TY - JOUR A1 - Clark, P.C.J A1 - Andresen, Elina A1 - Sear, M. J. A1 - Favaro, M. A1 - Girardi, L. A1 - van de Krol, R. A1 - Resch-Genger, Ute A1 - Starr, D.E. T1 - Quantification of the Activator and Sensitizer Ion Distributions in NaYF4:Yb3+, Er3+ Upconverting Nanoparticles Via Depth-Profiling with Tender X-Ray Photoemission N2 - The spatial distribution and concentration of lanthanide activator and sensitizer dopant ions are of key importance for the luminescence color and efficiency of upconverting nanoparticles (UCNPs). Quantifying dopant ion distributions and intermixing, and correlating them with synthesis methods require suitable analytical techniques. Here, X-ray photoelectron spectroscopy depth-profiling with tender X-rays (2000–6000 eV), providing probe depths ideally matched to UCNP sizes, is used to measure the depth-dependent concentration ratios of Er3+ to Yb3+, [Er3+]/[Yb3+], in three types of UCNPs prepared using different reagents and synthesis methods. This is combined with data simulations and inductively coupled plasma-optical emission spectroscopy (ICP-OES) measurements of the lanthanide ion concentrations to construct models of the UCNPs’ dopant ion distributions. The UCNP sizes and architectures are chosen to demonstrate the potential of this approach. Core-only UCNPs synthesized with XCl3·6H2O precursors (β-phase) exhibit a homogeneous distribution of lanthanide ions, but a slightly surface-enhanced [Er3+]/[Yb3+] is observed for UCNPs prepared with trifluroacetate precursors (α-phase). Examination of Yb-core@Er-shell UCNPs reveals a co-doped, intermixed region between the single-doped core and shell. The impact of these different dopant ion distributions on the UCNP's optical properties is discussed to highlight their importance for UCNP functionality and the design of efficient UCNPs. KW - Shell KW - Nanomaterial KW - Nano KW - Upconversion nanoparticle KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Excitation power density KW - Surface KW - Coating KW - Core-shell KW - XPS KW - Intermixing KW - HAXPES KW - Method PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552075 DO - https://doi.org/10.1002/smll.202107976 SN - 1613-6813 SP - 1 EP - 13 PB - Wiley-VCH-Verlag CY - Weinheim, Germany AN - OPUS4-55207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Nirmalananthan-Budau, Nithiya A1 - Tavernaro, Isabella 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 - 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 - JOUR A1 - Kromer, Ch. A1 - Schwibbert, K. A1 - Gadicherla, A. K. A1 - Thiele, D. A1 - Nirmalananthan-Budau, Nithiya A1 - Laux, P. A1 - Resch-Genger, Ute A1 - Luch, A. A1 - Tschiche, H. R. T1 - Monitoring and imaging pH in biofilms utilizing a fluorescent polymeric nanosensor N2 - Biofilms are ubiquitous in nature and in the man-made environment. Given their harmful effects on human health, an in-depth understanding of biofilms and the monitoring of their formation and growth are important. Particularly relevant for many metabolic processes and survival strategies of biofilms is their extracellular pH. However, most conventional techniques are not suited for minimally invasive pH measurements of living biofilms. Here, a fluorescent nanosensor is presented for ratiometric measurements of pH in biofilms in the range of pH 4.5–9.5 using confocal laser scanning microscopy. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with pH-inert dye Nile Red and is surface functionalized with a pH-responsive fluorescein dye. Its performance was validated by fluorometrically monitoring the time-dependent changes in pH in E. coli biofilms after glucose inoculation at 37 °C and 4 °C. This revealed a temperature-dependent decrease in pH over a 4-h period caused by the acidifying glucose metabolism of E. coli. These studies demonstrate the applicability of this nanosensor to characterize the chemical microenvironment in biofilms with fluorescence methods. KW - Dye KW - Fluorescence KW - Signal enhancement KW - Sensor KW - Quantum yield KW - Synthesis KW - Nanoparticle KW - Nano KW - Polymer KW - Ph KW - Biofilm KW - MIC KW - Corrosion KW - Microorganism KW - Bacteria PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550751 DO - https://doi.org/10.1038/s41598-022-13518-1 SN - 2045-2322 VL - 12 IS - 1 SP - 1 EP - 10 PB - Nature Publishing Group CY - London AN - OPUS4-55075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - 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 - Fa, X. A1 - Lin, Sh. A1 - Yang, J. A1 - Shen, Ch. A1 - Liu, Y. A1 - Gong, Y. A1 - Qin, A. A1 - Ou, Jun A1 - Resch-Genger, Ute T1 - −808 nm-activated Ca2+ doped up-conversion nanoparticles that release no inducing liver cancer cell (HepG2) apoptosis N2 - Anear-infrared (NIR) light-triggered release method for nitric oxide (NO) was developed utilizing core/shell NaYF4: Tm/Yb/Ca@NaGdF4:Nd/Yb up-conversion nanoparticles (UCNPs) bearing a mesoporous silica (mSiO2) shell loaded with theNOdonor S-nitroso-N-acetyl-DL-penicillamine (SNAP). To avoid overheating in biological samples, Nd3+ was chosen as a sensitizer, Yb3+ ions as the bridging sensitizer, andTm3+ ions as UV-emissive activator while co-doping with Ca2+ was done to enhance the luminescence of the activatorTm3+.NOrelease from SNAP was triggered by an NIR-UV up-conversion process, initiated by 808nmlight absorbed by the Nd3+ ions.NOrelease was confirmed by the Griess method. Under 808nmirradiation, the viability of the liver cancer cell line HepG2 significantly decreased with increasing UCNPs@mSiO2-SNAP concentration. For a UCNPs@mSiO2-SNAP concentration of 200 μgml−1, the cell survival probability was 47%. These results demonstrate that UCNPs@mSiO2-SNAP can induce the release of apoptosis-inducingNOby NIR irradiation. KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - Excitation power density KW - Brightness KW - NIR KW - Mechanism KW - Triggered KW - Release KW - Cell KW - PDT KW - Dye KW - Therapy KW - Surface KW - Coating PY - 2022 DO - https://doi.org/10.1088/2050-6120/ac5524 VL - 10 IS - 2 SP - 1 EP - 9 PB - IOP Publishing AN - OPUS4-54842 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 - 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 - 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 - JOUR A1 - Bastos, V. A1 - Oskoei, P. A1 - Andresen, Elina A1 - Saleh, Maysoon I. A1 - Rühle, Bastian A1 - Resch-Genger, Ute A1 - Oliveira, H. T1 - Stability, dissolution, and cytotoxicity of NaYF4‑upconversion nanoparticles with different coatings N2 - Upconversion nanoparticles (UCNPs) have attracted considerable attention owing to their unique photophysical properties. Their utilization in biomedical applications depends on the understanding of their transformations under physiological conditions and their potential toxicity. In this study, NaYF4: Yb,Er UCNPs, widely used for luminescence and photophysical studies, were modified with a set of four different coordinatively bound surface ligands, i.e., citrate, alendronate (AA), ethylendiamine tetra(methylene phosphonate) (EDTMP), and poly(maleic anhydride-alt-1-octadecene) (PMAO), as well as silica coatings with two different thicknesses. Subsequently, the aging-induced release of fluoride ions in water and cell culture media and their cytotoxic profile to human keratinocytes were assessed in parallel to the cytotoxic evaluation of the ligands, sodium fluoride and the lanthanide ions. The cytotoxicity studies of UCNPs with different surface modifications demonstrated the good biocompatibility of EDTMP-UCNPs and PMAO-UCNPs, which is in line with the low amount of fluoride ions released from these samples. An efficient prevention of UCNP dissolution and release of cytotoxic ions, as well as low cytotoxicity was also observed for UCNPs with a sufficiently thick silica shell. Overall, our results provide new insights into the understanding of the contribution of surface chemistry to the stability, dissolution behavior, and cytotoxicity of UCNPs. Altogether, the results obtained are highly important for future applications of UCNPs in the life sciences and bioimaging studies. KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Excitation power density KW - Surface chemistry KW - Coating PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544681 DO - https://doi.org/10.1038/s41598-022-07630-5 SN - 2045-2322 VL - 12 SP - 1 EP - 13 PB - Springer Nature CY - London AN - OPUS4-54468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -