TY - JOUR A1 - Rietsch, P. A1 - Zeyat, M. A1 - Hübner, Oskar A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Kutter, M. A1 - Paskin, A. A1 - Uhlig, J. A1 - Lentz, D. A1 - Eigler, S. T1 - Substitution Pattern-Controlled Fluorescence Lifetimes of Fluoranthene Dyes N2 - The absorption and emission properties of organic dyes are generally tuned by altering the substitution pattern. However, tuning the fluorescence lifetimes over a range of several 10 ns while barely affecting the spectral features and maintaining a moderate fluorescence quantum yield is challenging. Such properties are required for lifetime multiplexing and barcoding applications. Here, we show how this can be achieved for the class of fluoranthene dyes, which have substitution-dependent lifetimes between 6 and 33 ns for single wavelength excitation and emission. We explore the substitution-dependent emissive properties in the crystalline solid state that would prevent applications. Furthermore, by analyzing dye mixtures and embedding the dyes in carboxyfunctionalized 8 μm-sized polystyrene particles, the unprecedented potential of these dyes as labels and encoding fluorophores for time-resolved fluorescence detection techniques is demonstrated. KW - Fluorescence KW - Label KW - Fluoranthene KW - Quantum yield KW - Reporter KW - Crystal KW - Encoding KW - Multiplexing KW - Particle KW - Bead KW - Lifetime KW - Dye KW - Barcoding PY - 2021 DO - https://doi.org/10.1021/acs.jpcb.0c08851 SN - 1520-5207 VL - 125 IS - 4 SP - 1207 EP - 1213 PB - American Chemical Society AN - OPUS4-52087 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella A1 - Sander, P. A1 - Andresen, Elina A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Potentiometric and Optical Titration for Cost- Efficient Quantification of Surface Functional Groups on Silica Nanoparticles N2 - Surface chemistry of engineered nanomaterials (NMs) plays a critical role not only in determining their interactions with the environment but also in their stability, safety, and functionality across diverse applications ranging from catalysis to biomedicine. Accurate quantification of surface functional groups (FGs) is therefore essential for quality control, risk assessment, and performance optimization.[1] However, many existing analytical techniques are either cost-intensive, require specialized instrumentation, or lack scalability for routine use. In this study, we present a comparative evaluation of potentiometric and optical titration as two simple, cost-efficient, and automatable methods for quantifying surface functional groups on a variety of surface-modified silica nanoparticles (SiO₂ NPs). These NPs were chosen as they are among the most frequently utilized engineered NMs in the life and material sciences. Potentiometric titration, based on pH monitoring during acid-base neutralization, offers a direct and label-free approach to determine the total amount of FGs. Optical titration provides a complementary method with potential for high-throughput screening. To examine the accuracy and robustness of our stepwise-optimized workflows and the achievable relative standard deviations (RSDs), measurements were performed by multiple operators in two laboratories. Method validation was conducted through cross-comparison with traceable, chemo-selective quantitative nuclear magnetic resonance spectroscopy (qNMR) and thermogravimetric analysis (TGA). A comparison with optical assays highlights the importance of measuring both quantities for comprehensive characterization of surface-modified NMs.[2] A combined NM surface analysis using optical assays and pH titration will simplify quality control of NM production processes and stability studies, and can yield large datasets for NM grouping in sustainable and safe(r)-by-design studies. T2 - eMRS Fall Meeting 2025 CY - Warsaw, Poland DA - 15.09.2025 KW - Fluorescence KW - Advanced material KW - Synthesis KW - Characterization KW - Nano KW - Particle KW - Silica KW - Surface analysis KW - Validation KW - qNMR KW - Fluram assay KW - Functional group KW - Quantification KW - Potentiometry KW - Amino groups KW - Fluorescamine KW - Calibration KW - Method comparison PY - 2025 AN - OPUS4-64205 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Quantifying functional groups and coatings on nanoobjects N2 - Engineered nanomaterials (NM) of different size, shape, chemical composition, and surface chemistry are increasingly used for many key technologies of the 21st century and consumer products. This includes polymer and silica or silica-coated nanoparticles (NP) with covalently bound surface groups, semiconductor quantum dots (QD), metal and metal oxide NP, and lanthanide NP with coordinatively or electrostatically bound ligands, as well as surface-coated nanostructures like micellar encapsulated NP. Decisive for most applications of NMs are their specific surface properties, which are largely determined by the chemical nature and amounts of ligands and functional groups (FGs) on the NM surface. The surface chemistry can strongly affect the physicochemical properties of NM, their charge, hydrophilicity/hydrophobicity, reactivity, function, stability, and processability and thereby their impact on human health and environment. Knowledge of NM surface chemistry plays an important role for NM functionality and performance in (bio)applications and the fate, exposure, dissolution, transformation, and accumulation of NM, and thus, the potential risks for human health and the environment. This highlights the importance of reliable, validated, and eventually standardized analytical methods for analyzing and quantifying NM surface chemistry for process and quality control of NM production, safe use of NMs, design of novel NM, and sustainable concepts for NM fabrication.[1-3] In this context, interlaboratory comparisons (ILCs) are needed to assess method reliability and reference materials with known surface chemistries for establishing surface analytical methods and their performance validation.[2,4] Also, to respond to the increasing number of samples to be analyzed, cost-efficient automation concepts for surface analysis are needed that can be realized with affordable and preferably commercial instrumentation.[5] Here, we provide an overview of analytical methods for FG analysis and quantification used by us for quantifying broadly utilized FGs and ligands on different types of NMs with electrochemical titration methods, optical assays, nuclear magnetic resonance (NMR) and vibrational (IR) spectroscopy, and X-ray based and thermal analysis methods.[1,2] Thereby, method- and material-related challenges are addressed, and the importance of multi-method characterization approaches easing method validation by method cross-validation. Special emphasis is dedicated to simple, versatile, and cost-efficient methods such as optical assays and electrochemical titration methods. T2 - eMRS Fall Meeting 2025 CY - Warsaw, Poland DA - 15.09.2025 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 - Interlaboratory comparison KW - Uncertainty PY - 2025 AN - OPUS4-64183 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 - CONF A1 - Resch-Genger, Ute T1 - Assessing different types of silica networks for the complete protection of nir luminescent molecular rubies from oxygen quenching in air N2 - The application of emerging luminophores such as near-infrared (NIR) emissive earth-abundant chromium(III) (CrIII) complexes and triplet-triplet annihilation upconversion (TTA-UC) systems in air as optical reporters for bioimaging or photonic materials for energy conversion requires simple and efficient strategies for their complete protection from luminescence quenching by oxygen. Therefore, we explored the influence of sol-gel synthesis routes on the oxygen protection efficiency of the resulting core and core/shell silica nanoparticles (SiO2 NPs), utilizing the molecular ruby-type luminophores CrPF6 ([Cr(ddpd)2](PF6)3; ddpd = N,N’-dimethyl- N,N’-dipyridin-2-ylpyridin-2,6-diamine) and CrBF4 ([Cr(ddpd)2](BF4)3) with their oxygen-dependent, but polarity-, proticity-, viscosity-, and concentration-independent luminescence as optical probes for oxygen permeability. The sol-gel chemistry routes we assessed include the classical Stöber method and the underexplored larginine approach, which relies on the controlled hydrolysis of tetraethoxysilane (TEOS) in a biphasic cyclohexane/water system with the catalyst l-arginine. As demonstrated by luminescence measurements of air- and argon-saturated dispersions of CrPF6- and CrBF4-stained SiO2 NPs of different size and particle architecture, utilizing the luminescence decay kinetics of argon-saturated solutions of CrPF6 and CrBF4 in acetonitrile (ACN) as benchmarks, only SiO2 NPs or shells synthesized by the l-arginine approach provided complete oxygen protection of the CrIII complexes under ambient conditions. We ascribe the different oxygen shielding efficiencies of the silica networks explored to differences in density and surface chemistry of the resulting nanomaterials and coatings, leading to different oxygen permeabilities. Our l-arginine based silica encapsulation strategy can open the door for the efficient usage of oxygen-sensitive luminophores and TTA-UC systems as optical reporters and spectral shifters in air in the future. T2 - eMRS Strasbourg CY - Strasbourg, France DA - 26.05.2025 KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Synthesis KW - Quantum yield KW - NIR KW - Mechanism KW - Characterization KW - Electron microscopy KW - Silica KW - Oxygen sensing KW - Surface KW - Doping KW - Lifetime KW - Cr(III) complex PY - 2025 AN - OPUS4-63300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Güttler, Arne A1 - Richter, Maria A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - New Reference Materials for the Quantification and Standardization of Fluorescence-based Measurements N2 - Luminescence techniques are amongst the most commonly used analytical methods in the life and material sciences due to their high sensitivity and non-destructive and multiparametric character. Photoluminescence signals are, however, affected by wavelength-, polarization-, and time-dependent instrument specific effect and the compound-specific photoluminescence quantum yield. The former hamper the comparability of fluorescence measurements, while the relative determination of the latter requires suitable quantum yield standards with well-known photoluminescence quantum yields (QY). For the simple correction of instrument specific effects in the wavelength region of 300 nm to 950 nm, the set of the five certified spectral fluorescence standards BAM-F001 – BAM-F005, has been extended to the NIR range by including two new fluorescence standards currently under certification. For the reliable and accurate determination of QY which is the key performance parameter for the comparison of different luminophores, we certified a set of 12 quantum yield standards, which absorb and emit in the wavelength range from 300 nm to 1000 nm. T2 - Methods and Applications in Fluorescence CY - Gothenburg, Sweden DA - 11.09.2022 KW - Luminescence KW - Photoluminescence KW - Fluorescence KW - Quantum yield KW - Certified reference material KW - Standard PY - 2022 AN - OPUS4-55914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Getting it right with photoluminescence quantum yields of molecular and nanoscale luminophores and luminescent particles N2 - Photophysical and mechanistic studies, the comparison of different emitter classes, and the rational design of the next generation of molecular and nanoscale reporters require quantitative photoluminescence measurements and the reliable determination of the key performance parameter photoluminescence quantum yield (QY), i.e., the number of emitted per absorbed photons. This is of special importance for all photoluminescence applications in the life and material sciences in the UV/vis/NIR/SWIR. To improve the reliability and comparability of photoluminescence and QY measurements across laboratories, pitfalls, achievable uncertainties, and material-specific effects related to certain emitter classes must be explored. Also, suitable protocols and reference materials are needed which have been validated in interlaboratory comparisons for different wavelength regions and transparent and scattering luminophores.[1] Based on absolute and relative photoluminescence measurements of functional dyes and nanomaterials like semiconductor quantum dots and rods, spectrally shifting lanthanide upconversion nanocrystals, perovskites, and YAG:Cer converter materials, reliable methods for determining QY of transparent and scattering luminophores, nonlinear emitters, and solid luminescent nanomaterials have been developed.[2,3] Thereby, material- and method-related uncertainties of relative and absolute QY measurements and achievable uncertainties could be quantified for linear and nonlinear UV/vis/NIR/SWIR emitters and lately for also luminescent and scattering materials and solid phoshors, here in an interlaboratory comparison of three labs utilizing integrating sphere spectroscopy.[4,5] In addition, to provide simple tools for a better comparability of QY measurements, recently, a first set of UV/vis/NIR quantum yield standards has been developed and certified with complete uncertainty budgets.[6] In the following, the outcome of these studies will be presented, thereby addressing common pitfalls and providing recommendations on the performance of reliable QY measurements of linear and non-linear emitters in transparent, scattering, and solid samples. T2 - 29th Lecture Conference on Photochemistry (LCP 2024) GDCh CY - Mainz, Germany DA - 16.09.2024 KW - Nanoparticle KW - Nano KW - Luminescence KW - Quality assurance KW - Synthesis KW - Standardization KW - Reference material KW - Quantum yield KW - Fluorescence KW - Reference data KW - Integrating sphere spectroscopy KW - ILC KW - Converter material KW - YAG:Ce KW - Optoceramic PY - 2024 AN - OPUS4-61075 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 - JOUR A1 - Biesen, L. A1 - Nirmalananthan-Budau, Nithiya A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - Solid-State Emissive Aroyl-S,N-Ketene Acetals with Tunable N2 - N-Benzyl aroyl-S,N-ketene acetals can be readily synthesized by condensation of aroyl chlorides and N-Benzyl 2-methyl benzothiazolium salts in good to excellent yields, yielding a library of 35 chromophores with bright solid-state emission and aggregation-induced emission characteristics. Varying the substituent from electron-donating to electronwithdrawing enables the tuning of the solid-state emission Color from deep blue to red. KW - Nano KW - Nanoparticle KW - Photoluminescence KW - Fluorescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - dye KW - Enhancement KW - Particle KW - Polarity KW - AIE KW - Aggregation KW - Aggregation-induced emission KW - Solid state emission PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509072 DO - https://doi.org/10.1002/anie.201916396 VL - 59 IS - 25 SP - 10037 EP - 10041 PB - Wiley Online Libary AN - OPUS4-50907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Denißen, M. A1 - Hannen, R. A1 - Itskalov, D. A1 - Biesen, L. A1 - Nirmalananthan-Budau, Nithiya A1 - Hoffmann, Katrin A1 - Reiss, G. J. A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - One-pot synthesis of a white-light emissive bichromophore operated by aggregation-induced dual emission (AIDE) and partial energy transfer N2 - Merocyanine–triarylamine bichromophores are readily synthesized by sequentially Pd-catalyzed insertion alkynylation–Michael–Suzuki four-component reactions. White-light emissive systems form upon aggregation in 1 : 99 and 0.1 : 99.9 vol% CH2Cl2–cyclohexane mixtures, ascribed to aggregation-induced dual emission (AIDE) in combination with partial energy transfer between both chromophore units as supported by spectroscopic studies. KW - Energy transfer KW - Nano KW - Nanoparticle KW - Photoluminescence KW - Fluorescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - Dye KW - Enhancement KW - Particle KW - Polarity KW - AIE KW - Aggregation KW - Aggregation-induced emission KW - Solid state emission KW - Merocyanine PY - 2020 DO - https://doi.org/10.1039/d0cc03451g VL - 56 IS - 54 SP - 7407 PB - Royal Society of Chemistry AN - OPUS4-50936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Biesen, L. A1 - May, L. A1 - Nirmalananthan-Budau, Nithiya A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - Communication of Bichromophore Emission upon Aggregation – Aroyl-S,N-ketene Acetals as Multifunctional Sensor Merocyanines N2 - Aroyl-S,N-ketene acetal-based bichromophores can be readily synthesized in a consecutive three-component synthesis in good to excellent yields by condensation of aroyl chlorides and an N-(p-bromobenzyl) 2-methyl benzothiazolium salt followed by a Suzuki coupling, yielding a library of 31 bichromophoric fluorophores with substitution patterntunable emission properties. Varying both chromophores enables different communication pathways between the chromophores, exploiting aggregation-induced emission (AIE) and energy transfer (ET) properties, and thus, furnishing aggregation-based fluorescence switches. Possible applications range from fluorometric analysis of alcoholic beverages to pH sensors. KW - Dye KW - Fluorescence KW - Aggregation induced emission KW - Signal enhancement KW - Energy transfer KW - Switch KW - Sensor KW - Quantum yield KW - Lifetime KW - Photophysics KW - Synthesis PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531123 DO - https://doi.org/10.1002/chem.202102052 VL - 27 IS - 53 SP - 13426 EP - 13434 PB - Wiley-VCH AN - OPUS4-53112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frenzel, F. A1 - Fiedler, S. A1 - Bardan, A. A1 - Güttler, Arne A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Influence of Measurement Geometry and Blank on Absolute Measurements of Photoluminescence Quantum Yields of Scattering Luminescent Films N2 - For a series of 500 μm-thick polyurethane films containing different concentrations of luminescent and scattering YAG:Ce microparticles, we systematically explored and quantified pitfalls of absolute measurements of photoluminescence quantum yields (Φf) for often employed integrating sphere (IS) geometries, where the sample is placed either on a sample holder at the bottom of the IS surface or mounted in the IS center. Thereby, the influence of detection and illumination geometry and sample position was examined using blanks with various scattering properties for measuring the number of photons absorbed by the sample. Our results reveal that (i) setup configurations where the scattering sample is mounted in the IS center and (ii) transparent blanks can introduce systematic errors in absolute Φf measurements. For strongly scattering, luminescent samples, this can result in either an under- or overestimation of the absorbed photon flux and hence an under- or overestimation of Φf. The size of these uncertainties depends on the scattering properties of the sample and instrument parameters, such as sample position, IS size, wavelength-dependent reflectivity of the IS surface coating, and port configuration. For accurate and reliable absolute Φf measurements, we recommend (i) a blank with scattering properties closely matching those of the sample to realize similar distributions of the diffusely scattered excitation photons within the IS, and (ii) a sufficiently high sample absorption at the excitation wavelength. For IS setups with center-mounted samples, measurement geometries should be utilized that prevent the loss of excitation photons by reflections from the sample out of the IS. KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Quantum yield KW - Characterization KW - Silica KW - Scattering KW - Uncertainty KW - Film KW - Pphosphor KW - YAG:Ce KW - LED KW - Converter material KW - Solid material KW - Polymer KW - Composite material KW - Advanced material PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638304 DO - https://doi.org/10.1021/acs.analchem.4c06726 SN - 1520-6882 SP - 1 EP - 8 PB - ACS Publications AN - OPUS4-63830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radunz, Sebastian A1 - Tschiche, Harald Rune A1 - Moldenhauer, Daniel A1 - Resch-Genger, Ute T1 - Broad range ON/OFF pH sensors based on pKa tunable fluorescent BODIPYs N2 - A set of highly fluorescent, pH-responsive boron dipyrromethene dyes covering the pH range of 5-12 is presented for broad range pH measurements in mixed aqueous-organic median and polymer matrices. Readout in the intensity Domain with low cost and miniaturized Instrumentation utilizes reversible protonation induced switching ON of their initially completely quenched flourescence mediated by photoinduced electron Transfer. All dyes, rationally designed to reveal closely matching Absorption and Emission properties, are accessible via facile two-step reactions in Overall yields of up to 20%. By modifying the Substitution pattern of the meso-Aryl substiuent, the pKa values could be fine-tuned from 6 to 11. Integration of these molecules into polymeric films by a simple mixing procedure yielded reversible and longterm stable pH sensors for naked eye detection. KW - Fluorescence KW - Sensor KW - PH KW - Dye KW - BODIPY KW - Synthesis KW - Quantification KW - Film KW - Quantum yield KW - Lifetime KW - PET PY - 2017 DO - https://doi.org/10.1016/j.snb.2017.05.080 SN - 0925-4005 VL - 251 SP - 490 EP - 494 PB - Elsevier AN - OPUS4-41782 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Güttler, Arne T1 - Certified Reference Materials for the Quantification and Standardization of Fluorescence-based Measurements N2 - The size and shape of photoluminescence signals is affected by wavelength-, polarization-, and time-dependent instrumentspecific contributions and the compound- and environment-specific photoluminescence quantum yield. The former hamper the comparability of fluorescence measurements performed on different measuring devices. The commonly relatively done determination of the performance parameter requires suitable quantum yield standards with well-known. The performance of such measurements is, e.g., described in the written standard IEC 62607 currently revised. T2 - Colloquium für Optische Spektrometrie 2025 CY - Jena, Germany DA - 24.09.2025 KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Advanced material KW - Calibration KW - Characterization KW - Fluorescence quantum yield KW - Phosphor KW - Absolute KW - Integrating sphere spectroscopy KW - Dye KW - Standardization KW - Reference material KW - Interlaboratory comparison KW - Uncertainty PY - 2025 AN - OPUS4-64213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meyerhofer, F. A1 - Dissinger, F. A1 - Weigert, Florian A1 - Jungclaus, J. A1 - Müller-Caspary, K. A1 - Waldvogel, S. R. A1 - Resch-Genger, Ute A1 - Voss, T. T1 - Citric Acid Based Carbon Dots with Amine Type Stabilizers: pHSpecific N2 - We report the synthesis and spectroscopic characteristics of two different sets of carbon dots (CDs) formed by hydrothermal reaction between citric acid and polyethylenimine (PEI) or 2,3-diaminopyridine (DAP). Although the formation of amide-based species and the presence of citrazinic acid type derivates assumed to be responsible for a blue emission is confirmed for both CDs by elemental analysis, infrared spectroscopy, and mass spectrometry, a higher abundance of sp2-hybridized nitrogen is observed for DAP-based CDs, which causes a red-shift of the n-π* absorption band relative to the one of PEI-based CDs. These CD Systems possess high photoluminescence quantum yields (QY) of ∼40% and ∼48% at neutral pH, demonstrating a possible tuning of the optical properties by the amine precursor. pH-Dependent spectroscopic studies revealed a drop in QY to < 9% (pH ∼ 1) and < 21% (pH ∼ 12) for both types of CDs under acidic and basic conditions. In contrast, significant differences in the pHdependency of the n-π* transitions are found for both CD types which are ascribed to different (de)protonation sequences of the CD-specific fluorophores and functional groups using Zeta potential analysis. KW - Fluorescence KW - Particle KW - Nano KW - Surface group analysis KW - Carbon dot KW - C-dot KW - Fluorescent probe KW - Quantum yield KW - Synthesis KW - IR KW - MS KW - Polymer KW - Ligand PY - 2020 DO - https://doi.org/10.1021/acs.jpcc.9b11732 VL - 124 IS - 16 SP - 8894 EP - 8904 PB - American Chemical Society AN - OPUS4-50813 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Pilch, A. A1 - Würth, Christian A1 - Kaiser, Martin A1 - Wawrzynczyk, D. A1 - Kurnatowska, M. A1 - Arabasz, S. A1 - Prorok, K. A1 - Samoc, M. A1 - Strek, W. A1 - Bednarkiewicz, A. T1 - Shaping luminescent properties of Yb3+ and Ho3+ co-doped upconverting core-shell ß-NaYF4 nanoparticles by dopant distribution and spacing N2 - At the core of luminescence color and lifetime Tuning of rare earth doped upconverting nanoparticles (UCNPs), is the understanding of the Impact of the particle architecture for commonly used sensitizer (S) and activator (A) Ions. In this respect, a series of core@Shell NaYF4 UCNPs doped with Yb3+ and Ho3+ ions are presented here, where the same dopant concentrations are distributed in different particle architectures following the scheme: YbHo core and YbHo@..., ...@YbHo, Yb@Ho, Ho@Yb, YbHo@Yb, and Yb@YbHo core-Shell NPs. As refealed by quantitative steady-state and time-resolved luminescence studies, the relative spatial Distribution of the A and S ions in the UCNPs and their protection from surface quenching has a critical Impact on ther luminescence characteristics. Although the increased amount of Yb3+ Ions boosts UCNP Performance by amplifying the Absorption, the Yb3+ ions can also efficiently dissipate the energy stored in the material through energy Migration to the surface, thereby reducing the Overall energy Transfer Efficiency to the activator ions. The results provide yet another proof that UC Phosphor chemistry combined with materials Engineering through intentional core@shell structures may help to fine-tune the luminescence Features of UCNPs for their specific future applications in biosensing, bioimaging, photovoltaics, and Display technologies. KW - Fluorescence KW - Upconversion KW - NIR KW - Nonlinear KW - Nanoparticle KW - Surface chemistry KW - Quantum yield KW - Liftetime KW - Nanocrystal KW - Lanthanide KW - Ho(III) KW - Yb(III) KW - Mechanism KW - Absolute flourescence KW - Excitation power density dependence PY - 2017 DO - https://doi.org/10.1002/smll.201701635 SN - 1613-6810 VL - 13 IS - 47 SP - 1701635, 1 EP - 13 PB - WILEY-VCH Verlag GmbH & co. KGaA CY - Weinheim AN - OPUS4-43629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, T. A1 - Wang, J. A1 - Cheng, Z. A1 - Yang, J. A1 - Qiao, X. A1 - Wen, J. A1 - Resch-Genger, Ute A1 - Ou, J. T1 - Fluorescence temperature sensing of NaYF4:Yb3+/Tm3+@NaGdF4:Nd3+/Yb3+ nanoparticles at low and high temperatures N2 - NaYF4:Yb3+/Tm3+@NaGdF4:Nd3+/Yb3+ upconversion nanoparticles (UCNPs) were prepared using a solvothermal method, and the effects of key factors such as the content of sensitiser Nd 3+ and Yb3+ on their luminescence properties were investigated. The nanoparticles are homogeneous in size and well dispersed. Under 808 nm excitation, it can produce strong upconversion fluorescence. At the same time, the nanoparticles have good temperature-sensing properties at the thermally coupled energy levels of 700 nm and 646 nm for Tm3+. Using its fluorescence intensity ratio (FIR), accurate temperature measurements can be performed, and it has been found that it exhibits different temperature sensing properties in low and high-temperature regions. The maximum relative sensitivity was found to be 0.88% K-1 and 1.89% K-1 for the lowtemperature region of 285 K-345 K and the high-temperature region of 345 K-495 K. The nanoparticles were applied to the internal temperature measurement of lithium batteries and the actual high-temperature environment, respectively, and were found to have good temperature measurementt performance. KW - Fluorescence KW - Sensor KW - Temperature KW - Ratiometric KW - Lanthanide KW - Quantum yield KW - Integrating sphere spectroscopy KW - Absolute fluorescence KW - Quality assurance KW - Nano KW - Particle KW - Application KW - Upconversion nanoparticle PY - 2022 DO - https://doi.org/10.1088/1361-6528/ac84e4 SN - 1361-6528 VL - 33 IS - 34 SP - 1 EP - 15 PB - IOP Publishing CY - Bristol AN - OPUS4-55454 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Quantifying the total and accessible amount of surface functionalities and ligands on nanomaterials N2 - Engineered nanomaterials (NMs) of various chemical composition and surface functionalization are routinely fabricated for industrial applications such as medical diagnostics, drug delivery, sensing, catalysis, energy conversion and storage, opto-electronics, and information storage. NM dispersibility, stability, processability, and function as well as the interaction with biological species and environmental fate are largely determined by NM surface functionalities, i.e., functional groups (FGs) and ligands. Therefore, reliable, reproducible, and eventually standardized surface characterization methods are vital for quality control of NMs, and mandatory to meet increasing concerns regarding their safety. Suitable methods for determining surface functionalities on ligand-stabilized core and core/shell NPs include advanced techniques such as traceable quantitative nuclear magnetic resonance (qNMR) as well as X-ray electron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS), and simpler optical and electrochemical methods.[1] The latter less costly and fast methods, which can be automated, are often used by NM producers for process and quality control.[1,2] To validate methods, establish measurement uncertain-ties, test reference materials, and produce reference data, multi-method characterization studies are needed.[3,4] as well as interlaboratory comparisons (ILC) on determining NM surface chemistry and well characterized test and reference NMs providing benchmark values.[5,6] Here, we present examples for quantifying common surface FGs such as amino and carboxyl groups on functional NMs of different chemical composition such as silica, polymer, iron oxide, and lanthanide-based upconversion nanoparticles with optical assays, electrochemical titration methods, qNMR, and chromatographic separation techniques. In addition, ongoing interlaboratory comparisons will be presented. T2 - Yucomat 2025 CY - Herec Novi, Montenegro DA - 01.09.2025 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 - Interlaboratory comparison KW - Uncertainty PY - 2025 AN - OPUS4-64182 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Measurements of Photoluminescence Quantum Yields of Scattering LED Converter Materials N2 - How to Get it Right with the Absolute Measurement of Photoluminescence Quantum Yields of Scattering LED Converter Materials Saskia Fiedler+,a, Florian Frenzel+,a, Christian Würth a, Isabella Tavernaro a, Michelle Grüne c, Stefan Schweizer c,d, Axel Engel e, and Ute Resch-Genger a* a Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstaetter-Strasse 11, D-12489 Berlin, Germany; email: ute.resch@bam.de b Present address: Photonic Materials, NWO-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands c Faculty of Electrical Engineering, South Westphalia University of Applied Sciences, Lübecker Ring 2, 59494, Soest, Germany d Fraunhofer Application Center for Inorganic Phosphors, Branch Lab of Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Lübecker Ring 2, 59494, Soest, Germany e Schott AG Technical Services, Hattenbergstrasse 10, D-55122 Mainz, Germany Optical measurements of scattering materials such as luminescent nano- and microparticles and phosphors dispersed in liquid and solid matrices play an important role in energy conversion, solid-state lighting, medical diagnostics, and security barcoding. A key performance parameter is the photoluminescence quantum yield QY, i.e., the number of emitted per number of absorbed photons. QY of transparent luminophore solutions can be obtained relative to a fluorescence QY standard of known QY, meanwhile available as certified reference materials.[1] The determination of QY of scattering liquid and solid samples like nanoparticle dispersions, phosphors, and optoceramics requires, however, absolute measurements with an integrating sphere setup. Despite the need for reliable absolute QY measurements, no interlaboratory comparison (ILCs) on measurement uncertainties has been performed and scattering standards with known QY are not available. We present the results of an ILC of 3 labs from academia and industry on measurements of transparent and scattering dye solutions and solid phosphors and converter materials like YAG:Ce optoceramics with commercial stand-alone integrating sphere setups of different illumination and detection geometries. Special emphasis was dedicated to the influence of measurement geometry, optical properties of the blank for determining the number of incident photons absorbed by the sample, and sample-specific surface roughness. Matching QY values could be obtained for transparent dye solutions and scattering dispersions with a blank with scattering properties closely matching those of the sample, QY measurements of optoceramic samples with different blanks revealed substantial differences of more than 20 %. Based on our data, we recommend non-absorbing blank materials with a high reflectivity (>95 %) such as a 2 mm-thick PTFE target placed on the sample holder as blanks. T2 - eMRS CY - Strasbourg, France DA - 26.05.2025 KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Quantum yield KW - NIR KW - Characterization KW - Electron microscopy KW - Film KW - Integrating sphere spectroscopy KW - Calibration KW - Lifetime KW - Advanced materials KW - LED converter KW - YAG:Ce KW - ILC KW - Measurement uncertainty KW - Absolute quantum yield PY - 2025 AN - OPUS4-63327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rezvani, A. A1 - Wang, Z. A1 - Wegner, Karl David A1 - Soltanmoradi, H. A1 - Kichigin, A. A1 - Zhou, X. A1 - Gantenberg, T. A1 - Schram, J. A1 - Zubiri, B. A. A1 - Spiecker, E. A1 - Walter, J. A1 - Resch-Genger, Ute A1 - Segets, D. T1 - Separation of Indium Phosphide/Zinc Sulfide Core−Shell Quantum Dots from Shelling Byproducts through Multistep Agglomeration N2 - Semiconductor quantum dots (QDs) possess unique electronic and optical properties, making them promising candidates for applications in lightemitting diodes, solar cells, bioimaging, and photocatalysis. Precise control over their size, shape, and chemical and electronic structure is crucial to ensure the desired functional properties and optimize device performance. However, challenges in QD synthesis and post-synthesis modification persist, especially in large-scale production. This study addresses the classification of QDs synthesized in a tubular flow reactor consisting of a mixture of the desired InP/ZnS core−shell QDs and QDs made from the shell material, i.e., here ZnS QDs formed as a byproduct during the formation step of the ZnS shell. The homogeneous nucleation of ZnS nanoparticles from the shelling material introduces a heterogeneity in size and composition and affects the optical properties of the resulting QDs. To address this issue, we developed a size-selective agglomeration (SSA) technique by incrementally introducing ethanol as a poor solvent and classified the synthesized QDs into 13 distinct fractions. These 13 fractions are sorted into three distinct groups: (i) larger InP/ZnS QDs, (ii) a combination of smaller InP/ZnS QDs and larger ZnS QDs, and (iii) predominant ZnS QDs with some very tiny InP/ZnS QDs. The comprehensive characterization of the fractions was conducted using UV−visible absorption spectroscopy, photoluminescence spectroscopy, high-resolution scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, total reflection X-ray fluorescence, and analytical ultracentrifugation. We could demonstrate that our method effectively separated unwanted ZnS QDs from the target InP/ZnS QDs. In addition, the fractions enriched in smaller InP/ZnS QDs exhibited a higher photoluminescence quantum yield compared to the fractions with larger QDs. This demonstrates the efficacy of SSA in finetuning the composition of QD mixtures produced on a larger scale to improve their functional properties. This approach provides fundamental understanding toward the development of a scalable two-dimensional classification process for such ultrasmall nanoparticles by particle size and composition. KW - Quality assurance KW - Reference material KW - Nano KW - Particle KW - Quantum dot KW - Synthesis KW - Flow reactor KW - InP KW - Shell KW - ZnS KW - Surface chemistry KW - Method KW - Fluorescence KW - Quantum yield KW - TEM PY - 2025 DO - https://doi.org/10.1021/acsnano.4c18530 SN - 1936-086X VL - 19 IS - 20 SP - 19080 EP - 19094 PB - ACS Publications AN - OPUS4-63215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella T1 - pH- and O2-Responsive Nanoparticles – The MiGraGen Project N2 - In recent years, the demand for reliable, versatile, fluorescent pH and oxygen sensors has increased rapidly in many biomedical applications since these analytes are important indicators of cell function or certain diseases. Therefore, sensor particles are needed that are small enough to penetrate cells, non-toxic, and allow for close-up optical monitoring. When developing such sensor systems, one must consider the pH and oxygen range detectable by the sensor dye and the matrix material of the used carrier particles. Here, we present the development of pH- and oxygen-responsive polymeric beads functionalized with fluorescent dyad molecules that consist of an analyte-responsive fluorophore and an analyte-inert dye. T2 - MiGraGen Project Meeting 09.08.2023 CY - Online Meeting DA - 09.08.2023 KW - Nano- and microsensors KW - Functionalized silica and polymeric particles KW - pH sensing KW - Oxygen sensing KW - Fluorescence PY - 2023 AN - OPUS4-58071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kage, Daniel A1 - Hoffmann, Katrin A1 - Borcherding, H. A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Lifetime encoding in flow cytometry for bead‑based sensing of biomolecular interaction N2 - To demonstrate the potential of time-resolved flow cytometry (FCM) for bioanalysis, clinical diagnostics, and optically encoded bead-based assays, we performed a proof-of-principle study to detect biomolecular interactions utilizing fluorescence lifetime (LT)-encoded micron-sized polymer beads bearing target-specific bioligands and a recently developed prototype lifetime flow cytometer (LT-FCM setup). This instrument is equipped with a single excitation light source and different fluorescence detectors, one operated in the photon-counting mode for time-resolved measurements of fluorescence decays and three detectors for conventional intensity measurements in different spectral windows. First, discrimination of bead-bound biomolecules was demonstrated in the time domain exemplarily for two targets, Streptavidin (SAv) and the tumor marker human chorionic gonadotropin (HCG). In a second step, the determination of biomolecule concentration levels was addressed representatively for the inflammation-related biomarker tumor necrosis factor (TNF-α) utilizing fluorescence intensity measurements in a second channel of the LT-FCM instrument. Our results underline the applicability of LT-FCM in the time domain for measurements of biomolecular interactions in suspension assays. In the future, the combination of spectral and LT encoding and multiplexing and the expansion of the time scale from the lower nanosecond range to the longer nanosecond and the microsecond region is expected to provide many distinguishable codes. This enables an increasing degree of multiplexing which could be attractive for high throughput screening applications. KW - Fluorescence KW - Sensor KW - Assay KW - Protein KW - Multiplexing KW - Flow cytometry KW - Barcoding KW - Lifetime KW - Dye KW - Bead KW - Bead-based assay KW - Method KW - Quantification PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516007 DO - https://doi.org/10.1038/s41598-020-76150-x VL - 10 IS - 1 SP - 19477 PB - Nature AN - OPUS4-51600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, Katrin A1 - Nirmalananthan-Budau, Nithiya A1 - Resch-Genger, Ute T1 - Fluorescence calibration standards made from broadband emitters encapsulated in polymer beads for fluorescence microscopy and flow cytometry N2 - We present here the design and characterization of a set of spectral calibration beads. These calibration beads are intended for the determination and regular control of the spectral characteristics of fluorescence microscopes and other fluorescence measuring devices for the readout of bead-based assays. This set consists of micrometer-sized polymer beads loaded with dyes from the liquid Calibration Kit Spectral Fluorescence Standards developed and certified by BAM for the wavelength-dependent Determination of the spectral responsivity of fluorescencemeasuring devices like spectrofluorometers. To cover the wavelength Region from 400 to 800 nm, two new near-infrared emissive dyes were included, which were spectroscopically characterized in solution and encapsulated in the beads. The resulting set of beads presents the first step towards a new platform of spectral calibration beads for the determination of the spectral characteristics of fluorescence instruments like fluorescence microscopes, FCM setups, and microtiter plate readers, thereby meeting the increasing demand for reliable and comparable fluorescence data especially in strongly regulated areas, e.g., medical diagnostics. This will eventually provide the basis for standardized calibration procedures for imaging systems as an alternative to microchannel slides containing dye solutions previously reported by us. KW - Fluorescence standard KW - Fluorescence KW - Dye KW - Microscopy KW - Bead KW - Particle KW - NIR KW - calibration KW - Quality assurance KW - Traceability PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508117 DO - https://doi.org/10.1007/s00216-020-02664-y SN - 1618-2642 VL - 412 IS - 24 SP - 6499 EP - 6507 PB - Springer AN - OPUS4-50811 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Methods for the determination of the optical properties and the surface chemistry of fluorescent particles N2 - Fluorescent particles like nm- and m-sized polymeric beads doped or labeled with different types of fluorophores and nanocrystalline systems like quantum dots and upconversion phosphors emitting in the visible (vis), near-infrared (NIR), and IR (infrared) region are of increasing importance as fluorescent reporters for bioanalysis and medical diagnostics. The assessment and comparison of material performance and the development of rational design strategies for improved systems requires suitable spectroscopic tools for the determination of signal-relevant optical properties and analytical tools for the determination of the number of surface groups, ligands, biomolecules and /or fluorophores per bead. In this respect, suitable spectroscopic tools for the characterization of the optical properties of such materials like photoluminescence quantum yields and brightness values and the determination of their surface chemistry are introduced. This includes integrating sphere setups for absolute measurements of fluorescence quantum yields of liquid and solid, transparent and scattering materials in the wavelength region of 350 nm to 1600 nm at varying excitation power densities for the study of multi-photon processes and simple optical assays, validated by comparison with established analytical techniques relying on different detection principles. Here, different examples for the optical and analytical characterization of different types of nanoscale reporters are presented. T2 - MoLife Research Seminar CY - Bremen, Germany DA - 26.04.2016 KW - Optical assay KW - Fluorescence KW - Integrating sphere spectroscopy KW - Quantum yield KW - NIR KW - IR KW - Optical spectroscopy KW - Nanomaterials KW - Semiconducor nanocrystals KW - Upconversion nanocrystals KW - Surface analysis KW - Ligand analysis PY - 2016 AN - OPUS4-35954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Hoffmann, Katrin A1 - Würth, Christian A1 - Behnke, Thomas A1 - Resch-Genger, Ute T1 - Standardization of fluorescence measurements in the UV/vis/NIR/IR N2 - Photoluminescence techniques are amongst the most widely used Tools in the life sciences, with new and exciting applications in medical diagnostics and molecular Imaging continuously emerging. Advantages include their comparative ease of use, unique sensitivity, non-invasive character, and potential for Multiplexing, remote sensing, and miniaturization. General drawbacks are, however, signals, that contain unwanted wavelength- and polarization contributions from Instrument-dependent effects, which are also time-dependent due to aging of Instrument-components, and difficulties to measure absolute flourescence entensities. Moreover, scattering Systems require Special measurement geometries and the interest in new optical Reporters with Emission > 1000 nm strategies for reliable measurements in the second diagnostic for the comparison of material Performance and the rational designg of new flourophores with improved properties. Here, we present strategies to versatile method-adaptable liquid and solid flourescence Standards for different flourescence paramters including traceable Instrument calibration procedures and the design of integrating spere setups for the absolute measurements of emission spectra and Quantum yields in the wavelength Region of 350 to 1600 nm. Examples are multi-Emitter glasses, spectral flourescence Standards, and quantum yield Standards for the UV/vis/NIR. T2 - Conference on Molecular-Guided Surgery - Molecules, Devices, and Applications III CY - San Francisco, CA, USA DA - 28.01.2017 KW - Fluorescence KW - Reference material KW - Standard KW - Calibration KW - Nanoparticle KW - Absolute flourometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Quantum yield standard KW - Emission standards PY - 2017 SN - 978-1-5106-0539-8 DO - https://doi.org/10.1117/12.2255728 SN - 0277-786X VL - 10049 SP - 1 PB - Proceedings of SPIE AN - OPUS4-41783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Resch-Genger, Ute A1 - Richter, Maria A1 - Güttler, Arne A1 - Pauli, Jutta A1 - Vogel, K. A1 - Homann, Christian A1 - Würth, Christian T1 - Extending