conjugate KW - Cell KW - FLIM KW - PEG KW - Flow cytometry KW - Lifetime KW - Energy transfer KW - Quantitative spectroscopy KW - Nano KW - Particle KW - Fluorescence KW - Dye KW - Amplification KW - Microscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602197 DO - https://doi.org/10.1038/s41598-024-62548-4 SN - 2045-2322 VL - 14 IS - 1 SP - 1 EP - 11 AN - OPUS4-60219 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohammad, W. A1 - Wegner, Karl David A1 - Comby-Zerbino, C. A1 - Trouillet, V. A1 - Ogayer, M. P. A1 - Coll, J.-L. A1 - Marin, R. A1 - Jaque Garcia, D. A1 - Resch-Genger, Ute A1 - Antoine, R. A1 - Le Guevel, X. T1 - Enhanced brightness of ultra-small gold nanoparticles in the second biological window through thiol ligand shell control N2 - Gold-based nanoparticles below 2 nm in size are promising as luminescent probes for in vivo bioimaging, owing to their brightness and rapid renal clearance. However, their use as contrast agents in the near-infrared II (NIR-II, 1000–1700 nm) range remains challenging due to their low photoluminescence (PL) quantum yield. To address this, PL enhancement can be achieved by either rigidifying the ligand-shell structure or increasing the size of the ligand shell. In this study, we synthesized ultra-small gold nanoparticles stabilized by co-ligands, namely monothiol and short dithiol molecules. By precisely controlling the amount of reducing agent used during particle preparation, we successfully modulated the physicochemical properties of the co-ligand shell, including its size, composition, and structure. Consequently, we achieved a remarkable 60-fold increase in the absorption cross-section at 990 nm while maintaining the small size of the 1.5-nm metal core. The analytical and optical characterization of our thiol-capped gold nanoparticles indicates that the ligand shell size is governed by the quantity of the reducing agent, which, in turn, impacts the balance between radiative and non-radiative processes, thereby influencing the PL quantum yield. KW - Gold nanocluster KW - NIR-II fluorescence KW - SWIR KW - Nanomaterial design KW - Calibrated fluorescence measurements PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-588117 DO - https://doi.org/10.1039/D3TC03021K SN - 2050-7526 VL - 11 IS - 42 SP - 14714 EP - 14724 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58811 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - López-Iglesias, C. A1 - Markovina, A. A1 - Nirmalananthan-Budau, N. A1 - Resch-Genger, Ute A1 - Klinger, D. T1 - Optically monitoring the microenvironment of a hydrophobic cargo in amphiphilic nanogels: influence of network composition on loading and release N2 - Amphiphilic nanogels (ANGs) are promising carriers for hydrophobic cargos such as drugs, dyes, and catalysts. Loading content and release kinetics of these compounds are controlled by type and number of hydrophobic groups in the amphiphilic copolymer network. Thus, understanding the interactions between cargo and colloidal carrier is mandatory for a tailor-made and cargo-specific ANG design. To systematically explore the influence of the network composition on these interactions, we prepared a set of ANGs of different amphiphilicity and loaded these ANGs with varying concentrations of the solvatochromic dye Nile Red (NR). Here, NR acts as a hydrophobic model cargo to optically probe the polarity of its microenvironment. Analysis of the NR emission spectra as well as measurements of the fluorescence quantum yields and decay kinetics revealed a decrease in the polarity of the NR microenvironment with increasing hydrophobicity of the hydrophobic groups in the ANG network and dye–dye interactions at higher loading concentrations. At low NR concentrations, the hydrophobic cargo NR is encapsulated in the hydrophobic domains. Increasing NR concentrations resulted in probe molecules located in a more hydrophilic environment, i.e., at the nanodomain border, and favored dye–dye interactions and NR aggregation. These results correlate well with release experiments, indicating first NR release from more hydrophilic network locations. Overall, our findings demonstrate the importance to understand carrier–drug interactions for efficient loading and controlled release profiles in amphiphilic nanogels. KW - Particle KW - Energy transfer KW - Limit of detection KW - Polymer KW - Luminescence KW - Quantitative spectroscopy KW - Nano KW - Quantum yield KW - Lifetime KW - Quality assurance KW - Dye KW - Probe KW - Sensor KW - Nile Red PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601603 DO - https://doi.org/10.1039/d4nr00051j SN - 2040-3364 IS - 16 SP - 9525 EP - 9535 PB - The Royal Society of Chemistry AN - OPUS4-60160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tavernaro, Isabella A1 - Sander, P. C. A1 - Andresen, Elina A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Expanding the Toolbox of Simple, Cost-Efficient, and Automatable Methods for Quantifying Surface Functional Groups on Nanoparticles� Potentiometric Titration N2 - Measuring surface functional groups (FGs) on nanomaterials (NMs) is essential for designing dispersible and stable NMs with tailored and predictable functionality. FG screening and quantification also plays a critical role for subsequent processing steps, NM long-term stability, quality control of NM production, and risk assessment studies and enables the implementation of sustainable and safe(r)-by-design concepts. This calls for simple and cost-efficient methods for broadly utilized FGs that can be ideally automated to speed up FG screening, monitoring, and quantification. To expand our NM surface analysis toolbox, focusing on simple methods and broadly available, cost-efficient instrumentation, we explored a NM-adapted pH titration method with potentiometric and optical readout for measuring the total number of (de)protonable FGs on representatively chosen commercial and custom-made aminated silica nanoparticles (SiO2 NPs). The accuracy and robustness of our stepwise optimized workflows was assessed by several operators in two laboratories and method validation was done by cross-comparison with two analytical methods relying on different signal generation principles. This included traceable, chemo-selective quantitative nuclear magnetic resonance spectroscopy (qNMR) and thermogravimetric analysis (TGA), providing the amounts of amino silanes released by particle dissolution and the total mass of the surface coatings. A comparison of the potentiometric titration results with the reporter-specific amounts of surface amino FGs determined with the previously automated fluorescamine (Fluram) assay highlights the importance of determining both quantities for surface-functionalized NMs. In the future, combined NM surface analysis with optical assays and pH titration will simplify quality control of NM production processes and stability studies and can yield large data sets for NM grouping that facilitates further developments in regulation and standardization. KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Synthesis KW - Characterization KW - Advanced material KW - Surface KW - Standardization KW - Reference material KW - Functional group KW - Quantification KW - Coating KW - Automation KW - Potentiometry KW - Method KW - Validation KW - Optical assay KW - Fluram KW - Fluorescamine KW - qNMR KW - Comparison KW - ILC PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642371 DO - https://doi.org/10.1021/acsmeasuresciau.5c00062 SN - 2694-250X SP - 1 EP - 13 PB - American Chemical Society CY - Washington, DC AN - OPUS4-64237 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deumer, J. A1 - Andresen, Elina A1 - Gollwitzer, C. A1 - Schürmann, R. A1 - Resch-Genger, Ute T1 - Adding More Shape to Nanoscale Reference Materials-LiYF4:Yb,Tm Bipyramids as Standards for Sizing Methods and Particle Number Concentration N2 - The increasing industrial use of nanomaterials calls for the reliable characterization of their physicochemical key properties like size, size distribution, shape, and surface chemistry, and test and reference materials (RMs) with sizes and shapes, closely matching real-world nonspheric nano-objects. An efficient strategy to minimize efforts in producing nanoscale RMs (nanoRMs) for establishing, validating, and standardizing methods for characterizing nanomaterials are multimethod nanoRMs. Ideal candidates are lanthanide-based, multicolor luminescent, and chemically inert nanoparticles (NPs) like upconversion nanoparticles (UCNPs), which can be prepared in different sizes, shapes, and chemical composition with various surface coatings. This makes UCNPs interesting candidates as standards not only for sizing methods, but also for element-analytical methods like laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), quantitative bioimaging methods like X-ray fluorescence computed tomography (XFCT), and luminescence methods and correlative measurements. Here, we explore the potential of two monodisperse LiYF4:Yb,Tm bipyramids with peak-to-peak distances of (43 ± 2) nm and (29 ± 2) nm as size standards for small-angle X-ray scattering (SAXS) and tools for establishing and validating the sophisticated simulations required for the analysis of SAXS data derived from dispersions of nonspheric nano-objects. These SAXS studies are supplemented by two-dimensional (2D)-transmission electron microscopy measurements of the UCNP bipyramids. Additionally, the particle number concentration of cyclohexane dispersions of these UCNP bipyramids is determined by absolute SAXS measurements, complemented by gravimetry, thermogravimetric analysis (TGA), and inductively coupled plasma optical emission spectrometry (ICP-OES). This approach enables traceable particle number concentration measurements of ligand-capped nonspheric particles with unknown chemical composition. KW - Fluorescence KW - Upconversion nanoparticles KW - SAXS KW - Particle number concentration KW - Reference material KW - Traceability KW - Quality assurance KW - Quantum yield KW - Spectroscopy KW - Synthesis KW - Quantification KW - NanoRM KW - Nano KW - Particle KW - Bipyramid KW - Reference data KW - Simulation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-617940 DO - https://doi.org/10.1021/acs.analchem.4c03641 SP - 1 EP - 8 PB - ACS Publications AN - OPUS4-61794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Otto, S. A1 - Förster, C. A1 - Wang, Cui A1 - Resch-Genger, Ute A1 - Heinze, K. T1 - A Strongly Luminescent Chromium(III) ComplexAcid N2 - The synthesis, structure, reactivity,and photophysical properties of anovel acidic,luminescentchromium(III) complex [Cr(H2tpda)2]3+ (23+ +)bearing the tridentate H2tpda (2,6-bis(2-pyridylamino)pyridine) ligand are presented. Excitation of 23+ + at 442 nm results in strong, long-lived NIR luminescence at 782 nm in water and in acetonitrile. X-ray diffraction analysis and IR spectroscopy revealhydrogen-bonding interactions of the counter ions to the NH groups of 23+ + in the solidstate. Deprotonation of the NH groups of 23+ + by using anon-nucleophilic Schwesinger base in CH3CN switches off the luminescence. Re-protonation by using HClO4 restores the emission. In water,the pKa value of 23+ + amountsto8 .8, yet deprotonation is not reversible in the presence of hydroxide ions. Dioxygen quenches the emission of 23+ +,but to aweaker extent than expected. This is possibly due to the strong ion-pairing properties of 23+ + even in solution, reducing the energy transfer efficiency to O2.Deuteration of the NH groups of 23+ + approximately doubles the quantum yield and lifetime in water,demonstrating the importance of multiphoton relaxation in these NIR emitters. KW - Cr(III) complex KW - Oxygen sensor KW - pH sensor KW - Luminescence KW - Luminescence lifetime KW - Quantum yield KW - NIR emitter PY - 2018 DO - https://doi.org/10.1002/chem.201802797 SN - 0947-6539 VL - 24 IS - 48 SP - 12555 EP - 12563 PB - Wiley‐VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-45929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ahiboz, D. A1 - Andresen, Elina A1 - Manley, P. A1 - Resch-Genger, Ute A1 - Würth, Christian A1 - Becker, C. T1 - Metasurface-Enhanced Photon Upconversion upon 1550 nm Excitation N2 - Photon upconversion upon 1550 nm excitation is of high relevance for applications in the third biological excitation window, for photovoltaics beyond current limitations, and enables appealing options in the field of glass Fiber telecommunications. Trivalent doped erbium ions (Er3+) are the material of choice for 1550 nm excited upconversion, however, they suffer from a low absorption cross-section and a low brightness. Therefore, the ability of Silicon metasurfaces to provide greatly enhanced electrical near-fields is employed to enable efficient photon upconversion even at low external Illumination conditions. Hexagonally shaped β-NaYF4:Er3+ nanoparticles are placed on large-area silicon metasurfaces designed to convert near-infrared (1550 nm) to visible light. More than 2400-fold enhanced photon upconversion luminescence is achieved by using this metasurface instead of a planar substrate. With the aid of optical simulations based on the finite-element method, this result is attributed to the coupling of the excitation source with metasurface resonances at appropriate incident angles. Analysis of the excitation power density dependence of upconversion luminescence and red-to-green-emission ratios enables the estimation of nanoscale near-field enhancement on the metasurface. The findings permit the significant reduction of required external excitation intensities for photon upconversion of 1550 nm light, opening perspectives in biophotonics, telecommunication, and photovoltaics. KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - Excitation power density KW - Single particle KW - Brightness KW - NIR KW - Mechanism KW - Single enhancement KW - SWIR KW - Method PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537193 DO - https://doi.org/10.1002/adom.202101285. SN - 2195-1071 VL - 9 IS - 24 SP - 2101285 PB - Wiley-VCH-GmbH AN - OPUS4-53719 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rühle, Bastian A1 - Resch-Genger, Ute A1 - Kembuan, C A1 - Graf, C T1 - Gold-shell coated NaYF4:Er3+, Yb3+ nanoparticles for the enhancement of fluorescence emission N2 - In the present work, we aim to explore how far the UCNP emission intensity can be enhanced by the aid of plasmonic interactions using a gold shell. The distance between the UCNP core and the gold shell is varied by adding a silica spacer of different thicknesses. The synthetic conditions for obtaining UCNP@SiO2@Au core-shell nanoparticles with precisely tuneable silica shell thicknesses were investigated. A gold shell on the UCNP@SiO2 nanoparticles is expected to give rise to a noticeable enhancement of particle brightness and fluorescence, given that the thicknesses of the silica shell and the gold coating can be controlled and fine-tuned. First single particle studies revealing shortening of the Er3+ lifetimes suggest that plasmonic enhancement occurs. T2 - 2nd Conference and Spring School on Properties, Design and Applications of Upconversion Nanomaterials CY - Valencia, Spain DA - 02.04.2018 KW - Upconversion nanoparticles KW - Silica coating KW - Plasmonic enhancement PY - 2018 AN - OPUS4-44958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholtz, Lena A1 - Eckert, J. G. A1 - Graf, Rebecca T. A1 - Kunst, A. A1 - Wegner, Karl David A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Correlating semiconductor nanoparticle architecture and applicability for the controlled encoding of luminescent polymer microparticles N2 - Luminophore stained micro- and nanobeads made from organic polymers like polystyrene (PS) are broadly used in the life and material sciences as luminescent reporters, for bead-based assays, sensor arrays, printable barcodes, security inks, and the calibration of fluorescence microscopes and flow cytometers. Initially mostly prepared with organic dyes, meanwhile luminescent core/shell nanoparticles (NPs) like spherical semiconductor quantum dots (QDs) are increasingly employed for bead encoding. This is related to their narrower emission spectra, tuneability of emission color, broad wavelength excitability, and better photostability. However, correlations between particle architecture, morphology, and photoluminescence (PL) of the luminescent nanocrystals used for encoding and the optical properties of the NP-stained beads have been rarely explored. This encouraged us to perform a screening study on the incorporation of different types of luminescent core/shell semiconductor nanocrystals into polymer microparticles (PMPs) by a radical-induced polymerization reaction. Nanocrystals explored include CdSe/CdS QDs of varying CdS shell thickness, a CdSe/ZnS core/shell QD, CdSe/CdS quantum rods (QRs), and CdSe/CdS nanoplatelets (NPLs). Thereby, we focused on the applicability of these NPs for the polymerization synthesis approach used and quantified the preservation of the initial NP luminescence. The spectroscopic characterization of the resulting PMPs revealed the successful staining of the PMPs with luminescent CdSe/CdS QDs and CdSe/CdS NPLs. In contrast, usage of CdSe/CdS QRs and CdSe QDs with a ZnS shell did not yield luminescent PMPs. The results of this study provide new insights into structure–property relationships between NP stained PMPs and the initial luminescent NPs applied for staining and underline the importance of such studies for the performance optimization of NP-stained beads. KW - Quantitative spectroscopy KW - Energy transfer KW - Synthesis KW - Surface chemistry KW - Semiconductor quantum dot KW - Luminescence KW - Nano KW - Particle KW - Quantum yield KW - Lifetime KW - Quality assurance KW - Polymer particle KW - Quantum rod KW - Nanoplatelet PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602206 DO - https://doi.org/10.1038/s41598-024-62591-1 SN - 2045-2322 VL - 14 SP - 1 EP - 16 AN - OPUS4-60220 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Godard, A. A1 - Kalot, G. A1 - Pliquett, J. A1 - Busser, B. A1 - Le Guével, X. A1 - Wegner, Karl David A1 - Resch-Genger, Ute A1 - Russelin, Y. A1 - Coll, J.-L. A1 - Denat, F. A1 - Bodio, E. A1 - Goze, C. A1 - Sancey, L. T1 - Water-Soluble Aza-BODIPYs: Biocompatible Organic Dyes for High Contrast In Vivo NIR-II Imaging N2 - A simple NIR-II emitting water-soluble system has been developed and applied in vitro and in vivo. In vitro, the fluorophore quickly accumulated in 2D and 3D cell cultures and rapidly reached the tumor in rodents, showing high NIR-II contrast for up to 1 week. This very efficient probe possesses all the qualities necessary for translation to the clinic as well as for the development of NIR-II emitting materials. KW - Aza-BODIPY KW - NIR-II Imaging KW - In vivo imaging KW - organic dyes KW - SWIR KW - Cancer KW - Fluorescence PY - 2020 DO - https://doi.org/10.1021/acs.bioconjchem.0c00175 VL - 31 IS - 4 SP - 1088 EP - 1092 PB - ACS Publications AN - OPUS4-50695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Homann, C. A1 - Krukewitt, Lisa A1 - Frenzel, Florian A1 - Grauel, Bettina A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Haase, M. T1 - NaYF4:Yb,Er/NaYF4 Core/Shell Nanocrystals with High Upconversion Luminescence Quantum Yield N2 - Upconversion core/shell nanocrystals with different mean sizes ranging from 15 to 45 nm were prepared via a modified synthesis procedure based on anhydrous rare‐earth acetates. All particles consist of a core of NaYF4:Yb,Er, doped with 18 % Yb3+ and 2 % Er3+, and an inert shell of NaYF4, with the shell thickness being equal to the radius of the core particle. Absolute measurements of the photoluminescence quantum yield at a series of different excitation power densities show that the quantum yield of 45 nm core/shell particles is already very close to the quantum yield of microcrystalline upconversion phosphor powder. Smaller core/shell particles prepared by the same method show only a moderate decrease in quantum yield. The quantum yield of 15 nm core/shell particles, for instance, is reduced by a factor of three compared to the bulk upconversion phosphor at high power densities (100 W cm−2) and by approximately a factor of 10 at low power densities (1 W cm−2). KW - Core shell structure KW - Upconversion KW - Non lienear processes KW - Nanoparticle KW - Quantum yield PY - 2018 DO - https://doi.org/10.1002/anie.201803083 VL - 57 IS - 28 SP - 8765 EP - 8769 PB - Wiley-VCH AN - OPUS4-45574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krappe, Alexander R. A1 - Mayer, Jacob C. A1 - Zhang, Wuai A1 - Filla, Lina M. A1 - Ligorio, Giovanni A1 - Hermerschmidt, Felix A1 - Eitelhuber, Larissa S. A1 - Güttler, Arne A1 - Weber, Manuela A1 - Paulus, Beate A1 - Resch-Genger, Ute A1 - List-Kratochvil, Emil J.W. A1 - Eigler, Siegfried T1 - Highly Emissive Hexa-peri-benzocoronene-fluoranthene Hybrid as Easily Processable and Stable OLED Material N2 - We report the synthesis of a fluorescent polycyclic aromatic hydrocarbon dye with a “symmetry-broken” core, derived from the related hexa-peri-benzocoronene (HBC) core with fluoranthene subunit. The fluorophore is composed of a pure Carbon skeleton without heteroatoms and exhibits remarkable photo luminescence properties with a photoluminescence Quantum yield (PLQY) of up to 67% in toluene, exceeding that of theparent HBC by a factor of 30. The single crystal X-ray structure reveals the distorted polycyclic aromatic hydrocarbon structure, which is responsible for the optoelectronic properties, as supported by density functional theory calculations. We show that the new fluorescent dye can be readily used for the fabrication of organic light-emitting diodes (OLED) without extensive optimization, whereby solubility in a variety of solvents and successful film formation are decisive. KW - Quantum Yield KW - OLED KW - Fluorescence KW - Synthesis PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-631298 DO - https://doi.org/10.1002/chem.202500742 SN - 1521-3765 SP - 1 EP - 7 PB - John Wiley & Sons, Inc AN - OPUS4-63129 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engel, A. A1 - Ottermann, C. A1 - Klahn, J. A1 - Korb, T. A1 - Resch-Genger, Ute A1 - Hoffmann, Katrin A1 - Kynast, U. A1 - Rupertus, V. ED - Dan V. Nicolau, ED - Daniel L. Farkas, ED - Robert C. Leif, T1 - Anorganic fluorescence reference materials for decay time of fluorescence emission N2 - Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools, detection methods and imaging applications for product and process control, material sciences, environmental and bio-technical analysis, molecular genetics, cell biology, medical diagnostics, and drug screening. According to DIN/ISO 17025 certified standards are used for steady state fluorescence diagnostics, a method having the drawback of giving relative values for fluorescence intensities only. Therefore reference materials for a quantitative characterization have to be related directly to the materials under investigation. In order to evaluate these figures it is necessary to calculate absolute numbers such as absorption/excitation cross sections and quantum yield. This has been done for different types of dopands in different materials such as glass, glass ceramics, crystals or nano crystalline material embedded in polymer matrices. Samples doped with several fluophores of different emission wavelengths and decay times are required for fluorescent multiplexing applications. Decay times shorter than 100 ns are of special interest. In addition, a proper knowledge is necessary of quantum efficiency in highly scattering media. Recently, quantum efficiency in YAG:Ce glass ceramics has been successfully investigated. Glass and glass ceramics doped with threefold charged rare earth elements are available. However, these samples have the disadvantage of emission decay times much longer than 1 microsecond, due to the excitation and emission of their optical forbidden electronic transitions. Therefore first attempts have been made to produce decay-time standards based on organic and inorganic fluophores. Stable LUMOGEN RED pigments and YAG:Ce phosphors are diluted simultaneously in silicone matrices using a wide range of concentrations between 0.0001 and 2 wt%. Organic LUMOGEN RED has decay times in the lower nanosecond range with a slight dependency on concentration and temperature. In addition, the well-known decay properties of inorganic YAG:Ce are observed also embedded in silicone matrix. Luminescent silicone layers are obtained with thicknesses between 150 and 300 m and no change of decay time, which has been determined to be between 60 and 62 ns. Finally, first results are shown for fluorescent CaF2:Pb glass ceramics embedded in a silicate glass matrix. Wavelength accuracy and lifetime are characterized for different environmental conditions such as temperature treatment and UV irradiation. Moreover, intensity patterns, e.g. line profiles and results, are discussed on homogeneity and photo and thermal stability, respectively. Fluorescence (steady state, decay time) and absorption (remission, absorption) spectroscopy are employed as diagnostic methods to get a microscopic view of the relevant physical processes. The work is funded by BMBF under project number 13N8849. KW - Fluorescence KW - Reference material KW - Glass KW - Glass ceramic KW - Phosphor KW - Doped glass and glass ceramics PY - 2008 SN - 978-0-8194-7034-8 DO - https://doi.org/10.1117/12.767633 VL - 6859 SP - 68591A-1 - 68591A-10 PB - SPIE, the International Society for Optical Engineering CY - Bellingham, Wash. AN - OPUS4-19800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lisy, M.-R. A1 - Goermar, A. A1 - Thomas, C. A1 - Pauli, Jutta A1 - Resch-Genger, Ute A1 - Kaiser, W.A. A1 - Hilger, I. T1 - In Vivo Near-infrared Fluorescence Imaging of Carcinoembryonic Antigen-expressing Tumor Cells in Mice N2 - Purpose: To prospectively depict carcinoembryonic antigen (CEA)-expressing tumors in mice with a high-affinity probe consisting of a near-infrared (NIR) fluorochrome and the clinically used anti-CEA antibody fragment arcitumomab. Materials and Methods: This study was approved by the regional animal committee. By coupling a NIR fluorescent (NIRF) cyanine dye (DY-676) to a specific antibody fragment directed against CEA (arcitumomab) and a nonspecific IgG Fab fragment, a bio-optical high-affinity fluorescent probe (anti-CEA–DY-676) and a low-affinity fluorescent probe (FabIgG–DY-676) were designed. The dye-to-protein ratios were determined, and both probes were tested for NIRF imaging in vitro on CEA-expressing LS-174T human colonic adenocarcinoma cells and CEA-nonexpressing A-375 human melanoma cells by using a bio-optical NIR small-animal imager. In vivo data of xenografted LS-174T and A-375 tumors in mice (n = 10) were recorded and statistically analyzed (Student t test). Results: The dye-to-protein ratios were determined as 3.0–3.5 for both probes. In vitro experiments revealed the specific binding of the anti-CEA–DY-676 probe on CEA-expressing cells as compared with CEA-nonexpressing cells; the FabIgG–DY-676 probe showed a markedly lower binding affinity to cells. In vivo LS-174T tumors xenografted in all mice could be significantly distinguished from A-375 tumors with application of the anti-CEA–DY-676 but not with that of the FabIgG–DY-676 at different times (2–24 hours, P < .005) after intravenous injection of the probes. Semiquantitative analysis revealed maximal fluorescence signals of anti-CEA–DY-676 to CEA-expressing tumors about 8 hours after injection. Conclusion: Findings of this study indicate the potential use of the high-affinity probe anti-CEA–DY-676 for specific NIRF imaging in in vivo tumor diagnosis. KW - Fluorescence spectroscopy KW - NIR fluorescent dye KW - NIRF imaging KW - Antibogy fragment arcitumomab KW - Carcinoembryonic antigen PY - 2008 DO - https://doi.org/10.1148/radiol.2472070123 SN - 0033-8419 SN - 1527-1315 VL - 247 IS - 3 SP - 779 EP - 787 PB - Radiological Society of North America CY - Oak Brook, Ill. AN - OPUS4-17629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Noble, J.E. A1 - Wang, L. A1 - Cerasoli, E. A1 - Knight, A.E. A1 - Porter, R.A. A1 - Gray, E. A1 - Howe, C. A1 - Hannes, E. A1 - Corbisier, P. A1 - Wang, J. A1 - Wu, L. A1 - Altieri, I. A1 - Patriarca, M. A1 - Hoffmann, Angelika A1 - Resch-Genger, Ute A1 - Ebert, B. A1 - Voigt, Jan A1 - Shigeri, Y. A1 - Vonsky, M.S. A1 - Konopelko, L.A. A1 - Gaigalas, A.K. A1 - Bailey, M. J. A. T1 - An international comparability study to determine the sources of uncertainty associated with a non-competitive sandwich fluorescent ELISA KW - ELISA KW - Fluorescence KW - Interferon KW - Uncertainty KW - Round Robin KW - Immunoassay KW - Quality assurance KW - Fluorescein PY - 2008 SN - 1434-6621 SN - 1437-8523 VL - 46 IS - 7 SP - 1033 EP - 1045 PB - De Gruyter CY - Berlin AN - OPUS4-18283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sloniec, Jagoda A1 - Schnurr, M. A1 - Witte, C. A1 - Resch-Genger, Ute A1 - Schröder, L. A1 - Hennig, Andreas T1 - Biomembrane interactions of functionalized cryptophane-A: combined fluorescence and 129Xe NMR studies of a bimodal contrast agent N2 - Fluorescent derivatives of the 129Xe NMR contrast agent cryptophane-A were obtained by functionalization with near infrared fluorescent dyes DY680 and DY682. The resulting conjugates were spectrally characterized, and their interaction with giant and large unilamellar vesicles of varying phospholipid composition was analyzed by fluorescence and NMR spectroscopy. In the latter, a chemical exchange saturation transfer with hyperpolarized 129Xe (Hyper-CEST) was used to obtain sufficient sensitivity. To determine the partitioning coefficients, we developed a method based on fluorescence resonance energy transfer from Nile Red to the membrane-bound conjugates. This indicated that not only the hydrophobicity of the conjugates, but also the phospholipid composition, largely determines the membrane incorporation. Thereby, partitioning into the liquid-crystalline phase of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine was most efficient. Fluorescence depth quenching and flip-flop assays suggest a perpendicular orientation of the conjugates to the membrane surface with negligible transversal diffusion, and that the fluorescent dyes reside in the interfacial area. The results serve as a basis to differentiate biomembranes by analyzing the Hyper-CEST signatures that are related to membrane fluidity, and pave the way for dissecting different contributions to the Hyper-CEST signal. KW - Biosensors KW - Fluorescence KW - FRET KW - Hyperpolarization KW - Lipids KW - Xenon PY - 2013 DO - https://doi.org/10.1002/chem.201203773 SN - 0947-6539 SN - 1521-3765 VL - 19 IS - 9 SP - 3110 EP - 3118 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-28980 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Markus, M. A. A1 - Napp, J. A1 - Behnke, Thomas A1 - Mitkovski, M. A1 - Monecke, S. A1 - Dullin, C. A1 - Kilfeather, S. A1 - Dressel, R. A1 - Resch-Genger, Ute A1 - Alves, F. T1 - Tracking of inhaled near-infrared fluorescent nanoparticles in lungs of SKH-1 mice with allergic airway inflammation N2 - Molecular imaging of inflammatory lung diseases, such as asthma, has been limited to date. The recruitment of innate immune cells to the airways is central to the inflammation process. This study exploits these cells for imaging purposes within the lung, using inhaled polystyrene nanoparticles loaded with the near-infrared fluorescence dye Itrybe (Itrybe-NPs). By means of in vivo and ex vivo fluorescence reflectance imaging of an ovalbumin-based allergic airway inflammation (AAI) model in hairless SKH-1 mice, we show that subsequent to intranasal application of Itrybe-NPs, AAI lungs display fluorescence intensities significantly higher than those in lungs of control mice for at least 24 h. Ex vivo immunofluorescence analysis of lung tissue demonstrates the uptake of Itrybe-NPs predominantly by CD68+CD11c+ECF-L+MHCIIlow cells, identifying them as alveolar M2 macrophages in the peribronchial and alveolar areas. The in vivo results were validated by confocal microscopy, overlapping tile analysis, and flow cytometry, showing an amount of Itrybe-NP-containing macrophages in lungs of AAI mice significantly larger than that in controls. A small percentage of NP-containing cells were identified as dendritic cells. Flow cytometry of tracheobronchial lymph nodes showed that Itrybe-NPs were negligible in lung draining lymph nodes 24 h after inhalation. This imaging approach may advance preclinical monitoring of AAI in vivo over time and aid the investigation of the role that macrophages play during lung inflammation. Furthermore, it allows for tracking of inhaled nanoparticles and can hence be utilized for studies of the fate of potential new nanotherapeutics. KW - Itrybe nanoparticles KW - In vivo near-infrared fluorescence imaging KW - Allergic airway inflammation KW - Cell tracking KW - Alveolar macrophages PY - 2015 DO - https://doi.org/10.1021/acsnano.5b04026 SN - 1936-0851 VL - 9 IS - 12 SP - 11642 EP - 11657 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-35302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moll, J. A1 - Wang, Cui A1 - Päpcke, A. A1 - Förster, C. A1 - Resch-Genger, Ute A1 - Lochbrunner, S. A1 - Heinze, K. T1 - Green Light Activation of Push-Pull Ruthenium(II) Complexes N2 - Synthesis, characterization, electrochemistry, and photophysics of novel homo- and heteroleptic ruthenium(II) complexes [Ru(cpmp)2] 2+ (22+) and [Ru(cpmp)(ddpd)]2+ (32+) bearing the tridentate ligands 6,2’’-carboxypyridyl-2,2’-methylamine-pyridylpyridine (cpmp) and N,N’-dimethyl-N,N’-dipyridin-2-ylpyridine-2,6-diamine (ddpd) are reported. The complexes possess one (32+) or two (22+) electron-deficient dipyridyl ketone fragments as electron accepting sites enabling intraligand charge transfer (ILCT), ligand-toligand charge transfer (LL’CT) and low-energy metal-to-ligand charge transfer (MLCT) absorptions. The latter peak around 544 nm (green light). 22+ shows 3MLCT phosphorescence in the red to near-infrared spectral region at room temperature in deaerated acetonitrile solution with an emission quantum yield of 1.3 % and a 3MLCT lifetime of 477 ns, while 3 2+ is much less luminescent. This different behaviour is ascribed to the energy gap law and the shape of the parasitic excited 3MC state potential energy surface. This study highlights the importance of the excited state energies and geometries for the actual excited state dynamics. Aromatic and aliphatic amines reductively quench the excited state of 22+ paving the way to photocatalytic applications using low-energy green light as exemplified with the green-light sensitized thiol-ene click reaction. KW - Green light excitation KW - Ruthenium(II) complexes KW - Phosphorescence KW - MLCT KW - Photoinduced electron transfer PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506759 DO - https://doi.org/10.1002/chem.202000871 SP - 1 EP - 13 PB - Wiley-VCH Verlag AN - OPUS4-50675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kalot, G. A1 - Godard, A. A1 - Busser, B. A1 - Pliquett, J. A1 - Broekgaarden, M. A1 - Motto-Ros, V. A1 - Wegner, Karl David A1 - Resch-Genger, Ute A1 - Köster, U. A1 - Denat, F. A1 - Coll, J.-L. A1 - Bodio, E. A1 - Goze, C. A1 - Sancey, L. T1 - Aza-BODIPY: A New Vector for Enhanced Theranostic Boron Neutron Capture Therapy Applications N2 - Boron neutron capture therapy (BNCT) is a radiotherapeutic modality based on the nuclear capture of slow neutrons by stable 10B atoms followed by charged particle Emission that inducing extensive damage on a very localized level (<10 um). To be effcient, a suffcient amount of 10B should accumulate in the tumor area while being almost cleared from the normal surroundings. A water-soluble aza-boron-dipyrromethene dyes (BODIPY) fluorophore was reported to strongly accumulate in the tumor area with high and BNCT compatible Tumor/Healthy Tissue ratios. The clinically used 10B-BSH (sodium borocaptate) was coupled to the water-soluble aza-BODIPY platform for enhanced 10B-BSH tumor vectorization. We demonstrated a strong uptake of the compound in tumor cells and determined its biodistribution in mice-bearing tumors. A model of chorioallantoic membrane-bearing glioblastoma xenograft was developed to evidence the BNCT potential of such compound, by subjecting it to slow neutrons. We demonstrated the Tumor accumulation of the compound in real-time using optical imaging and ex vivo using elemental imaging based on laser-induced breakdown spectroscopy. The tumor growth was significantly reduced as compared to BNCT with 10B-BSH. Altogether, the fluorescent aza-BODIPY/10B-BSH compound is able to vectorize and image the 10B-BSH in the tumor area, increasing its theranostic potential for effcient approach of BNCT. KW - Aza-BODIPY KW - SWIR KW - NIR-I KW - Theranostic KW - Boron compound KW - Optical imaging PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512280 DO - https://doi.org/10.3390/cells9091953 VL - 9 IS - 9 SP - 1953 PB - MDPI AN - OPUS4-51228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hu, Y. A1 - Neumann, C. A1 - Scholtz, Lena A1 - Turchanin, A. A1 - Resch-Genger, Ute A1 - Eigler, S. T1 - Polarity, intramolecular charge transfer, and hydrogen bond comediated solvent effects on the optical properties of graphene quantum dots N2 - Graphene quantum dots (GQDs) have attracted increasing attention due to their favorable optical properties and have been widely used, e.g., in the biomedical field. However, the properties related to the chemical structure of GQDs, resulting in solventdependent optical properties, still remain unclear. Herein, we present the synthesis of long-wavelength emitting GQDs with a size of about 3.6 nm via a solvothermal method using oxo-functionalized graphene (oxo-G) and p-phenylenediamine as precursors and their structural and surface chemical analysis by transmission electron and atomic force microscopy (TEM; AFM) as well as Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopy (FTIR; Raman; XPS). Subsequently, the influence of solvent polarity and proticity on the optical properties of the as-prepared GQDs bearing –OH, –NH2, –COOH and pyridine surface groups was investigated. Based on the results of the absorption and fluorescence (FL) studies, a possible luminescence mechanism is proposed. The observed solvent-induced changes in the spectral position of the FL maximum, FL quantum yield, and FL decay kinetics in protic and aprotic solvents of low and high polarity are ascribed to a combination of polarity effects, intramolecular charge transfer (ICT) processes, and hydrogen bonding. Moreover, the potential of GQDs for the optical sensing of trace amount of water was assessed. The results of our systematic spectroscopic study will promote the rational design of GQDs and shed more light on the FL mechanism of carbon based fluorescent nanomaterials. KW - Graphene quantum dots KW - Solvent polarity KW - solvent-induced changes KW - Charge transfer PY - 2022 DO - https://doi.org/10.1007/s12274-022-4752-1 SN - 1998-0124 SP - 1 EP - 8 PB - Springer AN - OPUS4-56030 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wasternack, J. A1 - Schröder, H. V. A1 - Witte, J. F. A1 - Ilisson, M. A1 - Hupatz, H. A1 - Hille, J. F. A1 - Gaedke, M. A1 - Valkonen, A. M. A1 - Sobottka, S. A1 - Krappe, A. A1 - Schubert, M. A1 - Paulus, B. A1 - Rissanen, K. A1 - Sarkar, B. A1 - Eigler, S. A1 - Resch-Genger, Ute A1 - Schalley, C. A. T1 - Switchable protection and exposure of a sensitive squaraine dye within a redox active rotaxane N2 - In nature,molecular environments in proteins can sterically protect and stabilize reactive species such as organic radicals through non-covalent interactions.Here, wereport a near-infrared fluorescent rotaxane in which the stabilization of a chemically labile squaraine fluorophore by the coordination of a tetralactam macrocycle can be controlled chemically and electrochemically. The rotaxane can be switched between two co-conformations inwhich thewheel either stabilizes or exposes the fluorophore. Coordination by the wheel affects the squaraine’s stability across four redox states and renders the radical anion significantly more stable—by a factor of 6.7—than without protection by a mechanically bonded wheel. Furthermore, the fluorescence properties can be tuned by the redox reactions in a stepwise manner. Mechanically interlockedmolecules provide an excellent scaffold to stabilize and selectively expose reactive species in a co-conformational switching process controlled by external stimuli. KW - Fluorescence KW - Dye KW - Sensor KW - Quantum yield KW - Spectroscopy KW - Photophysics KW - Synthesis KW - Squaraine KW - Switch KW - Redox-active KW - Rotaxane PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614959 DO - https://doi.org/10.1038/s42004-024-01312-1 VL - 7 SP - 1 EP - 11 AN - OPUS4-61495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ramirez, Alejandra A1 - Pauli, Jutta A1 - Crasselt, C. A1 - Simon, S. A1 - Schmidt, W. A1 - Resch-Genger, Ute T1 - The effect of a polycarboxylate ether on C3A / CaSO4.2H2O passivation monitored by optical spectroscopy N2 - Polycarboxylate ethers (PCEs) are widely used in construction, but the exact nature of their interaction with cement is still debated. Aiming at a better understanding of the role of tricalcium Aluminate (C3A) in cement hydration, we assessed the potential of optical spectroscopy in combination with a water-soluble fluorescent organic reporter dye (S0586) to monitor the early hydration of C3A in the presence of 26 wt% CaSO4.2H2O (C3A26G-S) with and without PCE. As optical methods, steady-state fluorescence and diffuse reflectance (UV–VisDR) spectroscopy were employed. Phase characterization and particle size distribution were performed with in-situ X-ray diffraction (in-situ XRD) and dynamic light scattering (DLS). Our results show that fluorescence and UV–VisDR spectroscopy can be used to monitor the formation of metastable phases by the disaggregation of the dye S0586 in a cement paste as well as changes in ettringite formation. Addition of PCE slowed down the disaggregation of the dye as reflected by the corresponding changes of the dyes absorption and fluorescence. This prolonged induction period is a well-known side effect of PCEs and agrees with previous reported calorimetric studies and the Inhibition of gypsum dissolution observed by in-situ XRD. This demonstrates that fluorescence and UV–VisDR spectroscopy together with a suitable optical probe can provide deeper insights into the influence of PCE on C3A-gypsum hydration which could be e.g., utilized as screening method for comparing the influences of different types of PCEs. KW - Fluorescence KW - Cement KW - Nano KW - Particle KW - Optical spectroscopy KW - PCE KW - XRD KW - Calorimetry KW - Monitoring KW - Diffuse KW - Reflection KW - Phase KW - Dye KW - Optical probe KW - Cyanine KW - Sensor KW - Method KW - Analysis PY - 2020 DO - https://doi.org/10.1016/j.conbuildmat.2020.121856 VL - 270 SP - 121856 PB - Elsevier Ltd. AN - OPUS4-52118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Behnke, Thomas A1 - Mathejczyk, J.E. A1 - Brehm, Robert A1 - Würth, Christian A1 - Gomes, F.R. A1 - Dullin, C. A1 - Napp, J. A1 - Alves, F. A1 - Resch-Genger, Ute T1 - Target-specific nanoparticles containing a broad band emissive NIR dye for the sensitive detection and characterization of tumor development N2 - Current optical probes including engineered nanoparticles (NPs) are constructed from near infrared (NIR)-emissive organic dyes with narrow absorption and emission bands and small Stokes shifts prone to aggregation-induced self-quenching. Here, we present the new asymmetric cyanine Itrybe with broad, almost environment-insensitive absorption and emission bands in the diagnostic window, offering a unique flexibility of the choice of excitation and detection wavelengths compared to common NIR dyes. This strongly emissive dye was spectroscopically studied in different solvents and encapsulated into differently sized (15, 25, 100 nm) amino-modified polystyrene NPs (PSNPs) via a one-step staining procedure. As proof-of-concept for its potential for pre-/clinical imaging applications, Itrybe-loaded NPs were surface-functionalized with polyethylene glycol (PEG) and the tumor-targeting antibody Herceptin and their binding specificity to the tumor-specific biomarker HER2 was systematically assessed. Itrybe-loaded NPs display strong fluorescence signals in vitro and in vivo and Herceptin-conjugated NPs bind specifically to HER2 as demonstrated in immunoassays as well as on tumor cells and sections from mouse tumor xenografts in vitro. This demonstrates that our design strategy exploiting broad band-absorbing and -emitting dyes yields versatile and bright NIR probes with a high potential for e.g. the sensitive detection and characterization of tumor development and progression. KW - Nanoparticle KW - Fluorescence KW - In vitro test KW - In vivo test KW - Surface modification KW - Cytotoxicity PY - 2013 DO - https://doi.org/10.1016/j.biomaterials.2012.09.028 SN - 0142-9612 VL - 34 IS - 1 SP - 160 EP - 170 PB - Elsevier CY - Oxford AN - OPUS4-26877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Daly, H.C A1 - Matikonda, S.S A1 - Steffens, H.C A1 - Rühle, Bastian A1 - Resch-Genger, Ute A1 - Ivanic, J. A1 - Schermann, M.J T1 - Daly_Photochem Photobiol 2021_Ketone Incorporation Extends the Emission Properties of the Xanthene Scaffold N2 - Imaging in the shortwave-infrared region (SWIR, λ = 1000–2500 nm) has the potential to enable deep tissue imaging with high resolution. Critical to the development of these Methods is the identification of low molecular weight, biologically compatible fluorescent probes that emit beyond 1000 nm. Exchanging the bridging oxygen atom on the xanthene scaffold (C10’ position) with electron withdrawing groups has been shown to lead to significant redshifts in absorbance and emission. Guided by quantum chemistry computational modeling studies, we investigated the installation of a Ketone bridge at the C10’ position. This simple modification extends the absorbance maxima to 860 nm and the emission beyond 1000 nm, albeit with reduced photon output. Overall, These studies demonstrate that broadly applied xanthene dyes can be extended into the SWIR range. KW - Flourescence KW - Optical probe KW - Dye KW - Photophysics KW - Quantum yield KW - Mechanism KW - NIR KW - SWIR KW - Imaging KW - Reliability KW - Method KW - Quality assurance PY - 2021 DO - https://doi.org/10.1111/php.13544 SN - 1751-1097 VL - 98 IS - 2 SP - 325 EP - 333 PB - Wiley Online Library AN - OPUS4-54080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lezhnina, M.M. A1 - Kätker, H. A1 - Kaiser, Martin A1 - Stegemann, L. A1 - Voss, E. A1 - Resch-Genger, Ute A1 - Strassert, C. A1 - Kynast, U. T1 - Chemical behavior and spectroscopic properties of rare earth borates in glazes N2 - Efficient Near UV excited materials (350<λ<400 nm) responding with green line emission are sparse in comparison to higher energy UV excited emitters (λ<350 nm), while corresponding red line emitters are more abundant, albeit typically also restricted to excitation wavelengths below 400 nm. This situation is disadvantageous for several important actual and potential applications. Among these, excitation with high power UV-LEDs and laser diodes are of particular interest. Here we present results on green emitting YBO3:Ce, Tb, which can be excited with 370–380 nm radiation at quantum efficiencies of up to 60% and decay times in excess of 2 ms. Moreover, as powderous phosphors typically require stable matrices to be hosted in, we investigated low melting, lead- and fluoride-free glasses for their capability to accommodate the phosphor and yet retain its optical properties. In these, we even observed an increase of the quantum efficiencies of up to 70% at decay times approaching 3 ms. Finally, we characterized the thermal quenching behavior, which showed a clear advantage of the phosphors in glassy matrices. KW - Rare earth phosphors KW - Energy transfer KW - Luminescent glasses and glazes PY - 2016 DO - https://doi.org/10.1016/j.jlumin.2015.05.005 SN - 0022-2313 SN - 1872-7883 VL - 170 SP - 387 EP - 394 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Billimoria, K. A1 - Diaz Fernandez, Y. A. A1 - Andresen, Elina A1 - Sorzabal-Bellido, I. A1 - Huelga-Suarez, G. A1 - Bartczak, D. A1 - Ortiz de Solórzano, C. A1 - Resch-Genger, Ute A1 - Goenaga Infante, H. T1 - The potential of bioprinting for preparation of nanoparticle-based calibration standards for LA-ICP-ToF-MS quantitative imaging N2 - This paper discusses the feasibility of a novel strategy based on the combination of bioprinting nano-doping technology and laser ablation-inductively coupled plasma time-of-flight mass spectrometry analysis for the preparation and characterization of gelatin- based multi-element calibration standards suitable for quantitative imaging. To achieve this, lanthanide up-conversion nanoparticles were added to a gelatin matrix to produce the bioprinted calibration standards. The features of this bioprinting approach were com- pared with manual cryosectioning standard preparation, in terms of throughput, between batch repeatability and elemental signal homogeneity at 5 μm spatial resolution. By using bioprinting, the between batch variability for three independent standards of the same concentration of 89 Y (range 0–600 mg/kg) was reduced to 5% compared to up to 27% for cryosectioning. On this basis, the relative standard deviation ( RSD ) obtained between three independent calibration slopes measured within 1 day also reduced from 16% (using cryosectioning ) to 5% (using bioprinting), supporting the use of a single standard preparation replicate for each of the concentrations to achieve good calibration performance using bioprinting. This helped reduce the analysis time by approximately 3-fold. With cryosectioning each standard was prepared and sectioned individually, whereas using bio-printing it was possible to have up to six different standards printed simultaneously, reducing the preparation time from approximately 2 h to under 20 min (by approxi- mately 6-fold). The bio-printed calibration standards were found stable for a period of 2 months when stored at ambient temperature and in the dark. KW - Environmental analysis KW - LA-ICP-MS KW - Lanthanide KW - Tag KW - Fluorescence KW - Nanoparticles KW - Reference material KW - Quality assurance KW - 3D-printing KW - Synthesis KW - Production KW - Multimodal PY - 2022 DO - https://doi.org/10.1093/mtomcs/mfac088 SN - 1756-591X VL - 14 IS - 12 SP - 1 EP - 9 PB - Oxford University Press CY - Oxford AN - OPUS4-57018 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kreitner, C. A1 - Grabolle, Markus A1 - Resch-Genger, Ute A1 - Heinze, K. T1 - Dual emission and excited-state mixed-valence in a quasi-symmetric dinuclear Ru-Ru complex N2 - The synthesis and characterization of the new dinuclear dipeptide [(EtOOC-tpy)Ru(tpy-NHCO-tpy)Ru(tpy-NHCOCH3)]4+ 34+ of the bis(terpyridine)ruthenium amino acid [(HOOC-tpy)Ru(tpy-NH2)]2+ 12+ are described, and the properties of the dipeptide are compared to those of the mononuclear complex [(EtOOC-tpy)Ru(tpy-NHCOCH3)]2+ 42+ carrying the same functional groups. 34+ is designed to serve a high electronic similarity of the two ruthenium sites despite the intrinsic asymmetry arising from the amide bridge. This is confirmed via UV–vis absorption and NMR spectroscopy as well as cyclic voltammetry. 42+ and 34+ are emissive at room temperature, as expected. Moreover, 34+ exhibits dual emission from two different triplet states with different energies and lifetimes at room temperature. This is ascribed to the presence of a unique thermal equilibrium between coexisting [RuII(tpy-NHCO-tpy·–)RuIII] and [RuIII(tpy-NHCO-tpy·–)RuII] states leading to an unprecedented excited-state RuIIRuIII mixed-valent system via the radical anion bridge tpy-NHCO-tpy·–. The mixed-valent cation 35+, on the other hand, shows no measurable interaction of the RuIIRuIII centers via the neutral bridge tpy-NHCO-tpy (Robin–Day class I). Reduction of 34+ to the radical cation 33+ by decamethylcobaltocene is bridge-centered as evidenced by rapid-freeze electron paramagnetic resonance spectroscopy. Interestingly, all attempts to observe 33+ via NMR and UV–vis absorption spectroscopy only led to the detection of the diamagnetic complex 3-H3+ in which the bridging amide is deprotonated. Hence 3-H3+ (and 4-H+) appear to reduce protons to dihydrogen. The ease of single and double deprotonation of 42+ and 34+ to 4-H+, 3-H3+, and 3-2H2+ was demonstrated using a strong base and was studied using NMR and UV–vis absorption spectroscopies. The equilibrating excited triplet states of 34+ are reductively quenched by N,N-dimethylaniline assisted by hydrogen bonding to the bridging amide. KW - Dual emission KW - Excited state mixed-valence KW - Electron transfer KW - Ruthenium KW - Terpyridine KW - Amide acidity PY - 2014 DO - https://doi.org/10.1021/ic5020362 SN - 0020-1669 SN - 1520-510X VL - 53 IS - 24 SP - 12947 EP - 12961 PB - American Chemical Society CY - Washington, DC AN - OPUS4-32536 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Resch-Genger, Ute A1 - Pfeifer, Dietmar A1 - Hoffmann, Katrin A1 - Flachenecker, Günter A1 - Hoffmann, Angelika A1 - Monte, C. ED - Resch-Genger, Ute ED - O.S. Wolfbeis, T1 - Linking fluorometry to radiometry with physical and chemical transfer standards: instrument characterization and traceable fluorescence measurements N2 - Problems associated with the measurement of photoluminescence are briefly reviewed, including relevant instrument parameters affecting these measurements. Procedures for the characterization of relevant instruments are discussed, focusing on spectrofluorometers, and fit-for-purpose methods including suitable standards are recommended. The aim here is to increase the awareness of the importance of reliable instrument characterization and to improve the comparability of measurements of photoluminescence. KW - Calibration KW - Emission standards KW - Fluorescence intensity standards KW - Fluorescence standards KW - Quality assurance KW - Spectral correction PY - 2008 SN - 978-3-540-75206-6 DO - https://doi.org/10.1007/4243_2008_054 SN - 1617-1306 N1 - Serientitel: Springer Series on Fluorescence – Series title: Springer Series on Fluorescence VL - 5 IS - Part II SP - 65 EP - 99 PB - Springer AN - OPUS4-18301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Würth, Christian A1 - Manley, P. A1 - Voigt, R. A1 - Ahiboz, D. A1 - Becker, C. A1 - Resch-Genger, Ute T1 - Metasurface Enhanced Sensitized Photon Upconversion: Toward Highly Efficient Low Power Upconversion Applications and Nanoscale E-Field Sensors N2 - Large-scale nanoimprinted metasurfaces based on silicon photonic crystal slabs were produced and coated with a NaYF4:Yb3+/Er3+ upconversion nanoparticle (UCNP) layer. UCNPs on these metasurfaces yield a more than 500-fold enhanced upconversion emission compared to UCNPs on planar surfaces. It is also demonstrated how the optical response of the UCNPs can be used to estimate the local field energy in the coating layer. Optical simulations using the finite element method validate the experimental results and the calculated spatial three-dimensional field Energy distribution helps us to understand the emission enhancement mechanism of the UCNPs closely attached to the metasurface. In addition, we analyzed the spectral shifts of the resonances for uncoated and coated metasurfaces and metasurfaces submerged in water to enable a prediction of the optimum layer thicknesses for different excitation wavelengths, paving the way to applications such as electromagnetic field sensors or bioassays. KW - Nanoparticles KW - Upconversion KW - Metasurface KW - Field sensor KW - Emission enhancement KW - Photonic crystal PY - 2020 DO - https://doi.org/10.1021/acs.nanolett.0c02548 VL - 20 IS - 9 SP - 6682 EP - 6689 PB - ACS Publications AN - OPUS4-51427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Homann, C. A1 - Krukewitt, Lisa A1 - Frenzel, Florian A1 - Grauel, Bettina A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Haase, M. T1 - Aufwärtskonvertierende NaYF4:Yb,Er/NaYF4‐Kern/Schale‐Nanokristalle mit hoher Lumineszenzquantenausbeute N2 - Eine modifizierte Syntheseroute auf der Basis wasserfreier Seltenerdacetate wurde zur Synthese aufwärtskonvertierender Kern/Schale‐Nanokristalle mit mittleren Größen zwischen 15 bis 45 nm eingesetzt. Die nahezu monodispersen Partikel bestehen aus einem NaYF4:Yb,Er‐Kern, dotiert mit 18 % Yb3+ und 2 % Er3+, und einer inerten Schale aus NaYF4, wobei die Dicke der Schale dem jeweiligen Radius des Kernpartikels entspricht. Absolutmessungen der Photolumineszenz‐Quantenausbeuten bei verschiedenen Anregungsleistungsdichten zeigen, dass die Quantenausbeuten von 45 nm Kern/Schale‐Partikeln schon fast an die Quantenausbeute des mikrokristallinen aufwärtskonvertierenden Leuchtstoffs heranreichen. Kleinere Kern/Schale‐Partikel, die nach der gleichen Methode hergestellt wurden, zeigen nur eine moderate Abnahme der Quantenausbeute. Beispielsweise ist die Quantenausbeute von 15 nm großen Kern/Schale‐Partikeln bei hohen Leistungsdichten (100 W cm−2) nur um einen Faktor drei kleiner als die des mikrokristallinen Leuchtstoffpulvers und um ungefähr einen Faktor 10 kleiner bei niedrigen Leistungsdichten (1 W cm−2). KW - Nicht lineare Prozesse KW - Nanopartikel KW - Quantenausbeute PY - 2018 DO - https://doi.org/10.1002/ange.201803083 VL - 130 IS - 28 SP - 8901 EP - 8905 PB - Wiley VCH Verlag AN - OPUS4-45573 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Otto, S. A1 - Moll, J. A1 - Förster, C. A1 - Geißler, Daniel A1 - Wang, Cui A1 - Resch-Genger, Ute A1 - Heinze, K. T1 - Three-in-One Crystal: The Coordination Diversity of Zinc Polypyridine Complexes N2 - The syntheses, structures, and photophysical properties of two new zinc(II) complexes bearing the tridentate N,N′-dimethyl-N,N′-dipyridin-2-ylpyridine-2,6-diamine (ddpd) ligand are presented. Structural investigations through single-crystal X-ray diffractometry, NMR spectroscopy, and density functional theory calculations revealed a diverse coordination behavior that depends on the counterion. Spectroscopic (UV/Vis and emission spectroscopy) and theoretical techniques (DFT and time-dependent DFT calculations) were employed to explore the photophysical properties of the complexes. KW - Zinc(II) complexes KW - X-ray diffractometry (XRD) KW - NMR spectroscopy KW - Density functional theory (DFT) KW - UV/Vis and emission spectroscopy PY - 2017 DO - https://doi.org/10.1002/ejic.201700948 SN - 1434-1948 SN - 1099-0682 VL - 43 SP - 5033 EP - 5040 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-43274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -