TY - JOUR A1 - McGonigle, Rebecca A1 - Glasgow, Jodie A1 - Houston, Catriona A1 - Cameron, Iain A1 - Homann, Christian A1 - Black, Dominic J. A1 - Pal, Robert A1 - MacKenzie, Lewis E. ED - MacKenzie, Lewis E. T1 - Autoclave reactor synthesis of upconversion nanoparticles, unreported variables, and safety considerations N2 - Autoclave reactors are widely used across chemical and biological sciences, including for the synthesis of upconversion nanoparticles (UCNPs) and other nanomaterials. Yet, the details of how autoclave reactors are used in such synthesis are rarely reported in the literature, leaving several key synthesis variables widely unreported and thereby hampering experimental reproducibility. In this perspective, we discuss the safety considerations of autoclave reactors and note that autoclaves should only be used if they are (a) purchased from reputable suppliers/manufacturers and (b) have been certified compliant with relevant safety standards. Ultimately, using unsuitable autoclave equipment can pose a severe physical hazard and may breach legal safety requirements. In addition, we highlight several parameters in autoclave synthesis that should be reported as standard to maximise the reproducibility of autoclave synthesis experiments across materials and chemistry research. We encourage users of autoclave synthesis vessels to: (1) adopt high-safety autoclaves and (2) report the many experimental variables involved to enhance experimental reproducibility. KW - Reference material KW - Nano KW - Particle KW - Shell KW - Fluorescence KW - Lifetime KW - Decay kinetics KW - Synthesis KW - Quality assurance KW - Method KW - Energy transfer KW - Upconversion KW - Autoclave synthesis KW - Data comparability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625672 DO - https://doi.org/10.1038/s42004-025-01415-3 VL - 8 IS - 1 SP - 1 EP - 7 PB - Springer Science and Business Media LLC AN - OPUS4-62567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oskolkova, Tatiana O. A1 - Matiushkina, Anna A1 - Borodina, Lyubov' N. A1 - Smirnova, Ekaterina S. A1 - Dadadzhanova, Antonina I. A1 - Sewid, Fayza A. A1 - Veniaminov, Andrey V. A1 - Moiseeva, Ekaterina O. A1 - Orlova, Anna O. T1 - FRET‐Amplified Singlet Oxygen Generation by Nanocomposites Comprising Ternary AgInS2/ZnS Quantum Dots and Molecular Photosensitizers N2 - Antibacterial photodynamic therapy (a‐PDT) has emerged as a promising non‐invasive therapeutic modality that utilizes the combination of a photosensitive agent, molecular oxygen, and excitation light to generate reactive oxygen species (ROS), demonstrating remarkable activity against multidrug‐resistant bacterial infections. However, the effective use of conventional photosensitizers is significantly limited by a number of their shortcomings, namely, poor water solubility and low selectivity. Herein, we present a novel biocompatible water‐soluble nanocomposite based on hydrophobic tetraphenylporphyrin (TPP) molecules and hydrophilic ternary AgInS2/ZnS quantum dots incorporated into a chitosan matrix as an improved photosensitizer for a‐PDT. We demonstrated that TPP molecules could be successfully transferred into chitosan solution while remaining primarily in the form of monomers, which are capable of singlet oxygen generation. We performed a detailed analysis of the Förster resonance energy transfer (FRET) between quantum dots and TPP molecules within the nanocomposite and proposed the mechanism of the singlet oxygen efficiency enhancement via FRET. KW - Nano KW - Particle KW - Quantum dot KW - Fluorescence KW - Synthesis KW - Optical spectroscopy KW - Energy transfer KW - Quality assurance KW - Lifetime KW - Quantum yield PY - 2024 DO - https://doi.org/10.1002/cnma.202300469 SN - 2199-692X VL - 10 IS - 3 SP - 1 EP - 11 PB - Wiley AN - OPUS4-59728 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 - Ansari, A. A. A1 - Ou, Jun A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Preparation of core–shell structured NaYF4:Yb3+/ Tm3+@NaYF4:Yb3+/Er3+ nanoparticles with high sensitivity, low resolution and good reliability and application of their fluorescence temperature properties N2 - A series of NaYF4:Yb3+/Tm3+@NaYF4:Yb3+/Er3+ nanoparticles doped with Tm3+ and Er3+ were successfully prepared by the solvothermal method. Under 980 nm laser excitation, intense upconversion emission peaks of Tm3+ and Er3+ were observed for all samples. By doping Tm3+ and Er3+ with core–shell partitioning, not only a significant increase in fluorescence intensity could be achieved, but also simultaneous temperature measurements on multiple thermocouple energy levels could be realised. In addition, the temperature sensing performance of different thermocouple energy levels was also investigated, and it was found that the 3 F3 → 3 H6 and 1 G4 → 3 F4 thermocouple energy level pairs of Tm3+ were the best, with maximum absolute sensitivity and maximum relative sensitivity of up to 0.0250 K−1 and 2.155% K−1 respectively, higher than the sensitivity of other thermocouple energy levels. It has a temperature resolution of less than 0.0139 K, which is lower than that of most materials available today. By using this material as a probe to build a fiber optic temperature sensor platform, it was found to have reliable temperature measurement performance. KW - Flourescence KW - Optical probe KW - Sensor KW - Dye KW - Temperature KW - Nano KW - Particle KW - Upconversion KW - Lanthanide KW - Qantum yield KW - Quality assurance KW - Monitoring KW - Infrastructure PY - 2022 DO - https://doi.org/10.1039/d1ce01729b VL - 24 IS - 9 SP - 1752 EP - 1763 PB - RSC Publishing AN - OPUS4-54416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Design, characterization, and application of fluorescent sensor particles N2 - pH and oxygen are amongst the most important and frequently measured analytes in the life and material sciences, indicating, e.g., diseases and corrosion processes. This includes the optical monitoring of pH in living cells for studying cellular internalization pathways, such as phagocytosis, endocytosis, and receptor ligand internalization with the aid of molecular and nanoscale fluorescent sensors. Nanoparticle (NP)-based sensors, that are labeled or stained with a multitude of sensor dyes, have several advantages as compare to conventional molecular probes like enhanced brightness, i.e., amplified signals, ease of designing ratiometric systems by combining analyte sensitive and inert reference dyes, and increased photostability. Moreover, this can enable the use of hydrophobic dyes in aqueous environments. Versatile templates and carriers for the fabrication of nanosensors by the staining and/or labelling with different fluorophores and sensor molecules or surface functionalized NP like silica (SiO2-NP) and polystyrene (PS-NP) particles provide. Here we present the design of a versatile platform of color emissive nanosensors and stimuli-responsive microparticles for the measurement of pH, oxygen, and other targets utilizing both types of matrices and sets of spectrally distinguishable sensor and reference dyes and their characterization and demonstrate the applicability of representative sensor particle for cellular studies. T2 - Vortrag bei dem Projekttreffen MicraGen CY - Copenhagen, Denmark DA - 18.08.2022 KW - Dye KW - Luminescence KW - Quantitative spectroscopy KW - Photophysics KW - Quality assurance KW - Nano KW - Particle KW - Quantum yield KW - Lifetime KW - Standard KW - Integrating sphere spectroscopy KW - Sensor KW - pH KW - Oxygen KW - Microfluidics KW - Cancer KW - Cell KW - Life sciences PY - 2022 AN - OPUS4-57049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella T1 - Amorphous, fluorescent silica particles for bioimaging applications N2 - Nowadays amorphous silica nanoparticles (SiO2 NP) are one of the most abundant engineered nanomaterials, with an annual production of hundreds of thousands of tons, that are used in a broad field of industrial products and processes. Since SiO2 NP are highly stable and easily produced on a large scale at low cost, they are widely employed as fillers for rubbers and composites, absorbents, catalysts, advanced coating additives as well as plant growth agents in agriculture, anti-caking agents in food products, or as carrier material in cosmetic industry. Moreover, they are promising candidates for colloidal scaffolds in biomedical applications like bioimaging, sensing or controlled drug delivery. SiO2 NP modified with luminescent chromophores have several advantages as compared to conventional molecular probes like enhanced brightness, ease of designing ratiometric systems, and increased photostability. Here we present our work on multicolored SiO2 NP for imaging and sensing applications. T2 - FUNGLASS Workshop CY - Berlin, Germany DA - 06.03.2024 KW - Sensors KW - Nano KW - Particles KW - Silica KW - Luminescence KW - Fluorescence KW - Quality assurance KW - Method KW - Synthesis KW - Dye KW - pH KW - Surface analysis PY - 2024 AN - OPUS4-62167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geißler, Daniel A1 - Wegner, Karl David A1 - Fischer, C. A1 - Resch-Genger, Ute T1 - Exploring Simple Particle-Based Signal Amplification Strategies in a Heterogeneous Sandwich Immunoassay with Optical Detection N2 - Heterogeneous sandwich immunoassays are widely used for biomarker detection in bioanalysis and medical diagnostics. The high analyte sensitivity of the current “gold standard” enzyme-linked immunosorbent assay (ELISA) originates from the signal-generating enzymatic amplification step, yielding a high number of optically detectable reporter molecules. For future point-of-care testing (POCT) and point-of-need applications, there is an increasing interest in more simple detection strategies that circumvent time-consuming and temperature-dependent enzymatic reactions. A common concept to aim for detection limits comparable to those of enzymatic amplification reactions is the usage of polymer nanoparticles (NP) stained with a large number of chromophores. We explored different simple NP-based signal amplification strategies for heterogeneous sandwich immunoassays that rely on an extraction-triggered release step of different types of optically detectable reporters. Therefore, streptavidinfunctionalized polystyrene particles (PSP) are utilized as carriers for (i) the fluorescent dye coumarin 153 (C153) and (ii) hemin (hem) molecules catalyzing the luminol reaction enabling chemiluminescence (CL) detection. Additionally, (iii) NP labeling with hemin-based microperoxidase MP11 was assessed. For each amplification approach, the PSP was first systematically optimized regarding size, loading concentration, and surface chemistry. Then, for an immunoassay for the inflammation marker C- eactive protein (CRP), the analyte sensitivity achievable with optimized PSP ystems was compared with the established ELISA concept for photometric and CL detection. Careful optimization led to a limit of detection (LOD) of 0.1 ng/mL for MP11-labeled PSP and CL detection, performing similarly well to a photometric ELISA (0.13 ng/mL), which demonstrates the huge potential of our novel assay concept. KW - Nanoparticle KW - Fluorescence KW - Immunoassay KW - Quality assurance KW - Antibody KW - Polymer KW - Dye KW - Signal enhancement KW - CRP KW - Biosensing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597853 DO - https://doi.org/10.1021/acs.analchem.3c03691 SN - 1520-6882 VL - 96 IS - 13 SP - 5078 EP - 5085 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-59785 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Resch-Genger, Ute A1 - Abram, Sarah-Luise A1 - Tavernaro, Isabella A1 - Zou, Shan A1 - Johnston, Linda T1 - Behind the Paper: Nanoscale Reference and Test Materials for the Validation of Characterization Methods for Engineered Nanomaterials – Current State, Limitations and Needs N2 - Engineered nanomaterials (NMs) of different material composition, morphology, and surface chemistry are widely used in material and life sciences. For NM quality control and risk assessment, NM key properties must be characterized with validated methods, requiring reference materials (RMs). KW - Engineered Nanomaterials KW - Nanoscale reference materials KW - Interlaboratory comparisons KW - Traceability KW - Standardization and Regulation KW - Nano KW - Particle KW - Quality assurance KW - Surface chemistry PY - 2025 UR - https://communities.springernature.com/posts/nanoscale-reference-and-test-materials-for-the-validation-of-characterization-methods-for-engineered-nanomaterials-current-state-limitations-and-needs SP - 1 EP - 3 PB - Springer Nature CY - Online AN - OPUS4-62572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haroun, A. A. A. A1 - Derbala, H. A. A1 - Bassioni, G. A1 - Resch-Genger, Ute A1 - Shafik, E. S. A1 - Hassan, A. M. A. T1 - N-aminophthalimide as a novel UV-stabilizer to promote physico-mechanical properties of highdensity polyethylene (HDPE) N2 - This study aimed to evaluate the efficacy of Naminophthalimide (NAP) as a novel UV-stabilizer for highdensity polyethylene (HDPE) in improving its physicomechanical properties under UV exposure. NAP was synthesized by interaction between phthalimide and hydrazine hydrate. It was incorporated into HDPE with different weight ratios (1, 1.5, 2, and 3%), and its performancewas compared with Hostavin as a traditional UV stabilizer. The HDPE composites were exposed to UV irradiation for different periods (7 and 14 days) to evaluate their photodegradation behavior. Tensile strength, elongation at break were assessed before and after UV exposure. Also, oxidation induction time (OIT), melt flow rate (MFR), Vicat softening temperature were evaluated. Hostavin incorporation reduced tensile strength from 22.36 to 20.62MPa at higher concentrations. It has been found that 3% Hostavin, significantly improved elongation at break, increasing from 423% to 1,170%, suggesting enhanced flexibility. In contrast, NAP increased tensile strength to 22.9MPa and moderately enhanced elongation but slightly declined at 3%due to potential over-stabilization. Under UV exposure, retained tensile strength and elongation was improved with stabilizer content, which increasing tensile strength retention. The HDPE that containing NAP showed enhanced UV resistance and superior retention of mechanical properties compared to Hostavin. KW - Polymer KW - Advanced materials KW - Quality assurance KW - Stabilizer KW - Synthesis KW - Physico-mechanical properties PY - 2025 DO - https://doi.org/10.1515/polyeng-2024-0262 SN - 2191-0340 SP - 1 EP - 8 PB - De Gruyter CY - Berlin AN - OPUS4-63534 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Reliable Photoluminescence Quantum Yields – New Reference Materials and Interlaboratory Comparisons N2 - The rational design and choice of molecular and nanoscale reporters, the comparison of different emitter classes, and photophysical and mechanistic studies 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 luminescent nanomaterials, reliable methods for determining QY of transparent and scattering luminophores, nonlinear emitters, and solid luminescent nanomaterials have been developed.[1-4] 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. In this context, we present the development and certification of a first set of UV/vis/NIR quantum yield standards with a complete uncertainty budget,[5] which present simple tools for a better comparability of QY measurements. In addition, a first interlaboratory comparison of absolute QY measurements of solid and scattering LED converter materials with integrating sphere spectroscopy has been performed.[5] The outcome of this study is presented, thereby addressing common pitfalls and measurement uncertainties and providing recommendations for the performance of reliable QY measurements of linear and non-linear emitters in transparent, scattering, and solid samples. T2 - Anakon 2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Quality assurance KW - Reference material KW - Method KW - Fluorescence KW - Quantum yield KW - Absolute KW - Integrating sphere spectroscopy KW - Interlaboratory comparison KW - Dye KW - Film KW - Nano KW - Particle KW - Scattering KW - Uncertainty KW - LED converter PY - 2025 AN - OPUS4-62792 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schweizer, S. T1 - Interlaboratory comparison on absolute PL quantum yield measurements of scattering luminescent materials N2 - Optical measurements of scattering luminescent materials dispersed in liquid and solid matrices and luminescent powders play an important role in fundamental research and industry. Typical examples are luminescent nano- and microparticles and phosphors of different composition in different matrices or incorporated into ceramics with applications in energy conversion, solid-state lighting, medical diagnostics, and security barcoding. The key parameter for the performance of these materials is the photoluminescence quantum yield QY, i.e., the number of emitted photons per number of absorbed photons. QY of transparent luminophore solutions can be determined relatively to a fluorescence quantum yield standard of known QY. Such standards are meanwhile available as certified reference materials.[1] The determination of QY of scattering liquid and solid samples like dispersions of luminescent nanoparticles, solid phosphors, and optoceramics requires, however, absolute measurements with an integrating sphere setup. Although the importance of reliable absolute QY measurements has been recognized, no interlaboratory comparisons (ILCs) on measurement uncertainties and the identification of typical sources of uncertainty have been yet reported. Also, no scattering reference materials with known QY are available. We present here the results of a first ILC of 3 laboratories from academia and industry performed to identify and quantify sources of uncertainty of absolute QY measurements of scattering samples. Thereby, two types of commercial stand-alone integrating sphere setups with different illumination and detection geometries were utilized for measuring QY of transparent and scattering dye solutions and solid phosphors. As representative and industrially relevant solid and scattering samples, YAG:Ce optoceramics of varying surface roughness were chosen, applied, e.g., as converter materials for blue light emitting diodes. Special emphasis was dedicated to the influence of the measurement geometry, the optical properties of the blank, utilized to determine the number of photons of the incident excitation light absorbed by the sample, and the sample-specific surface roughness. While matching QY values could be