Certified Spectral Fluorescence Standards for the Calibration and Performance Validation of Fluorescence Instruments to the NIR – Closing the Gap from 750 nm to 940 nm with Two Novel NIR Dyes N2 - Fluorescence methods provide spectral, intensity, polarization, and lifetime information, which contain sample- and instrument-specific contributions. Fluorescence data, comparable across instruments and laboratories, require validated calibration procedures and certified fluorescence standards. KW - Quality assurance KW - Reference material KW - Fluorescence KW - Dye KW - Traceability KW - Metrology KW - Calibration KW - Reference data KW - Reference product KW - Digital certificate KW - NIR KW - Instrument performance validation PY - 2025 SP - 1 EP - 4 PB - Springer Nature CY - London AN - OPUS4-62739 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Andreato, E. A1 - Panov, N. A1 - Artiga, A. A1 - Osipova, Viktoriia A1 - Resch-Genger, Ute A1 - Ximendes, E. A1 - Molina, P. A1 - Canton, P. A1 - Marin, R. T1 - Indium-Based Fluoride Nanoparticles Doped with Chromium for Near-Infrared Luminescence N2 - Transition metal (TM) and rare earth (RE) ion-doped nanoparticles (NPs) are photoluminescent materials of technological relevance in bioimaging, sensing, and light conversion. Fluoride NPs are particularly attractive in this context, since they combine low-energy phonons, high chemical stability, optical transparency, size, and architecture tunability. Yet, nearly all reported colloidal fluoride NPs (e.g., NaYF4 and LiYF4) can only be efficiently doped with RE3+ and not with luminescent TM ions. Herein, we contribute to filling this gap in materials science by reporting Na3InF6 NPs doped with Cr3+ as a model luminescent TM ion. We unveil the heat-driven NP formation mechanism, which involves a cubic-to-monoclinic phase conversion, similarly to the cubic-tohexagonal phase conversion in NaYF4. Reaction temperatures above 225 °C and reaction time have a limited impact on the NP morphology, while the amount of fluoride precursor and oleylamine grants control over the NP size. After verifying that Na3InF6 NPs show negligible cytotoxicity toward U-87 cell line, we study the optical properties of these NPs upon Cr3+ doping. Temperature-dependent photoluminescence measurements indicate that Cr3+ ions experience a weak crystal field in the Na3InF6 host lattice, while their photoluminescence lifetime varies linearly in the 20−50 °C range. These results set the ground for further studies of photoluminescent TM-doped fluoride NPs, toward their applications in bioimaging, sensing, and light-converting devices. KW - Quality assurance KW - Fluorescence KW - Traceability KW - Nano KW - Particle KW - Synthesis KW - Quantum yield KW - NIR KW - Mechanism KW - Characterization KW - XRD KW - Phase transition KW - Ligand KW - Surface KW - Doping KW - Lifetime PY - 2025 DO - https://doi.org/10.1021/acs.chemmater.4c03335 SN - 1520-5002 SP - 1 EP - 14 PB - American Chemical Society AN - OPUS4-63073 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawlitza, Kornelia T1 - Using Dual Fluorescent Molecularly Imprinted Particles Coupled with a Miniaturized Opto-Microfluidic Platform for On-Site Detection of Perfluoroalkyl Carboxylic Acids N2 - Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic organofluorine chemicals widely used in the production of various materials, including firefighting foams, adhesives, and coatings that resist stains and oil. In recent years, PFAS have gained attention as emerging environmental contaminants, with particular emphasis on perfluoroalkyl carboxylic acids (PFCAs), the most common type of PFAS. PFCAs are defined by a fully fluorinated carbon chain and a charged carboxylic acid group. They have been classified as Substances of Very High Concern and included in the REACH Candidate List due to their persistence, resistance to biodegradation, and toxicological impacts. Traditional methods for analyzing PFCAs, like GC-MS, HRMS, and HPLC-based techniques, are time-consuming, non-portable, expensive, and require specialized expertise. On the other hand, fluorescence assays offer a user-friendly, portable, and cost-effective alternative with high sensitivity and quick results, particularly when the binding of the analyte causes a specific increase in the probe’s fluorescence. Combining these probes with a carrier platform and a miniaturized optofluidic device presents a promising approach for PFCA monitoring. In this study, a new guanidine BODIPY fluorescent indicator monomer was synthesized, characterized, and incorporated into a molecularly imprinted polymer (MIP) designed for the specific detection of perfluorooctanoic acid (PFOA). The MIP layer was formed on silica core nanoparticles doped with tris(bipyridine)ruthenium(II) chloride, serving as an optical internal reference for calibration-free assays. In combination with an extraction step prior to sample analysis, this system enables selective and reliable detection of PFCAs in surface water samples, minimizing interference from competing substances, matrix effects, and other factors. When integrated into an opto-microfluidic setup, the assay provided a compact, user-friendly detection system capable of detecting micromolar levels of PFOA in under 15 minutes from surface water samples. T2 - ANAKON2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Perfluorooctanoic Acid (PFOA) KW - On-site detection KW - Fluorescence KW - Microfluidics KW - Molecularly Imprinted Polymers PY - 2025 AN - OPUS4-62712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wagner, Sabine T1 - Integration of microspheres coated with fluorescent molecularly imprinted polymers with a fiber optic array for the detection of antibiotics N2 - The widespread use of antibiotics in livestock farming leads to trace residues in food products and wastewater, potentially entailing antimicrobial resistance in food-borne pathogens. The determination of antibiotics in aqueous environments and foodstuff is thus of major concern. Analytical assays based on molecularly imprinted polymers (MIPs) have emerged as a valuable tool in this field due to the low production costs, stability, format adaptability and the possibility to imprint and thus their ability to recognize a wide variety of target analytes. With regard to optical sensing technologies, however, MIPs have only been used in considerably few applications, especially in fluorescence sensors. This limitation is basically due to the fact that the incorporation of a fluorescently responding moiety into a polymer matrix is challenging. One way to overcome this limitation is to use tailor-made fluorescent indicator monomers for direct transfer of the binding event into an optical signal. If such a monomer is integrated into a thin MIP-shell on microspheres such core/shell particles can be readily used in advanced multiplexing sensory fiber-optic microarrays. Here, we propose such a fiber-optic microarray based on fluorescent MIP microspheres for antibiotics. The binding behavior and the selectivity of a microarray using these MIP were examined and compared with a non-imprinted polymer (NIP) control, employing the target molecules and other structurally closely related antibiotics. T2 - Europt(r)ode XIII CY - Graz, Austria DA - 20.03.2016 KW - Molecularly imprinted polymers KW - Fiber-optic microarray KW - Fluorescence PY - 2016 AN - OPUS4-37294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Homann, Christian A1 - Peeters, Régis A1 - Mirmajidi, Hana A1 - Berg, Jessica A1 - Fay, Michael A1 - Rodrigues, Lucas Carvalho Veloso A1 - Radicchi, Eros A1 - Jain, Akhil A1 - Speghini, Adolfo A1 - Hemmer, Eva T1 - Rapid microwave-assisted synthesis of morphology-controlled luminescent lanthanide-doped Gd2O2S nanostructures N2 - Gadolinium oxysulfide (Gd2O2S) is an attractive material of demonstrated suitability for a variety of imaging applications, leveraging its magnetic, scintillating, and luminescent properties, particularly when doped with optically active lanthanide ions (Ln3+). For many of these applications, control over size and morphology at the nanoscale is crucial. This study demonstrates the rapid microwave-assisted Synthesis of colloidal Ln2O2S (Ln = Gd and dopants Yb, Er, Tb) nanostructures in as little as 20 min. Structural characterization using X-ray diffraction analysis (XRD), Raman spectroscopy, as well as Transmission electron microscopy (TEM), including elemental mapping via energy dispersive X-ray spectroscopy (EDS), unveiled the key role of elemental sulphur (S8) in the reaction mixtures for materials growth. By systematically varying the Ln-to-S ratio from 1 : 0.5 to 1 : 15, controlled morphologies ranging from triangular nanoplatelets to berry- and flower-like shapes were achieved. Doping with Er3+/Yb3+ endowed the nano-triangles with upconverting and near-infrared emitting properties. Tb3+-doped Gd2O2S exhibited the characteristic green Tb3+ emission under UV excitation, while also showing X-ray excited optical luminescence (XEOL), rendering the material interesting as a potential nano-scintillator. KW - Upconversion KW - Microwave-assisted synthesis KW - Synthesis KW - Fluorescence KW - Nano KW - Particle KW - NIR KW - XRD KW - X-ray fluoressence KW - Morphology control KW - Raman PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647907 DO - https://doi.org/10.1039/D5TC01646K SN - 2050-7526 VL - 13 IS - 35 SP - 18492 EP - 18507 PB - Royal Society of Chemistry (RSC) AN - OPUS4-64790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fidan, Z. A1 - Wende, A. A1 - Resch-Genger, Ute T1 - Visible and red emissive molecular beacons for optical temperature measurements and quality control in diagnostic assays utilizing temperature-dependent amplification reactions N2 - Quality control requirements imposed on assays used in clinical diagnostics and point-of-care-diagnostic testing (POCT), utilizing amplification reactions performed at elevated temperatures of 35 to 95 °C are very stringent. As the temperature of a reaction vessel has a large impact on the specificity and sensitivity of the amplification reaction, simple tools for local in situ temperature sensing and monitoring are required for reaction and assay control. We describe here a platform of stem-and-loop structured DNA hairpins (molecular beacons, MBs), absorbing and emitting in the visible and red spectral region, rationally designed for precise temperature measurements in microfluidic assays for POCT, and their ap-plication for temperature measurements in a common DNA-based molecular biological assay utilizing thermophilic helicase-dependent amplification (tHDA). Spectroscopic studies of these MBs, rationally designed from DNA se-quences of different thermal stabilities, chosen not to interact with the DNA probes applied in the nucleic acid amplification assay, and temperature-dependent fluorescence measurements of MB-assay mixtures revealed the suitability of these MBs for temperature measurements directly in such an assay with a temperature resolution of about 0.5 °C without interferences from assay components. Combining two spectrally distinguishable MBs provides a broader response range and an increase in temperature sensitivity up to 0.1 °C. This approach will find future application for temperature monitoring and quality control in commercialized diagnostics assays using dried reagents and microfluidic chips as well as assays read out with tube and microplate readers and PCR detection systems for temperature measurements in the range of 35 to 95 °C. KW - Miniaturization KW - Fluorescence KW - Temperature KW - Sensor KW - Assay KW - Microfluidics KW - DNA KW - Dye KW - Molecular beacon KW - Molecular diagnostics PY - 2016 DO - https://doi.org/10.1007/s00216-016-0088-6 SN - 1618-2642 VL - 409 IS - 6 SP - 1519 EP - 1529 PB - Springer CY - Heidelberg AN - OPUS4-39589 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Srivastava, Priyanka A1 - Tavernaro, Isabella A1 - Genger, C. A1 - Welker, P. A1 - Huebner, Oskar A1 - Resch-Genger, Ute T1 - Multicolor Polystyrene Nanosensors for the Monitoring of Acidic, Neutral, and Basic pH Values and Cellular Uptake Studies N2 - A first tricolor fluorescent pH nanosensor is presented, which was rationally designed from biocompatible carboxylated polystyrene nanoparticles and two analyte-responsive molecular fluorophores. Its fabrication involved particle staining with a blue-red-emissive dyad, consisting of a rhodamine moiety responsive to acidic pH values and a pH-inert quinoline fluorophore, followed by the covalent attachment of a fluorescein dye to the particle surface that signals neutral and basic pH values with a green fluorescence. These sensor particles change their fluorescence from blue to red and green, depending on the pH and excitation wavelength, and enable ratiometric pH measurements in the pH range of 3.0−9.0. The localization of the different sensor dyes in the particle core and at the particle surface was confirmed with fluorescence microscopy utilizing analogously prepared polystyrene microparticles. To show the application potential of these polystyrene-based multicolor sensor particles, fluorescence microscopy studies with a human A549 cell line were performed, which revealed the cellular uptake of the pH nanosensor and the differently colored emissions in different cell organelles, that is, compartments of the endosomal-lysosomal pathway. Our results demonstrate the underexplored potential of biocompatible polystyrene particles for multicolor and multianalyte sensing and bioimaging utilizing hydrophobic and/or hydrophilic stimuli-responsive luminophores. KW - Microparticle KW - Fluorescence KW - Sensor KW - pH KW - Quantum yield KW - Multiplexing KW - Imaging KW - Cell KW - Quality assurance KW - Nano KW - Polymer KW - Bioimaging KW - Particle KW - Application PY - 2022 DO - https://doi.org/10.1021/acs.analchem.2c00944 VL - 94 IS - 27 SP - 9656 EP - 9664 PB - ACS AN - OPUS4-55365 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauli, Jutta A1 - Würth, Christian A1 - Güttler, Arne A1 - Resch-Genger, Ute T1 - Reliable Determination of the Signal-Relevant Spectroscopic Key Characteristics of Luminescent Reporters and Optical Probes for Imaging in the vis/NIR/SWIR N2 - Introduction. Comparing different emitter classes and rationally designing the next generation of molecular and nanoscale probes for bioimaging applications require accurate and quantitative methods for the measurement of the key parameter photoluminescence quantum yield f.1 f equals the number of emitted per number of absorbed photons. This is particularly relevant for increasingly used fluorescence imaging in the short wave-infrared region (SWIR) ≥ 900 nm providing deeper penetration depths, a better image resolution, and an improved signal-to-noise or tumor-to-background ratio.2, 3 However, spectroscopic measurements in the SWIR are more challenging and require specific calibrations and standards. T2 - EMIM 2021 CY - Göttingen, Germany DA - 24.08.2021 KW - Fluorescence KW - Optical probe KW - Dye KW - Photophysics KW - Quantum yield KW - Mechanism KW - NIR KW - SWIR KW - Imaging KW - Reference material KW - Reliability KW - Nano KW - Particle KW - Method KW - Quality assurance PY - 2021 AN - OPUS4-53233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Design and Quantitative Characterization of Functional Molecular Chromophores and Nanomaterials with UV/vis/NIR/IR Emission – An Overview of Research Activities in Division Biophotonics N2 - In the focus of division Biophotonics are the design, preparation, analytical and spectroscopic characterization, and application of molecular and nanoscale functional materials, particularly materials with a photoluminescence in the visible, near infrared (NIR) and short-wave infrared (SWIR). This includes optical reporters for bioimaging and sensing, security and authentication barcodes, and materials for solid state lighting, energy conversion, and photovoltaics. For the identification of optimum particle structures quantitative spectroscopic studies are performed under application-relevant conditions, focusing on the key performance parameter photoluminescence quantum yield. In addition, simple, cost-efficient, and standardizable strategies for quantifying functional groups on the surface of nano- and microparticles are developed, here with a focus on optical assays and electrochemical titration methods, cross-validated by more advanced methods such as quantitative NMR. In addition, reference materials and reference products are developed for optical methods, particularly luminescence techniques, and for analytical methods utilized for the characterization of nanomaterials. T2 - Projekttreffen Nile-Chrome 2.0 CY - Mainz, Germany DA - 11.12.2023 KW - Fluorescence KW - Quantum yield KW - Optical spectroscopy KW - Reference material KW - Reference data KW - Quality assurance KW - Dye KW - Reference product KW - NIR KW - SWIR KW - Nano KW - Particle KW - Silica KW - Polymer KW - Surface group analysis KW - Sensor molecules PY - 2023 AN - OPUS4-59123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute ED - Otto, S. ED - Scholz, Norman ED - Behnke, Thomas ED - Heinze, K. T1 - Thermo-Chromium: A Contactless Optical Molecular Thermometer N2 - The unparalleled excited-state potential-energy landscape of the chromium(III)-based dye [1]3+ ([Cr(ddpd)2]3+; ddpd=N,N’-dimethyl-N,N’-dipyridin-2-ylpyridin-2,6-diamine) enables a strong dual emission in the near infrared region. The temperature dependence of this dual emission allows the use of [1]3+ as an unprecedented molecular ratiometric thermometer in the 210–373 K temperature range in organic and in aqueous media. Incorporation of [1]3+ in biocompatible nanocarriers, such as 100 nm-sized polystyrene nanoparticles and solutol micelles, provides nanodimensional thermometers operating under physiological conditions. KW - Temperature KW - Sensor KW - Dual emission KW - Fluorescence KW - Cr complex KW - Nano KW - Particle KW - Micelle KW - Probe KW - Environment PY - 2017 DO - https://doi.org/10.1002/chem.201701726 SN - 0947-6539 VL - 23 IS - 50 SP - 12131 EP - 12135 PB - Wiley-VCH AN - OPUS4-42539 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Quantification of Parameters Affecting the Upconversion Luminescence of Lanthanide-Based Upconversion Nanocrystals N2 - Lanthanide-based upconversion nanoparticles (UCNPs) like hexagonal Beta-NaYF4 UCNPs doped with Yb3+ and Er3+, which efficiently convert 976 nm light to ultraviolet, visible, and near infrared photons, offer new strategies for luminescence-based sensing, barcoding, and imaging. The properties of their upconversion (UC) luminescence (UCL) are, however, strongly influenced by particle size, the concentration and spatial arrangement of the dopant ions, surface chemistry including presence and thickness of surface passivation and shielding shells, microenvironment/presence of quenchers with high energy vibrations, and excitation power density (P). We present here a comprehensive study of the influence of UCNP size and particle architecture for Yb3+ and Er3+ co-doped NaYF4 core-only and core-shell nanostructures in the size range of about 5 nm to 50 nm, which underlines the importance of particle synthesis, surface chemistry, and quantitative luminescence measurements for mechanistic insights and the determination of application-relevant matrix- and P-dependent optimum dopand concentrations. T2 - Materials Challenges in Alternative and Renewable Energy (MCARE) 2018 CY - Vancouver, BC, Canada DA - 20.08.2018 KW - Upconverting nanoparticles KW - Size KW - Energy transfer KW - Fluorescence KW - Absolute fluorescence quantum yield KW - Fluorescence decay kinetics KW - Power density dependence PY - 2018 AN - OPUS4-46393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella T1 - Design of Fluorescent, Amorphous Silica-NPs and their Versatile Use in Sensing Applications N2 - Surface functionalized silica nanoparticles (SiO2-NP) gained great interest in the life and material sciences, as they can be used e.g. as drug carriers, fluorescent sensors, and multimodal labels in bioanalytical assays and imaging applications. They are highly stable, are easily produced and modified on a large scale at low cost and can be labeled or stained with a multitude of sensor dyes. These dye modified particle conjugates have several advantages as compared to conventional molecular probes like enhanced brightness, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, stained nanoparticles can enable the use of hydrophobic dyes in aqueous environments. Here we present our work on multicolored sensors for the measurement of pH, oxygen and saccharides utilizing amorphous SiO2 NPs. T2 - Focus Area Day Analytical Sciences 2023 CY - Berlin, Germany DA - 20.04.2023 KW - Amorphous silica particles KW - Particle Synthesis KW - Nano KW - Ratiometric Sensors KW - Fluorescence KW - pH probe KW - Dye PY - 2023 AN - OPUS4-59151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Measuring the Upconversion Luminescence of Ensemble and Single Particle Lanthanide-Based Upconversion Nanocrystals N2 - Lanthanide-based upconversion nanoparticles (UCNPs) like hexagonal 𝛽-NaYF4 UCNPs doped with Yb3+ and Er3+, which efficiently convert 976 nm light to ultraviolet, visible, and near infrared photons, offer new strategies for luminescence-based sensing, barcoding, and Imaging. Their upconversion (UC) luminescence (UCL) features like UCL intensity, quantum yield, relative spectral distribution / UCL luminescence color, and luminescence decay kinetics are, however, strongly influenced by particle size, dopant ion concentration, particle architecture, surface chemistry including presence and thickness of surface passivation and shielding shells, microenvironment/presence of quenchers with high energy vibrations, and excitation power density (P). We present here a comprehensive study of the influence of excitation power density on the UCL features of different types of UCNPs, focusing on Yb3+ and Er3+ co-doped NaYF4 core-only and core-shell nanostructures with different sizes and doping ion concentration, which underlines the importance of P-dependent optimum dopant concentrations for UCNP performance and the potential of P-tuning of UCL. T2 - Materials Challenges in Alternative & Renewable Energy 2021 (MCARE 2021) CY - Online meeting DA - 19.07.2021 KW - Fluorescence KW - Lifetime KW - Method KW - Stability KW - Coating KW - Surface chemistry KW - Lanthanide KW - Upconversion KW - Nano KW - Particle KW - Single particle spectroscopy KW - Quantum yield KW - Microscopy KW - Photophysics PY - 2021 AN - OPUS4-53111 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David T1 - Advancing Short-Wave Infrared (SWIR) Emission N2 - There is a growing interest in the exploitation of the short-wave infrared (SWIR), which refers to the wavelength band of light between 900 nm and 2500 nm. Luminophores that emit in the SWIR are used in various areas of telecommunications, photovoltaics, security systems (night vision), and in biomedicine. In particular for biomedical applications, the SWIR range is highly promising because light scattering, absorption, and autofluorescence of tissue and biological compounds are strongly reduced compared to the visible (400–700 nm) and NIR (~700–900 nm). The benefits of SWIR-emissive QDs have been demonstrated for a variety of applications, such as in thermal sensing, as photoelectrochemical biosensor, in in vivo vascular imaging, and for fluorescence-guided surgery.[1] Full exploitation of SWIR photoluminescence (PL) imaging and sensing is currently hampered by i.) a lack of suitable advanced nanomaterials with a high PL quantum yield (PL QY) and a high brightness, that can be used safely in vivo and ii.) a lack of quantitative and reliable data on the optical properties of many SWIR emitters. Promising nanomaterials for the SWIR are heavy metal-free Ag2S quantum dots (QDs). Aiming for the development of SWIR advanced nanomaterials with optimum performance, we have dived deeper into the photophysical processes occurring in these nanomaterials, thereby exploring in depth how the environment such as temperature, surface ligand composition, and the incorporation of transition metals influence the optical properties Ag2S QDs. We observed a strong enhancement of the SWIR emission of upon addition of metal ions such as Zn2+, yielding PL quantum yields of about 10% and thus making them highly suitable for non-invasive deep imaging of vascular networks and 3D fluid flow mapping. T2 - Anakon 2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Quantum dots KW - Nano KW - Particle KW - SWIR KW - Fluorescence KW - Temperature KW - Ag2S KW - Quality assuarance KW - Ligand KW - Sensor PY - 2025 AN - OPUS4-62769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Sloniec-Myszk, Jagoda ED - Hennig, Andreas T1 - Chiral, J-aggregate-forming dyes for alternative signal modulation mechanisms in self-immolative enzyme-activatable optical probes N2 - Enzyme-activatable optical probes are important for future advances in cancer imaging, but may easily suffer from low signal-to-background ratios unless not optimized. To address this shortcoming, numerous mechanisms to modulate the fluorescence signal have been explored. We report herein newly synthesized probes based on selfimmolative linkers containing chiral J-aggregate-forming dyes. Signal modulation by formation of chiral J-aggregates is yet unexplored in optical enzyme probe design. The comprehensive characterization of the probes by absorption, CD, fluorescence, and time-resolved fluorescence spectroscopy revealed dye−dye interactions not observed for the free dyes in solution as well as dye−protein interactions with the enzyme. This suggested that J-aggregate formation is challenging to achieve with current probe design and that interactions of the dyes with the Enzyme may interfere with achieving high signal-to-background ratios. The detailed understanding of the interactions provided herein provides valuable guidelines for the future design of similar probes. KW - Signal amplification KW - Fluorescence KW - Quantum yield KW - Optical spectroscopy KW - Dye KW - Cyanine KW - Characterization KW - Assay KW - Chiral KW - Aggregation KW - Activatable probe PY - 2016 DO - https://doi.org/10.1021/acs.jpcb.5b10526 SN - 1520-5207 SN - 1520-6106 VL - 120 IS - 5 SP - 877 EP - 885 PB - ACS Publications AN - OPUS4-35949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Absolute spectroscopic characterization of the optical properties of semiconductor and upconversion nanocrystals in the vis and IR N2 - Nanocrystalline fluorophores like semiconductor quantum dots and rods and recently also lanthanide-based upconversion phosphors with emission in the visible (vis), near-infrared (NIR), and IR (infrared) region are increasingly being used in bioimaging studies and fluorescence assays as well as in photovoltaics and solid state lighting. The assessment and comparison of material performance as well as the development of rational design strategies for improved systems require spectroscopic tools, which enable the determination of the signal-relevant optical properties like photoluminescence quantum yields and brightness values. In the case of nonlinear fluorescence as shown by upconversion materials, such measurements must be also performed as function of excitation power density. In this work, we report on methods for the absolute determination of the photoluminescence quantum yield and brightness of fluorescent particles in dispersion and as powders based on integrating sphere spectroscopy and underline the importance of such measurements for the understanding of the photophysics of such nanocrystals. T2 - International Conference on Fundamental Processes in Semiconductor Nanocrystals (FQDots16) CY - Berlin, Germany DA - 05.09.2016 KW - Fluorescence KW - Nanoparticle KW - Semiconductor quantum dot KW - Upconversion nanocrystal KW - NIR KW - Integrating sphere spectroscopy KW - Fluorescence quantum yield KW - Method PY - 2016 AN - OPUS4-38695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Effect of Particle Size and Excitation Power Density on the Luminescence Efficiency of Upconversion Nanocrystals in Different Dispersion Media N2 - Upconversion nanoparticles (UCNPs) offer new strategies for luminescence-based sensing and imaging. One of the best studied materials are ..-NaYF4 UCNPs doped with 20 % Yb3+ and 2 % Er3+, which efficiently convert 976 nm light to photons emitted at 540 nm, 655 nm, and 845 nm, respectively, reveal long luminescence lifetimes (> 100 µs), are photostable and chemically inert. Their upconversion (UC) luminescence (UCL) properties are, however, strongly influenced by particle size, surface chemistry, and microenvironment. In addition, the multiphotonic absorption processes responsible for UCL render UCL excitation power density (..) dependent. This makes quantitative UCL measurements as well as the determination of UC quantum yields (.UC) very challenging. The rational design of brighter UCNPs particle architectures and the interest in identifying optimum particle architectures for FRET-based sensing and imaging schemes, which often rely on core-only UCNPs to minimize donor-acceptor distances, encouraged us to assess the influence of particle size and P on UCL. Here, we present the photophysical properties of a series of hexagonal NaYF4 UCNPs with sizes from 10 to 43 nm with different surface ligands dispersed in organic solvents and water studied by steady state and time-resolved fluorometry as well as quantitatively by integrating sphere spectrometry with P varied over about three orders of magnitude. Our results underline the need for really quantitative luminescence studies for mechanistic insights and the potential of high P to compensate for UCL quenching due to high energy phonons and surface effects. T2 - 15th Conference on Methods and Applications in Fluorescence CY - Bruges, Belgium DA - 10.09.2017 KW - Upconversion KW - Nanoparticle KW - Absolute fluorometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Fluorescence KW - Surface chemistry KW - Deactivation pathways KW - Photophysics KW - Quantum yield PY - 2017 AN - OPUS4-43181 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute ED - Scholz, Norman ED - Behnke, Thomas T1 - Determination of the critical micelle concentration of neutral and ionic surfactants with fluorometry, conductometry, and surface tension - a method comparison N2 - Micelles are of increasing importance as versatile carriers for hydrophobic substances and nanoprobes for a wide range of pharmaceutical, diagnostic, medical, and therapeutic applications. A key Parameter indicating the Formation and stability of micelles is the critical micelle concentration (CMC). In this respect, we determined the CMC of common anionic, cationic, and non-ionic surfactants fluorometrically using different fluorescent probes and fluorescence Parameters for Signal detection and ompared the results with conductometric and surface Tension measurements. Based upon These results, requirements, Advantages, and pitfalls of each methods are discussed. Our study underlines the versatility of fluorometric methods that do not impose specific requirements on surfactants and are especially suited for the quantification of very low CMC values. Conductivity and surface Tension measurements yield smaller uncertainties particularly for high CMC values, yet are more time- and substance consuming and not suitable for every surfactant. KW - Fluorescence KW - Methods KW - Critical micelle concentration (CMC) KW - Conductometry KW - Fluorescence probe KW - Dye KW - Nile Red KW - Pitfalls KW - Method evaluation KW - Uncertainty PY - 2017 DO - https://doi.org/10.1007/s10895-018-2209-4 SN - 1053-0509 SN - 1573-4994 VL - 28 IS - 1 SP - 465 EP - 476 AN - OPUS4-43905 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Gorris, H.H. T1 - Perspectives and challenges of photon-upconversion nanoparticles - Part I: routes to brighter particles and quantitative spectroscopic studies N2 - Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been the Focus of many Research activities in materials and life sciences in the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. To fully exploit the application potential of These facinating nanomaterials, a number of challenges have to be overcome, such as the low brightness, particularly of small UCNPs, and the reliable quantification of the excitation-power-density-dependent upconversion luminescence. In this series of critical Reviews, recent developments in the design, Synthesis, optical-spectroscopic characterization, and application of UCNPs are presented with Special Focus on bioanalysis and the life sciences. Here we guide the reader from the Synthesis of UCNPs to different concepts to enhance their luminescence, including the required optical-spectroscopic assessment to quantify material Performance; surface modification strategies and bioanalytical applications as well as selected examples of the use of UCNPs as reporters in different Assay formats are addressed in part II. Future Trends and challenges in the field of upconversion are discussed with Special emphasis on UCNP Synthesis and material characterization, particularly quantitative luminescence studies. KW - Fluorescence KW - Lanthanide KW - Upconversion KW - Brightness KW - Quantification KW - Nanoparticle KW - Absolute fluorometry KW - NIR KW - IR KW - Quantum yield PY - 2017 DO - https://doi.org/10.1007/s00216-017-0499-z SN - 1618-2650 SN - 1618-2642 VL - 409 IS - 25 SP - 5855 EP - 5874 PB - Springer AN - OPUS4-41665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Witte, F. A1 - Rietsch, P. A1 - Sinha, S. A1 - Krappe, A. A1 - Joswig, J.-O. A1 - Götze, J. P. A1 - Nirmalananthan-Budau, Nithiya A1 - Resch-Genger, Ute A1 - Eigler, S. A1 - Paulus, B. T1 - Fluorescence Quenching in J‑Aggregates through the Formation of Unusual Metastable Dimers N2 - Molecular aggregation alters the optical properties of a system as fluorescence may be activated or quenched. This is usually described within the well-established framework of H- and J-aggregates. While H-aggregates show nonfluorescent blueshifted absorption bands with respect to the isolated monomer, Jaggregates are fluorescent displaying a redshifted peak. In this publication, we employ a combined approach of experiment and theory to study the complex aggregation features and photophysical properties of diaminodicyanoquinone derivatives, which show unusual and puzzling nonfluorescent redshifted Absorption bands upon aggregation. Our theoretical analysis demonstrates that stable aggregates do not account for the experimental observations. Instead, we propose an unprecedented mechanism involving metastable dimeric species formed from stable dimers to generate nonfluorescent J-aggregates. These results represent a novel kind of aggregation-induced optical effect and may have Broad implications for the photophysics of dye aggregates. KW - Fluorescence KW - Llifetime KW - Dye KW - Quantum yield KW - Label KW - Reporter KW - Aggregation KW - Monomer KW - Heory KW - Mechanism KW - photophysics PY - 2021 DO - https://doi.org/10.1021/acs.jpcb.1c01600 SN - 1520-5207 VL - 125 IS - 17 SP - 4438 EP - 4446 PB - ACS Publikations AN - OPUS4-52619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Introduction to Fluorescence Spectroscopy N2 - A brief introduction to fluorescence spectroscopy will be provided, ranging from typically measured fluorescence quantities over instrument-specific contributions to measured fluorescence signals to selected applications. In this context, an overview of the photoluminescence properties of molecular and nanoscale luminescence reporters will be given including a brief insight into their photophysics and fluorescence standards designed by division Biophotonics for the calibration and instrument performance validation of fluorescence measuring devices will be presented. T2 - Analytical Academy BAM CY - Online meeting DA - 17.11.2020 KW - Fluorescence KW - Quality assurance KW - Quantification KW - Linearity KW - Measurement uncertainty KW - Method KW - Nano particle KW - Dye PY - 2020 AN - OPUS4-51619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Design and Quantitative Characterization of Functional Molecular Chromophores and Nanomaterials with UV/vis/NIR/IR Emission and Traceable Optical Measurements N2 - Research of division Biophotonics at the Federal Institute for Materials Research and Testing (BAM) covers several topics including photophysics of molecular and nanocrystalline emitters, the development of signal enhancement, multiplexing, and barcoding strategies, surface group quantification, the rational design of different types of stimuli-responsive optical probes, and concepts and reference materials for the validation of optical-spectroscopic measurements. In the following representative examples for each of these topics are given. Also, current developments like single particle spectroscopy and flow cytometry with lifetime detection and newly certified fluorescence quantum yield standards are presented. T2 - Kolloquium BfR CY - Berlin, Germany DA - 12.10.2020 KW - Fluorescence KW - Quantitative spectroscopy KW - Single particle spectroscopy KW - Multiplexing KW - Reference materials KW - Optical probes KW - Sensor molecules KW - Assay KW - Dye KW - Quantum yield KW - Method development KW - surface group analysis KW - synthesis KW - fluorescence standards PY - 2020 AN - OPUS4-51449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scholtz, Lena T1 - Luminescent, Semiconductor Nanoparticle-loaded Polymer Microbeads - Comparing Particle Architectures N2 - The synthesis of luminescent polymer microparticles stained with different, including non-spherical, semiconductor nanoparticles (NPs) was developed and optimized while ensuring a good preservation of the particle photoluminescence. The aplicability of the different semiconductor NPs was determined to depend on their surface chemistry and shape. Thus, a first correlation of semiconductor NP architecture and applicability could be deduced, which has not been reported before. T2 - 821. WE-Heraeus-Seminar CY - Bad Honnef, Germany DA - 12.11.2024 KW - Nanoparticle KW - Surface chemistry KW - Synthesis KW - Fluorescence KW - Luminescence PY - 2024 AN - OPUS4-61732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Resch-Genger, Ute ED - Schäferling, Michael T1 - Luminescent nanoparticles for chemical sensing and imaging N2 - The implementation of fluorescent methods is of outstanding importance in the field of optical chemical sensor Technology and biosciences. Their bioanalytical applications are manifold including fluorescence microscopy, fluorescence in situ hybridization, DNA sequencing, fluorescence-activated cell sorting, immunoassays, analysis of DNA and Protein microarrays, and quantitative PCR, just to name a few examples. Particularly, fluorescence microscopy is a valuable method in the versatile field of biomedical imaging methods which nowadays utilizes different fluorescence Parameters like emission wavelength/Color and lifetime for the discrimination between different targets. Sectional Images are available with confocal microscopes. Tissue, cells or single cellular compartments can be stained and visualized with fluorescent dyes and biomolecules can be selectively labeled with fluorescent dyes to Monitor biomolecular interactions inside cells or at Membrane bound receptors. On the other hand , fluorophores can act as indicator (or "molecular probe") to visualize intrinsically colorless and non-fluorescent ionic and neutral analytes such as pH, Oxygen (pO2), metal ions, anions, hydrogen peroxide or bioactive small organic molecules such as Sugars or nucleotides. Thereby, their photoluminescent properties (fluorescence or phoporescence intensity, exitation and/or Emission wavelength, emission lifetime or anisotropy) respond to the presence of these species in their immediate Environment. In general, the use of luminescent probes has the advantage that they can be delivered directly into the sample, and detected in a contactless remote mode. By now, these probes are often encapsulated in different types of nanoparticles (NPs) made from (biodegradable) organic polymers, biopolymers or inorganic materials like silica or bound to their surface. KW - Fluorescence KW - Upconversion KW - NIR KW - Sensor KW - Nanoparticle KW - Surface chemistry KW - Quantum yield KW - Liftetime KW - Nanocrystal KW - Lanthanide KW - Semiconductor KW - Polymer KW - Silica KW - Imaging KW - Application KW - Dye KW - Quantum dot PY - 2017 SN - 978-3-319-48260-6 SN - 978-3-319-48259-0 DO - https://doi.org/10.1007/978-3-319-48260-6_5 SN - 1573-8086 SP - 71 EP - 109 PB - SPRINGER INTERNATIONAL PUBLISHING AG CY - Cham, Schweiz AN - OPUS4-44011 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Spectroscopic properties of upconversion nanoparticles N2 - Lanthanide-doped up-converting nanoparticles (UCNPs) are promising reporters for medical diagnostics and bioimaging. Current limitations present their relative low absorption cross sections and low fluorescence efficiencies, with the latter being affected by particle size, surface chemistry, and microenvironment, particularly water. Here, we present results from systematic studies of the excitation power density dependent upconversion luminescence spectra, intensities/intensity ratios of the individual emission bands, slope factors, and quantum yields of UCNPs of varying size, dopant concentration, and surface chemistry in different microenvironments as well as the up- and downconversion luminescence decay kinetics of the different emission bands. Moreover, first studies of the energy transfer from UCNPs to surface-bound organic dyes acting as fluorescence acceptors are shown. Based upon these measurements, fluorescence deactivation channels are identified and spectroscopic parameters for the screening of material performance are derived. T2 - Projekttreffen COST CY - Straßbourg, France DA - 09.01.2017 KW - Upconverting nanoparticles KW - Size KW - FRET KW - Fluorescence KW - Absolute fluorescence quantum yield KW - Fluorescence decay kinetics KW - Power density dependence PY - 2017 AN - OPUS4-39076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Characterization of nanocrystalline particles with NIR emission - Spectroscopic properties and surface group analysis N2 - There is an increasing interest in optical reporters like semiconductor quantum dots and upconversion nanocrystals with emission > 800 nm for bioanalysis, medical diagnostics, and safety barcodes. Prerequisites for the comparison of material performance, the mechanistic understanding of nonradiative decay channels, and the rational design of new nanomaterials with improved properties are reliable fluorescence measurements and validated methods for the assessment of their surface chemistry. The latter is of special relevance for nanocrystalline emitters, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Here, we present the design of integrating sphere setups for the excitation power density-dependent absolute measurement of emission spectra and photoluminescence quantum yields in the wavelength region of 350 to 1600 nm and results from spectroscopic studies of semiconductor quantum dots and upconversion nanocrystals of different size and surface chemistries in various environments. Subsequently, examples for simple approaches to surface group and ligand analysis are presented. T2 - 1st International Biophotonics Conference CY - Singapure DA - 25.07.2016 KW - Fluorescence KW - Integrating sphere spectroscopy KW - Quantum yield KW - NIR KW - IR KW - Optical spectroscopy KW - Nanomaterials KW - Semiconducor nanocrystals KW - Surface analysis KW - Ligand analysis KW - Optical assay PY - 2016 AN - OPUS4-36998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Recent insights in the spectroscopic properties of upconversion nanoparticles N2 - Lanthanide-doped up-converting nanoparticles (UCNPs) are promising reporters for medical diagnostics and bioimaging, which are excited in the near infrared (NIR) by multiphoton absorption processes, and show multiple narrow emission bands in the visible (vis) and NIR, long luminescence lifetimes in the μs range, and excellent photostability. Current limitations present their relative low absorption cross sections and low fluorescence efficiencies, with the latter being affected by particle size, surface chemistry, and microenvironment, particularly water. Here, we present results from systematic studies of the excitation power density dependent upconversion luminescence spectra, intensities/intensity ratios of the individual emission bands, slope factors, and quantum yields of UCNPs of varying size, dopant concentration, and surface chemistry in different microenvironments as well as the up- and downconversion luminescence decay kinetics of the different emission bands. Moreover, first studies of the energy transfer from UCNPs to surface-bound organic dyes acting as fluorescence acceptors are shown. Based upon these measurements, fluorescence deactivation channels are identified and spectroscopic parameters for the screening of material performance are derived. T2 - Spie Photonics west 2017 CY - San Francisco, USA DA - 28.01.2017 KW - Upconverting nanoparticles KW - Size KW - FRET KW - Fluorescence KW - Absolute fluorescence quantum yield KW - Fluorescence decay kinetics KW - Power density dependence PY - 2017 AN - OPUS4-39075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Choi, Youungeun A1 - Kotthoff, Lisa A1 - Olejko, L. A1 - Resch-Genger, Ute A1 - Bald, Ilko T1 - DNA origami-based Förster resonance energy-transfer nanoarrays and their application as ratiometric sensors N2 - DNA origami nanostructures provide a platform where dye molecules can be arranged with nanoscale accuracy allowing to assemble multiple fluorophores without dye–dye aggregation. Aiming to develop a bright and sensitive ratiometric sensor system, we systematically studied the optical properties of nanoarrays of dyes built on DNA origami platforms using a DNA template that provides a high versatility of label choice at minimum cost. The dyes are arranged at distances, at which they efficiently interact by Förster resonance energy transfer (FRET). To optimize array brightness, the FRET efficiencies between the donor fluorescein (FAM) and the acceptor cyanine 3 were determined for different sizes of the array and for different arrangements of the dye molecules within the array. By utilizing nanoarrays providing optimum FRET efficiency and brightness, we subsequently designed a ratiometric pH nanosensor using coumarin 343 as a pH-inert FRET donor and FAM as a pH-responsive acceptor. Our results indicate that the sensitivity of a ratiometric sensor can be improved simply by arranging the dyes into a well-defined array. The dyes used here can be easily replaced by other analyte-responsive dyes, demonstrating the huge potential of DNA nanotechnology for light harvesting, signal enhancement, and sensing schemes in life sciences. KW - DNA origami KW - FRET KW - Sensing KW - Ratiometric sensing KW - Fluorescence PY - 2018 DO - https://doi.org/10.1021/acsami.8b03585 SN - 1944-8244 SN - 1944-8252 VL - 10 IS - 27 SP - 23295 EP - 23302 PB - ACS AN - OPUS4-46002 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Suitable geometries for the measurement of photoluminescence quantum yields of luminescent and scattering samples – The DIN TNS project N2 - The characterization of the optical properties of photoluminescent systems, that scatter, like dispersions of nanoparticles with sizes exceeding about 25 nm or solid nanophosphors is of increasing importance for many applications in the life and material sciences. Examples present nanoscale optical reporters and dye-doped microparticles for bioimaging, fluorescence assays or DNA sequencing as well as nanocrystalline emitters like semiconductor quantum dots and rods or lanthanide-based nanophosphors embedded into solid matrices for solid state lighting, display technologies, or barcoding/security applications. The assessment and comparison of material performance as well as the development of rational design strategies for improved systems require spectroscopic tools, which enable the determination of the signal-relevant optical properties like photoluminescence quantum yields and brightness values. This encouraged us to built up an integrating sphere setup enabling absolute measurements of photoluminescence spectra and quantum yields of transparent and scattering photoluminescent dispersions and solid samples in different measurement geometries, i.e., direct and indirect illumination and the combination of both geometries and perform first measurements with selected emitters. Here, the design of this setup is presented and first recommendations concerning suitable measurement geometries are given. T2 - DKE-Sitzung CY - Frankfurt am Main, Germany DA - 31.08.2016 KW - Nanoparticle KW - Integrating sphere KW - Fluorescence KW - Quantum yield KW - Method KW - Standardization KW - Calibration KW - Reference material PY - 2016 AN - OPUS4-38643 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute ED - Mousavi, M. ED - Thomasson, B. ED - Li, M. ED - Kraft, Marco ED - Würth, Christian ED - Andersson-Engels, S. T1 - Beam-profile-compensated quantum yield measurements of upconverting nanoparticles N2 - The quantum yield is a critically important parameter in the development of lanthanide-based upconverting nanoparticles (UCNPs) for use as novel contrast agents in biological imaging and optical reporters in assays. The present work focuses on the influence of the beam Profile in measuring the quantum yield (f) of nonscattering dispersions of nonlinear upconverting probes, by establishing a relation between f and excitation light power density from a rate equation analysis. A resulting 60% correction in the measured f due to the beam profile utilized for excitation underlines the significance of the beam profile in such measurements, and its impact when comparing results from different Setups and groups across the world. KW - Fluorescence KW - Lanthanide KW - Upconversion KW - Brithtness KW - Quantification KW - Nanoparticle KW - Absolute fluoreometry KW - NIR KW - IR KW - Quantum yield KW - Integrating sphere spectroscopy KW - Method PY - 2017 DO - https://doi.org/10.1039/c7cp03785f SN - 1463-9076 SN - 1463-9084 VL - 19 IS - 33 SP - 22016 EP - 22022 PB - Royal Society of Chemistry AN - OPUS4-42583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Simple methods, validation concepts, and reference materials for the characterization of functional nanomaterials and microparticles N2 - The surface chemistry / functionalization of nanomaterials and microparticles largely controls the stability of these materials as well as their solubility and subsequent biofunctionalization and their interactions with biological systems. Moreover, in the case of some nanomaterials like semiconductor quantum dots or lanthanide-based upconversion nanocrystals, the ligand shell strongly affects their optical properties, e.g., via passivation of surface states and traps that favor luminescence quenching or the protection of surface atoms from quenching water molecules. This renders analytical methods for the quantification of surface groups like functionalities very important. Targets of broad interest are here amino, carboxyl, alkine and maleimide groups used for common bioconjugation reactions and typical ligands like thiols and polyethylene glycol (PEG) molecules of varying length, used for the tuning of material hydrophilicity and biocompatibility, minimization of unspecific interactions, prevention of biofouling, and enhancement of blood circulation times as well as surface-bound biomolecules like streptavidin or other biomolecules relevant e.g., for diagnostic assays. Here, we focus on simple optical methods relying on standard laboratory instrumentation, validated by method comparison and/or mass balances and present examples for their use for the characterization of different types of nanomaterials and microparticles. T2 - Innovationsforum Senftenberg CY - Senftenberg, Germany DA - 01.06.2016 KW - Surface chemistry KW - Functional group analysis KW - Thiol assay KW - Fluorescence KW - Nanomaterial KW - Nanoparticle KW - PEG KW - Ligand KW - Semiconductor quantum dot KW - Quantum yield KW - Quantification KW - Method validation KW - Integrating sphere spectroscopy KW - Fluorescence standard PY - 2016 N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. AN - OPUS4-37111 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David T1 - Luminescent Quantum dots – the next-generation nano light bulbs N2 - Fluorescent semiconductor nanocrystals, also known as quantum dots (QDs), enabled many advancements in biotechnology, photovoltaics, photocatalysis, quantum computing and display devices. The high versatility of this nanomaterial is based on their unique size-tunable photoluminescence properties, which can be adjusted from the visible to the near-infrared range. In contrast to other nanomaterials, QDs made the transition from a laboratory curiosity to the utilization in commercial products, like the QLED television screen or in smartphone displays. The best investigated QDs are composed of heavy metals like cadmium or lead, which is not the best choice in terms of toxicity and environmental pollution. A more promising material is Indium Phosphide (InP), which is also currently used by Samsung, Sony and co. in the QLED displays. In this contribution, I would like to give you a sneak peek behind the curtains of nanomaterial synthesis and show how this material is produced, how to stabilize their structural properties, and assess their toxicity in environmentally relevant conditions. Furthermore, I would like to present a synthesis method to accomplish the last open challenge in display technology of a blue luminescent LED based on QDs by introducing a new element to the InP QDs. T2 - The Berlin Postdoc Day CY - Berlin, Germany DA - 03.11.2022 KW - InP KW - Quantum dots KW - Fluorescence KW - Aging KW - Doping KW - Nanomaterial KW - Cytotoxicity PY - 2022 AN - OPUS4-56194 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Semiconductor nanocrystals with VIS and NIR/IR emission - spectroscopy properties and surface chemistry N2 - Semiconductor nanocrystals with a spherical (QDs) core and a spherical or a rod-shaped Shell, u.a., so-called Quantum dot-Quantum rods (QDQRs) are increasingly used as fluorescent Reporters or optically active components in the life and material science, e.g., in solid state lightening including Plasma Displays. (1,2) Morever, there is an increasing interest in materials with emission >800 nm for bioanalysis, medical diagnostics, and safety barcodes. Prerequisites for the mechanistic understanding of nonradiativ decay channels needed for the rational design of improved nanomaterials and the comparison of material Performance are reliable fluorescence measurements and validated methods for the assessment of their surface chemistry. (3,4) The latter is of particular importance for nanocrystalline Emitters, where surface states and the accessibility of emissive states by quenchers largely control photoluminescence properties. (5) Here, we present results from systematic spectroscopic studies including absolutely measured photolumunescence Quantum yields of different vissible and NIR emisisve QD and QDQRs Systems of varying particle architecture size and surface chemistries in Dispersion and embedded in salt crystals. (6,7) T2 - MCare 2017 CY - Jeju, South Korea DA - 20.02.2017 KW - Semiconductor quantum dot KW - Nanoparticle KW - Absolute fluorometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Fluorescence KW - Surface chemistry KW - Photophysics KW - Quantum yield KW - Single particle PY - 2017 AN - OPUS4-43133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David T1 - Exploring the photoluminescence of gold NCs and Ag2S NPs to boost their SWIR emission N2 - Current challenges and objectives for non-invasive optical bioimaging are deep tissue penetration, high detection sensitivity, high spatial and temporal resolution, and fast data acquisition. A promising spectral window to tackle these challenges is the short-wave infrared (SWIR) ranging from 900 nm to 1700 nm where scattering, absorption, and autofluorescence of biological components are strongly reduced compared to the visible/NIR. At present, the best performing SWIR contrast agents are based on nanomaterials containing toxic heavy-metal ions like cadmium or lead, which raises great concerns for biological applications. Promising heavy-metal free nanoscale candidates are gold nanoclusters (AuNCs) and Ag2S nanoparticles (NPs). The photoluminescence (PL) of both types of nanomaterials is very sensitive to their size, composition of their surface ligand shell, and element composition, which provides an elegant handle to fine-tune their absorption and emission features and boost thereby the size of the signals recorded in bioimaging studies. Aiming for the development of SWIR contrast agents with optimum performance, we dived deeper into the photophysical processes occurring in these nanomaterials, thereby exploring in depth how the environment, surface ligand composition, and the incorporation of transition metals influence the optical properties of AuNCs and Ag2S NPs. We observed a strong enhancement of the SWIR emission of AuNCs upon exposure to different local environments (in solution, polymer, and in the solid state). Addition of metal ions such as Zn2+ to Ag2S based NPs led to a strong PL enhancement, yielding PL quantum yields of about 10% and thus making them highly suitable for non-invasive deep imaging of vascular networks and 3D fluid flow mapping. T2 - NaNaX 10 - Nanoscience with Nanocrystals CY - Klosterneuburg, Austria DA - 03.07.2023 KW - Quantum dots KW - Ag2S KW - Fluorescence KW - SWIR KW - Gold nanocluster KW - Nanomaterial KW - bioimaging PY - 2023 AN - OPUS4-58104 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, K. A1 - Liu, H. A1 - Kraft, Marco A1 - Shikha, S. A1 - Zheng, X. A1 - Agren, H. A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Zhang, Y. T1 - A protected excitation-energy reservoir for efficient upconversion luminescence N2 - Lanthanide-doped upconversion nanoparticles (UCNPs) are of great interest for biomedical applications. Currently, the applicability of UCNP bionanotechnology is hampered by the generally low luminescence intensity of UCNPs and inefficient energy Transfer from UCNPs to surface-bound chromophores used e.g. for photodynamic therapy or analyte sensing. In this work, we address the low-Efficiency issue by developing versatile core-Shell nanostructures, where high-concentration sensitizers and activators are confined in the core and Shell Region of representative hexagonal NaYF2:Yb,Er UCNPs. After Doping concentration optimization, the sensitizer-rich core is able to harvest/accumulate more excitation energy and generate almost one order of Magnitude higher luminescence intesity than conventional homogeneously doped nanostructures. At the same time, the activator Ions located in the Shell enable a ~6 times more efficient resonant energy Transfer from UCNPs to surface-bound acceptor dye molecules due to the short distance between donor-acceptor pairs. Our work provides new insights into the rational design of UCNPs and will greatly encrease the General applicability of upconversion nanotechnologies. KW - Fluorescence KW - Lanthanide KW - Upconversion KW - Brightness KW - Quantification KW - Nanoparticle KW - Absolute fluorometry KW - NIR KW - IR KW - Quantum yield KW - Integrating sphere spectroscopy KW - Method KW - Energy transfer KW - Shell KW - Particle architecture PY - 2017 DO - https://doi.org/10.1039/c7nr06900f SN - 2040-3372 SN - 2040-3364 VL - 10 IS - 1 SP - 250 EP - 259 PB - The Royal Society of Chemistry AN - OPUS4-43893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Standardization of fluorescence measurements: Design, development, validation, and fabrication of format-adaptable fluorescence standards for intensity, spectral, and temporal quantities N2 - Photoluminescence techniques are amongst the most widely used tools in the material and life sciences, with new and exciting applications continuously emerging, due to their many advantages like comparative ease of use, unique sensitivity, non-invasive character, and potential for multiplexing, remote sensing, and miniaturization. Drawbacks are , however, signals, that contain unwanted wavelength- and polarization contributions from instrument-dependent effects, which are time-dependent due to the aging of instrument components, and difficulties to measure absolute fluorescence intensities. Thus, there is a considerable need for standards for intensity, spectral, and temporal fluorescence quantities to meet the increasing need for instrument performance validation and global trends to harmonize physicochemical measurements. In this respect, instrument calibration strategies together with different types of fluorescence standards are presented as well as design concepts for robust, easy-to-use, and format-adaptable fluorescence standards useable for the determination of different fluorescence parameters and a broad variety of fluorescence techniques. T2 - SALSA-Kolloquien CY - Berlin, Germany DA - 07.06.2016 KW - Fluorescence KW - Standard KW - Quality assurance KW - Spectral correction KW - Quantum yield PY - 2016 AN - OPUS4-37070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Quantitative Characterization of Functional Nanomaterials with vis/NIR Emission N2 - The rational design of functional nanomaterials for optical applications in the material and life sciences requires optical-spectroscopic methods for the quantitative characterization of their signal-relevant optical properties. Additionally, methods for the simple and quantitative analysis of the surface chemistry are desired as the chemical nature and number of the surface groups and ligands can affect the optical features and controls the interaction of these nanomaterials with their environment. Here, we present quantitative photoluminescenvce studies of different types of vis/NIR-emissive nanomaterials like semiconductor quantum dots and upconversion nanocrystals will be presented and their relevance for the mechanistic understanding of nonradiative decay channels and the rational design of new nanomaterials will be underpinned. In this respect, also validation concepts for such measurements and absolute fluorometry will be introduced. In addition, the potential of optical spectroscopy for surface group and ligand analysis surface chemistry will be demonstrated exemplarily for semiconductor quantum dots T2 - AK Prof. Voss CY - Uni Brunswick, Germany DA - 03.08.2017 KW - Semiconductor KW - Upconversion KW - Nanoparticle KW - Fluorescence KW - Surface group analysis KW - NIR KW - Absolute fluoreometry KW - Integrating sphare spectroscopy KW - Optical probe KW - Assay KW - Thiol ligand PY - 2017 N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. AN - OPUS4-41366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Photoluminescence quantum yields of molecular & nanoscale luminophores in the UV/VIS/NIR/SWIR in dispersion and in the solid state N2 - Photophysical and mechanistic studies, the comparison of different emitter classes, and the rational design of the next generation of molecular and nanoscale reporters require quantitative photoluminescence measurements and the reliable determination of the key performance parameter photoluminescence quantum yield (QY), i.e., the number of emitted per absorbed photons. This is of special importance for all photoluminescence applications in the life and material sciences in the UV/vis/NIR/SWIR. T2 - MAF 2024 Conference CY - Valencia, Spain DA - 08.09.2024 KW - Nanoparticle KW - Nano KW - Luminescence KW - Quality assurance KW - Synthesis KW - Standardization KW - Reference material KW - Quantum yield KW - Fluorescence KW - Reference data KW - Integrating sphere spectroscopy KW - ILC KW - Converter material PY - 2024 AN - OPUS4-61072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, J. A1 - Güttler, Arne A1 - Schneider, T. A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Fluorescence Quantum Yield Standards for the UV/Visible/NIR: Development, Traceable Characterization, and Certification N2 - The rational design of next generation molecular and nanoscale reporters and the comparison of different emitter classes require the determination of the fluorometric key performance parameter fluorescence quantum yield (Φf), i.e., the number of emitted photons per number of absorbed photons. Main prerequisites for reliable Φf measurements, which are for transparent luminophore solutions commonly done relative to a reference, i.e., a fluorescence quantum yield standard of known Φf, are reliable and validated instrument calibration procedures to consider wavelength-, polarization-, and time-dependent instrument specific signal contributions, and sufficiently well characterized fluorescence quantum yield standards. As the standard’s Φf value directly contributes to the calculation of the sample’s Φf, its accuracy presents one of the main sources of uncertainty of relative Φf measurements. To close this gap, we developed a first set of 12 fluorescence quantum yield standards, which absorb and emit in the wavelength region of 330−1000 nm and absolutely determined their Φf values with two independently calibrated integrating sphere setups. Criteria for standard selection and the configuration of these novel fluorescence reference materials are given, and the certification procedure is presented including homogeneity and stability studies and the calculation of complete uncertainty budgets for the certified Φf values. The ultimate goal is to provide the community of fluorescence users with available reference materials as a basis for an improved comparability and reliability of quantum yield data since the measurement of this spectroscopic key property is an essential part of the characterization of any new emitter. KW - Optical spectroscopy KW - Traceability KW - Reference product KW - Dye KW - Fluorescence KW - Quantum yield KW - Reference material KW - Reference data KW - Certification KW - Quality assurance PY - 2023 DO - https://doi.org/10.1021/acs.analchem.2c05530 VL - 95 SP - 5671 EP - 5677 PB - American Chemical Society AN - OPUS4-58151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Absolute Determination of Photoluminescence Quantum Yields of Scattering LED Converter Materials – How to Get it Right N2 - Optical measurements of scattering luminescent materials dispersed in liquid and solid matrices and luminescent powders play an important role in fundamental research and industry. Typical examples are luminescent nano- and microparticles and phosphors of different composition in different matrices or incorporated into ceramics with applications in energy conversion, solid-state lighting, medical diagnostics, and security barcoding. The key parameter for the performance of these materials is the photoluminescence quantum yield QY, i.e., the number of emitted photons per number of absorbed photons. QY of transparent luminophore solutions can be determined relatively to a fluorescence quantum yield standard of known QY. Such standards are meanwhile available as certified reference materials.[1] The determination of QY of scattering liquid and solid samples like dispersions of luminescent nanoparticles, solid phosphors, and optoceramics requires, however, absolute measurements with an integrating sphere setup. Although the importance of reliable absolute QY measurements has been recognized, no interlaboratory comparisons (ILCs) on measurement uncertainties and the identification of typical sources of uncertainty have been yet reported. Also, no scattering reference materials with known QY are available. We present here the results of a first ILC of 3 laboratories from academia and industry performed to identify and quantify sources of uncertainty of absolute QY measurements of scattering samples. Thereby, two types of commercial stand-alone integrating sphere setups with different illumination and detection geometries were utilized for measuring QY of transparent and scattering dye solutions and solid phosphors. As representative and industrially relevant solid and scattering samples, YAG:Ce optoceramics of varying surface roughness were chosen, applied, e.g., as converter materials for blue light emitting diodes. Special emphasis was dedicated to the influence of the measurement geometry, the optical properties of the blank, utilized to determine the number of photons of the incident excitation light absorbed by the sample, and the sample-specific surface roughness. While matching QY values could be obtained for transparent dye solutions and scattering dispersions, here using a blank with scattering properties closely matching those of the sample, QY measurements of optoceramic samples with different blanks revealed substantial differences, with the blank's optical properties accounting for measurement uncertainties of more than 20 %. Based upon the ILC results, we recommend non-absorbing blank materials with a high reflectivity (>95 %) such as a 2 mm-thick PTFE target placed on the sample holder which reveals a near-Lambertian light scattering behavior, yielding a homogeneous light distribution within the integrating sphere. T2 - e-MRS 2024 CY - Strasbourg, France DA - 27.05.2024 KW - Luminescence KW - Quantitative spectroscopy KW - Nano KW - Particle KW - Quantum yield KW - Lifetime KW - Quality assurance KW - Phosphor KW - Converter marterial KW - Fluorescence KW - Interlaboratory KW - Comparison KW - Method KW - Uncertainty KW - Reference material PY - 2024 AN - OPUS4-60490 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella T1 - Development of amorphous silica particle based reference materials for surface functional group quantification N2 - Functionalized nanomaterials (NM) with their unique size-dependent properties are of increasing relevance for current and future developments in various fields such as medical and pharmaceutical industry, computing, electronics or food and consumer products. The performance and safety of NM are determined by the sum of their intrinsic physicochemical properties.1 Besides other key parameters, the particle surface chemistry, which is largely controlled by the chemical nature and density of functional groups and ligands, must be considered for a better performance, stability, and processibility of NM, as well as their interaction with the environment. Thus, particle standards with well-designed surfaces and methods for functional group quantification can foster the sustainable development of functional and safe(r) NM.2 Here we provide a brief overview of the ongoing research in division Biophotonics to design tailored amorphous silica reference particles with bioanalytically relevant functional groups and ligands, for the development of standardized and validated surface functional group quantification methods. T2 - Workshop NanoRiskSD project CY - Berlin, Germany DA - 09.06.2022 KW - Nanoparticle KW - Surface analysis KW - Silica KW - Fluorescence KW - Assay PY - 2022 AN - OPUS4-55004 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Challenges and examples for quantitative fluorescence measurements > 800 nm with semiconductor and lanthanide-doped nanocrystals N2 - There is an increasing interest in molecular and nanoscale with emission > 800 nm and recently also > 1000 nm for bioanalysis, medical diagnostics, bioimaging, and safety barcodes. Mandatory for the comparison of different emitter classes and the rational design of the next generation of reporters for the short wavelength infrared (SWIR) Region are reliable and quantitative photoluminescence measurements in this challenging wavelength region. This is of special relevance for nanocrystalline emitters like semiconductor quantum dots and rods as well as lanthanide-based upconversion and downconversion nanocrystals, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Such measurements are currently hampered by the lack of suitable methods and standards for instrument calibration and validation and quantum yield standards with emission > 800 nm and especially > 1000 nm. In this respect, we present the design of integrating sphere setups for absolute and excitation power density-dependent measurements of emission spectra and photoluminescence quantum yields in the wavelength Region of 650 to 1650 nm including calibration strategies and first candidates for potential fluorescence standards. Subsequently, the photoluminescence properties of different types of nanocrystals are presented including the upconversion and downconversion emission of differently sized and surface functionalized lanthanide-doped nanoparticles and photoluminescence quenching effects are quantified. T2 - SHIFT 2017 CY - Teneriffa, Spain DA - 13.11.2017 KW - Upconversion KW - Nanoparticle KW - Absolute fluorometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Fluorescence KW - Surface chemistry KW - Deactivation pathways KW - Semiconductor quantum dot KW - SWIR KW - Quantum yield PY - 2017 AN - OPUS4-43203 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Spectroscopic characterization of semiconductor and lanthanide-based nanocrystals with vis and NIR emission N2 - The increasing interest in molecular and nanoscale emitters with photoluminescence > 800 nm and recently also > 1000 nm for bioanalysis, medical diagnostics, bioimaging, and safety Barcodes requires quantitative spectroscopic studies, which are, however still challenging in this long wavelength region. This is of special relevance for nanocrystalline emitters like semiconductor quantum dots and rods as well as lanthanide-based upconversion and downconversion nanocrystals, where surface states and the accessibility of emissive states by quenchers largely control accomplishable photoluminescence quantum yields and hence, signal sizes and detection sensitivities from the reporter side. Moreover, nonlinear emitters like lanthanide-based upconversion nanocrystals require also power density-dependent studies of their luminescence spectra, quantum yields, and decay kinetics. Here, we present suitable absolute methods and underline the impact of such measurements on a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different chemical composition and particle architecture. T2 - PCNSPA 2018 - Photonic Colloidal Nanostructures: Synthesis, Properties, and Applications CY - St. Petersburg, Russia DA - 04.06.2018 KW - Semiconductor KW - Nanoparticle KW - Quantum dot KW - Absolute fluorometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Fluorescence KW - Surface chemistry KW - Deactivation pathways KW - Photophysics KW - Modeling PY - 2018 AN - OPUS4-45796 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - The European Upconversion Network: From the Design of Photon-upconverting Nanomaterials to (Biomedical) Applications (CM1403) WG1 Materials Research & Photophysical Characterization N2 - Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been in the focus of many research activities in the material and life sciences over the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. In order to fully exploit the application potential of these fascinating nanomaterials, a number of challenges has to be overcome such as the low brightness particularly of small UCNPs and the reliable quantification of the excitation power density (P)-dependent upconversion luminescence (UCL). Here, the need and requirements on the characterization of the optical properties of UCNPs are discussed with special focus on the reliabiliy and comparability of relative and quantitative luminescence measurements and prerequisites for their standardization. T2 - COST Treffen CY - Aveiro, Portugal DA - 26.06.2017 KW - Upconversion KW - Nanoparticle KW - Fluorescence KW - NIR KW - Absolute fluorometry KW - Integrating sphere spectroscopy KW - Reference maerial KW - Standardization KW - Quantum yield PY - 2017 AN - OPUS4-41367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella T1 - Rational Design of Analyte-responsive Fluorescent Particle Sensors for Life Sciences Applications N2 - Engineered and tailor-made nanomaterials (NM) are of increasing relevance for current and future developments in the life and material sciences for applications, e.g., as drug carriers, fluorescent sensors, and multimodal labels in bioanalytical assays, and reporters for imaging applications. For instance, NM-based reporters and sensors, that are labelled or stained with a multitude of conventional or sensor dyes, have several advantages as compared to molecular probes like enhanced brightness, i.e., amplified signals, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, this can enable the use of hydrophobic dyes in aqueous environments. For rational NM design, choosing and tailoring the intrinsic physicochemical properties, such as particle size, size distribution, morphology, and surface chemistry of the NM application-specific considerations like biocompatibility, ease and low cost of preparation, and colloidal stability and performance in the targeted environment must be considered. In this lecture, different design concepts of inorganic, organic, and hybrid NM and microparticles with hydrophilic surface chemistries and different functionalities are presented that can be used for the targeting of lysosomes; and to monitor functional parameters of endo-lysosomal compartments, like pH or enable oxygen sensing. T2 - Chemical Probes for Lysosomal Biology CY - York, United Kingdom DA - 09.09.2024 KW - Luminescence KW - Quantification KW - Nano KW - Particle KW - Quality assurance KW - Fluorescence KW - Method KW - Uncertainty KW - Reference material KW - Sensor KW - Synthesis KW - Dye KW - pH KW - Silica KW - Polystyrene KW - Surface analysis PY - 2024 AN - OPUS4-62173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Scholtz, Lena A1 - Resch-Genger, Ute T1 - Behind the Paper - Dual color pH probes made from silica and polystyrene nanoparticles and their performance in cell studies N2 - In this contribution we highlight the importance of comparison for scientific research while developing a new, functional pH sensor system, and the valuable insights this can provide. KW - Dye KW - Optical Spectroscopy KW - pH probe KW - Silica and Polystyrene Particles KW - Nano KW - Surface groups KW - Safe-by-Design KW - Cell studies KW - Sensors KW - Particle Synthesis KW - Fluorescence PY - 2023 UR - https://communities.springernature.com/posts/dual-color-ph-probes-made-from-silica-and-polystyrene-nanoparticles-and-their-performance-in-cell-studies SP - 1 EP - 2 PB - Springer Nature CY - London AN - OPUS4-59150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Pauli, J. A1 - Güttler, Arne A1 - Richter, Maria A1 - Fiedler, Saskia A1 - Frenzel, Florian A1 - Wegner, Karl David A1 - Würth, Christian T1 - Photoluminescence Quantum Yields of Luminescent Nanocrystals and Particles in the UV/vis/NIR/SWIR N2 - The rational design of functional luminescent materials such as semiconductor quantum dots and lanthanide-based upconversion nanoparticles, all photophysical and mechanistic studies, and the comparison of different emitters require accurate and quantitative photoluminescence measurements. Particularly the reliable determination of the key performance parameter photoluminescence quantum yield (f), the number of emitted per absorbed photons, and the brightness are of special importance for luminescence applications in the life and material sciences and nano(bio)photonics.[1] In this context, examples for absolute measurements of the photoluminescence quantum yields of UV/vis/NIR/SWIR emissive semiconductor quantum dots and rods, made from different materials, and spectrally shifting lanthanide upconversion nanocrystals with different surface chemistries in transparent matrices are presented including excitation wavelength and power density dependent studies utilizing integration sphere spectroscopy.[2,3] In addition, procedures for the absolute determination of the photoluminescence quantum yields of scattering dispersions of larger size quantum rods and differently sized inorganic particles have been developed as well as procedures for the characterization of solid luminescent nanomaterials such as different perovskites and YAG:Cer converter materials.[4] Thereby, challenges and pitfalls of f measurements in different wavelength regions including the SWIR and material-specific effects related to certain emitter classes are addressed, achievable uncertainties are quantified, and relative and absolute measurements of photoluminescence quantum yield measurements are compared to underline limitations of the former approach. Finally, a set of novel UV/vis/NIR quantum yield standards is presented including their certification with a complete uncertainty budget.[5] T2 - NANAX 10 CY - Klosterneuburg, Austria DA - 03.07.2023 KW - Fluorescence KW - Optical spectroscopy KW - Reference data KW - Traceability KW - NIR KW - Scattering KW - Reference material KW - Certification KW - Quality assurance KW - Dye KW - Reference product KW - SWIR KW - Nano KW - Particle KW - Perovskite KW - Integrating sphere spectroscopy KW - Quantum yield PY - 2023 AN - OPUS4-58238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR ED - Resch-Genger, Ute ED - Koch, Matthias ED - Meermann, Björn ED - Weller, Michael G. T1 - Topical collection: Analytical methods and applications in the materials and life sciences N2 - Current trends in materials and life sciences are flanked by the need to push detection limits to single molecules or single cells, enable the characterization of increasingly complex matrices or sophisticated nanostructures, speed up the time of analysis, reduce instrument complexity and costs, and improve the reliability of data. This requires suitable analytical tools such as spectroscopic, separation and imaging techniques, mass spectrometry, and hyphenated techniques as well as sensors and their adaptation to application-specific challenges in the environmental, food, consumer product, health sector, nanotechnology, and bioanalysis. Increasing concerns about health threatening known or emerging pollutants in drinking water, consumer products, and food and about the safety of nanomaterials led to a new awareness of the importance of analytical sciences. Another important driver in this direction is the increasing demand by legislation, particularly in view of the 17 sustainable development goals by the United Nations addressing clean energy, industry, and innovation, sustainable cities, clean water, and responsible consumption and production. In this respect, also the development of analytical methods that enable the characterization of material flows in production processes and support recycling concepts of precious raw materials becomes more and more relevant. In the future, this will provide the basis for greener production in the chemical industry utilizing recycled or sustainable starting materials. This makes analytical chemistry an essential player in terms of the circular economy helping to increase the sustainability of production processes. In the life sciences sector, products based on proteins, such as therapeutic and diagnostic antibodies, increase in importance. These increasingly biotechnologically produced functional biomolecules pose a high level of complexity of matrix and structural features that can be met only by highly advanced methods for separation, characterization, and detection. In addition, metrological traceability and target definition are still significant challenges for the future, particularly in the life sciences. However, innovative reference materials as required for the health and food sector and the characterization of advanced materials can only be developed when suitable analytical protocols are available. The so-called reproducibility crisis in sciences underlines the importance of improved measures of quality control for all kinds of measurements and material characterization. This calls for thorough method validation concepts, suitable reference materials, and regular interlaboratory comparisons of measurements as well as better training of scientists in analytical sciences. The important contribution of analytical sciences to these developments is highlighted by a broad collection of research papers, trend articles, and critical reviews from these different application fields. Special emphasis is dedicated to often-overlooked quality assurance and reference materials. T2 - 150 years BAM: Science with impact CY - Berlin, Germany DA - 01.01.2021 KW - 150th anniversary KW - ABC KW - Analysis KW - Analytical sciences KW - BAM KW - Collection KW - Environment KW - Fluorescence KW - Life sciences KW - Limit of detection KW - Material sciences KW - Method KW - Nanoparticle KW - Pollutant KW - Quality assurance KW - Reference material KW - Sensor KW - Special issue KW - Bundesanstalt für Materialforschung und -prüfung KW - Jahrestag PY - 2022 UR - https://link.springer.com/journal/216/topicalCollection/AC_16a2ef9b81853377e321ef84d9c4a431 SN - 1618-2642 SN - 1618-2650 VL - 414 SP - 4267 EP - 4529 PB - Springer CY - Berlin AN - OPUS4-55670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Instrument Calibration and Standardization of Fluorescence Measurements in the UV/vis/NIR/IR N2 - Comparison of fluorescence measurements performed on different fluorescence instruments, analyte quantification from fluorescence intensities as well as the determination of fluorescence quantum yields require instrument calibration and consideration of the wavelength-dependent instrument-specific quantities spectral photon flux reaching the sample and spectral responsivity. Here, we present guidelines and recommendations for the qualification of fluorescence instruments and introduce suitable chromophore-based reference materials. Moreover, the design concepts of the different BAM fluorescence standards are discussed. T2 - COST 2017 CY - Turku, Finland DA - 03.04.2017 KW - Fluorescence KW - Dye KW - Glass KW - Calibration KW - Fluorescence standard KW - Integrating sphere spectroscopy KW - Fluorescence quantum yield KW - Instrument qualification KW - Quality assurance KW - NIR KW - IR PY - 2017 AN - OPUS4-43174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Automated determination of genotoxicity of nanoparticles with DNA-based optical assays - The NANOGENOTOX project N2 - The overall interest in nanotoxicity, triggered by the increasing use of nanomaterials in the material and life sciences, and the synthesis of an ever increasing number of new functional nanoparticles calls for standardized test procedures1,2 and for efficient approaches to screen the potential genotoxicity of these materials. Aiming at the development of fast and easy to use, automated microscopic methods for the determination of the genotoxicity of different types of nanoparticles, we assess the potential of the fluorometric γH2AX assay for this purpose. This assay, which can be run on an automated microscopic detection system, relies on the detection of DNA double strand breaks as a sign for genotoxicity3. Here, we provide first results obtained with broadly used nanomaterials like CdSe/CdS and InP/ZnS quantum dots as well as iron oxide, gold, and polymer particles of different surface chemistry with previously tested colloidal stability and different cell lines like Hep-2 and 8E11 cells, which reveal a dependence of the genotoxicity on the chemical composition as well as the surface chemistry of these nanomaterials. These studies will be also used to establish nanomaterials as positive and negative genotoxicity controls or standards for assay performance validation for users of this fluorometric genotoxicity assay. In the future, after proper validation, this microscopic platform technology will be expanded to other typical toxicity assays. T2 - SPIE 2018 CY - San Francisco, USA DA - 27.01.2018 KW - Nanoparticle KW - Fluorescence KW - Surface chemistry KW - Size KW - Assay KW - Microscopy KW - Nanotoxicity KW - Toxicity KW - Automation KW - Calibration KW - Standard PY - 2018 AN - OPUS4-44186 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geißler, Daniel T1 - NanoGenotox - Automatable Determination of the Genotoxicity of Nanoparticles with DNA-based Optical Assays N2 - Nanomaterials are used in many different applications in the material and life sciences. Examples are optical reporters, barcodes, and nanosensors, magnetic and optical contrast agents, and catalysts. Due to their small size and large surface area, there are also concerns about their interaction with and uptake by biological systems. This has initiated an ever increasing number of cyctoxicity studies of nanomaterials of different chemical composition and surface chemistry, but until now, the toxicological results presented by different research groups often do not address or differ regarding a potential genotoxicity of these nanomaterials. This underlines the need for a standardized test procedure to detect genotoxicity.1,2 Aiming at the development of fast, easy to use, and automatable microscopic methods for the determination of the genotoxicity of different types of nanoparticles, we assess the potential of the fluorometric γH2AX assay for this purpose. This assay, which can be run on an automated microscopic detection system, relies on the determination of DNA double strand breaks as a sign for genotoxicity.3 Here, we present first results obtained with broadly used nanomaterials like CdSe/CdS and InP/ZnS quantum dots as well as iron oxide, gold, and polymer particles of different surface chemistry with previously tested colloidal stability. These studies will be also used to establish nanomaterials as positive and negative genotoxicity controls or standards for assay performance validation for users of this fluorometric genotoxicity assay. In the future, after proper validation, this microscopic platform technology will be expanded to other typical toxicity assays. References. (1) Landsiedel, R.; Kapp, M. D.; Schulz, M.; Wiench, K.; Oesch, F., Reviews in Mutation Research 2009, 681, 241-258. (2) Henriksen-Lacey, M.; Carregal-Romero, S.; Liz-Marzán, L. M., Bioconjugate Chem. 2016, 28, 212-221. (3) Willitzki, A.; Lorenz, S.; Hiemann, R.; Guttek, K.; Goihl, A.; Hartig, R.; Conrad, K.; Feist, E.; Sack, U.; Schierack, P., Cytometry Part A 2013, 83, 1017-1026. T2 - 9th International Conference on Nanotoxicology - New tools in risk assessment of nanomaterials CY - Dusseldorf/Neuss, Germany DA - 18.09.2018 KW - Nano KW - Nanotoxicity KW - Fluorescence KW - Quantum dot KW - Surface KW - Passivation shell KW - Automated assay KW - Nanoparticle PY - 2018 AN - OPUS4-47540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radunz, Sebastian A1 - Kraus, Werner A1 - Bischoff, F. A. A1 - Emmerling, Franziska A1 - Resch-Genger, Ute A1 - Tschiche, Harald T1 - Temperature- and Structure-Dependent Optical Properties and Photophysics of BODIPY Dyes N2 - We report on the temperature- and structural-dependent optical properties and photophysics of a set of boron dipyrromethene (BODIPY) dyes with different substitution patterns of their meso-aryl subunit. Single-crystal Xray diffraction analysis of the compounds enabled a classification of the dyes into a sterically hindered and a unhindered group. The steric hindrance refers to a blocked rotational motion of the aryl subunit around the bond connecting this moiety to the meso-position of the BODIPY core. The energy barriers related to this rotation were simulated by DFT calculations. As follows from the relatively low rotational barrier calculated to about 17 kcal/mol, a free rotation is only possible for sterically unhindered compounds. Rotational barriers of more than 40 kcal/mol determined for the sterically hindered compounds suggest an effective freezing of the rotational motion in These molecules. With the aid of temperature-dependent spectroscopic measurements, we could show that the ability to rotate directly affects the optical properties of our set of BODIPY dyes. This accounts for the strong temperature dependence of the fluorescence of the sterically unhindered compounds which show a drastic decrease in fluorescence quantum yield and a significant shortening in fluorescence lifetime upon heating. The optical properties of the sterically hindered compounds, however, are barely affected by temperature. Our results suggest a nonradiative deactivation of the first excited singlet state of the sterically unhindered compounds caused by a conical intersection of the potential energy surfaces of the Ground and first excited state which is accessible by rotation of the meso-subunit. This is in good agreement with previously reported deactivation mechanisms. In addition, our results suggest the presence of a second nonradiative depopulation pathway of the first excited singlet state which is particularly relevant for the sterically hindered compounds. KW - Fluorescence KW - Sensor KW - Switch KW - pH KW - BODIPY KW - Dye KW - Probe KW - Synthesis KW - Photophysics KW - Mechanism PY - 2020 DO - https://doi.org/10.1021/acs.jpca.9b11859 SN - 1089-5639 VL - 124 IS - 9 SP - 1787 EP - 1797 PB - American Chemical Society AN - OPUS4-50639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute ED - Martynenko, Irina ED - Baimuratov, A. S. ED - Osipova, V. A. ED - Kuznetsova, V. A. ED - Purcell-Milton, F. ED - Rukhlenko, I. D. ED - Fedorov, A. V. ED - Gun'ko, Y. K. ED - Baranov, A. V. T1 - Excitation energy dependence of the photoluminescence quantum yield of core/shell CdSe/CdS quantum dots and correlation with circular dichroism N2 - Quantum dot (QD) based nanomaterials are very promising materials for the fabrication of optoelectronic devices like solar cells, light emitting diodes (LEDs), and photodetectors as well as as reporters for chemo- and biosensing and bioimaging. Many of These applications involve the monitoring of changes in photoluminescence intensity and energy transfer processes which can strongly depend on excitation wavelength or energy. In this work, we analyzed the excitation energy dependence (EED) of the photoluminescence quantum yields (PL QYs) and decay kinetics and the circular dichroism (CD) spectra of CdSe/CdS core/shell QDs with different thicknesses of the surface passivation shell. Our results demonstrate a strong correlation between the spectral position of local maxima observed in the EED of PL QY and the zero-crossing points of the CD profiles. Theoretical analysis of the energy band structure of the QDs with effective mass approximation suggests that these structures could correspond to exciton energy levels. This underlines the potential of CD spectroscopy for the study of electronic energy structure of chiroptically active nanocrystals which reveal quantum confinement effects. KW - Fluorescence KW - Semiconductor KW - Nanoparticle KW - Surface chemistry KW - Quantum yield KW - Lifetime KW - Nanocrystal KW - Cysteine KW - Thiol KW - Ligand KW - Quantum dot KW - CdSe KW - Exciton KW - Circular dichroism KW - Theory KW - Excitation spectra KW - Excitation energy dependence PY - 2017 DO - https://doi.org/10.1021/acs.chemmater.7b04478 SN - 0897-4756 SN - 1520-5002 VL - 30 IS - 2 SP - 465 EP - 471 PB - ACS Publications AN - OPUS4-44034 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David T1 - SWIR luminescent nanomaterials – key chemical parameters for bright probes for in vivo bioimaging N2 - A current challenge for studying physio-pathological phenomena and diseaserelated processes in living organisms with non-invasive optical bioimaging is the development of bright optical reporters that enable deep tissue penetration, a high detection sensitivity, and a high spatial and temporal resolution. The focus of this project are nanomaterials, which absorb and emit in the shortwave infrared (SWIR) between ~900–2500 nm where scattering, absorption, and autofluorescence of the tissue are strongly reduced compared to the visible and NIR. T2 - QD2024 - 12th International Conference on Quantum Dots CY - Munich, Germany DA - 18.03.2024 KW - Quantum dots KW - Advanced nanomaterials KW - Fluorescence KW - Quality assurance KW - Gold nanocluster KW - Shortwave infrared KW - Spectroscopy KW - Bioimaging PY - 2024 AN - OPUS4-59783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Effect of surface chemistry on optical, chemical and electronic properties of blue luminescent graphene quantum dots N2 - Due to their unique physical properties, particularly their electronic and luminescent properties, graphene quantum dots (GQDs) are expected to be suitable for a wide range of applications in bioimaging, electro-optical and photonic materials or energy harvesting among others.1 Tuning the surface chemistry provides an efficient approach to modulate the fluorescence and distinct electronic properties of GQDs.2 Nevertheless, the role of surface chemistry on the electronic structure of GQDs remains poorly understood. In this presentation, we will compare systematically the electronic and chemical structures of GQDs functionalized with carboxylic and aminated groups to those of non-functionalized GQDs, combining theoretical and experimental approaches, here various photon-based spectroscopies. First, the electronic structure of GQDs was characterized by soft X-ray absorption (XA) and X-ray emission (XE) spectroscopies, probing unoccupied and occupied electronic states, respectively, at the carbon K edge for the first time. The interpretation of the XA/XE spectra was done based on theoretical calculations. Then, the chemical structure of the GQDs was characterized in situ by ATR-FTIR in water, thereby accounting for the importance of the interface between GQDs and water believed to play a central role in the chemical reactivity and the optical properties. We previously demonstrated that monitoring the OH vibrations of water molecules during exposure to humid air was a powerful method to probe H-bonding environment around carbon nanomaterials.3 For GQDs, clear surface-dependent water adsorption profiles are observed and discussed. Finally, UV/Vis absorption and photoluminescence measurements were done to characterize the optical properties of these GQDs. Our results suggest that the surface chemistry of the GQDs affects significantly their electronic structure and optical properties. These findings will contribute to an improved understanding of the structure–activity relationship of GQDs and other carbon nanomaterials with surface modifications. T2 - MRS Fall Meeting 2017 CY - Boston, USA DA - 26.11.2017 KW - Carbon KW - Nanoparticle KW - Fluorescence KW - NIR KW - IR KW - Surface chemistry KW - Deactivation pathways KW - Lifetime KW - Size KW - Giant carbon dot KW - Quantum yield PY - 2017 AN - OPUS4-43494 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Applications and challenges of luminescence-based detection methods in the life and material sciences N2 - Luminescence-based detection methods, ranging from fluorescence spectroscopy for photophysical and mechanistic studies over sensing applications, chromatographic separation techniques and the microarray technology with fluorescence detection to fluorescence microscopy, flow cytometry, single molecule spectroscopy, and molecular imaging to integrating sphere spectroscopy, are among the most widely used methods in the life and material sciences. This is due to e.g., their unique sensitivity enabling the detection of single molecules, potential for multiplexing, ease of combination with spatial resolution, and suitability for remote sensing. Many of these advantages are closely linked to the choice of suitable molecular and nanoscale fluorescent reporters, typically required for signal generation. This includes organic dyes without and with sensor function, fluorophore-encoded polymeric and silica nanoparticles as well as nanocrystalline systems like semiconductor quantum dots and upconversion phosphors, emitting in the visible (vis), near-infrared (NIR), and IR (infrared). Current challenges present the environment sensitivity of most fluorophores, rendering fluorescence spectra, measured intensities/fluorescence quantum yields, and fluorescence decay kinetics matrix-dependent, and instrument-specific distortions of measured fluorescence signals that need to be considered for quantification and comparability of data, particularly fluorescence spectra. Here, current applications of luminescence-based methods and different types of reporters will be presented. In this context, suitable spectroscopic tools for the characteri-zation of the optical properties of fluorescent reporters and fluorophore-encoded microparticles, analytical tools for the determination of the surface chemistry of different types of particles, and different multiplexing strategies will be discussed. T2 - 9th Meeting of Engineering of Functional Interfaces CY - Wildau,Germany DA - 03.07.2016 KW - Fluorescence KW - Multiplexing KW - Lifetime KW - Nanomaterial KW - Nanoparticle KW - PEG KW - Ligand KW - Semiconductor quantum dot KW - Quantum yield KW - Quantification KW - Upconversion nanoparticle KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Fluorescence standard KW - Calibration PY - 2016 AN - OPUS4-37112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Srivastava, Priyanka T1 - Multi-color nanosensors for ratiometric measurements of acidic, neutral, and basic pH based on silica and polystyrene particles N2 - pH presents one of the most important analytes in the life and material sciences, indicating, e.g., diseases and corrosion processes. This includes the optical monitoring of pH in living cells for studying cellular internalization pathways, such as phagocytosis, endocytosis, and receptor mediated internalization with the aid of molecular and nanoscale fluorescent sensors. Nanoparticle (NP)-based sensors, that are labelled or stained with a multitude of sensor dyes, have several advantages as compared to conventional molecular probes like enhanced brightness, i.e., amplified signals, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, this can enable the use of hydrophobic dyes in aqueous environments. Versatile templates and carriers for the fabrication of nanosensors by staining and/or labelling with different fluorophores and sensor molecules are surface-functionalized particles like silica (SiO2) and polystyrene (PS) particles. Here we present a platform of blue-red-green fluorescent pH nanosensors for the measurement of acidic, neutral, and basic pH utilizing both types of matrices and two spectrally distinguishable sensor dyes with an integrated reference dye and demonstrate its applicability for cellular studies. T2 - E-MRS Spring Meeting 2022 CY - Online meeting DA - 30.05.2022 KW - Nanosensors KW - pH sensing KW - Silica- and polystyrene particles KW - Ratiometric sensors KW - Fluorescence PY - 2022 AN - OPUS4-55597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Pérez-Padilla, Víctor A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Ratiometric detection of perfluoroalkyl carboxylic acids using dual fluorescent nanoparticles and a miniaturised microfluidic platform N2 - The widespread contamination of soil and water with perfluoroalkyl substances (PFAS) has caused considerable societal and scientific concern. Legislative measures and an increased need for remediation require effective on-site analytical methods for PFAS management. Here we report on the development of a green-fluorescent guanidine-BODIPY indicator monomer incorporated into a molecularly imprinted polymer (MIP) for the selective detection of perfluorooctanoic acid (PFOA). Complexation of PFOA by the indicator, which is mediated by concerted protonation-induced ion pairing-assisted hydrogen bonding, significantly enhances fluorescence in polar organic solvents. The MIP forms as a thin layer on silica nanoparticles doped with tris(bipyridine)ruthenium(II) chloride, which provides an orange emission signal as internal reference, resulting in low measurement uncertainties. Using a liquid-liquid extraction protocol, this assay enables the direct detection of PFOA in environmental water samples and achieves a detection limit of 0.11 µM. Integration into an opto-microfluidic system enables a compact and user-friendly system for detecting PFOA in less than 15 minutes. KW - PFAS KW - Molecular imprinting KW - Microfluidics KW - Fluorescence KW - Onsite assay PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650270 DO - https://doi.org/10.1038/s41467-025-66872-9 SN - 2041-1723 VL - 16 IS - 1 SP - 1 EP - 16 PB - Springer Science and Business Media LLC AN - OPUS4-65027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Andresen, Elina A1 - Resch-Genger, Ute A1 - Michaelis, Matthias A1 - Prinz, Carsten A1 - Würth, Christian T1 - Time-resolved luminescence spectroscopy for monitoring the stability and dissolution behaviour of upconverting nanocrystals with different surface coatings† N2 - We demonstrate the potential of time-resolved luminescence spectroscopy for the straightforward assessment and in situ monitoring of the stability of upconversion nanocrystals (UCNPs). Therefore, we prepared hexagonal NaYF4:Yb3+,Er3+ UCNPs with various coatings with a focus on phosphonate ligands of different valency, using different ligand exchange procedures, and studied their dissolution behaviour in phosphate-buffered saline (PBS) dispersions at 20 °C and 37 °C with various analytical methods. The amount of the released UCNPs constituting fluoride ions was quantified by potentiometry using a Fluoride ion-sensitive electrode and particle disintegration was confirmed by transmission electron microscopy studies of the differently aged UCNPs. In parallel, the luminescence features of the UCNPs were measured with special emphasis on the lifetime of the sensitizer emission to demonstrate its suitability as Screening parameter for UCNP stability and changes in particle composition. The excellent correlation between the changes in luminescence lifetime and fluoride concentration highlights the potential of our luminescence lifetime method for UCNP stability screening and thereby indirect monitoring of the release of potentially hazardous fluoride ions during uptake and dissolution in biological systems. Additionally, the developed in situ optical method was used to distinguish the dissolution dynamics of differently sized and differently coated UCNPs. KW - Fluorescence KW - Lifetime KW - Method KW - Quantification KW - Stability KW - Coating KW - Surface chemistry KW - Lanthanide KW - Fluoride KW - Electrochemistry KW - ICP-OES KW - Upconversion KW - Nano KW - Particle KW - Aging KW - Quality assurance KW - TEM PY - 2020 DO - https://doi.org/10.1039/d0nr02931a VL - 12 IS - 23 SP - 12589 EP - 12601 PB - Royal Society od Chemistry AN - OPUS4-52088 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böhmert, L. T1 - Fluorescence labeling study of silver nanoparticles N2 - During the last years, there has been a rapid rise in the use of nanomaterials in consumer products. Especially silver nanoparticles are frequently used because of their well-known optical and antimicrobial properties. However, the toxicological studies focusing on silver nanoparticles are controversial, either claiming or denying a specific nano-efffect. To contribute to localizing nanoparticles in toxicological studies and to investigate the interaction of particles with cells, a fluorescent marker is often used to monitor their transport and possible degradation. A major problem, in this context is the issue of binding stability of a fluorescent marker which is attached to the particle. In order to overcome this problem we provide an investigation of the binding properties of fluorescence-labeled BSA to small silver nanoparticles. Therefore, we synthesized small silver nanoparticles which are stabilized by poly(acrylic acid). The particles are available as reference candidate material and were thoroughly characterized in an earlier study. The ligand was exchanged by fluorescence marked albumin (BSA-FITC). The adsorption of the ligands was monitored by dynamic light scattering (DLS). To verify that the observed effects on the hydrodynamic radius originate from the successful ligand exchange and not from agglomeration or aggregation we used small angle X-ray scattering (SAXS). The fluorescent particles were characterized by UV/Vis and fluorescence spectroscopy. Afterwards, desorption of the ligand BSA-FITC was monitored by fluorescence spectroscopy and the uptake of particles in different in vitro models was studied. The particles are spherical and show no sign of aggregation after successful ligand exchange. The fluorescence intensity is quenched significantly by the presence of the silver cores as expected, but the remaining fluorescence intensity was high enough to use these particles in biological investigations. Half-life of fluorescence labeling on the particle was 21 d in a highly concentrated solution of non-labeled BSA. Thus, a very high dilution and long incubation times are needed to remove BSA-FITC from the particles. Finally, the fluorescence-labeled silver nanoparticles were used for uptake studies in human liver and intestinal cells, showing a high uptake for HepG2 liver cells and almost no uptake in differentiated intestinal Caco-2 cells. In conclusion, we showed production of fluorescence-marked silver nanoparticles. The fluorescence marker is strongly adsorbed to the silver surface which is crucial for future investigations in biological matrices. This is necessary for a successful investigation of the toxicological potential of silver nanoparticles. T2 - NanoTox 2018 - 9th International Conference on Nanotoxicology CY - Neuss, Germany DA - 18.09.2018 KW - Silver nanoparticles KW - Fluorescence KW - Cell imaging KW - Dynamic light scattering PY - 2018 AN - OPUS4-45639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tavernaro, Isabella A1 - Rajotte, Isabelle A1 - Thibeault, Marie-Pier A1 - Sander, Philipp C. A1 - Kodra, Oltion A1 - Lopinski, Gregory A1 - Radnik, Jörg A1 - Johnston, Linda J. A1 - Brinkmann, Andreas A1 - Resch-Genger, Ute T1 - Quantifying surface groups on aminated silica nanoparticles of different size, surface chemistry, and porosity with solution NMR, XPS, optical assays, and potentiometric titration N2 - We assessed the quantification of surface amino functional groups (FGs) for a large set of commercial and custom-made aminated silica nanoparticles (SiO2 NPs) with sizes of 20–100 nm, prepared with different sol–gel routes, different amounts of surface amino FGs, and different porosity with four methods providing different, yet connected measurands in a bilateral study of two laboratories, BAM and NRC, with the overall aim to develop standardizable measurements for surface FG quantification. Special emphasis was dedicated to traceable quantitative magnetic resonance spectroscopy (qNMR) performed with dissolved SiO2 NPs. For the cost efficient and automatable screening of the amount of surface amino FGs done in a first step of this study, the optical fluorescamine assay and a potentiometric titration method were utilized by one partner, i.e., BAM, yielding the amount of primary amino FGs accessible for the reaction with a dye precursor and the total amount of (de)protonatable FGs. These measurements, which give estimates of the minimum and maximum number of surface amino FGs, laid the basis for quantifying the amount of amino silane molecules with chemo-selective qNMR with stepwise fine-tuned workflows, involving centrifugation, drying, weighting, dissolution, measurement, and data evaluation steps jointly performed by BAM and NRC. Data comparability and relative standard deviations (RSDs) obtained by both labs were used as quality measures for method optimization and as prerequisites to identify method-inherent limitations to be later considered for standardized measurement protocols. Additionally, the nitrogen (N) to silicon (Si) ratio in the near-surface region of the SiO2 NPs was determined by both labs using X-ray photoelectron spectroscopy (XPS), a well established surface sensitive analytical method increasingly utilized for microparticles and nano-objects which is currently also in the focus of international standardization activities. Overall, our results underline the importance of multi-method characterization studies for quantifying FGs on NMs involving at least two expert laboratories for effectively identifying sources of uncertainty, validating analytical methods, and deriving NM structure–property relationships. KW - Advanced Materials KW - Amino Groups KW - Calibration KW - Characterization KW - Functional groups KW - Method Comparison KW - Nano Particle KW - Validation KW - XPS KW - Optical Assay KW - Quantification KW - Surface Analysis KW - Reference Materials KW - Synthesis KW - Fluorescence PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-649992 DO - https://doi.org/10.1039/d5na00794a VL - 7 IS - 21 SP - 6888 EP - 6900 PB - Royal Society of Chemistry AN - OPUS4-64999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - The emp project smurfnano – Standardizing the quantification of surface functionalities, ligands, and coatings on nanomaterials N2 - For industrial applications such as medical diagnostics, drug delivery, sensing, catalysis, energy conversion and storage, opto-electronics, and information storage, meanwhile engineered nanoparticles (NPs) with various chemical compositions and surface functionalities are routinely fabricated. NP function, interaction with biological species, and environmental fate are largely determined by surface functionalities. Reliable, reproducible, and standardized surface characterization methods are therefore vital for quality control of NPs, and mandatory to meet increasing concerns regarding their safety. Also, industry, international standardization organizations, regulatory agencies, and policymakers need validated and standardized measurement methods and reference materials. These needs are addressed by the recently started European metrology project SMURFnano involving 12 partners from different National Metrology Institutes, designated institutes, and research institutes, two university groups as well as one large company and one SME producing NPs. This project as well as first results derived from the development of test and reference materials with a well characterized surface chemistry and ongoing interlaboratory comparisons will be presented. T2 - LNE Workshop CY - Paris, France DA - 04.11.2025 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 - qNMR KW - Comparison KW - ILC PY - 2025 AN - OPUS4-64725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Influence of Surface Chemistry and Size on the Stability of β-NaYF4:Yb,Er Nanocrystals in Various Environments N2 - The use of inorganic lanthanide-doped upconversion nanoparticles (UCNP) in bioimaging and cellular studies requires biocompatible particles. One possible cause of UCNP toxicity is the release of potentially harmful fluoride and lanthanide ions as revealed by dilution studies in aqueous environments, particularly under high dilution conditions. To address this issue, suitable surface coatings preventing such effects in combination with fast screening methods suited for online monitoring and in situ analyses are desired. Here we present systematic studies of differently sized β-NaYF4:Yb,Er UCNP stabilized with different surface coatings and hydrophilic ligands varying in binding strength to the particle surface in various aqueous environments at different temperatures and UCNP concentrations. The concentration of the fluoride and lanthanide ions released upon particle dissolution was quantified electrochemically with a fluoride ion-sensitive electrode and inductively coupled plasma optical emission spectrometry (ICP-OES) and monitored fluorometrically, thereby exploiting the sensitivity of the upconversion luminescence to changes in size and surface chemistry. Moreover, changes in surface chemistry were determined with X-Ray photoelectron spectroscopy (XPS). Based upon our results, we could derive optimum screening parameters for UCNP stability studies and determine conditions and coating procedures and ligands for enhancing UCNP stability in aqueous environments. T2 - UPCON2021 CY - Online meeting DA - 06.04.2021 KW - Fluorescence KW - Lifetime KW - Method KW - Quantification KW - Stability KW - Coating KW - Surface chemistry KW - Lanthanide KW - Fluoride KW - Electrochemistry KW - ICP-OES KW - Upconversion KW - Nano KW - Particle KW - Aging KW - Quality assurance KW - Mass spectrometry KW - XPS PY - 2021 AN - OPUS4-52411 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - The SMURFnano project - standardized measurements of surface functionalities on nanoparticles N2 - Engineered nanoparticles (NPs) with various chemical compositions and surface functionalities are routinely fabricated for industrial applications such as medical diagnostics, drug delivery, sensing, catalysis, energy conversion and storage, optoelectronics, and information storage. NP function, interaction with biological species, and environmental fate are largely determined by surface functionalities. Reliable, reproducible, and standardized surface characterization methods are therefore vital for quality control of NPs, and mandatory to meet increasing concerns regarding their safety. Also, industry, international standardization organizations, regulatory agencies, and policymakers need validated and standardized measurement methods and reference materials. However, methodologies for determining NP surface properties, including the amount, chemical composition, and homogeneity of surface functionalities and coatings are largely non-standardized. Suitable methods for determining surface functionalities on ligand-stabilized core and core/shell NPs include advanced techniques such as traceable quantitative nuclear magnetic resonance (qNMR) as well as X-ray electron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS), and simpler optical and electrochemical methods. The latter less costly methods are often used by SMEs, e.g., for quality control. To validate methods, establish measurement uncertainties, test reference materials, and produce reference data, international interlaboratory comparisons (ILC) on NP surface functionalization measurements are required and well characterized test and reference nanomaterials providing benchmark values.[1] These needs are addressed by the recently started European metrology project SMURFnano involving 12 partners from different National Metrology Institutes, designated institutes, and research institutes, two university groups as well as one large company and one SME producing NPs. This project as well as first results derived from the development of test and reference materials with a well characterized surface chemistry and ongoing interlaboratory comparisons will be presented. T2 - eMRS CY - Strasbourg, France DA - 27.05.2025 KW - Quality assurance KW - Reference analysis KW - Standardization KW - Metrology KW - Reference products KW - Reference materials KW - Mission KW - Surface chemistry KW - Nano KW - Particle KW - qNMR KW - XPS KW - Fluorescence KW - Optical assays KW - Interlaboratory comparison KW - Uncertainty PY - 2025 AN - OPUS4-63243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella A1 - Abram, Sarah-Luise A1 - Homann, Christian A1 - Scholtz, Lena A1 - Radnik, Jörg A1 - Resch-Genger, Ute T1 - Validated and standardized measurements and quantification of surface functionalities on nanoparticles N2 - Surface-functionalized organic and inorganic engineered nanomaterials (NMs) are widely applied in the life and materials sciences. NM performance depends on key factors such as particle size and shape, crystal phase, morphology, chemical composition, and surface chemistry, i.e., surface coatings, functional groups (FGs), and ligands.1 The latter controls their processability and interaction with the environment and largely their possible toxicity. Thus, methods for FG quantification are important tools for quality control of NM production processes and can foster the sustainable development of functional and safe(r) NMs. This underlines the importance of validated and standardized analytical methods for surface analysis and reference materials.2 This encouraged us to explore simple and versatile tools for quantifying common bioanalytically relevant FGs such as optical assays, electrochemical titration methods, quantitative nuclear magnetic resonance spectroscopy (qNMR), and X-Ray photoelectron spectroscopy (XPS) and to perform a first interlaboratory comparison (ILC) on surface FG quantification.3,4 In a follow-up ILC, BAM and NRC explored qNMR sample preparation, measurement, and data evaluation protocols for commercial and custom-made aminated SiO2 NPs with sizes of 20-100 nm, different amounts of surface amino FGs, and different porosity.5,6 First, the number of amino FGs accessible for a dye reporter was determined with a cost-efficient, automated optical fluorescamine assay. Then, qNMR workflows and protocols were stepwise fine-tuned. The qNMR ILC was complemented by joint XPS measurements. BAM also examined the applicability of fast and automatable potentiometric titrations to screen the total amount of (de)protonable FGs on aminated SiO2 NPs. Our results underline the need to evaluate protocols for FG quantification in ILCs and the advantages of multi-method characterization strategies for efficient method cross validation. T2 - Surface and Micro/Nano Analysis Working Group CY - Paris, France DA - 08.04.2025 KW - Quality assurance KW - Reference material KW - Fluorescence KW - Nano KW - Particle KW - Surface analysis KW - XPS KW - Traceability KW - Metrology KW - Calibration KW - Reference data KW - Reference product KW - Digital certificate KW - QNMR KW - Potentiometry PY - 2025 AN - OPUS4-62969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Quantifying the total and accessible amount of surface functionalities and ligands on nano-materials: Overview and recommended methods N2 - Engineered nanoparticles (NPs) with various chemical compositions and surface functionalities are routinely fabricated for industrial applications such as medical diagnostics, drug delivery, sensing, catalysis, energy conversion and storage, opto-electronics, and information storage. NP function, interaction with biological species, and environmental fate are largely determined by surface functionalities. This calls for reliable, reproducible, and standardized surface characterization methods, which are vital for quality control of NPs, and mandatory to meet increasing concerns regarding their safety. Validated and standardized workflows for surface analysis are also increasingly requested by industry, international standardization organizations, regulatory agencies, and policymakers. To establish comparable measurements of surface functionalities across different labs and ease instrument performance validation, reference test materials and reference materials of known surface chemistry as well as reference data are needed. In the following, different methods for determining surface functionalities on ligand-stabilized core and core/shell NPs include advanced techniques are presented and discussed regarding method-inherent advantages and limitations. Special emphasis is dedicated to traceable quantitative nuclear magnetic resonance (qNMR), X-ray electron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS), and simpler optical and electrochemical methods. T2 - LNE Workshop CY - Paris, France DA - 04.11.2025 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 AN - OPUS4-64726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Standardized Measurements of Surface - Functionalities on Nanoparticles N2 - Engineered nanoparticles (NPs) with various chemical compositions and surface functionalities are routinely fabricated for industrial applications such as medical diagnostics, drug delivery, sensing, catalysis, energy conversion and storage, optoelectronics, and information storage. NP function, interaction with biological species, and environmental fate are largely determined by surface functionalities. Reliable, reproducible, and standardized surface characterization methods are therefore vital for quality control of NPs, and mandatory to meet increasing concerns regarding their safety. Also, industry, international standardization organizations, regulatory agencies, and policymakers need validated and standardized measurement methods and reference materials. However, methodologies for determining NP surface properties, including the amount, chemical composition, and homogeneity of surface functionalities and coatings are largely non-standardized. Suitable methods for determining surface functionalities on ligand-stabilized core and core/shell NPs include advanced techniques such as traceable quantitative nuclear magnetic resonance (qNMR) as well as X-ray electron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS), and simpler optical and electrochemical methods. The latter less costly methods are often used by SMEs, e.g., for quality control. To validate methods, establish measurement uncertainties, test reference materials, and produce reference data, international interlaboratory comparisons (ILC) on NP surface functionalization measurements are required and well characterized test and reference nanomaterials providing benchmark values.[1] These needs are addressed by the recently started European metrology project SMURFnano involving 12 partners from different National Metrology Institutes, designated institutes, and research institutes, two university groups as well as one large company and one SME producing NPs. This project as well as first results derived from the development of test and reference materials with a well characterized surface chemistry and ongoing interlaboratory comparisons will be presented. T2 - eMRS CY - Strasbourg, France DA - 27.05.2025 KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Synthesis KW - Silica KW - Upconversion nanoparticles KW - Optical assay KW - qNMR KW - Surface analysis KW - Ligand KW - Quantification KW - Functional group KW - XPS KW - ToF-SIMS KW - Polymer particle KW - Surface modification KW - Potentiometry KW - Metrology KW - Method KW - Validation KW - ILC PY - 2025 AN - OPUS4-63339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ren, J. A1 - Weigert, Florian A1 - Weber, F. A1 - Wang, Y. A1 - Choudhury, S. A1 - Xiao, J. A1 - Lauermann, I. A1 - Resch-Genger, Ute A1 - Bande, A. A1 - Petit, T. ED - Petit, Tristan T1 - Influence of surface chemistry on optical, chemical and electronic properties of blue luminescent carbon dots N2 - Carbon dots have attracted much attention due to their unique optical, chemical and electronic properties enabling a wide range of applications. The properties of carbon dots can be effectively adjusted through modifying their chemical composition. However, a major challenge remains in understanding the core and surface contributions to optical and electronic transitions. Here, three blue luminescent carbon dots with carboxyl, amino and hydroxyl groups were comprehensively characterized by UV-vis absorption and emission spectroscopy, synchrotron-based X-ray spectroscopy, and infrared spectroscopy. The influence of the surface functionality on their fluorescence was probed by pH-dependent photoluminescence measurements. Moreover, the hydrogen bonding interactions between water and the surface groups of carbon dots were characterized by infrared spectroscopy. Our results show that both core and surface electronic states of blue luminescent carbon dots contribute to electronic acceptor levels while the chemical nature of the surface groups determines the hydrogen bonding behavior of the carbon dots. This comprehensive spectroscopic study demonstrates that the surface chemistry has a profound influence on the electronic configuration and surface–water interaction of carbon dots, thus affecting their photoluminescence properties. KW - Quantum dots KW - Spectroscopy KW - UV Vis KW - Fluorescence KW - Surface chemistry PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472325 DO - https://doi.org/10.1039/c8nr08595a SN - 2040-3372 VL - 11 IS - 4 SP - 2056 EP - 2064 PB - RSC AN - OPUS4-47232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Photoluminescence Properties of Different Types of Nanocrystals at the Ensemble and Single Emitter Level N2 - Correlating the photoluminescence (PL) properties of nanomaterials like semiconductor nanocrystals (QDs) and upconversion nanocrystals (UCNPs) assessed in ensemble studies and at the single particle level is increasingly relevant for applications of these nanomaterials in the life sciences like bioimaging studies or their use as reporters in microfluidic assays. Here we present a comparison of the spectroscopic properties of ensembles and single emitters for QDs like II/VI QDs and cadmium-free AIS/ZnS QDs as well as different UCNPs. The overall goal of this study was to derive particle architectures well suited for spectroscopic and microscopic applications. T2 - BIOSSPIE CY - San Francisco, CA, USA DA - 02.02.2019 KW - Quantum yield KW - Nanomaterial KW - Photoluminescence KW - Absolute fluorometry KW - Integrating sphere spectroscopy, KW - NIR KW - IR KW - Fluorescence KW - Nanoparticle KW - Semiconductor KW - Quantum dot KW - Single particle spectroscopy KW - Surface chemistry PY - 2019 AN - OPUS4-47358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Relative and Absolute Methods for Measuring Photoluminescence Quantum Yields of UV/vis/NIR Emitters N2 - One of the key spectroscopic performance parameters of molecular and particulate emitters is the photoluminescence quantum yield (PL QY) that provides a direct measure for the number of emitted per absorbed photons. This triggered the interest in methods suitable for measuring this property for emitters in various environments in the UV/vis/NIR and above 1000 nm as well as on the ensemble and single emitter level. Moreover, for nonlinear emitters like lanthanide-based upconversion nanocrystals methods including instrumentation for power density-dependent PL QY studies are required. An overview of the research activities in Division Biophotonics of BAM is given and suitable relative and absolute methods for the deter-mination of PL QY of organic dyes and different types of application-relevant nanomaterials in dispersion and in the solid state are presen-ted. This covers also the design and calibration of integrating sphere setups, achievable uncertainties, and candidates for PL QY reference materials. T2 - OSRAM Veranstaltung CY - Regensburg, Germany DA - 09.01.2019 KW - Quantum yield KW - Calibration KW - Reference material KW - Uncertainty KW - Absolute fluorometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Fluorescence KW - Nanoparticle KW - Dye PY - 2019 AN - OPUS4-47263 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martynenko, Irina V. A1 - Kusic, Dragana A1 - Weigert, Florian A1 - Stafford, S. A1 - Donnelly, F. C. A1 - Evstigneev, R. A1 - Gromova, Y. A1 - Baranov, A. V. A1 - Rühl, Bastian A1 - Kunte, Hans-Jörg A1 - Gun'ko, Y. K. A1 - Resch-Genger, Ute T1 - Magneto-fluorescent microbeads for bacteria detection constructed from superparamagnetic Fe3O4 nanoparticles and AIS/ZnS quantum dots N2 - The efficient and sensitive detection of pathogenic microorganisms in aqueous environments, such as water used in medical applications, drinking water, and cooling water of industrial plants, requires simple and fast methods suitable for multiplexed detection such as flow cytometry (FCM) with optically encoded carrier beads. For this purpose, we combine fluorescent Cd-free Ag−In−S ternary quantum dots (t-QDs) with fluorescence Lifetimes (LTs) of several hundred nanoseconds and superparamagnetic Fe3O4 nanoparticles (SPIONs) with mesoporous CaCO3 microbeads to a magneto-fluorescent bead platform that can be surface-functionalized with bioligands, such as antibodies. This inorganic bead platform enables immuno-magnetic separation, target enrichment, and target quantification with optical readout. The beads can be detected with steady-state and time-resolved fluorescence microscopy and flow cytometry (FCM). Moreover, they are suited for readout by time gated emission. In the following, the preparation of these magneto-fluorescent CaCO3 beads, their spectroscopic and analytic characterization, and their conjugation with bacteria-specific antibodies are presented as well as proof-of-concept measurements with Legionella pneumophila including cell cultivation and plating experiments for bacteria quantification. Additionally, the possibility to discriminate between the long-lived emission of the LT-encoded capture and carrier CaCO3 beads and the short-lived Emission of the dye-stained bacteria with time-resolved fluorescence techniques and single wavelength excitation is demonstrated. KW - Fluorescence KW - method KW - lifetime KW - quantum yield KW - particle KW - magnetic nanoparticle KW - immunoseparation KW - flow cytometry KW - fluorescence microscopy KW - nanoparticle KW - quantum dot KW - AIS QD KW - fluorescence KW - bacteria detection KW - bacteria KW - antibody KW - Legionella KW - screening tes KW - FLIM PY - 2019 DO - https://doi.org/10.1021/acs.analchem.9b01812 SN - 0003-2700 SN - 1520-6882 VL - 91 SP - 12661 EP - 12669 PB - American Chemical Society CY - Washington, DC AN - OPUS4-50117 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gharaati, S. A1 - Wang, Cui A1 - Förster, C. A1 - Weigert, Florian A1 - Resch-Genger, Ute A1 - Heinze, K. T1 - Triplet–Triplet Annihilation Upconversion in a MOF with AcceptorFilled Channels N2 - In summary, we report a highly modular solid TTA-UC system comprising of a crystalline, thermally stable PCN222(Pd) MOF with CA-coated MOF channels and with a DPA annihilator embedded in a solution-like environment in the MOF channels. This solid material displays blue upconverted delayed emission with a luminescence lifetime of 373 us, a threshold value of 329 mW*cm-2 and a triplet–triplet energy transfer efficiency of 82%. This optical application adds another facet to the versatile chemistry of PCN-222 MOFs. The design concept is also applicable to other TTA-UC pairs and enables tuning of the UCL color, for example, by replacing DPA with other dyes as exemplarily shown for 2,5,8,11-tetra-tert-butyl-perylene, that yields UCL at 450 nm. Current work aims to reduce the oxygen sensitivity and to increase the retention of the trapped annihilators in organic environments, for example, by tuning the chain length of the carboxylic acid and by coating the MOF surface. In addition, the TTA-UC efficiency will be further enhanced by reducing the reabsorption of the UC emission caused by Pd(TCPP) and by optimizing the sensitizer/annihilator interface. KW - Porphyrin KW - Method KW - MOF KW - Fluorescence KW - Dye KW - Sensor KW - Oxygen sensitive KW - Single molecule KW - DPA KW - Lifetime KW - Upconverstion KW - Quantum yield KW - Triplet-triplet annihilation KW - Sensitization KW - Energy transfer KW - NMR PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-500580 DO - https://doi.org/10.1002/chem.201904945 VL - 26 IS - 5 SP - 1003 EP - 1007 PB - Wiley-VCH Verlag CY - Weinheim AN - OPUS4-50058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Advanced characterization of nanomaterials N2 - The rational synthesis and use of nanomaterials require the characterization of many different properties, ranging from particle size and size distribution over surface chemistry to more applicationrelevant features like optical, electrochemical, and magnetic properties. In the following, several methods for the characterization of functional groups on nanomaterials, like polymer and silica nanoparticles, semiconductor quantum dots, and lanthanide-based upconversion nanocrystals are presented. Additionally, procedures for the measurement of the key spectroscopic performance parameters of nanomaterials with linear and nonlinear photoluminescence, such as the photoluminescence quantum yield, are presented for the UV/vis/NIR/SWIR. T2 - Summerschool CY - Bad Honnef, Germany DA - 22.07.2019 KW - Quantum yield KW - Nanoparticle KW - Fluorescence KW - Quantum dot KW - NIR KW - SWIR KW - Quality assurance KW - Calibration PY - 2019 AN - OPUS4-48630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Determining Photoluminescence Quantum Yields of Molecular and Nanocrystal Emitters in the UV/vis/NIR/SWIR N2 - The comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters require accurate and quantitative photo-luminescence measurements. This is of special importance for all photoluminescence applications in the life and material sciences and nanobiophotonics. In the following, procedures for the determination of the spectroscopic key parameter photoluminescence quantum yield, i.e., the number of emitted per absorbed photons, in the UV/vis/NIR/SWIR are presented including pitfalls and achievable uncertainties and material-specific effects related to certain emitter classes are addressed. T2 - Kolloqium National Center for Nanoscience and Technology CY - Peking, People's Republic of China DA - 18.10.2019 KW - Fluorescence KW - Quantum yield KW - Integrating sphere spectroscopy KW - Dye KW - Nanocrystal KW - NIR KW - SWIR KW - Quantum dot KW - Fluorescence standard KW - Uncertainty KW - Calibration PY - 2019 AN - OPUS4-49362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübner, Oskar T1 - Luminescence lifetime encoding for flow cytometry with quantum-dot-encoded beads N2 - Spectral encoding of cells or particles and the discrimination of multiple spectral codes are a critical process in flow cytometry (FCM). Typical issues in spectral encoding are, e.g., the spectral overlap of codes, or the increasing complexity of instruments . The exploitation of the photoluminescence lifetime (LT) as an encoding parameter could be used to circumvent both of these issues, as it adds another dimension to the parameter space, or, when used as a stand-alone parameter, requiring only one excitation light source and one detector. While LT encoding was considered already decades ago it is still not implemented as a routine technique in FCM yet, mainly due to the challenge of very few photons being available within the limited transition time of a cell or particle through the laser spot. Recently, we demonstrated LT-FCM based on luminophores with ns LTs in a compact and low-cost flow cytometer. Measurements on polymer microbeads containing luminophores with distinctly different excited state LTs enabled the complete discrimination of three LT codes and five codes in total could be identified. Now, we have extended our approach towards considerably longer LTs by custom-made polymer microbeads loaded with different ratios of InP/ZnS and AgInS2 quantum dots. The use of these materials significantly expands the usable time range for LT encoding to up to several hundred ns. Our studies demonstrate the possibility to further increase the number of viable LT codes for multiplexing in LT-FCM without the need for extensive hardware modifications. T2 - Visions in Cytometry - 29th Annual Conference of the German Society for Cytometry CY - Berlin, Germany DA - 25.07.2019 KW - Multiplexing KW - Lifetime KW - Bead KW - Flow cytometry KW - Fluorescence KW - Quantum dot KW - InP KW - AIS KW - Dye KW - Encoding KW - Barcoding KW - Assay KW - Method PY - 2019 AN - OPUS4-49390 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -