TY - JOUR
A1 - Resch-Genger, Ute
A1 - Carl, F.
A1 - Grauel, Bettina
A1 - Pons, Monica
A1 - Würth, Christian
A1 - Haase, M.
T1 - LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals
N2 - We developed a procedure to prepare luminescent LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that approach those of high-quality laser crystals of LiYF4:Yb (Yb:YLF) and LiYF4:Yb,Er (Yb,Er:YLF) with identical doping concentrations. As the luminescence decay times of Yb3+ and Er3+ are known to be very sensitive to the presence of quenchers, the long decay times of the core/shell nanocrystals indicate a very low number of defects in the core particles and at the core/shell interfaces. This improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based synthesis. First, the shell was prepared via anewly developed method characterized by a very low nucleation rate for particles of pure LiYF4 shell material. Second, anhydrous acetates were used as precursors and additional drying steps were applied to reduce the incorporation of OH− in the crystal lattice, known to quench the emission of Yb3+ ions. Excitation power density (P)-dependent absolute measurements of the upconversion luminescence quantum yield (Φ,UC) of LiYF4:Yb,Er/LiYF4 core/shell particles reveal a maximum value of 1.25% at P of 180 W·cm−2.
Although lower than the values reported for NaYF4:18%Yb,2%Er core/shell nanocrystals with comparable sizes, these Φ, UC values are the highest reported so far for LiYF4:18%Yb,2%Er/LiYF4 nanocrystals without additional dopants. Further improvements May nevertheless be possible by optimizing the dopant concentrations in the LiYF4 nanocrystals.
KW - Nano
KW - Crystal
KW - Quantum yield
KW - LiYF4
KW - Synthesis
KW - Lifetime
KW - Fluorescence
KW - NIR
KW - Photoluminescence
KW - Lanthanide
KW - Upconversion nanoparticle
KW - Nanomaterial
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515395
DO - https://doi.org/10.1007/s12274-020-3116-y
SN - 1998-0124
VL - 14
IS - 3
SP - 797
EP - 806
PB - Springer
AN - OPUS4-51539
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Würth, Christian
A1 - Grauel, Bettina
A1 - Pons, Monika
A1 - Frenzel, Florian
A1 - Rissiek, P.
A1 - Rücker, Kerstin
A1 - Haase, Markus
A1 - Resch-Genger, Ute
T1 - Yb- and Er concentration dependence of the upconversion luminescence of highly doped NaYF4:Yb,Er/NaYF4:Lu core/shell nanocrystals prepared by a water-free synthesis
N2 - High sensitizer and activator concentrations have been increasingly examined to improve the performance of multi-color emissive upconversion (UC) nanocrystals (UCNC) like NaYF4:Yb,Er and first strategies were reported to reduce concentration quenching in highly doped UCNC. UC luminescence (UCL) is, however, controlled not only by dopant concentration, yet by an interplay of different parameters including size, crystal and shell quality, and excitation power density (P). Thus, identifying optimum dopant concentrations requires systematic studies of UCNC designed to minimize additional quenching pathways and quantitative spectroscopy. Here, we quantify the dopant concentration dependence of the UCL quantum yield (ΦUC) of solid
NaYF4:Yb,Er/NaYF4:Lu upconversion core/shell nanocrystals of varying Yb3+ and Er3+ concentrations (Yb3+ series: 20%‒98% Yb3+; 2% Er3+; Er3+ series: 60% Yb3+; 2%‒40% Er3+). To circumvent other luminescence quenching processes, an elaborate synthesis yielding OH-free UCNC with record ΦUC of ~9% and ~25 nm core particles with a thick surface shell were used. High Yb3+ concentrations barely reduce ΦUC from ~9% (20% Yb3+) to ~7% (98% Yb3+) for an Er3+ concentration of 2%, thereby allowing to strongly increase the particle absorption cross section and UCNC brightness. Although an increased Er3+ concentration reduces ΦUC from ~7% (2% Er3+) to 1% (40%) for 60% Yb3+. Nevertheless, at very high P (> 1 MW/cm2) used for microscopic studies, highly Er3+-doped UCNC display a high brightness because of reduced saturation. These findings underline the importance of synthesis control and will pave the road to many fundamental studies of UC materials.
KW - Upconverion
KW - Nanoparticle
KW - Lanthanides
KW - Quantum yield
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551346
DO - https://doi.org/10.1007/s12274-022-4570-5
SP - 1
EP - 8
PB - Springer
AN - OPUS4-55134
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Molecular and nanoscale emitters photophysics , photoluminescence quantum yields, and surface chemistry
N2 - Inorganic nanocrystals such as spectrally shifting lanthanide-based nanoparticles (LnNCs) like NaYF4: Yb, Er and semiconductor quantum dots, organic and inorganic particles stained with sensor molecules, and organic dyes showing aggregation-induced emission are meanwhile broadly applied in the life and material sciences. The identification of optimum particle architectures and molecular structures for photonic applications requires quantitative spectroscopic studies and methods to control and analyse particle surface chemistry. In the following, photoluminescence studies of different emitter classes are presented, thereby addressing the measurement of particle brightness and photoluminescence quantum yields in different spectral windows parameters required for an in-depth mechanistic understanding. In addition, examples for the quantification of surface functional groups on nanomaterials with optical spectroscopy are given.
T2 - GdCH Kolloquium
CY - Düsseldorf, Germany
DA - 11.11.2025
KW - Dye
KW - Fluorescence
KW - Quantum yield
KW - Lifetime
KW - Sensor materials
KW - Temperature
KW - Cr(III) complex
KW - Nano
KW - Particle
KW - Silica
KW - Polymer
KW - Metrology
KW - Quality assurance
KW - Reference material
KW - Surface chemistry
KW - Size
KW - Shape
KW - Particle number concentration
KW - Method
KW - Optical assay
KW - qNMR
KW - Validation
KW - Potentiometry
KW - XPS
PY - 2025
AN - OPUS4-64728
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Scholtz, Lena
A1 - Eckert, J. G.
A1 - Graf, Rebecca T.
A1 - Kunst, A.
A1 - Wegner, Karl David
A1 - Bigall, N. C.
A1 - Resch-Genger, Ute
T1 - Correlating semiconductor nanoparticle architecture and applicability for the controlled encoding of luminescent polymer microparticles
N2 - Luminophore stained micro- and nanobeads made from organic polymers like polystyrene (PS) are broadly used in the life and material sciences as luminescent reporters, for bead-based assays, sensor arrays, printable barcodes, security inks, and the calibration of fluorescence microscopes and flow cytometers. Initially mostly prepared with organic dyes, meanwhile luminescent core/shell nanoparticles (NPs) like spherical semiconductor quantum dots (QDs) are increasingly employed for bead encoding. This is related to their narrower emission spectra, tuneability of emission color, broad wavelength excitability, and better photostability. However, correlations between particle architecture, morphology, and photoluminescence (PL) of the luminescent nanocrystals used for encoding and the optical properties of the NP-stained beads have been rarely explored. This encouraged us to perform a screening study on the incorporation of different types of luminescent core/shell semiconductor nanocrystals into polymer microparticles (PMPs) by a radical-induced polymerization reaction. Nanocrystals explored include CdSe/CdS QDs of varying CdS shell thickness, a CdSe/ZnS core/shell QD, CdSe/CdS quantum rods (QRs), and CdSe/CdS nanoplatelets (NPLs).
Thereby, we focused on the applicability of these NPs for the polymerization synthesis approach used and quantified the preservation of the initial NP luminescence. The spectroscopic characterization of the resulting PMPs revealed the successful staining of the PMPs with luminescent CdSe/CdS QDs and CdSe/CdS NPLs. In contrast, usage of CdSe/CdS QRs and CdSe QDs with a ZnS shell did not yield luminescent PMPs. The results of this study provide new insights into structure–property relationships between NP stained PMPs and the initial luminescent NPs applied for staining and underline the importance of such studies for the performance optimization of NP-stained beads.
KW - Quantitative spectroscopy
KW - Energy transfer
KW - Synthesis
KW - Surface chemistry
KW - Semiconductor quantum dot
KW - Luminescence
KW - Nano
KW - Particle
KW - Quantum yield
KW - Lifetime
KW - Quality assurance
KW - Polymer particle
KW - Quantum rod
KW - Nanoplatelet
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602206
DO - https://doi.org/10.1038/s41598-024-62591-1
SN - 2045-2322
VL - 14
SP - 1
EP - 16
AN - OPUS4-60220
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - 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 - Petrov, Eugene
A1 - Würth, Christian
A1 - Richter, Maria
A1 - Resch-Genger, Ute
T1 - Fluorescence Standards from BAM - Dye Solutions and Polymer systems
N2 - For fluorescence microscopy, there is an increasing need for suitable calibration tools and reference materials for microscope calibration, the determination of performance parameters, and the regular control and validation of instrument performance. This is addressed in the BmWk-financed project FluMikal (WIPANO program) by two research groups from academia and two companies, that is coordinated by BAM. Here we present different approaches to liquid and solid fluorescence standards for the determination of the wavelength-dependent spectral sensitivity of fluorescence microscopes and ideas concerning the choice of suitable fluorescence lifetime standard for increasingly utilized fluorescence lifetime imaging (FLIM).
T2 - FluMiKal Projectmeeting
CY - Munich, Germany
DA - 27.11.2023
KW - Reference material
KW - Reference product
KW - Fluorescence microscopy
KW - Quality assurance
KW - Instrument performance validation
KW - Lifetime standard
PY - 2023
AN - OPUS4-59120
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Saleta Reig, D.
A1 - Grauel, Bettina
A1 - Konyushkin, V. A.
A1 - Nakladov, A. N.
A1 - Federov, P. P.
A1 - Busko, D.
A1 - Howard, I. A.
A1 - Richards, B. S.
A1 - Resch-Genger, Ute
A1 - Kuznetsov, S. V.
A1 - Turshatov, A.
A1 - Würth, Christian
T1 - Upconversion properties of SrF2:Yb3+,Er3+ single
N2 - Synthesis of new upconversion (UC) materials that can convert near-infrared excitation light into visible emission light with high efficiency has crucial importance for energy and bio-applications. Herein, SrF2 single crystals with a doping concentration of 2 mol% Er3+ and 2–8 mol% Yb3+ were synthesized and the optical properties were studied. The absorption cross-section of the different doping ions was calculated. To identify the most efficient and brightest material absolute excitation power dependent UC photoluminescence quantum yields (ϕUC) and brightness values were determined. In addition, excitation characteristics and luminescence lifetimes were analysed to understand the changes in population pathways and possible quenching mechanisms. A dominant two-photon population behaviour of the red and green emission bands was observed for all investigated doping concentrations of Yb3+ and Er3+. The ϕUC value of 6.5% measured using 230 W cm−2 of 976 nm excitation for SrF2 crystal co-doped with 2 mol% Er3+ and 3 mol% Yb3+. These findings broaden the scope of efficient UC materials apart from the record UC material β-NaYF4:Yb3+, Er3+ and provide benchmark values for cubic-phase and especially SrF2- nano and micrometer sized materials.
KW - Luorescence
KW - Upconversion
KW - Crystal
KW - Lanthanide
KW - Quantum yield
KW - Absolute
KW - Lifetime
KW - Er(III)
KW - Quality assurance
KW - Fluorescence standard
KW - SrF2
PY - 2020
DO - https://doi.org/10.1039/c9tc06591a
VL - 8
IS - 12
SP - 4093
EP - 4101
PB - Journal of Materials Chemistry C
AN - OPUS4-50825
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Luminescent Nanoparticles – Photophysics, Mechanistic Studies, and Applications
N2 - Inorganic nanocrystals with linear and nonlinear luminescence in the ultraviolet, visible, near infrared and short-wave infrared like semiconductor quantum dots and spectrally shifting lanthanide-based nanophosphors have meanwhile found many applications in the life and material sciences. This includes optical reporters for bioimaging and sensing, security and authentication barcodes, solid state lighting, converter materials, and photovoltaics. The identification of optimum particle structures requires quantitative spectroscopic studies under application-relevant conditions, focusing on the key performance parameter photoluminescence quantum yield, ideally flanked by single particle studies to assess spectroscopic inhomogeneities on a particle-to-particle level for typical preparation methods. In this context, methods to quantify the photoluminescence of these different nanoscale emitters are shown and utilized as a basis for a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different size and particle architecture in different environments. Exemplary for the application potential of such nanomaterials, in addition, the design of optical sensors from different nanomaterials and functional organic dyes is briefly summarized.
T2 - CRC 1411 Symposium
CY - Nürnberg, Germany
DA - 20.03.2023
KW - Semiconductor quantum dot
KW - Upconversion nanocrystal
KW - Luminescence
KW - Quantitative spectroscopy
KW - Photophysics
PY - 2023
AN - OPUS4-57364
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 - JOUR
A1 - Kage, Daniel
A1 - Hoffmann, Katrin
A1 - Nifontova, G.
A1 - Krivenkov, V.
A1 - Sukhanova, A.
A1 - Nabiev, I.
A1 - Resch-Genger, Ute
T1 - Tempo-spectral multiplexing in flow cytometry with lifetime detection using QD-encoded polymer beads
N2 - Semiconductor quantum dots (QDs) embedded into polymer microbeads are known to be very attractive emitters for spectral multiplexing and colour encoding. Their luminescence lifetimes or decay kinetics have been, however, rarely exploited as encoding parameter, although they cover time ranges which are not easily accessible with other luminophores. We demonstrate here the potential of QDs made from II/VI semiconductors with luminescence lifetimes of several 10 ns to expand the lifetime range of organic encoding luminophores in multiplexing applications using time-resolved flow cytometry (LT-FCM). For this purpose, two different types of QD-loaded beads were prepared and characterized by photoluminescence measurements on the ensemble level and by single-particle confocal laser scanning microscopy. Subsequently, these lifetime-encoded microbeads were combined with dye-encoded microparticles in systematic studies to demonstrate the potential of these QDs to increase the number of lifetime codes for lifetime multiplexing and combined multiplexing in the time and colour domain (tempo-spectral multiplexing). These studies were done with a recently developed novel luminescence lifetime flow cytometer (LT-FCM setup) operating in the time-domain, that presents an alternative to reports on phase-sensitive lifetime detection in flow cytometry.
KW - Fluorescence life time
KW - Flow cytometry
KW - Lifetime-encoded beads
KW - Quantum dots
KW - Multiplexing
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-503316
DO - https://doi.org/10.1038/s41598-019-56938-2
VL - 10
IS - 1
SP - Article number: 653
PB - nature.com
AN - OPUS4-50331
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 - CONF
A1 - Würth, Christian
A1 - Resch-Genger, Ute
T1 - Project Status report IEC TS 62607-3-1 ED2
N2 - Project Status report IEC TS 62607-3-1 ED2 reklative and absolute quantum yield determinations
T2 - IEC TC 113 Plenary Meeting
CY - Online meeting
DA - 17.04.2023
KW - Quantum yield
KW - Standardization
KW - Nanomaterials
KW - Nanomanufacturing
KW - IEC
PY - 2023
AN - OPUS4-57477
LA - deu
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 - Würth, Christian
A1 - Behnke, Thomas
A1 - Gienger, J.
A1 - Resch-Genger, Ute
T1 - Efficiency scale for scatteringluminescent particles linkedto fundamental and measurablespectroscopic properties
N2 - Comparing the performance of molecular and nanoscale luminophores and luminescent microand nanoparticles and estimating achievable signal amplitudes and limits of detection requires a standardizable intensity scale. This initiated the development of the relative MESF (number of molecules of equivalent soluble fluorochromes) and ERF (equivalent reference fluorophores) scales for flow cytometry and fluorescence microscopy. Both intensity scales rely on fluorescence intensity values assigned to fluorescent calibration beads by an intensity comparison to spectrally closely matching fluorophore solutions of known concentration using a spectrofluorometer. Alternatively, the luminophore or bead brightness (B) can be determined that equals the product of the absorption cross section (σa) at the excitation wavelength (σa(λex)) and the photoluminescence quantum yield (Φpl).
Thereby, an absolute scale based on fundamental and measurable spectroscopic properties can be realized which is independent of particle size, material, and luminophore staining or labeling density and considers the sensitivity of the optical properties of luminophores to their environment. Aiming for establishing such a brightness scale for light-scattering dispersions of luminescent particles with sizes exceeding a few ten nanometers, we demonstrate how the brightness of quasi-monodisperse 25 nm, 100 nm, and 1 μm sized polystyrene particles (PSP), loaded with two different dyes in varying concentrations, can be obtained with a single custom-designed integrating sphere setup that enables the absolute determination of Φpl and transmittance and diffuse reflectance measurements. The resulting Φpl, σa(λex), imaginary parts of the refractive index, and calculated B values of these samples are given in dependence of the number of incorporated dye molecule per particle. Finally, a unitless luminescence efficiency (LE) is defined allowing for the direct comparison of luminescence efficiencies of particles with different sizes.
KW - Brightness
KW - Quantum yield
KW - Cross section
KW - Lluminescence
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573680
DO - https://doi.org/10.1038/s41598-023-32933-6
VL - 13
IS - 1
SP - 14
PB - Nature
AN - OPUS4-57368
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 - 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 - CONF
A1 - Matiushkina, Anna
T1 - Quantification of Citrate Ligands on the Surface of Nanoparticles
N2 - In this study, different methods for determining nanoparticle surface ligands including thermogravimetric analysis (TGA) are explored to quantify citrate as one of the most popular hydrophilic ligands on the surface of nanoparticles such as iron oxide nanoparticles (IONPs). The purpose of work is to understand which analytical methods are best suited for surface chemistry analysis of citrate stabilized IONPs and to validate these methods.
T2 - SALSA Make and Measure 2024: Interfaces
CY - Berlin, Germany
DA - 11.09.2024
KW - Nano
KW - Particle
KW - Iron oxide
KW - Ligand
KW - Quantification
KW - Advanced material
KW - Surface analysis
KW - Functional group
PY - 2024
AN - OPUS4-62310
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
A1 - Wegner, Karl David
A1 - Kalot, G.
A1 - Busser, B.
A1 - Pliquett, J.
A1 - Köster, U.
A1 - Koll, J. C.
A1 - Denat, F.
A1 - Bodio, E.
A1 - Goze, C.
A1 - Sacey, L.
T1 - NIR aza-BODIPY: a new vector for boron neutron capture therapy (BNCT)
N2 - Boron neutron capture therapy (BNCT) relies on the activation of 10B by thermal neutrons, which results in small highly energetic particle emission inducing cancer cells damage. However, in order to overcome the limits of the currently used BNCT agents, it is necessary to design new systems, which can specifically accumulate and deliver a sufficient amount of 10B in tumors. In this study, we designed a 10B-BSH-containing aza-BODIPY (aza-SWIR-BSH). It enabled the efficient vectorization of clinically used 10B-BSH to the tumor, resulting in higher therapeutic activity than the 10B-BSH alone.
T2 - EMIM 2021
CY - Göttingen, Germany
DA - 24.08.2021
KW - Flourescence
KW - Optical probe
KW - Dye
KW - Photophysics
KW - Quantum yield
KW - Mechanism
KW - NIR
KW - SWIR
KW - Imaging
KW - Method
KW - Quality assurance
KW - BODIPY
KW - Boron Neutron Capture Therapy (BNCT)
KW - Medicine
KW - Life sciences
PY - 2021
AN - OPUS4-53731
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 - Xu, R.
A1 - Teich, W.
A1 - Frenzel, Florian
A1 - Hoffmann, Katrin
A1 - Radke, J.
A1 - Rösler, J.
A1 - Faust, K.
A1 - Blank, A.
A1 - Brandenburg, S.
A1 - Misch, M.
A1 - Vajkoczy, P.
A1 - Onken, J. S.
A1 - Resch-Genger, Ute
T1 - Optical characterization of sodium fluorescein in vitro and ex vivo
N2 - Objective: The utilization of fluorescein-guided biopsies and resection has been recently discussed as a suitable strategy to improve and expedite operative techniques for the resection of central nervous system (CNS) tumors. However, little is known about the optical properties of sodium fluorescein (NaFl) in human tumor tissue and their potential impact on ex vivo analyses involving fluorescence-based methods.
Methods: Tumor tissue was obtained from a study cohort of an observational study on the utilization of fluorescein-guided biopsy and resection (n=5). The optical properties of fluorescein-stained tissue were compared to the optical features of the dye in vitro and in control samples consisting of tumor tissue of high-grade glioma patients (n=3) without intravenous (i.v.) application of NaFl. The dye-exposed tumor tissues were used for optical measurements to confirm the detectability of NaFl emission ex vivo. The tissue samples were fixed in 4%PFA, immersed in 30% sucrose, embedded in Tissue-Tek OCT compound, and cut to 10 mm cryosections. Spatially resolved emission spectra from tumor samples were recorded on representative slides with a Confocal Laser Scanning Microscope FV1000 (Olympus GmbH, Hamburg, Germany) upon excitation with lexc = 488 nm.
Results: Optical measurements of fluorescein in 0.9% sodium chloride (NaCl) under in vitro conditions showed an absorption maximum of lmax abs = 479 nm as detected with spectrophotometer Specord 200 and an emission peak at lmax em = 538 nm recorded with the emCCD detection system of a custom-made microscope-based single particle setup using a 500 nm long-pass filter. Further measurements revealed pH- and concentration-dependent emission spectra of NaFl. Under ex vivo conditions, confocal laser scanning microscopy of fluorescein tumor samples revealed a slight bathochromic shift and a broadening of the emission band.
Conclusion: Tumor uptake of NaFl leads to changes in the optical properties – a bathochromic shift and broadening of the emission band – possibly caused by the dye’s high pH sensitivity and concentration-dependent reabsorption acting as an innerfilter of the dye’s emission, particularly in the short wavelength region of the Emission spectrum where absorption and fluorescence overlap. Understanding the ex vivo optical properties of fluorescein is crucial for testing and validating its further applicability as an optical probe for intravital microscopy, immunofluorescence localization studies, and flow cytometry analysis.
KW - Fluorescence
KW - Optical probe
KW - Sensor
KW - Fluorescein
KW - PH
KW - Imaging
KW - Tissue
KW - Cancer
KW - Medical diagnostics
KW - Tumor
KW - In vivo
KW - Ex vivo
KW - Quantum yield
KW - Dye
KW - Quality assurance
KW - Microscopy
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527843
DO - https://doi.org/10.3389/fonc.2021.654300
SN - 2234-943X
VL - 11
SP - 1
EP - 8
PB - Frontiers Media
CY - Lausanne
AN - OPUS4-52784
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 - Oskoei, Parastu
T1 - Thermoresponsive UCNP@MSN Nanoparticles for Doxorubicin Delivery in Melanoma Cells
N2 - Upconversion nanoparticles (UCNPs) possess unique photophysical characteristics, such as excita bility by near infrared (NIR) light, which facilitates deep tissue penetration, multi color emission , long luminescence lifetimes, and an excellent photostability. These features have made UCNPs promising tools for biomedical applications . M esoporous silica nanoparticles (MSNs) functionalized with stimuli responsive nanovalves or specific coatings enable the encapsulation and controlled release of therapeutic agen ts, thereby offering spatiotemporal precision in drug delivery 1 3 ]]. Among drug delivery strategies, photoresponsive systems have attracted growing attention due to their potential for clinical applications . This is especially relevant for melanoma, an aggressive skin cancer with increasing global incidence, for which conventional therapeutic modalities remain largely insufficient in advanced stage 4 In this work, core shell UCNP@MSN nanoparticles were synthetised by coating UCNPs with a mesoporous silica layer, which was subsequently functionalized with thermoresponsive retro Diels Alder nanovalves [ and loaded with the chemotherapeutic agent doxorubicin (DOX). Controlled drug release was effectively achieved under 980 nm NIR i llumination . Treatment with functionalized nanoparticles significantly reduced the viability of melanoma cell lines, with an enhanced cytotoxicity being observed upon combined nanoparticle exposure and NIR illumination . Mechanistic analyses revealed that neither UCNPs nor NIR i llumination alone could induce the production of reactive oxygen species (ROS); however, their combination induced a marked increase in ROS levels in two of the three tested cell lines. Furthermore, this dual treatment promoted substantial apoptotic and/or necrotic responses across all cell models. These findings underscore the potential of UCNP@MSN nanoplatforms, equipped with thermoresponsive ga tes , as efficient photoactivated drug delivery systems for melanoma therapy.
T2 - Conference Jornadas CICECO
CY - Aveiro, Portugal
DA - 09.10.2025
KW - Nano
KW - Particle
KW - Lanthanide
KW - Upconversion
KW - Surface chemistry
KW - Mesoporous silica
KW - Doxorubicin
KW - Nanomedicine
KW - Triggered release
KW - pH
KW - Cellular uptake
KW - Toxicity
KW - Folate
KW - Ligand
PY - 2025
AN - OPUS4-64371
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 - JOUR
A1 - Nelson, G.
A1 - Boehm, U.
A1 - Bagley, S.
A1 - Bajcsy, P.
A1 - Bischof, J.
A1 - Brown, C. M.
A1 - Dauphin, A.
A1 - Dobbie, I. M.
A1 - Eriksson, J. E.
A1 - Faklaris, O.
A1 - Fernandez-Rodriguez, J.
A1 - Ferrand, A.
A1 - Gelman, L,
A1 - Gheisari, A.
A1 - Hartmann, H.
A1 - Kukat, C.
A1 - Laude, A.
A1 - Mitkovski, M.
A1 - Munck, S.
A1 - North, A. J.
A1 - Rasse, T.
A1 - Resch-Genger, Ute
A1 - Schuetz, L. C.
A1 - Seitz, A.
A1 - Strambio-De-Castillia, C.
A1 - Swedlow, J. R.
A1 - Alexopoulos, I.
A1 - Aumayr, K.
A1 - Avilov, S.
A1 - Bakker, G.-J.
A1 - Bammann, R. R.
A1 - Bassi, A.
A1 - Beckert, H.
A1 - Beer, S.
A1 - Belyaev, Y.
A1 - Bierwagen, J.
A1 - Birngruber, K. A.
A1 - Bosch, M.
A1 - Breitlow, J.
A1 - Cameron, L. A.
A1 - Chalfoun, J.
A1 - Chambers, J. J.
A1 - Chen, C.-L.
A1 - Conde-Sousa, E.
A1 - Corbett, A. D.
A1 - Cordelieres, F. P.
A1 - Del Nery, E.
A1 - Dietzel, R.
A1 - Eismann, F.
A1 - Fazeli, E.
A1 - Felscher, A.
A1 - Fried, H.
A1 - Gaudreault, N.
A1 - Goh, W. I.
A1 - Guilbert, T.
A1 - Hadleigh, R.
A1 - Hemmerich, P.
A1 - Holst, G. A.
A1 - Itano, M. S.
A1 - Jaffe, C. B.
A1 - Jambor, H. K.
A1 - Jarvis, S. C.
A1 - Keppler, A.
A1 - Kirchenbuechler, D.
A1 - Kirchner, M.
A1 - Kobayashi, N.
A1 - Krens, G.
A1 - Kunis, S.
A1 - Lacoste, J.
A1 - Marcello, M.
A1 - Martins, G. G.
A1 - Metcalf, D. J.
A1 - Mitchell, C. A.
A1 - Moore, J.
A1 - Mueller, T.
A1 - Nelson, M. S.
A1 - Ogg, S.
A1 - Onami, S.
A1 - Palmer, A. L.
A1 - Paul-Gilloteaux, P.
A1 - Pimentel, J. A.
A1 - Plantard, L.
A1 - Podder, S.
A1 - Rexhepaj, E.
A1 - Royon, A.
A1 - Saari, M. A.
A1 - Schapman, D.
A1 - Schoonderwoert, V.
A1 - Schroth-Diez, B.
A1 - Schwartz, S.
A1 - Shaw, M.
A1 - Spitaler, M.
A1 - Stoeckl, M. T.
A1 - Sudar, D.
A1 - Teillon, J.
A1 - Terjung, S.
A1 - Thuenauer, R.
A1 - Wilms, C. D.
A1 - Wright, G. D.
A1 - Nitschke, R.
T1 - QUAREP-LiMi: A community-driven initiative to establish guidelines for quality assessment and reproducibility for instruments and images in light microscopy
N2 - A modern day light microscope has evolved from a tool devoted to making primarily empirical observations to what is now a sophisticated, quantitative device that is an integral part of both physical and life science research. Nowadays, microscopes are found in nearly every experimental laboratory. However, despite their prevalent use in capturing and quantifying scientific phenomena, neither a thorough understanding of the principles underlying quantitative imaging techniques nor appropriate knowledge of how to calibrate, operate and maintain microscopes can be taken for granted. This is clearly demonstrated by the well-documented and widespread difficulties that are routinely encountered in evaluating acquired data and reproducing scientific experiments. Indeed, studies have shown that more than 70% of researchers have tried and failed to repeat another scientist’s experiments, while more than half have even failed to reproduce their own experiments1. One factor behind the reproducibility crisis of experiments published in scientific journals is the frequent underreporting of imaging methods caused by a lack of awareness and/or a lack of knowledge of the applied technique2,3. Whereas quality control procedures for some methods used in biomedical research, such as genomics (e.g., DNA sequencing, RNA-seq) or cytometry, have been introduced (e.g. ENCODE4), this issue has not been tackled for optical microscopy instrumentation and images. Although many calibration standards and protocols have been published, there is a lack of awareness and agreement on common Standards and guidelines for quality assessment and reproducibility5.
In April 2020, the QUality Assessment and REProducibility for instruments and images in Light Microscopy (QUAREP-LiMi) initiative6 was formed. This initiative comprises imaging scientists from academia and industry who share a common interest in achieving a better understanding of the performance and limitations of microscopes and improved quality control (QC) in light microscopy. The ultimate goal of the QUAREP-LiMi initiative is to establish a set of common QC standards, guidelines, metadata models7,8, and tools9,10, including detailed protocols, with the ultimate aim of improving reproducible advances in scientific research.
This White Paper 1) summarizes the major obstacles identified in the field that motivated the launch of the QUAREP-LiMi initiative; 2) identifies the urgent need to address these obstacles in a grassroots manner, through a community of Stakeholders including, researchers, imaging scientists11, bioimage analysts, bioimage informatics developers, corporate partners, Funding agencies, standards organizations, scientific publishers, and observers of such; 3) outlines the current actions of the QUAREPLiMi initiative, and 4) proposes future steps that can be taken to improve the dissemination and acceptance of the proposed guidelines to manage QC.
To summarize, the principal goal of the QUAREP-LiMi initiative is to improve the overall quality and reproducibility of light microscope image data by introducing broadly accepted standard practices and accurately captured image data metrics.
KW - Fluorescence
KW - Microscopy
KW - Quality assurance
KW - Comparability
KW - Imaging
KW - Standards
KW - Reference materials
KW - Reliability
KW - Data
KW - Reference data
KW - Biology
KW - Medicine
KW - Life science
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-530629
DO - https://doi.org/10.1111/jmi.13041
SN - 1365-2818
VL - 284
IS - 1
SP - 56
EP - 73
PB - Wiley-Blackwell
CY - Oxford
AN - OPUS4-53062
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 - CONF
A1 - Tavernaro, Isabella
T1 - Development of multimodal methods to quantify the total and accessible number of functional groups and ligands on nanomaterials
N2 - Engineered and tailored nanomaterials (NM) are of great interest in the life and material sciences, as they can be used, e.g., as drug carriers, barcodes, fluorescent sensors, and multimodal labels in bioanalytical assays and imaging applications. Their performance and safety depend not only on their particle size, size distribution, and morphology, but also on their surface chemistry, i.e., the total number of surface functional groups (FG) and the number of FG accessible for subsequent functionalization with ligands or biomolecules, which in turn determines surface charge, colloidal stability, biocompatibility, and toxicity. It also underlines the importance of validated analytical methods that provide accurate information on these application-relevant physicochemical properties with a known uncertainty. In the case of FG quantification, this calls for robust, fast, inexpensive, and reliable methods which allow for the characterization of a broad variety of NM differing in size, chemical composition, and optical properties.
Methods
Aiming at the development of simple, versatile, and multimodal tools for the quantification of bioanalytically relevant FG such as amine, carboxy, thiol, and aldehyde functionalities, we investigated and compared various analytical methods commonly used for FG quantification. This includes electrochemical titration methods, dye-based optical assays, and other instrumental analytical techniques such as nuclear magnetic resonance (NMR), mass spectrometry (MS), and thermal analysis methods.
Results
Here, we will present examples for different types of NMs and FGs including results from a currently running interlaboratory comparison (ILC) with the National Research Council of Canada (NRC) to pave the road for method standardization.
Innovative aspects
• Surface analysis
• Performance and safety of nanomaterials
• Standardization
T2 - ANAKON 2023
CY - Vienna, Austria
DA - 11.04.2023
KW - Engineered Nanomaterials
KW - Surface group analysis
KW - Optical spectroscopy
KW - Quantitative NMR
KW - Ligands
KW - Dye
KW - Particle synthesis
KW - Optical Assays
KW - Titration
KW - Safe-by-Design
KW - Nano
KW - Nanosafety
KW - Silica- and Polystyrene Particles
PY - 2023
AN - OPUS4-59127
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 - Oskoei, Párástu
T1 - Cell mechanisms induced by doxorubicin-loaded UCNP@MSN nanoparticles with a thermosresponsive nanovalve in melanoma cells
N2 - Upconversion nanoparticles (UCNPs) exhibit several remarkable optical properties, including excitation by near infrared (NIR) light, which enables deep tissue penetration, multiple distinct emission bands across a wide range of wavelengths, long luminescen ce lifetimes, and high photostability. These features make them particularly attractive for various biomedical applications. Mesoporous silica nanoparticles (MSNs), functionalized with nanovalves or specific coatings, have been explored for controlled and targeted drug delivery, where therapeutic agents are encapsulated within the nanopores, allowing spatiotemporal release 1 3 ]]. Among the promising approaches, photoactivated drug delivery systems have drawn considerable interest due to their versatility and potential. One relevant application is in the treatment of melanoma, an aggressive form of skin cancer with a rising global incidence. In advanced stages, conventional therapies often fail to achieve complete tumour eradication, resulting in poor prognose s 4 In this study, UCNPs were coated with a mesoporous silica shell to form core shell UCNP@MSN nanoparticles, which were further functionalized with thermoresponsive retro Diels Alder nanovalves and loaded with doxorubicin (DOX), a chemotherapeutic drug used in melanoma treatment. Upon exposure to 980 nm NIR light, DOX release was successfully triggered in the culture medium. Exposure to functionalized UCNPs decreased the viability of the tested melanoma cell lines, with further reductions observed when the ex posure to the nanoparticles was combined with irradiation. Subsequently, t he toxicity mechanisms were evaluated and showed that w hile individual treatments with either the functionalized UCNPs or NIR irradiation alone had no effect on reactive oxygen species (ROS) production, their combination significantly increased ROS levels in two of the three tested cell lines. This combined treatment also led to notable increases in apoptotic , necrotic or both type of cells’ percentages on all cell lines. Overall, these findings highlight the potential of these nanoparticles with thermoresponsive gating mechanisms as effective platforms for targeted drug delivery in melanoma therapy.
T2 - EUROTOX 2025
CY - Athens, Greece
DA - 14.09.2025
KW - Nano
KW - Particle
KW - Lanthanide
KW - Upconversion
KW - Surface chemistry
KW - Mesoporous silica
KW - Doxorubicin
KW - Nanomedicine
KW - Triggered release
KW - pH
KW - Cellular uptake
KW - Toxicity
KW - Folate
KW - Ligand
PY - 2025
AN - OPUS4-64372
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Forschung in einer Bundesoberbehörde wie der BAM
N2 - Die Bundesanstalt für Materialforschung und -prüfung (BAM) ist eine forschende Bundesoberbehörde und Einrichtung der Ressortforschung der Bundesrepublik Deutschland. Unter ihrer Leitlinie „Sicherheit in Technik und Chemie“ ist sie zuständig für die öffentliche technische Sicherheit und für metrologische Aufgaben in der Chemie. Das Aufgabenspektrum der BAM, das sich an aktuellen Fragestellungen aus Wissenschaft, Wirtschaft, Politik und Normung orientiert, bietet sehr viele interessante Tätigkeitsfelder für Naturwissenschaftler*Innen und Ingenieur*Innen.
T2 - WIFO Leipzig 2023
CY - Leipzig, Germany
DA - 05.09.2023
KW - Quality assurance
KW - Optical spectroscopy
KW - Certification
KW - Reference product
KW - Integrating sphere spectroscopy
KW - Fluorescence
KW - Quantum yield
KW - Reference material
KW - Reference data
KW - Traceability
KW - Nano
KW - Particle
KW - Analytical chemistry
KW - Sensor
KW - Safety
PY - 2023
AN - OPUS4-58397
LA - mul
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 - Biesen, L.
A1 - Krenzer, J.
A1 - Nirmalananthan-Budau, Nithiya
A1 - Resch-Genger, Ute
A1 - Müller, Th. J. J.
T1 - Asymmetrically bridged aroyl-S,N-ketene acetalbased multichromophores with aggregationinduced tunable emission
N2 - Asymmetrically bridged aroyl-S,N-ketene acetals and aroyl-S,N-ketene acetal multichromophores can be readily synthesized in consecutive three-, four-, or five-component syntheses in good to excellent yields by several successive Suzuki-couplings of aroyl-S,N-ketene acetals and bis(boronic)acid esters. Different aroyl-S,N-ketene acetals as well as linker molecules yield a library of 23 multichromophores with substitution and linker pattern-tunable emission properties. This allows control of different communication pathways between the chromophores and of aggregation-induced emission (AIE) and energy transfer (ET) properties, providing elaborate aggregation-based fluorescence switches.
KW - Dye
KW - Aggregation
KW - Aggregation induced emission
KW - Signal enhancement
KW - Energy transfer
KW - Switch
KW - Sensor
KW - Quantum yield
KW - Lifetime
KW - Photophysics
KW - Sythesis
KW - Nanaoparticle
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550719
DO - https://doi.org/10.1039/d2sc00415a
VL - 13
SP - 5374
EP - 5381
PB - Royal Society of Chemistry
AN - OPUS4-55071
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Scholtz, Lena
T1 - Luminescence Encoding of Polymer Microbeads during Polymerization
N2 - Differently sized, luminescent polymer beads encoded with QDs were prepared with a simple, optimized procedure. The optical properties of the resulting particles were studied to ensure sufficient fluorescence and to evaluate the influence of the polymerization on QD fluorescence.
T2 - 84th Prague Meeting on Macromolecules - Frontiers of Polymer Colloids
CY - Prague, Czech Republic
DA - 24.07.2022
KW - Polymerization
KW - Fluorescence
KW - Quantum dots
KW - Microbeads
PY - 2022
AN - OPUS4-55447
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Moll, J.
A1 - Wang, Cui
A1 - Päpcke, A.
A1 - Förster, C.
A1 - Resch-Genger, Ute
A1 - Lochbrunner, S.
A1 - Heinze, K.
T1 - Green Light Activation of Push-Pull Ruthenium(II) Complexes
N2 - Synthesis, characterization, electrochemistry, and photophysics of novel homo- and heteroleptic ruthenium(II) complexes [Ru(cpmp)2] 2+ (22+) and [Ru(cpmp)(ddpd)]2+ (32+) bearing the tridentate ligands 6,2’’-carboxypyridyl-2,2’-methylamine-pyridylpyridine (cpmp) and N,N’-dimethyl-N,N’-dipyridin-2-ylpyridine-2,6-diamine (ddpd) are reported. The complexes possess one (32+) or two (22+) electron-deficient dipyridyl ketone fragments as electron accepting sites enabling intraligand charge transfer (ILCT), ligand-toligand charge transfer (LL’CT) and low-energy metal-to-ligand charge transfer (MLCT) absorptions. The latter peak around 544 nm (green light). 22+ shows 3MLCT phosphorescence in the red to near-infrared spectral region at room temperature in deaerated acetonitrile solution with an emission quantum yield of 1.3 % and a 3MLCT lifetime of 477 ns, while 3
2+ is much less luminescent. This different behaviour is ascribed to the energy gap law and the shape of the parasitic excited 3MC state potential energy surface. This study highlights the importance of the excited state energies and geometries for the actual excited state dynamics. Aromatic and aliphatic amines reductively quench the excited state of 22+ paving the way to photocatalytic applications using low-energy green light as exemplified with the green-light sensitized thiol-ene click reaction.
KW - Green light excitation
KW - Ruthenium(II) complexes
KW - Phosphorescence
KW - MLCT
KW - Photoinduced electron transfer
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506759
DO - https://doi.org/10.1002/chem.202000871
SP - 1
EP - 13
PB - Wiley-VCH Verlag
AN - OPUS4-50675
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Soares, J. X.
A1 - Wegner, Karl David
A1 - Ribeiro, D. S. M.
A1 - Melo, A.
A1 - Häusler, I.
A1 - Santos, J. L. M.
A1 - Resch-Genger, Ute
T1 - Rationally designed synthesis of bright AgInS2/ZnS quantum dots with emission control
N2 - In the blossoming field of Cd-free semiconductor quantum dots (QDs), ternary I–III–VI QDs have received increasing attention due to the ease of the environmentally friendly synthesis of high-quality materials in water, their high photoluminescence (PL) Quantum yields (QYs) in the red and near infrared (NIR) region, and their inherently low toxicity. Moreover, their oxygen-insensitive long PL lifetimes of up to several hundreds of nanoseconds close a gap for applications exploiting the compound-specific parameter PL lifetime. To overcome the lack of reproducible synthetic methodologies and to enable a design-based control of their PL properties, we assessed and modelled the synthesis of high-quality MPA-capped AgInS2/ZnS (AIS/ZnS) QDs. Systematically refined Parameters included reaction time, temperature, Ag:In ratio, S:In ratio, Zn:In ratio, MPA:In ratio, and pH using a design-of-experiment approach.
Guidance for the optimization was provided by mathematical models developed for the application-relevant PL parameters, maximum PL wavelength, QY, and PL lifetime as well as the elemental composition in terms of Ag:In:Zn ratio. With these experimental data-based models, MPA:In and Ag:In ratios and pH values were identified as the most important synthesis parameters for PL Control and an insight into the connection of these parameters could be gained. Subsequently, the experimental conditions to synthetize QDs with tunable emission and high QY were predicted. The excellent agreement between the predicted and experimentally found PL features confirmed the reliability of our methodology for the rational design of high quality AIS/ZnS QDs with defined PL features.
This approach can be straightforwardly extended to other ternary and quaternary QDs and to doped QDs.
KW - Modelling
KW - Nanoparticle
KW - AIS
KW - Semiconductor quantum dot
KW - Design of experiment
KW - Photoluminescence
KW - Quantum yield
KW - Surface chemistry
KW - Synthesis
KW - Lifetime
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510075
DO - https://doi.org/10.1007/s12274-020-2876-8
VL - 13
IS - 9
SP - 2438
EP - 2450
PB - Springer
AN - OPUS4-51007
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kalot, G.
A1 - Godard, A.
A1 - Busser, B.
A1 - Pliquett, J.
A1 - Broekgaarden, M.
A1 - Motto-Ros, V.
A1 - Wegner, Karl David
A1 - Resch-Genger, Ute
A1 - Köster, U.
A1 - Denat, F.
A1 - Coll, J.-L.
A1 - Bodio, E.
A1 - Goze, C.
A1 - Sancey, L.
T1 - Aza-BODIPY: A New Vector for Enhanced Theranostic Boron Neutron Capture Therapy Applications
N2 - Boron neutron capture therapy (BNCT) is a radiotherapeutic modality based on the nuclear capture of slow neutrons by stable 10B atoms followed by charged particle Emission that inducing extensive damage on a very localized level (<10 um). To be effcient, a suffcient amount of 10B should accumulate in the tumor area while being almost cleared from the normal surroundings. A water-soluble aza-boron-dipyrromethene dyes (BODIPY) fluorophore was reported to strongly accumulate in the tumor area with high and BNCT compatible Tumor/Healthy Tissue ratios.
The clinically used 10B-BSH (sodium borocaptate) was coupled to the water-soluble aza-BODIPY platform for enhanced 10B-BSH tumor vectorization. We demonstrated a strong uptake of the compound in tumor cells and determined its biodistribution in mice-bearing tumors. A model of chorioallantoic membrane-bearing glioblastoma xenograft was developed to evidence the BNCT potential of such compound, by subjecting it to slow neutrons. We demonstrated the Tumor accumulation of the compound in real-time using optical imaging and ex vivo using elemental imaging based on laser-induced breakdown spectroscopy. The tumor growth was significantly reduced as compared to BNCT with 10B-BSH. Altogether, the fluorescent aza-BODIPY/10B-BSH compound is able to vectorize and image the 10B-BSH in the tumor area, increasing its theranostic potential for effcient approach of BNCT.
KW - Aza-BODIPY
KW - SWIR
KW - NIR-I
KW - Theranostic
KW - Boron compound
KW - Optical imaging
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512280
DO - https://doi.org/10.3390/cells9091953
VL - 9
IS - 9
SP - 1953
PB - MDPI
AN - OPUS4-51228
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - 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 - JOUR
A1 - Rietsch, P.
A1 - Sobottka, S.
A1 - Hoffmann, K.
A1 - Popov, A. A.
A1 - Hildebrandt, P.
A1 - Sarkar, B.
A1 - Resch-Genger, Ute
A1 - Eigler, S.
T1 - Between Aromatic and Quinoid Structure: A Symmetrical UV to Vis/NIR Benzothiadiazole Redox Switch
N2 - Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible.
For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches.
KW - Dye
KW - Electrochemistry
KW - Switch
KW - Redox
KW - Sensor
KW - Photophysics
KW - Quantum yield
KW - photoluminescence
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517222
DO - https://doi.org/10.1002/chem.202004009
VL - 26
IS - 72
SP - 17361
EP - 17365
PB - Wiley-VCH GmbH
AN - OPUS4-51722
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - GEN
A1 - Deumer, J.
A1 - Andresen, Elina
T1 - SAXS data of bipyramidal LiYF4 nanoparticles
N2 - SAXS data of bipyramidal LiYF4 nanoparticles synthesized by the Federal Institute for Materials Research and Testing (BAM) and measured by the Physikalisch-Technische Bundesanstalt (PTB) at the synchrotron facility Bessy II, Berlin, Germany.
KW - Reference data set
KW - Simulation
KW - Reference material
KW - Upconversion nanoparticles
KW - Particle number concentration
KW - SAXS
PY - 2024
DO - https://doi.org/10.5281/zenodo.13691409
PB - Zenodo
CY - Geneva
AN - OPUS4-62134
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hu, Y.
A1 - Neumann, C.
A1 - Scholtz, Lena
A1 - Turchanin, A.
A1 - Resch-Genger, Ute
A1 - Eigler, S.
T1 - Polarity, intramolecular charge transfer, and hydrogen bond comediated solvent effects on the optical properties of graphene quantum dots
N2 - Graphene quantum dots (GQDs) have attracted increasing attention due to their favorable optical properties and have been widely used, e.g., in the biomedical field. However, the properties related to the chemical structure of GQDs, resulting in solventdependent optical properties, still remain unclear. Herein, we present the synthesis of long-wavelength emitting GQDs with a size of about 3.6 nm via a solvothermal method using oxo-functionalized graphene (oxo-G) and p-phenylenediamine as precursors and their structural and surface chemical analysis by transmission electron and atomic force microscopy (TEM; AFM) as well as Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopy (FTIR; Raman; XPS). Subsequently, the influence of solvent polarity and proticity on the optical properties of the as-prepared GQDs bearing –OH, –NH2, –COOH and pyridine surface groups was investigated. Based on the results of the absorption and fluorescence (FL) studies, a possible luminescence mechanism is proposed. The observed solvent-induced changes in the spectral position of the FL maximum, FL quantum yield, and FL decay kinetics in protic and aprotic solvents of low and high polarity are ascribed to a combination of polarity effects, intramolecular charge transfer (ICT) processes, and hydrogen bonding. Moreover, the potential of GQDs for the optical sensing of trace amount of water was assessed. The results of our systematic spectroscopic study will promote the rational design of GQDs and shed more light on the FL mechanism of carbon based fluorescent nanomaterials.
KW - Graphene quantum dots
KW - Solvent polarity
KW - solvent-induced changes
KW - Charge transfer
PY - 2022
DO - https://doi.org/10.1007/s12274-022-4752-1
SN - 1998-0124
SP - 1
EP - 8
PB - Springer
AN - OPUS4-56030
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Srivastava, Priyanka
A1 - Fürstenwerth, Paul Christian
A1 - Witte, J. F.
A1 - Resch-Genger, Ute
T1 - Synthesis and spectroscopic characterization of a fluorescent phenanthrene-rhodamine dyad for ratiometric measurements of acid pH values
N2 - We present the rational design, synthesis and spectroscopic characterization of a novel dual excitation, three color emitting, pH-responsive fluorescent probe consisting of two phenanthrene and one rhodamine B units linked by click chemistry. The rhodamine moiety, excitable at λEx = 315 nm and at λEx = 560 nm in its ring-opened form, provides the pH-responsive fluorophore, while the pH-insensitive phenanthrene, excited at λEx = 315 nm, serves as inert internal reference, The presence of two phenanthrene moieties enables a blue monomer and a blueish green excimer emission at 351 nm and 500 nm, respectively. Opening of the rhodamine B spirolactam ring at an acidic pH below 5.0 (pKa = 2.59 ± 0.04) switches on its emission at 580 nm. Simultaneously, the phenanthrene excimer emission decreases caused by a change in orientation of the phenanthrene units, while the monomer emission is barely affected. This sensor design enables ratiometric measurements in the low acidic pH range utilizing the intensity ratios of the rhodamine B and phenanthrene excimer emission at 580 nm and 500 nm. Alternatively, also the intensity ratios of the rhodamine B and the phenanthrene monomer emission could be exploited or the sum of the phenanthrene monomer and excimer fluorescence. To the best of our knowledge, this is the first report of ratiometric sensing utilizing such a versatile type of tricolor emissive dyad probe bearing phenanthrene moieties and showing phenanthrene monomer and excimer emission.
KW - Fluorescence
KW - Optical probe
KW - Sensor
KW - Dye
KW - Rhodamine
KW - Synthesis
KW - Photophysics
KW - PH
KW - Quantum yield
KW - Quality assurance
KW - Mechanism
KW - Chemodosimeter
KW - Phenanthrene
KW - Ratiometric
KW - Dyad
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-530554
DO - https://doi.org/10.1039/d1nj01573g
SN - 1144-0546
VL - 45
IS - 31
SP - 13755
EP - 13762
PB - Royal Society of Chemistry
AN - OPUS4-53055
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Matiushkina, Anna
T1 - Quantification of Hydrophilic Surface Ligands on Nanoparticles
N2 - The rapid development of nanotechnology is driven by a wide range of possible applications of nanoparticles (NPs) depending on their functions and composition, for example, in biomedicine, energy harvesting, and optoelectronics. Due to the large surface-to-volume ratio of nanoparticles, their properties and function are often highly dependent on surface chemistry, which also determines their stability and interaction with the environment. To ensure the successful advancement of nanomaterials in biomedical applications as well as in material sciences, it is hence crucial to develop reliable methods to control and quantify ligand molecules and functional groups on the NP surface for different NP processing steps including ligand exchange and the subsequent functionalization with, e.g., antifouling agents and recognition moieties. These methods must then be validated and eventually standardized. This also calls for suitable reference materials with known surface chemistries or functionalities.
Methods for determining and quantifying surface functional groups and NP capping ligands include quantitative nuclear magnetic resonance (qNMR) techniques, thermogravimetric analysis (TGA), mass spectrometric (MS) methods, high-performance liquid chromatography (HPLC), and optical assays with photometric and/or fluorometric readout.[1] In the focus of this study on ligand exchange and quantification are differently sized iron oxide nanoparticles (IONPs), already used in biomedicine with applications as magnetic resonance imaging (MRI) contrast agents or for magnetic hyperthermia. IONPs can be prepared by a high temperature synthesis in nonpolar solvents, resulting in a superior monodispersity and crystallinity compared to particles prepared by aqueous synthesis methods. Such IONPs bear, however, hydrophobic surface ligands, that need to be exchanged for hydrophilic molecules to ensure water dispersibility required for biomedical applications. For these applications, a complete removal of potentially toxic surface ligands remaining from IONP synthesis is crucial. Here, we will present the synthesis of differently sized spherical IONPs capped with hydrophobic oleic acid molecules and an in-depth study of the ligand exchange to hydrophilic molecules such as citrate. We assessed the size, size distribution, and colloidal stability of the IONPs utilizing transmission electron microscopy (TEM), dynamic light scattering (DLS), and Zeta potential measurements before and after ligand exchange. In addition, several approaches to ligand quantification have been explored involving a variety of analytical tools. Our ultimate goal is here to identify the optimal methods for ligand analysis and to develop schemes for method validation, via the comparison of analytical techniques relying on different principles of signal generation (method cross-validation).
T2 - E-MRS 2024 SPRING MEETING
CY - Strasbourg, France
DA - 27.05.2024
KW - Nano
KW - Particle
KW - Iron oxide
KW - Ligand
KW - Quantification
KW - Advanced material
KW - Surface analysis
KW - Functional group
PY - 2024
AN - OPUS4-62296
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zou, Q.
A1 - Marcelot, C.
A1 - Ratel-Ramond, N.
A1 - Yi, X.
A1 - Roblin, P.
A1 - Frenzel, Florian
A1 - Resch-Genger, Ute
A1 - Eftekhari, A.
A1 - Bouchet, A.
A1 - Coudret, C.
A1 - Verelst, M.
A1 - Chen, X.
A1 - Mauricot, R.
A1 - Roux, C.
T1 - Heterogeneous Oxysulfide@Fluoride Core/ Shell Nanocrystals for Upconversion-Based Nanothermometry
N2 - Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs) often suffer from weak luminescence, especially when their sizes are ultrasmall (less than 10 nm). Enhancing the upconversion luminescence (UCL) efficiency of ultrasmall UCNPs has remained a challenge that must be undertaken if any practical applications are to be envisaged. Herein, we present a Ln3+-doped oxysulfide@fluoride core/shell heterostructure which shows efficient UCL properties under 980nm excitation and good stability in solution. Through epitaxial heterogeneous growth, a ∼4 nm optically inert β-NaYF4 shell was coated onto ∼5 nm ultrasmall Gd2O2S:20%Yb,1%Tm. These Gd2O2S:20%Yb,1%Tm@NaYF4 core/shell UCNPs exhibit a more than 800-fold increase in UCL intensity compared to the unprotected core, a 180-fold increase in luminescence decay time of the 3H4 → 3H6 Tm3+ transition from 5 to 900 μs, and an upconversion quantum yield (UCQY) of 0.76% at an excitation power density of 155 W/cm2. Likewise, Gd2O2S:20%Yb,2%Er@NaYF4 core/shell UCNPs show a nearly 5000-fold
increase of their UCL intensity compared to the Gd2O2S:20%Yb,2%Er core and a maximum UCQY of 0.61%. In the Yb/Er core−shell UCNP system, the observed variation of luminescence intensity ratio seems to originate from a change in lattice strain as the temperature is elevated. For nanothermometry applications, the thermal sensitivities based on thermally coupled levels are estimated for both Yb/Tm and Yb/Er doped Gd2O2S@NaYF4 core/shell UCNPs.
KW - Upconversion nanoparticle
KW - Nanosensor
KW - Lanthanide
KW - Surface coating
KW - Quantum yield
KW - Photophysic
PY - 2022
DO - https://doi.org/10.1021/acsnano.2c02423
SN - 1936-0851
SP - 1
EP - 11
PB - ACS Publications
AN - OPUS4-55440
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Tavernaro, Isabella
A1 - Simon, Fabian
A1 - Gehrenkemper, Lennart
A1 - Tobias, Charlie
A1 - Resch-Genger, Ute
A1 - Meermann, Björn
T1 - Quantification of the amount of surface groups of aminated silica nano- and microparticles utilizing a fluorine tag and HR-CS-GFMAS
N2 - The performance, bioavailability, and safe use of engineered nanomaterials (NMs) depends not only on properties such as size, shape, and surface area, but largely on surface chemistry. While many sizing methods have been established, there is still a lack of validated screening methods for determining NM surface functional groups (FGs). In this context, we present a fast and simple method for FG quantification using high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) and assess its applicability for the surface analysis of representatively chosen aminated silica nanoparticles (NPs) and microparticles (MPs) in conjunction with amino FG labeling with a fluorine tag. For this proof-of-concept study, first surface amino FG screening of the silica NPs and MPs was done with a potentiometric back titration method, providing the total amount of protonatable surface FGs, and two optical assays relying on reporter dyes with sizes and spatial requirements, i.e., surface binding areas smaller or larger than that of the fluorine tag to estimate the maximum and reporter-accessible number of amino FGs. Subsequently, the surface amino FGs were labeled with the fluorine tag 4-(trifluoromethyl)benzoic acid (TFMB) and the amount of fluorine originating from the bound TFMB molecules was quantified by HR-CS-GFMAS in two common organic solvents, i.e., dimethyl sulfoxide (DMSO) or ethanol (EtOH) to assess possible interferences from organic matrices. Our study revealed limits of detection (LODs) and quantification (LOQs) for fluorine of 1.0 µg/L and 3.5 µg/L in EtOH and 1.5 µg/L and 5.0 µg/L in DMSO, respectively. Overall, a quick and simple method for analyzing surface FGs on NPs and MPs was presented utilizing broadly available fluorine tags and HR-CS-GFMAS for fluorine quantification, which can be applied, e.g., for homogeneity, stability, and aging studies of surface-modified particles. This could contribute to ease the understanding of property-safety relationships for surface-functionalized NMs.
KW - Fluorine Analysis
KW - Nano- and microparticles
KW - Surface group quantification
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-641965
DO - https://doi.org/10.1007/s00216-025-06107-4
SN - 1618-2642
SP - 1
EP - 11
PB - Springer Science and Business Media LLC
CY - Berlin ; Heidelberg
AN - OPUS4-64196
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Oskoei, Párástu
T1 - Effects of upconversion nanoparticles with a thermo-responsive nanovalve loaded with doxorubicin in melanoma cells
N2 - Melanoma skin cancer has an increasingly higher incidence , and w hen detected in advanced stages, tumour eradication is often incomplete, contributing to poor prognosis with conventional treatments. Upconversion nanoparticles (UCNPs) have unique properties, such as excitability under near infrared (NIR) excitation light, which confers a relatively high penetration depth in tissue that allow their effective use in several biomedical applications Mesoporous silica nanoparticles (MSN) with nanovalves or derived coatings have widely been used for triggered and targeted drug delivery in the past. Anticancer drugs can be loaded into the pores of MSN, enabling controlled drug release. In this work, UCNPs were coated with a mesoporous silica shell yielding UCNP@MSN core shell nanoparticles which were equipped with thermoresponsive retro Diels Alder nanovalves and then loaded with DOX , a chemotherapeutic agent for melanoma treatmen t (UCNP@MSN DOX) Subsequent DOX release from this drug delivery system was triggered by 980 nm NIR light. Melanoma cells exposed to UCNP@MSN DOX or the NIR laser exhibited no change in ROS production , while the combination of both induced an increase in ROS production. This combination of conditions also induced changes on apoptosis and necrosis levels. These findings underscore the potential use of UCNP @MSN drug delivery systems with thermoresponsive caps as effective drug delivery platforms for melanoma therapy.
T2 - VII iBiMED Symposium
CY - Aveiro, Portugal
DA - 23.05.2025
KW - Nano
KW - Particle
KW - Lanthanide
KW - Upconversion
KW - Surface chemistry
KW - Mesoporous silica
KW - Doxorubicin
KW - Nanomedicine
KW - Triggered release
KW - pH
KW - Cellular uptake
KW - Toxicity
KW - Folate
KW - Ligand
PY - 2025
AN - OPUS4-64373
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 - Wasternack, J.
A1 - Schröder, H. V.
A1 - Witte, J. F.
A1 - Ilisson, M.
A1 - Hupatz, H.
A1 - Hille, J. F.
A1 - Gaedke, M.
A1 - Valkonen, A. M.
A1 - Sobottka, S.
A1 - Krappe, A.
A1 - Schubert, M.
A1 - Paulus, B.
A1 - Rissanen, K.
A1 - Sarkar, B.
A1 - Eigler, S.
A1 - Resch-Genger, Ute
A1 - Schalley, C. A.
T1 - Switchable protection and exposure of a sensitive squaraine dye within a redox active rotaxane
N2 - In nature,molecular environments in proteins can sterically protect and stabilize reactive species such as organic radicals through non-covalent interactions.Here, wereport a near-infrared fluorescent rotaxane in which the stabilization of a chemically labile squaraine fluorophore by the coordination of a tetralactam macrocycle can be controlled chemically and electrochemically. The rotaxane can be switched between two co-conformations inwhich thewheel either stabilizes or exposes the fluorophore. Coordination by the wheel affects the squaraine’s stability across four redox states and renders the radical anion significantly more stable—by a factor of 6.7—than without protection by a mechanically bonded wheel. Furthermore, the fluorescence properties can be tuned by the redox reactions in a stepwise manner. Mechanically interlockedmolecules provide an excellent scaffold to stabilize and selectively expose reactive species in a co-conformational switching process controlled by external stimuli.
KW - Fluorescence
KW - Dye
KW - Sensor
KW - Quantum yield
KW - Spectroscopy
KW - Photophysics
KW - Synthesis
KW - Squaraine
KW - Switch
KW - Redox-active
KW - Rotaxane
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614959
DO - https://doi.org/10.1038/s42004-024-01312-1
VL - 7
SP - 1
EP - 11
AN - OPUS4-61495
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ramirez, Alejandra
A1 - Pauli, Jutta
A1 - Crasselt, C.
A1 - Simon, S.
A1 - Schmidt, W.
A1 - Resch-Genger, Ute
T1 - The effect of a polycarboxylate ether on C3A / CaSO4.2H2O passivation monitored by optical spectroscopy
N2 - Polycarboxylate ethers (PCEs) are widely used in construction, but the exact nature of their interaction with cement is still debated. Aiming at a better understanding of the role of tricalcium Aluminate (C3A) in cement hydration, we assessed the potential of optical spectroscopy in combination with a water-soluble fluorescent organic reporter dye (S0586) to monitor the early hydration of C3A in the presence of 26 wt% CaSO4.2H2O (C3A26G-S) with and without PCE. As optical methods, steady-state fluorescence and diffuse reflectance (UV–VisDR) spectroscopy were employed. Phase characterization and particle size distribution were performed with in-situ X-ray diffraction (in-situ XRD) and dynamic light scattering (DLS). Our results show that fluorescence and UV–VisDR spectroscopy can be used to monitor the formation of metastable phases by the disaggregation of the dye S0586 in a cement paste as well as changes in ettringite formation. Addition of PCE slowed down the disaggregation of the dye as reflected by the corresponding changes of the dyes absorption and fluorescence. This prolonged induction period is a well-known side effect of PCEs and agrees with previous reported calorimetric studies and the Inhibition of gypsum dissolution observed by in-situ XRD. This demonstrates that fluorescence and UV–VisDR spectroscopy together with a suitable optical probe can provide deeper insights into the influence of PCE on C3A-gypsum hydration which could be e.g., utilized as screening method for comparing the influences
of different types of PCEs.
KW - Fluorescence
KW - Cement
KW - Nano
KW - Particle
KW - Optical spectroscopy
KW - PCE
KW - XRD
KW - Calorimetry
KW - Monitoring
KW - Diffuse
KW - Reflection
KW - Phase
KW - Dye
KW - Optical probe
KW - Cyanine
KW - Sensor
KW - Method
KW - Analysis
PY - 2020
DO - https://doi.org/10.1016/j.conbuildmat.2020.121856
VL - 270
SP - 121856
PB - Elsevier Ltd.
AN - OPUS4-52118
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Wegner, Karl David
A1 - Walter, J.
T1 - Size-resolved emission properties of core/shell CdSe/CdS quantum dots via multiwavelength emission analytical ultracentrifugation
N2 - Colloids provide manifold opportunities for targeted product design due to their tunable properties with respect to size, shape, composition, surface, and spectral characteristics. However, the determination of structure-property relationships is quite challenging as most particulate samples exhibit polydispersity of their disperse properties. Analytical ultracentrifugation (AUC) is a fractionating technique and highly accurate method for the multidimensional analysis of nanoparticles as it permits the differentiation of spectral information linked to hydro- and thermodynamic properties of the particles.
So far, characterization capabilities for fluorescent nanoparticles by AUC were limited, as the formerly commercially available fluorescence detector could not provide any spectral information. Using a multiwavelength emission detector developed in our group, it is possible to extract spectra of fluorescent particles and biomolecules alongside their sedimentation and diffusion coefficients within a single centrifugation experiment.
In our contribution, we will highlight that even narrowly distributed core/shell CdSe/CdS quantum dots still show size- and structure-dependent shifts of their fluorescence spectra, which can be resolved with our AUC system in an ensemble measurement. Thereby, we can link spectral changes of only a few nanometers to particle sizes retrieved with Angstrom size resolution. Single-particle measurements not only supported the results obtained with the AUC system but also provided deeper insights into the photophysical processes of individual QDs, clearly demonstrating the complementary nature of the techniques used. With our novel multiwavelength emission detector and the established extinction-based detector for AUC, a comprehensive platform for the holistic characterization of fluorescent colloids is now available.
T2 - 26th International Analytical Ultracentrifugation Symposium
CY - Bad Staffelstein, Germany
DA - 24.07.2024
KW - Quantum dots
KW - Analytical ultracentrifugation
KW - Reference materials
KW - Calibrated fluorescence measurements
KW - Size-resolved emission
PY - 2024
AN - OPUS4-60814
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 - Matiushkina, Anna
T1 - Quantification of Citrate Ligands on Nanoparticle Surfaces
N2 - To ensure the successful advancement of nanomaterials (NM) in applications and their safe use, it is crucial to develop reliable methods to control and quantify ligands and functional groups (FG) on the nanoparticle (NP) surface as surface chemistry largely determines the interactions of NPs with their surroundings. Many analytical methods can be used for this purpose. However, their applicability strongly depends on the type of NM and ligand(s) and most of them require challenging protocols for sample preparation, i.e., the removal of the NPs or their dissolution, which can influence the accuracy of the measurements. While some methods allow the precise quantification of specific ligands such as quantitative nuclear magnetic resonance (qNMR), others provide only semi-quantitative results like Fourier Transform infrared spectroscopy (FTIR) or target more general analyte groups like thermogravimetric analysis (TGA) detecting mass losses (total organic content) or conductometry (e.g., (de)protonable FGs such as carboxyl or amine groups). [1] The calculation of the coverage of the NP surface with ligands, additionally requires knowledge of their total surface area, which can be obtained, e.g., from a precise characterization of NP size and concentration.
Citrate is one of the most frequently utilized surface ligand for stabilizing metal, metal oxide, and lanthanide-based upconversion NPs in hydrophilic environments. However, its quantification on NP surfaces has rarely been addressed although it is a frequent analyte in medical or food analysis. In this study we compare several methods for quantifying citrate as capping ligands of iron oxide NPs (IONPs), exemplarily chosen because of their broad applications in the life science. [2] The size of the IONPs was characterized by electron microscopy (EM) and dynamic light scattering (DLS), while their concentration was determined by quantifying iron ions after acidic particle dissolution using a colorimetric assay and inductively coupled plasma optical emission spectroscopy (ICP-OES). The simplest approach for citrate quantification, direct photometric UV-detection after acidic digestion of the IONPs, yielded only reasonable results when combined with reversed phase high-performance liquid chromatography (HPLC). These results were cross validated with qNMR that required the development of a reliable sample preparation protocol addressing not only particle dissolution in deuterated solvents but also the removal of the paramagnetic iron ions interfering with NMR measurements. Comparison with results from TGA gives insight into the sensitivity and specificity of these methods and their potential for quantifying surface ligands on NPs.
T2 - Anakon 2025
CY - Leipzig, Germany
DA - 10.03.2025
KW - Advanced material
KW - Functional group
KW - Iron oxide
KW - Ligand
KW - Nano
KW - Particle
KW - Quantification
KW - Surface analysis
PY - 2025
AN - OPUS4-64861
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Heuser, Lina
T1 - Silver in low-melting alkali zinc borate glasses
N2 - Ein aktuelles Forschungsziel ist die Substitution von Bleioxid in niedrig schmelzenden Gläsern z.B. zur Anwendung in Silber-Metallisationspasten. Im Fokus steht hier die Untersuchung der Silberdiffusion in Alkali-Zink-Boratgläsern (X2O-ZnO-B2O3, X = Li, Na, K, Rb). Zudem wird der Redoxzustand des Silbers (Ag) und somit die Art der diffundierenden Silberspezies bestimmt. Hierzu wurde eine metallische Silberschicht mittels Sputterns auf Glaswürfel aufgebracht. Die Wärmebehandlung erfolgte nahe der Glasübergangstemperatur bei 470 °C über 2 h unter Luft und Stickstoffatmosphäre. Die Schichtdicke der Silberbeschichtung betrug 1.8 µm nach der Wärmebehandlung, gemessen mittels Weißlicht-Interferometer.
Die Silberdiffusionsprofile wurden mittels Sekundär-Neutral-Teilchen-Massenspektrometrie gemessen. Die Diffusionskoeffizienten des Silbers liegen in der Größenordnung von ~10-14 cm2/s und unterscheiden sich nur gering in Abhängigkeit des Alkali-Ions im Glas.
Mittels Fluoreszenz-Spektroskopie ließen sich gelöste Ag+-Ionen und [Agm]n+-Cluster nach der Wärmebehandlung unterscheiden.
Zusätzlich konnten ausgeschiedene metallische Silber-Partikel im Natrium-enthaltenden Glas mittels Transmissionselektronenmikroskopie beobachtet werden. Diese haben einen mittleren Durchmesser von ~6 nm.
N2 - Substitution of lead oxide in low-melting glasses, e.g., for application in silver metallization pastes, is a current research goal. This work is focused on the investigation of silver diffusion in alkali zinc borate glasses (X2O-ZnO-B2O3, X = Li, Na, K, Rb). In addition, the redox state of silver (Ag) and thus the type of diffusing silver species were studied. For this purpose, a metallic silver coating was applied on glass cubes by means of sputtering. Heat treatment of the samples was performed close to the glass transition temperatures at 470 °C for 2 h under air and nitrogen atmosphere. Coating thickness was 1.8 µm after heat treatment, measured by a white light interferometer.
Silver diffusion profiles were measured by means of secondary neutral mass spectrometry. The silver diffusion coefficients are in the range of ~10-14 cm2/s and indicate no significant differences depending on the type of alkali ions in the glass. Dissolved Ag+-ions and [Agm]n+-clusters in the glasses were differentiated using fluorescence spectroscopy.
Precipitated metallic silver particles in the sodium containing glass were observed by means of transmission electron microcopy. Their mean particle diameter was ~6 nm.
T2 - Living Glass Surfaces XI - Year of Glass
CY - Ilmenau, Germany
DA - 14.09.2022
KW - Alkali zinc borate glasses
KW - Silver diffusion
KW - Transmission electron microscopy
KW - Fluorescence spectroscopy
KW - Silver cluster
PY - 2022
AN - OPUS4-55736
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 - CONF
A1 - Andresen, Elina
T1 - Upconversion for security tags and future applications
N2 - NIR-excitable lanthanide nanocrystals (LnNC) show multi-color emission pattern composed of a multitude of narrow bands of varying intensity in the ultraviolet, visible, near-infrared, and short-wave infrared detectable with miniaturized optical instruments and simple color (RGB) cameras in complex environments. This makes these chemically inert luminescent materials ideal candidates for anticounterfeiting and authentication applications as well as for modules in optical sensors in which the LnNCs can be used as nanolamps in combination with analyte-sensitive fluorophores or the temperature sensitivity of defined emission bands can be utilized.
Therefore, we are building up and exploring a platform of LnNC with application-specifically tuned size, composition, and surface chemistry.
T2 - SHIFT 2022
CY - La Laguna, Tenerife, Spain
DA - 10.10.2022
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
PY - 2022
AN - OPUS4-56229
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Scholtz, Lena
T1 - Luminescent, nanoparticle-loaded polymer microparticles - comparing synthesis routes
N2 - Our comparison showed that the route used for the synthesis of luminescent, NP-loaded PSMPs can play a significant role for the luminescence properties, as well as the number of accessible SFGs, and hence subsequent functionalization. This should be considered for future applications.
T2 - Bunsen-Tagung 2023
CY - Berlin, Germany
DA - 05.06.2023
KW - Fluorescence
KW - Polymerization
KW - Microbeads
KW - Quantum dots
KW - Comparison
PY - 2023
AN - OPUS4-57628
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 - JOUR
A1 - Daly, H.C
A1 - Matikonda, S.S
A1 - Steffens, H.C
A1 - Rühle, Bastian
A1 - Resch-Genger, Ute
A1 - Ivanic, J.
A1 - Schermann, M.J
T1 - Daly_Photochem Photobiol 2021_Ketone Incorporation Extends the Emission Properties of the Xanthene Scaffold
N2 - Imaging in the shortwave-infrared region (SWIR, λ = 1000–2500 nm) has the potential to enable deep tissue imaging with high resolution. Critical to the development of these Methods is the identification of low molecular weight, biologically compatible fluorescent probes that emit beyond 1000 nm.
Exchanging the bridging oxygen atom on the xanthene scaffold (C10’ position) with electron withdrawing groups has been shown to lead to significant redshifts in absorbance and emission. Guided by quantum chemistry computational modeling studies, we investigated the installation of a Ketone bridge at the C10’ position. This simple modification extends the absorbance maxima to 860 nm and the emission beyond 1000 nm, albeit with reduced photon output. Overall, These studies demonstrate that broadly applied xanthene dyes can be extended into the SWIR range.
KW - Flourescence
KW - Optical probe
KW - Dye
KW - Photophysics
KW - Quantum yield
KW - Mechanism
KW - NIR
KW - SWIR
KW - Imaging
KW - Reliability
KW - Method
KW - Quality assurance
PY - 2021
DO - https://doi.org/10.1111/php.13544
SN - 1751-1097
VL - 98
IS - 2
SP - 325
EP - 333
PB - Wiley Online Library
AN - OPUS4-54080
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Wang, Cui
A1 - Reichenauer, F.
A1 - Kitzmann, W.R.
A1 - Kerzig, Ch.
A1 - Heintze, K.
A1 - Resch-Genger, Ute
T1 - Efficient Triplet-Triplet Annihilation Upconversion Sensitized by a Chromium(III) Complex via an Underexplored Energy Transfer Mechanism
N2 - Sensitized triplet-triplet annihilation upconversion (sTTA-UC) mainly relies on precious metal complexes thanks to their high intersystem crossing (ISC) efficiencies, excited state energies, and lifetimes, while complexes of abundant first-row transition metals were only rarely utilized and with often moderate UC quantum yields. [Cr(bpmp)2]3+ (bpmp = 2,6-bis(2-pyridylmethyl)pyridine) containing earth-abundant chromium possesses an absorption band suitable for green light excitation, a doublet excited state energy matching the triplet energy of 9,10-diphenyl anthracene (DPA), a close to millisecond excited state lifetime, and high photostability. Combined ISC and doublet-triplet energy transfer from excited [Cr(bpmp)2]3+ to DPA gives 3DPA with close-to-unity quantum yield. TTA of 3DPA furnishes greento-blue UC with a quantum yield of 12.0 % (close to the theoretical maximum). Sterically less-hindered anthracenes undergo a [4+4] cycloaddition with [Cr(bpmp)2]3+ and green light.
KW - Fluorescence
KW - Optical probe
KW - Sensor
KW - ph
KW - Quantum yield
KW - Quality assurance
KW - Cr(III)
KW - Lifetime
KW - Ligand
KW - Theory
KW - TTA-UC
KW - Energy transfer
KW - Upconversion
KW - Mechanism
KW - Anthracene
KW - Photochemistry
KW - DFT
KW - Cycloaddition
KW - Transient absorbtion spectroscopy
PY - 2022
DO - https://doi.org/10.1002/anie.202202238
VL - 61
IS - 24
SP - 1
EP - 8
PB - Wiley online library
AN - OPUS4-54604
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
A1 - Würth, Christian
A1 - Frenzel, Florian
A1 - Weigert, Florian
A1 - Andresen, Elina
A1 - Grauel, Bettina
A1 - Wegner, Karl David
T1 - Semiconductor (SCNC) & Upconversion Nanocrystals (UCNC) – Optical Properties, Applications & Challenges
N2 - Inorganic nanocrystals with linear and nonlinear luminescence in the ultraviolet, visible, near infrared and shortwave infrared like semiconductor quantum dots and spectrally shifting lanthanide-based nanophosphors have meanwhile found applications in the life and material sciences ranging from optical reporters for bioimaging and sensing over security barcodes to solid state lighting and photovoltaics. These nanomaterials commonly have increasingly sophisticated core/shell particle architectures with shells of different chemical composition and thickness to minimize radiationless deactivation at the particle surface that is usually the main energy loss mechanism [1]. For lanthanide-based spectral shifters, particularly for very small nanoparticles, also surface coatings are needed which protect near-surface lanthanide ions from luminescence quenching by high energy vibrators like O-H groups and prevent the disintegration of these nanoparticles under high dilution conditions. [2,3,4]. The identification of optimum particle structures requires quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield [5,6], ideally flanked by single particle studies to assess spectroscopic inhomogeneities on a particle-to-particle level for typical preparation methods [7], Moreover, in the case of upconversion nanoparticles with a multi-photonic and hence, excitation power density (P)-dependent luminescence, quantitative luminescence studies over a broad P range are required to identify particle architectures that are best suited for applications in fluorescence assays up to fluorescence microscopy. Here, we present methods to quantify the photoluminescence of these different types of emitters in the vis/NIR/SWIR and as function of Pand demonstrate the importance of such measurements for a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different size and particle architecture in different environments.
T2 - 27th Annual Meeting of the Slovenian Chemical Society
CY - Portoroz-Portorose, Slovenia
DA - 21.09.2021
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Surface chemistry
KW - Single particle
KW - Brightness
KW - NIR
KW - Synthesis
KW - Semiconductur
KW - Quantum dot
KW - Nanocrystal
KW - SWIR
PY - 2021
AN - OPUS4-53723
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
T1 - Tumore abbilden, Biomarker nachweisen, Messungen standardisieren
N2 - Zu den am häufigsten eingesetzten Analysemethoden in den Lebens- und Materialwissenschaften gehören Lumineszenzmethoden. Sie nutzen die Emission von Licht nach Absorption von Energie, um Signale zu erzeugen, und umfassen spektroskopische und mikroskopische Messungen.
KW - Quality assurance
KW - Sensor
KW - Imaging
KW - Reference material
KW - Nano
KW - Particle
KW - Nanomaterial
KW - Upconversion
KW - Nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Excitation
KW - Power density
KW - Single particle
KW - Brightness
KW - NIR
PY - 2021
SP - 75
EP - 77
PB - GDCH
AN - OPUS4-53526
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Engineered Nanomaterials- Novel Approaches for Risk Assessment and Safe-by-Design
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 not only for standardized test procedures1,2 and for efficient approaches to screen the potential genotoxicity of these materials, but also for standardized and validated methods for surface analysis.
4,5 The analysis and quantification of surface chemistry is hence in the focus of an increasing number of standardization organizations and interlaboratory comparisons with different analytical methods are being done.5 For the monitoring of nanomaterial synthesis and the fast assessment of the number of functional groups such as carboxyl and amino functionalities, which are very commonly used functionalities in the life sciences, simple and validated methods are needed that can be performed with common laboratory instrumentation. 5,6 Here we provide a brief overview of the ongoing research in division Biophotonics employing quantitative NMR (qNMR), conductometry, and colorimetric and fluorometric optical assays for the determination of the total and the accessible number of carboxyl and amino groups on differently sized polymer and silica nano- and microparticles.5-7
T2 - Workshop NanoRiskSD project
CY - Berlin, Germany
DA - 09.06.2022
KW - Nanoparticle
KW - Surface analysis
KW - Standardization
KW - Quality assurance
KW - Validation
KW - qNMR
KW - Silica
KW - Polymer
KW - Fluorescence
KW - Assay
KW - Conductometry
KW - Method comparison
KW - Analytical sciences
PY - 2022
AN - OPUS4-54999
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 - Applications of photoluminescence lifetime measurements in the life and material sciences
N2 - Bioanalytical, diagnostic, and security applications require the fast and sensitive determination of a steadily increasing number of analytes or events in parallel in a broad variety of detection formats and increased sensitivities. This – flanked by recent technical advancements and the availability of simple to use, commercial time-resolved photoluminescence measuring devices at reasonable costs - calls for the exploitation of the species- and environment-specific photoluminescence parameter luminescence lifetime. In this context, time-resolved photoluminescence measurements of different classes of molecular and nanocrystalline emitter and luminescent particles in different time windows are presented and examples for applications such as lifetime multiplexing and barcoding in conjunction with fluorescence lifetime imaging microscopy (FLIM) and flow cytometry are given.
T2 - Eingeladener Vortrag bei dem Workshop von Picoquant „Time-resolved fluorescence“
CY - Berlin, Germany
DA - 17.11.2022
KW - Dye
KW - Quantum dot
KW - Upconversion nanocrystal
KW - Luminescence
KW - Quantitative spectroscopy
KW - Photophysics
KW - Quality assurance
KW - Nano
KW - Particle
KW - Quantum yield
KW - Lifetime
KW - Standard
KW - Reference material
PY - 2022
AN - OPUS4-57048
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 - 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 - CONF
A1 - Andresen, Elina
T1 - Lanthanide based multi element nanoparticles: a versatile platform for surface chemistry analysis and potential reference materials
N2 - The use of engineered nanoparticles of different size, shape, and composition is continuously increasing in the life and materials sciences. This calls for methods and reference materials enabling the reliable and accurate determination of nanoparticle size, particle size distribution, shape, number concentration, degree of aggregation and agglomeration in different environments as well as for nanoparticle dispersibility and stability.
We are currently building up and exploring a platform of lanthanide-based nanocrystals (LnNCs) with application-specifically tuned size, shape, composition, architecture, optical properties, and surface chemistry for emerging applications in life sciences. As a prerequisite for the broad applicability of these nanomaterials, we assess simple, robust, and easily upscaleable synthesis protocols for LnNCs with defined morphologies and tunable optical properties, and the short-term and long-term stability of LnNCs with selected surface coatings in aqueous environments under different application-relevant conditions.
T2 - Anakon 2025
CY - Leipzig, Germany
DA - 10.03.2025
KW - Nano
KW - Particle
KW - Method
KW - Lanthanide
KW - Synthesis
KW - Upconversion
KW - Ligand
KW - Quality assurance
KW - Particle number concentration
KW - Reference material
KW - Surface chemistry
PY - 2025
AN - OPUS4-62768
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Tavernaro, Isabella
T1 - How to Quantify the Total and Accessible Number of Functional Groups and Ligands on Nanomaterials Using a Multimodal Approach – A Bilateral Comparison
N2 - Surface-functionalized organic and inorganic engineered nanomaterials (NM) have gained increasing interest in various fields of application such as nanomedicine, bioimaging and sensing, or as additives in food and consumer products. The performance and safe use of these NM in such applications depend not only on their composition, primary particle size, and morphology, but also on surface chemistry, which controls surface charge, colloidal stability, biocompatibility, and toxicity.[1] NM surface chemistry is mainly determined by the total number of surface functional groups (FG) and the number of FG accessible for subsequent functionalization with ligands or biomolecules. Thus, methods for FG quantification are not only important tools for the control of NM production processes, but can also foster the sustainable development of functional and safe(r) NM. In addition, this need underlines the importance of validated and standardized analytical methods that provide accurate information on application-relevant physicochemical properties with known uncertainties, flanked by suitable quality control samples and reference materials. Aiming at the development of simple, versatile, and multimodal tools for the quantification of common bioanalytically relevant FG, we investigated and compared various analytical methods commonly used for FG quantification.[2,3] The potential of multimodal approaches for FG quantification was recently demonstrated in a bilateral comparison of the surface analysis of commercially available aminated silica nanoparticles (SiO2-NP).[3] These results demonstrate not only an influence of the size and synthesis methods on the number of FG but also on NM performance. This concept is currently explored in a second bilateral comparison of quantitative nuclear magnetic resonance (qNMR) measurements and optical assays for differently sized commercial and in-house synthesized SiO2-NP with varying amounts of amine functionalities, utilizing further optimized protocols for sample preparation, qNMR measurements, and data evaluation. This strategy can contribute to establishing multi-method characterization strategies for NMs and can provide a more detailed picture of structure-properties relationships for different types of functional NM.
T2 - E-MRS Spring Meeting 2024 & ALTECH 2024
CY - Strasbourg, France
DA - 27.05.2024
KW - Quantification
KW - Nano
KW - Particle
KW - Quality assurance
KW - Interlaboratory comparison
KW - Method
KW - Uncertainty
KW - Reference material
KW - Sensors
KW - Synthesis
KW - Silica
KW - Surface analysis
PY - 2024
AN - OPUS4-62161
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 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 effects 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. 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 (CRM) BAM-F001 – BAM-F005, has been extended to the NIR range by including two new fluorescence standards currently under certification.
T2 - 17th conference on 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 - OPUS4-56441
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zhao, J.
A1 - Hu, Y.
A1 - wei Lin, S.
A1 - Resch-Genger, Ute
A1 - Zhang, R.
A1 - Wen, J.
A1 - Kong, X.
A1 - Qin, A.
A1 - Ou, J.
T1 - Enhanced luminescence intensity of near-infraredsensitized sensitized upconversion nanoparticles via Ca²+ doping for a nitric oxide release platform
N2 - Light-induced NO release based on exogenous NO donors has attracted substantial attention in clinical applications; the induction light source usually converts near-infrared light to blue or ultraviolet light.
However, the low efficiency of near-infrared light-assisted chemical light energy conversion remains a challenge, especially for NaYF4:Yb3+/Tm3+ photoconverting near-infrared light to ultraviolet (UV) and blue light. In this paper, a luminescence-enhanced strategy is reported by doping Ca2+ into NaYF4:Yb3+/Tm3+ and coating it with NaGdF4 through a two-step solvothermal method. Then, UCNPs modified with methyl-b-cyclodextrin (M-b-CD) are loaded on a ruthenium nitrosyl complex [(3)Ru(NO)(Cl)] as nitric oxide release-molecules (NORMs). X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) data demonstrated that Ca2+ was successfully doped into NaYF4:Yb3+/Tm3+ nanoparticles as the core, and a pure hexagonal phase, NaYF4, was obtained from the doping of Ca2+. TEM revealed that the crystallinity was significantly improved after Ca2+ doping, and the core–shell structure was successfully synthesized, with NaGdF4 directionally grown on the NaYF4:Ca/Yb/Tm core. Fluorescence tests showed that, especially in the ultraviolet and blue light excitation wavelength regions, the UC emission intensity of the Ca-doped NaYF4:Yb3+/Tm3+@NaGdF4 core–shell UCNPs increased by 302.95 times vs. NaYF4:Yb3+/Tm3+ UCNPs. Finally, the release of NO was tested by the Griess method. Under 980 nm irradiation, the cell viability distinctly decreased with increasing UCNPs@M-b-CD-NORMs concentration. This study Shows that NORM release of NO is triggered by enhanced up-converted UV and blue light, which can be used for the development of UV photo-sensitive drugs.
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Lifetime
KW - Sensor
KW - Surface chemistry
KW - Single particle
KW - Brightness
KW - NIR
KW - PDT
PY - 2020
DO - https://doi.org/10.1039/d0tb00088d
VL - 8
IS - 30
SP - 6481
EP - 6489
PB - Journal of Materials Chemistry B
AN - OPUS4-51262
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Typical Measurements in Optical Spectroscopy – Absorption Spectroscopy or Photometry
N2 - The basics of absorption spectroscopy (termed also photometry) will be presented with focus on transparent solutions of different molecular and nanocrystalline absorbers and the ultraviolet (UV), visible (vis), and near-infrared (NIR) spectral region. Thereby, also typical sources of uncertainty will be addressed. Subsequently, several examples for typical applications of absorption measurements in the life and material sciences will be briefly shown ranging from aggregation studies and dye labeling densities of biomolecules (dye-to-biomolecule ratios) over optical assays for thiol and protein quantification to the optical determination of the size of semiconductor nanocrystals using size curves.
T2 - pHD Seminar
CY - Online meeting
DA - 03.11.2020
KW - Quantification
KW - Absorption
KW - Dye
KW - Nano particle
KW - Method
KW - Measurement uncertainty
KW - Linearity
PY - 2020
AN - OPUS4-51621
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 - JOUR
A1 - Frenzel, Florian
A1 - Würth, Christian
A1 - Dukhno, O.
A1 - Przybilla, F.
A1 - Wiesholler, L. M.
A1 - Muhr, V.
A1 - Horsch, T.
A1 - Mély, Y.
A1 - Resch-Genger, Ute
T1 - Multiband emission from single β-NaYF4(Yb,Er) nanoparticles at high excitation power densities and comparison to ensemble studies
N2 - Ensemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core–shell β-NaYF4:Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb3+ and 1% or 3% Er3+ performed over a P regime of 6 orders of magnitude reveal an increasing contribution of the emission from high energy Er3+ levels at P > 1 kW/cm2.
This changes the overall emission color from initially green over yellow to white. While initially the green and with increasing P the red emission dominate in ensemble measurements at P < 1 kW/cm2, the increasing population of higher Er3+ energy levels by multiphotonic processes at higher P in single particle studies results in a multitude of emission bands in the ultraviolet/visible/near infrared (UV/vis/NIR) accompanied by a decreased contribution of the red luminescence. Based upon a thorough analysis of the P-dependence of UCL, the emission bands activated at high P were grouped and assigned to 2–3, 3–4, and 4 photonic processes involving energy transfer (ET), excited-state absorption (ESA), cross-relaxation (CR), back energy transfer (BET), and non-radiative relaxation processes (nRP). This underlines the P-tunability of UCNP brightness and color and highlights the potential of P-dependent measurements for mechanistic studies required to manifest the population pathways of the different Er3+ levels.
KW - Nano
KW - Nanomaterial
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Photoluminescence
KW - Quantum yield
KW - Photophysics
KW - Llifetime
KW - Sensor
KW - Excitation power density
KW - Single particle
KW - Brightness
KW - NIR
KW - Mechanism
KW - Color tuning
PY - 2021
DO - https://doi.org/10.1007/s12274-021-3350-y
SN - 1998-0124
VL - 14
IS - 11
SP - 4107
EP - 4115
PB - Nano Research
AN - OPUS4-52364
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 - Luminescence encoding of polymer microbeads with nanocrystals during polymerization
N2 - The Goal & Motivation
- Spherical polymer beads
- Controlled size in the low µm range
- Narrow size distribution
- Homogeneous encoding with molecular and nanoscale luminophores (dyes , QDs, platelets etc.)
- Sufficient fluorescence
- Easy, accessible procedure
T2 - GrK Nanohybrid Conference
CY - Hamburg, Germany
DA - 04.10.2022
KW - Polymerization
KW - Nanocrystals
KW - Fluorescence
KW - Microbeads
PY - 2022
AN - OPUS4-56028
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Billimoria, K.
A1 - Diaz Fernandez, Y. A.
A1 - Andresen, Elina
A1 - Sorzabal-Bellido, I.
A1 - Huelga-Suarez, G.
A1 - Bartczak, D.
A1 - Ortiz de Solórzano, C.
A1 - Resch-Genger, Ute
A1 - Goenaga Infante, H.
T1 - The potential of bioprinting for preparation of nanoparticle-based calibration standards for LA-ICP-ToF-MS quantitative imaging
N2 - This paper discusses the feasibility of a novel strategy based on the combination of bioprinting nano-doping technology and laser ablation-inductively coupled plasma time-of-flight mass spectrometry analysis for the preparation and characterization of gelatin- based multi-element calibration standards suitable for quantitative imaging. To achieve this, lanthanide up-conversion nanoparticles were added to a gelatin matrix to produce the bioprinted calibration standards. The features of this bioprinting approach were com- pared with manual cryosectioning standard preparation, in terms of throughput, between batch repeatability and elemental signal homogeneity at 5 μm spatial resolution. By using bioprinting, the between batch variability for three independent standards of the same concentration of 89 Y (range 0–600 mg/kg) was reduced to 5% compared to up to 27% for cryosectioning. On this basis, the relative standard deviation ( RSD ) obtained between three independent calibration slopes measured within 1 day also reduced from 16% (using cryosectioning ) to 5% (using bioprinting), supporting the use of a single standard preparation replicate for each of the concentrations to achieve good calibration performance using bioprinting. This helped reduce the analysis time by approximately 3-fold. With cryosectioning each standard was prepared and sectioned individually, whereas using bio-printing it was possible to have up to six different standards printed simultaneously, reducing the preparation time from approximately 2 h to under 20 min (by approxi- mately 6-fold). The bio-printed calibration standards were found stable for a period of 2 months when stored at ambient temperature and in the dark.
KW - Environmental analysis
KW - LA-ICP-MS
KW - Lanthanide
KW - Tag
KW - Fluorescence
KW - Nanoparticles
KW - Reference material
KW - Quality assurance
KW - 3D-printing
KW - Synthesis
KW - Production
KW - Multimodal
PY - 2022
DO - https://doi.org/10.1093/mtomcs/mfac088
SN - 1756-591X
VL - 14
IS - 12
SP - 1
EP - 9
PB - Oxford University Press
CY - Oxford
AN - OPUS4-57018
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - 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 - CONF
A1 - Krenzer, Julius
A1 - Mueller, Thomas
T1 - Aroyl-S,N-ketene acetal based bichromophores exhibiting energy transfer and aggregation induced (dual) emission
N2 - A series of aroyl-S,N-ketene acetal based bichromophores is readily synthesized by Buchwald-Hartwig amination and Ullmann reaction in moderate to good yields. The aminated aroyl-S,N-ketene acetals are emissive in the solid state and in the aggregate, but not in solution, thus, they are AIEgens (aggregation induced emission chromogens). Aggregation is induced by fractional alternation of the solvent mixture, here by increasing the water fraction of ethanol/water mixtures. For most derivatives, the emission upon induced aggregation stems solely from the aroyl-S,N-ketene acetal chromophore, regardless whether excitation occurs at the absorption maximum of the triarylamine or the aroyl-S,N-ketene acetal. Therefore, a pronounced energy transfer from the triarylamine donor to the aroyl-S,N-ketene acetal acceptor can be inferred. The color of the emission can be controlled by choosing the para-aroyl substituent. A partial energy transfer could also be observed for some bichromophores, leading to aggregation-induced dual emission (AIDE). In addition, four examples of aminated diaroyl-S,N-ketene acetals were added to the compound library. The electron-withdrawing properties of the additional aroyl group provide a bathochromic shift of the emission band of the aroyl-S,N-ketene acetal. These bichromophores also show AIDE and in one case even aggregation-induced white light emission as a result of additive color mixing.
T2 - Beilstein Symposium on pi-Conjugated Molecules and Materials
CY - Limburg, Germany
DA - 07.11.2023
KW - aggregation-induced dual emission (AIDE)
PY - 2023
AN - OPUS4-59006
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Tavernaro, Isabella
T1 - A Multimodal Approach to Quantify Surface Functional Groups on Nanomaterials for Safe and Sustainable by Design
N2 - Engineered nanomaterials (NM) with their large surface-to-volume ratios and their for some materials observed size-dependent functional properties are of increasing relevance for current and future developments in various fields such as medical and pharmaceutical industry, computing and electronics or food and consumer products. The performance and safety of NM are determined by the sum of their intrinsic physicochemical properties. Especially, the particle surface chemistry, which is largely controlled by the chemical nature and density of functional groups (FG) and ligands, is an important key driver for NM performance, stability, and processibility as well as the interaction of NM with the environment. Thus, methods for FG quantification can foster the sustainable development of functional and safe(r) NM.
Aiming at the development of simple, versatile, and multimodal tools for the quantification of many bioanalytically relevant FG and ligands, we investigated and compared various analytical methods commonly used for FG quantification. This includes electrochemical titration methods, dye-based optical assays, and other instrumental analytical techniques such as nuclear magnetic resonance and thermal analysis methods.
The potential of our multimodal approach for FG quantification was demonstrated for commercial and custom-made polymeric and silica particles of varying FG, used as optical pH sensors. In the future, our strategy can contribute to establish multi-method characterization strategies to provide a more detailed picture of the structure-properties relationship.
T2 - NanoSAFE & NanoSafety Cluster 2023
CY - Grenoble, France
DA - 05.06.2023
KW - Engineered Nanomaterials
KW - Safe-by-Design
KW - Sustainable-by-Design
KW - Surface Group Analysis
KW - Silica and Polystyrene Particles
KW - Surface Modification
KW - Dye
KW - Optical Spectroscopy
KW - Quantitative NMR
KW - Electrochemical Titration
KW - Functionalized Nanomaterials
KW - Nanosafety
PY - 2023
AN - OPUS4-59126
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Osipova, Viktoriia
T1 - Incorporation of near-infrared light emitting chromium (III) complexes into silica nanoparticles and spectroscopic characterization
N2 - In recent years, chromium (III) complexes have received a lot of attention as novel near-infrared (NIR) emitters triggered by the report on the first molecular ruby Cr(ddpd)2(BF4)3 with a high photoluminescence quantum yield of 13.7% of its near infrared (NIR) emission band and a long luminescence lifetime of 1.122 ms at room temperature.[1] However, in an oxygen-containing environment, the photoluminescence quantum yields and luminescence lifetimes of these chromium(III) complexes show only very small values. This hampers their application as NIR luminescence labels. This application, that cannot be tackled by conventional deoxygenating approaches, requires suitable strategies to protect the luminescence of the chromium(III) complexes from oxygen quenching. An elegant approach to reduce the undesired luminescence quenching by triplet oxygen explored by us presents the incorporation of these chromium(III) complexes into different types of amorphous, non-porous silica nanoparticles, that can be simply surface functionalized, e.g., with targeting ligands and/or other sensor molecules. In this work, as first proof-of-concept experiments, a set of chromium (III) complexes constituting of different ligands and counter anions, were embedded into the core of silica nanoparticles. Subsequently, the optical properties of the resulting luminescent silica nanoparticles were spectroscopically assessed by steady state and time-resolved luminescence spectroscopy. First results of time-resolved luminescence measurements confirm our design concept of nanoscale NIR emissive Cr(III) complex-based reporters
T2 - Projekttreffen Nile-Chrome 2.0
CY - Mainz, Germany
DA - 11.12.2023
KW - Cr(III) complex
KW - NIR
KW - Luminescence
KW - Nano
KW - Silica
KW - Lifetime
KW - Quantum Yields
KW - Particle Synthesis
KW - Sensors
KW - Probe
KW - Surface Group Analysis
PY - 2023
AN - OPUS4-59149
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
A1 - Wegner, Karl David
T1 - Luminescent Nanoparticles – From Photophysics to the Measurement of Photoluminescence Quantum Yields
N2 - Inorganic nanocrystals with linear and nonlinear photoluminescence in the ultraviolet, visible, near infrared and short-wave infrared like spectrally shifting lanthanide-based nanoparticles (LnNCs) like NaYF4: Yb, Er and semiconductor quantum dots have meanwhile found applications in the life and material sciences ranging from optical reporters for bioimaging and sensing over security barcodes to solid state lighting and photovoltaics. The identification of optimum particle architectures for photonic applications requires quantitative spectroscopic studies, ideally flanked by single particle studies to assess spectroscopic inhomogeneities on a particle-to-particle level for typical preparation methods. In the following, photoluminescence studies of LnNCs are presented, addressing parameters such as particle size, surface coating, and dopant ion concentration as well as excitation power density mandatory for a profound mechanistic understanding of the nonradiative deactivation pathways in these nanocrystals. In addition, methods for the determination of particle brightness and photoluminescence quantum yield in different spectral windows are presented.
T2 - Phoenix Colloquium
CY - Hannover, Germany
DA - 22.06.2023
KW - Semiconductor quantum dot
KW - Upconversation nanocrystal
KW - Luminescence
KW - Quantitative spectroscopy
KW - Photophysics
KW - Quality assurance
KW - Nano
KW - Particle
KW - Quantum yield
KW - Lifetime
KW - Standard
KW - Reference material
KW - Surface analysis
KW - Quantification
PY - 2023
AN - OPUS4-57797
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Mazurenka, Mikhail
T1 - NIR fluorescence imaging system for (pre)clinical applications: design, construction, and validation
N2 - We developed, built, and validated a new versatile fluorescence imaging system. The system is intended to reliably test new tracers and contrast agents at different stages of (pre)clinical research. The system, in its current version, is optimized for the detection of ICG emission. The modular design enables to adapt the scanner to emerging spectral windows with traceable and standardized measurements conditions.
T2 - Projektmeeting
CY - Berlin, Germany
DA - 28.10.2023
KW - Fluorescence imaging
KW - Imaging system
KW - Standardization
PY - 2023
AN - OPUS4-58909
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Meng, M.
A1 - Zhang, R.
A1 - Fa, X.
A1 - Yang, J.
A1 - Cheng, Z.
A1 - Qiao, X.
A1 - Ou, J.
A1 - Würth, Christian
A1 - Resch-Genger, Ute
T1 - Core−Shell NaYF4:Yb3+/Tm3+@NaGdF4:Ce3+/Eu3+ Nanoparticles for Upconversion and Downconversion Dual-Mode Fluorescence-Based Temperature Sensing
N2 - NaYF4 as the core and NaGdF4 as the outer layer were used to obtain
NaYF4:Yb3+/Tm3+@NaYF4:Ce3+/Eu3+ nanoparticles. Physical and morphological investigations indicated that the obtained nanoparticles were prepared in a hexagonal shape, with the NaGdF4 shell layer uniformly encapsulated on the NaYF4 core.
Strong Tm3+ upconversion emission peaks were observed for a 980-nm-laser-excited sample, while strong Eu3+ downconversion emission peaks were observed for a 254-nm-laser-excited sample. By zonal doping of Tm3+ and Eu3+, their fluorescence intensity can be significantly increased; more importantly, simultaneous temperature measurements with dual-mode upconversion/downconversion can be achieved. The temperature measurement properties of the dual mode were also investigated, and it was discovered that the upconversion 3F3 → 3H6 and 1G4 → 3F4 thermocouple energy levels gave the best temperature measurements with maximum absolute and relative sensitivities of 0.0877 K−1 and 1.95% K−1, respectively, which are better than the current temperature measurement sensitivities of most rare-earth-based materials. This material was prepared as fiber-optic temperature-sensing probes to detect the temperature in the environment in real time and was found to perform excellently for temperature measurement.
KW - Upconversion nanoparticle
KW - Lanthanide
KW - Sensing; temperature
KW - Photophysics
PY - 2022
DO - https://doi.org/10.1021/acsanm.2c01611
VL - 5
IS - 7
SP - 9266
EP - 9276
PB - American Chemical Society
AN - OPUS4-55363
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Nirmalananthan-Budau, Nithiya
A1 - Tavernaro, Isabella
T1 - Synthesis and Optical Quantification of Surface Groups on Organic and Inorganic Particle-Carriers
N2 - Differently sized organic and inorganic particles are of 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.1 Particle performance in such applications depends mainly on the sum of their intrinsic physicochemical properties. Here, the surface chemistry, i.e., the total number of surface functional groups (FG) and the number of FG accessible for subsequent modification with ligands and/or biomolecules, is one of the key parameters. Moreover, the surface chemistry of these materials controls the behavior and fate of the particles when released to the environment or taken up by cells. Nevertheless, it is still relatively rare that FG are quantified in particle safety studies. Methods for FG quantification should be simple, robust, reliable, fast, and inexpensive, and allow for the characterization of a broad variety of materials differing in size, chemical composition, and optical properties.
Aiming at the development of simple, versatile, and multimodal tools for the quantification of bioanalytically relevant FG such as amine2,3, carboxy2,3, thiol, and aldehyde4 functionalities, we designed a catch-and-release assay utilizing cleavable probes that enable the quantification of the cleaved-off reporters in the supernatant after particle separation, and thus, circumvent interferences resulting from particle light scattering and sample-inherent absorption or emission.2 The potential of our cleavable probes for the quantification of carboxy and amino groups was demonstrated for commercial and custom-made polymer and silica particles of varying FG densities, underlining the benefit of the catch-and-release assays as a versatile method for the FG quantification on all types of transparent, scattering, absorbing and/or fluorescent particles.2,3 In the future, our cleavable probe strategy can be easily adapted to other analytical techniques requiring different reporters, or to different types of linkers that can be cleaved thermally, photochemically, or by pH, utilizing well-established chemistry, e.g. from drug delivery systems. It can contribute to establish multi-method characterization strategies for particles to provide a more detailed picture of the structure-properties relationship and thus can support the design of sustainable and safe(r) materials.
T2 - Nanosafety 2020
CY - Online meeting
DA - 05.10.2020
KW - Optical quantification
KW - Surface functional groups
KW - Polymer particles
KW - Silica particles
KW - Cleavable probe
PY - 2020
AN - OPUS4-51418
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Würth, Christian
A1 - Manley, P.
A1 - Voigt, R.
A1 - Ahiboz, D.
A1 - Becker, C.
A1 - Resch-Genger, Ute
T1 - Metasurface Enhanced Sensitized Photon Upconversion: Toward Highly Efficient Low Power Upconversion Applications and Nanoscale E-Field Sensors
N2 - Large-scale nanoimprinted metasurfaces based on silicon photonic crystal slabs were produced and coated with a NaYF4:Yb3+/Er3+ upconversion nanoparticle (UCNP) layer. UCNPs on these metasurfaces yield a more than 500-fold enhanced upconversion emission compared to UCNPs on planar surfaces. It is also demonstrated how the optical response of the UCNPs can be used to estimate the local field energy in the coating layer. Optical simulations using the finite element method validate the experimental results and the calculated spatial three-dimensional field Energy distribution helps us to understand the emission enhancement mechanism of the UCNPs closely attached to the metasurface. In addition, we analyzed the spectral shifts of the resonances for uncoated and coated metasurfaces and metasurfaces submerged in water to enable a prediction of the optimum layer thicknesses for different excitation wavelengths, paving the way to applications such as electromagnetic field sensors or bioassays.
KW - Nanoparticles
KW - Upconversion
KW - Metasurface
KW - Field sensor
KW - Emission enhancement
KW - Photonic crystal
PY - 2020
DO - https://doi.org/10.1021/acs.nanolett.0c02548
VL - 20
IS - 9
SP - 6682
EP - 6689
PB - ACS Publications
AN - OPUS4-51427
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Geißler, Daniel
T1 - Development of reference materials for flow cytometric analysis of extracellular vesicles
N2 - The aim of task 1.4 within the EMPIR project 18HLT01 MetVesII is to produce low-RI solid particles with an effective RI between 1.37 and 1.42. To prepare these low-RI solid particles, polymer cores will be coated with a silica shell. Although the bulk RI of polymers, such as polystyrene (RI = 1.59) and PMMA (RI = 1.49), and fused silica (RI = 1.46) are higher than desired, an effective RI below 1.42 will be achieved by using a mesoporous silica shell with tuneable shell-thickness and a polymer core with sufficiently small size. This approach has four advantages: (1) monodisperse commercial polymer particles and silica shell chemistry are available, (2) low-RI solid particles will have a tuneable size and RI, (3) fluorescence can be added by incorporating fluorescent dyes into the polymer cores via an established staining procedure, and (4) fluorescent dyes within the polymer cores are shielded against influences from the sample matrix, e.g. fluorescence quenching effects altering the emission properties of the reference materials.
T2 - MetVesII M9 Progress Meeting
CY - Budapest, Hungary
DA - 12.02.2020
KW - EMPIR 18HLT01 MetVesII
KW - Extracellular vesicles (EV)
KW - Flow cytometry (FCM)
KW - Reference materials
KW - Fluorescent particles
PY - 2020
AN - OPUS4-50451
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Optical-Spectroscopic Studies of Soot Particles
N2 - Aiming at the development of a non-destructive optical measurement methods for the characterization of nano-sized airborne particulate pollutants we performed fluorescence spectroscopic investigations of their relevant emission properties. Here, we present first results from studies of soot particles from synthetic aerosols deposited on PTFE membranes.
T2 - EMPIR 18HLT02 AeroTox M9 meeting
CY - London, UK
DA - 29.01.2020
KW - Aaerosol particles
KW - Airborne particulate pollutants
KW - Fluorescence spectroscopy
PY - 2020
AN - OPUS4-50511
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Resch-Genger, Ute
T1 - Functional Luminophores – From Photophysics to Standardized Luminescence Measurements
N2 - Inorganic nanocrystals with linear and nonlinear luminescence in the ultraviolet, visible, near infrared and short-wave infrared like semiconductor quantum dots and spectrally shifting lanthanide-based nanophosphors have meanwhile found applications in the life and material sciences ranging from optical reporters for bioimaging and sensing over security barcodes to solid state lighting and photovoltaics. These nanomaterials commonly have increasingly sophisticated core/shell particle architectures with shells of different chemical composition and thickness to minimize radiationless deactivation at the particle surface that is usually the main energy loss mechanism [1]. For lanthanide-based spectral shifters, particularly for very small nanoparticles, also surface coatings are needed which protect near-surface lanthanide ions from luminescence quenching by high energy vibrators like O-H groups and prevent the disintegration of these nanoparticles under high dilution conditions. [2,3,4]. The identification of optimum particle structures requires quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield [5,6], ideally flanked by single particle studies to assess spectroscopic inhomogeneities on a particle-to-particle level for typical preparation methods [7,8], Moreover, in the case of upconversion nanoparticles with a multi-photonic and hence, excitation power density (P)-dependent luminescence, quantitative luminescence studies over a broad P range are required to identify particle architectures that are best suited for applications in fluorescence assays up to fluorescence microscopy. Here, we present methods to quantify the photoluminescence of these different types of emitters in the vis/NIR/SWIR and as function of P and demonstrate the importance of such measurements for a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different size and particle architecture in different environments.
T2 - Eingeladener Vortrag Uni Erlangen
CY - Erlangen, Germany
DA - 18.01.2023
KW - Semiconductor quantum dot
KW - Upconversion nanocrystal
KW - Luminescence
KW - Quantitative spectroscopy
KW - Photophysics
KW - Quality assurance
KW - Nano
KW - Particle
KW - Quantum yield
KW - Lifetime
KW - Standard
KW - Reference material
KW - Surface analysis
KW - Quantification
PY - 2023
AN - OPUS4-57011
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Tavernaro, Isabella
T1 - pH-Responsive Dyad Molecules: MiGraGen Project
N2 - Optical pH sensors utilizing colorimetric or fluorescent indicator dyes are highly promising in many biomedical and life science applications where electrochemical sensors fail. For instance, optical sensors are not prone to electrical interferences, they are noninvasive and enable remote measurements. Moreover, fluorescence detection is very fast, highly sensitive, and provides several readout parameters ideal for multiplexing with nanometer resolution using simple, inexpensive, and miniaturizable instrumentation. Here, we present the design of a dyad sensor molecule, consisting of an analyte-responsive and an analyte inert reference fluorophore.
T2 - MiGraGen Project Meeting 16.06.2023
CY - Online Meeting
DA - 16.06.2023
KW - Dyad molecules
KW - pH sensing
KW - Fluorescent indicator
KW - Ratiometric sensors
PY - 2023
AN - OPUS4-58070
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 - A journey in science from a graduate student in physical chemistry to head of division biophotonics
N2 - I will provide a personal overview of the most important steps of my career in science, a journey from a graduate student in physical chemistry in an environment dominated by male-scientists over a postdoc with a female professor in the US to the leader of a research group, head of division Biophotonics at BAM. This will include my choices of research topics, how I learnt to write well cited publications, even on topics such as reference materials and quality assurance,1-4 and eventually started to give lectures at Free University Berlin granting me the right to act as first supervisor of undergraduate and graduate students.
T2 - Women in Science
CY - Erlangen, Germany
DA - 22.07.2024
KW - Lanthanide
KW - Nanoparticle
KW - Silica
KW - Quantum dot
KW - Polymer
KW - Surface group
KW - Luminescence
KW - Quantitative spectroscopy
KW - Quantum yield
KW - Lifetime
KW - Quality assurance
KW - Synthesis
KW - Surface modification
KW - Photophysics
PY - 2024
AN - OPUS4-60724
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 -