obtained for transparent dye solutions and scattering dispersions, here using a blank with scattering properties closely matching those of the sample, QY measurements of optoceramic samples with different blanks revealed substantial differences, with the blank's optical properties accounting for measurement uncertainties of more than 20 %. Based upon the ILC results, we recommend non-absorbing blank materials with a high reflectivity (>95 %) such as a 2 mm-thick PTFE target placed on the sample holder which reveals a near-Lambertian light scattering behavior, yielding a homogeneous light distribution within the integrating sphere. T2 - 8th IWASOM CY - Gdánsk, Poland DA - 07.07.2024 KW - Nano KW - Particle KW - Fluorescence KW - Quantum yield KW - Method KW - Sensor KW - Film KW - Absolute quantum yield KW - Scattering KW - YAG:Ce KW - Quality assurance KW - Lanthanide KW - Upconverter KW - LED KW - Uncertainty KW - Standardization KW - Reference material PY - 2024 AN - OPUS4-62100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Osiopova, Viktoriia A1 - Tavernaro, Isabella A1 - Ge, L. A1 - Kitzmann, W. R. A1 - Heinze, K. A1 - Reithofer, M. R. A1 - Resch-Genger, Ute T1 - Complete protection of NIR-luminescent molecular rubies from oxygen quenching in air by L-arginine-mediated silica nanoparticles N2 - The application of emerging luminophores such as near-infrared (NIR) emissive complexes based on earth-abundant chromium as central ion 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 uminescence 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 oxygendependent, 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 Larginine 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. KW - Quality assurance KW - Fluorescence KW - Quantification KW - Advanced materials KW - Nano KW - Quantum yield KW - NIR KW - Characterization KW - Electron microscopy KW - Silica KW - Synthesis KW - Oxygen sensing KW - Surface KW - Doping KW - Lifetime KW - Cr(III) complex KW - Shielding KW - Sensing PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638271 DO - https://doi.org/10.26599/NR.2025.94907241 SN - 1998-0000 VL - 18 IS - 3 SP - 1 EP - 13 PB - SciOpen AN - OPUS4-63827 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Reliable measurements of the photoluminescence quantum yield of transparent and scattering luminophores N2 - Optical measurements of transparent solutions of organic dyes and semiconductor quantum dots and scattering materials such as luminescent nanocomposites 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.[1] Meanwhile, a first set of certified fluorescence QY standards is available.[2] Such relative QY measurements require a calibrated spectrofluorometer.[1,3] For determining QY of scattering liquid and solid samples, absolute measurements of QY with a calibrated integrating sphere setup are mandatory.[1,4,5] However, scattering QY standards are not available and uncertainties of such measurements have not yet been assessed in interlaboratory comparisons (ILCs). To determine typical sources of uncertainty of absolute QY measurements, we assessed the influence of the measurement geometry and the optical properties of the blank for determining the number of incident photons absorbed by the sample in an ILC using commercial integrating sphere setups and a custom-designed integrating sphere setup. Samples examined included transparent and scattering dye solutions, solid phosphors such as YAG:Ce optoceramics used as LED converter material, and polymer films stained with different amounts of phosphor microparticles. 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, while 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 2025 Fall Meeting CY - Warsaw, Poland DA - 15.09.2025 KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Advanced material KW - Synthesis 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 - OPUS4-64184 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Amouroux, B. A1 - Würth, Christian A1 - Roux, C. A1 - Eftekhari, A. A1 - Sliwa, M. A1 - Bouchet, A. A1 - Micheau, J.-C. A1 - Resch-Genger, Ute A1 - Coudret, C. T1 - Time-Resolved Rate Equation Analysis Disclose Kinetics Controlling Luminescence of Nanometer Tm-Upconverting Nanoparticles N2 - Upconversion luminescence of lanthanide-based upconversion nanoparticles (UCNPs) is a nonlinear step-wise process in which the consecutive absorption of multiple, low-energy photons results in the subsequent emission of a high-energy photon. The primary upconversion mechanism is energy transfer upconversion (ETU) from a sensitizer (Yb3+) to an activator (Tm3+). It requires the absorption of several excitation lowenergy photons by Yb3+, followed by the sequential energy transfer to Tm3+ions. Excited states relax to their ground states either radiatively by emitting a high-energy photon or non-radiatively by multiphonon relaxation through the crystalline host matrix. The time-resolved rise and decay luminescence curves of a set of five ultrasmall have been recorded under varying power near-infrared μs pulses. Six wavelengths have been used to monitor the evolution of the main Yb and Tm excited states. We use an average rate equations model to decipher the relationships between the compositional constraints and size of these ultrasmall UCNPs and the luminescence kinetic parameters. Several rate constants of ETU and other depopulation processes involving the multiple states of the Tm3+ energy scaffold have been retrieved from the simultaneous fit of the recorded curves. Their values have been interpreted by considering bulk and surface quenching, radiative and multi-phonon relaxations, and ion-to-ion hopping. Energy transfer between Yb3+ and Tm3+ is mainly occurring within neighbor atoms. The importance of mismatches on multiphonon relaxations, ETUs, and back-transfers has also been highlighted. For these numerical modeling, it appears that changing the composition and synthesis conditions with the aim to improve a single-specific parameter could remain a major challenge as this modification would automatically impact other properties with immediate consequences on UCNP dynamics. KW - Nano KW - Particle KW - Synthesis KW - Shell KW - Fluorescence KW - Lifetime KW - Decay kinetics KW - Method KW - Modelling KW - Quality assurance KW - Energy transfer KW - Upconversation PY - 2024 DO - https://doi.org/10.1021/acs.jpcc.4c04969 VL - 128 IS - 44 SP - 18836 EP - 18848 PB - ACS Publications AN - OPUS4-61645 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Tavernaro, Isabella A1 - Abram, Sarah-Luise A1 - Andresen, Elina A1 - Matiushkina, Anna T1 - Quantifying the number of total and accessible functional groups on nanomaterials N2 - Inorganic and organic functional nanomaterials (NM) of different size, shape, chemical composition, and surface chemistry are relevant for many key technologies of the 21st century. Decisive for most applications of NM are their specific surface properties, which are largely controlled by the chemical nature and number of ligands and functional groups (FG on the NM surface. The surface chemistry can strongly affect the physicochemical properties of NM, their charge, hydrophilicity/hydrophobicity, reactivity, stability, and processability and thereby their impact on the environment and biological species as well as their possible risk for human health. Thus, reliable, validated, and eventually standardized analytical methods for the characterization of NM surface chemistry, i.e., the chemical identification, quantification, and accessibility of FG and surface ligands 1,2] flanked by interlaboratory comparisons, control samples, and reference materials, 2 ,3 are of considerable importance for process and quality control of NM production and function. This is also important for the safe use of NM the design of novel NM, and sustainable concepts for NM fabrication. Here, we provide an overview of analytical methods for FG analysis and quantification and highlight method and material related challenges for selected NM. Analytical techniques address ed include electrochemical titration methods, optical assays, nuclear magnetic resonance (NMR) and vibrational (IR) spectroscopy, and X ray based and thermal analysis methods. Criteria for method classification and evaluation include the need for a signal generating label, provision of either the total or derivatizable number of FG, and suitability for process and production control. T2 - AUC - Analytical Ultracentrifugation CY - Nuremberg, Germany DA - 22.07.2024 KW - Nanoparticle KW - Particle KW - Microparticle KW - Silica KW - Quantum dot KW - Polymer KW - Surface group KW - Luminescence KW - Quality assurance KW - Synthesis KW - Surface modification KW - ILC KW - Optical assay KW - Functional group KW - Ligand KW - qNMR KW - Conductometry KW - Potentiometry KW - Standardization KW - Reference product KW - Reference material PY - 2024 AN - OPUS4-60749 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Amouroux, B. A1 - Eftekhari, A. A1 - Roux, C. A1 - Micheau, J. A1 - Roblin, P. A1 - Pasturel, M. A1 - Gauffre, F. A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Sliwa, M. A1 - Bouchet, A. A1 - Coudret, C. T1 - Synthesis and Emission Dynamics of Sub-3 nm Upconversion Nanoparticles N2 - Reducing the size of upconversion nanoparticles (UCNPs) down to a few nm yields luminescent materials containing a very small number of emitters. Considering the bottom limit of one activator per particle ultrasmall UCNPs offer an unprecedented platform to study the contributions of the energy transfers at play in upconversion luminescence. Maintaining detectable emission despite the limited number of emitting ions and the high surface-to-volume ratio requires suitable particle architectures. Na(Gd-Yb)F4:Tm3+ emissive sub-3 nm diameter 𝜷-phase UCNPs are prepared using a gadolinium-rich composition in situ mixing of the precursors and a microwave high-temperature cycling sequence allowing precise control of the particle size and dispersity. These cores are coated with a NaGdF4 inert shell to minimize the deleterious influence of surface quenching (SQ). Time-resolved luminescence measurements combining standard NIR excitation of the Yb3+ sensitizer and direct UV excitation of the Tm3+ activator are performed to quantify cross relaxation and surface quenching processes. The fine tuning of the number of activators per particle via an optimized synthesis pathway along with the use of an appropriate excitation scheme enabled to provide an accurate analysis of the different mechanisms at play in these model nanoparticles and to characterize the structure of the core-shell architecture. KW - Lanthanide KW - Nanoparticle KW - Luminescence KW - Quantitative spectroscopy KW - Quantum yield KW - Energy transfer KW - Quality assurance KW - Synthesis KW - Surface modification KW - Photophysics PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606877 DO - https://doi.org/10.1002/adom.202303283 SN - 2195-1071 SP - 1 EP - 13 AN - OPUS4-60687 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stroyuk, O. A1 - Raievska, O. A1 - Barabash, A. A1 - Batentschuk, M. A1 - Osvet, A. A1 - Fiedler, Saskia A1 - Resch-Genger, Ute A1 - Hauch, J. A1 - Brabec, C. J. T1 - "Green" synthesis of highly luminescent lead-free Cs2AgxNa1-xBiyIn1-yCl6 perovskites N2 - A new “green” and mild synthesis of highly stable microcrystalline Cs2AgxNa1-xBiyIn1-yCl6 (CANBIC) perovskites under ambient conditions was developed that is scalable to the multi-gram production. Under UV illumination, the CANBIC perovskites emit intense broadband photoluminescence (PL) with a quantum yield (QY) of 92% observed for x = 0.35 and y = 0.01-0.02. The combination of strong UV absorbance and broadband visible emission, high PL QY, and long PL lifetimes of up to 1.4 μs, along with an outstanding stability makes these CANBICs a promising material class for many optical applications. KW - Fluorescence KW - Perovskites KW - Solar cell KW - Automated synthesis KW - Green synthesis KW - Quantum yield KW - Integrating sphere spectroscopy KW - Absolute fluorescence KW - Quality assurance KW - Nano KW - Particle KW - Application KW - Semiconductor KW - Quantum dot KW - Renewable energy PY - 2022 DO - https://doi.org/10.1039/d2tc02055f SN - 2050-7526 VL - 10 IS - 27 SP - 9938 EP - 9944 PB - Royal Society of Chemistry AN - OPUS4-55453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Cui A1 - Kitzmann, W.R. A1 - Weigert, Florian A1 - Förster, Ch. A1 - Wang, X. A1 - Heintze, K. A1 - Resch-Genger, Ute T1 - Matrix Effects on Photoluminescence and Oxygen Sensitivity of a Molecular Ruby N2 - The molecular ruby analogue [Cr(ddpd)2]3+ (ddpd=N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine) exhibits near infrared (NIR) emission with a high photoluminescence (PL) quantum yield ΦPL of 11 % and a lifetime of 898 μs in deaerated water at room temperature. While ligand-based control of the photophysical properties has received much attention, influences of the counter anions and microenvironment are still underexplored. In this study, the luminescence properties of the molecular ruby were systematically examined for the counter anions Cl−, Br−, [BF4]−, [PF6]−, [BPh4]−, and [BArF24]− in acetonitrile (MeCN) solution, in crystals, and embedded into polystyrene nanoparticles (PSNP). Stern-Volmer analyses of the oxygen quenching studies in the intensity and lifetime domain showed the highest oxygen sensitivity of the complexes with the counter anions of [BF4]− and [BArF24]−, which also revealed the longest luminescence lifetimes. Embedding [Cr(ddpd)2][PF6]3 in PSNPs and shielding with poly(vinyl alcohol) yields a strongly NIR-emissive oxygen-insensitive material with a record ΦPL of 15.2 % under ambient conditions. KW - Fluorescence KW - Sensor KW - Oxygen KW - Quantum yield KW - Quality assurance KW - Complex KW - Cr(III) KW - Lifetime KW - Ligand KW - Solid state KW - X-Ray analysis KW - Structure-property relationship KW - Nano KW - Polymer KW - Particle PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546057 DO - https://doi.org/10.1002/cptc.202100296 SN - 2367-0932 VL - 6 IS - 6 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abram, Sarah-Luise A1 - Tavernaro, Isabella A1 - Resch-Genger, Ute A1 - Johnston, L. J. A1 - Zou, S. T1 - Nanoscale reference and test materials for the validation of characterization methods for engineered nanomaterials — current state, limitations, and needs N2 - The rational design of engineered nanomaterials (NMs) with improved functionality and their increasing industrial application requires reliable, validated, and ultimately standardized characterization methods for their application-relevant, physicochemical key properties such as size, size distribution, shape, or surface chemistry. This calls for nanoscale (certified) reference materials (CRMs; RMs) and well-characterized reference test materials (RTMs) termed also quality control (QC) samples, assessed, e.g., in interlaboratory comparisons, for the validation and standardization of commonly used characterization methods. Thereby, increasing concerns regarding potential risks of NMs are also addressed and the road for safe and sustainable-by-design concepts for the development of new functional NMs and their use as nanomedicines is paved. With this respect, we will provide an overview of relevant international standardization and regulatory activities, definitions, and recommendations on characterization methods and review currently available organic or inorganic nanoscale CRMs, RMs, and RTMs, including their characterization or certification. In addition, we will highlight typical applications to streamline the regulatory approval process and improve manufacturability including the special challenges imposed by the colloidal nature and sometimes limited stability of NMs. Subsequently, we will critically assess the limitations of currently available nanoscale RMs and RTMs and address the gaps to be filled in the future such as the availability of NMs that come with reference data on properties other than commonly addressed particle size, such as surface chemistry or particle number concentration, or more closely resemble commercially available formulations or address application-relevant matrices. KW - Nano KW - Particle KW - Silica KW - Quality assurance KW - Reference material KW - Review KW - Surface chemistry KW - Size KW - Shape KW - Particle number concentration KW - Lipid nanoparticles KW - Metal nanoparticles KW - Liposomes PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625746 DO - https://doi.org/10.1007/s00216-024-05719-6 SN - 1618-2650 SP - 1 EP - 21 PB - Springer AN - OPUS4-62574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Labrador-Paez, Lucia, L. A1 - Kankare, J. A1 - Hyppanen, I. A1 - Soukka, T. A1 - Andresen, Elina A1 - Resch-Genger, Ute A1 - Widengren, J A1 - Liu, H. T1 - Frequency-Domain Method for Characterization of Upconversion Luminescence Kinetics N2 - The frequency-domain (FD) method provides an alternative to the commonly used time-domain (TD) approach in characterizing the luminescence kinetics of luminophores, with its own strengths, e.g., the capability to decouple multiple lifetime components with higher reliability and accuracy. While extensively explored for characterizing luminophores with down-shifted emission, this method has not been investigated for studying nonlinear luminescent materials such as lanthanide-doped upconversion nanoparticles (UCNPs), featuring more complicated kinetics. In this work, employing a simplified rate-equation model representing a standard two-photon energy-transfer upconversion process, we thoroughly analyzed the response of the luminescence of UCNPs in the FD method. We found that the FD method can potentially obtain from a single experiment the effective decay rates of three critical energy states of the sensitizer/activator ions involved in the upconversion process. The validity of the FD method is demonstrated by experimental data, agreeing reasonably well with the results obtained by TD methods. KW - Quality assurance KW - Luminescence KW - Method KW - Quantitative spectroscopy KW - Nano KW - Particle KW - Lifetime KW - Method development PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597435 DO - https://doi.org/10.1021/acs.jpclett.3c00269 SP - 3436 EP - 3444 AN - OPUS4-59743 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 CY - Berlin, Germany DA - 13.01.2020 KW - Linearity KW - Fluorescence KW - Dye KW - Quality assurance KW - Nnano particle KW - Method KW - Measurement uncertainty KW - Quantification PY - 2020 AN - OPUS4-51618 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -