TY - JOUR A1 - Scholtz, Lena A1 - Tavernaro, Isabella A1 - Eckert, J. G. A1 - Lutowski, Marc A1 - Geißler, Daniel A1 - Hertwig, Andreas A1 - Hidde, Gundula A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Influence of nanoparticle encapsulation and encoding on the surface chemistry of polymer carrier beads N2 - Surface-functionalized polymer beads encoded with molecular luminophores and nanocrystalline emitters such as semiconductor nanocrystals, often referred to as quantum dots (QDs), or magnetic nanoparticles are broadly used in the life sciences as reporters and carrier beads. Many of these applications require a profound knowledge of the chemical nature and total number of their surface functional groups (FGs), that control bead charge, colloidal stability, hydrophobicity, and the interaction with the environment and biological systems. For bioanalytical applications, also the number of groups accessible for the subsequent functionalization with, e.g., biomolecules or targeting ligands is relevant. In this study, we explore the influence of QD encoding on the amount of carboxylic acid (COOH) surface FGs of 2 μm polystyrene microparticles (PSMPs). This is done for frequently employed oleic acid and oleylamine stabilized, luminescent core/shell CdSe QDs and two commonly used encoding procedures. This included QD addition during bead formation by a thermally induced polymerization reaction and a post synthetic swelling procedure. The accessible number of COOH groups on the surface of QD-encoded and pristine beads was quantified by two colorimetric assays, utilizing differently sized reporters and electrostatic and covalent interactions. The results were compared to the total number of FGs obtained by a conductometric titration and Fourier transform infrared spectroscopy (FTIR). In addition, a comparison of the impact of QD and dye encoding on the bead surface chemistry was performed. Our results demonstrate the influence of QD encoding and the QD-encoding strategy on the number of surface FG that is ascribed to an interaction of the QDs with the carboxylic acid groups on the bead surface. These findings are of considerable relevance for applications of nanoparticle-encoded beads and safe-by-design concepts for nanomaterials. KW - Optical spectroscopy KW - Particle KW - Optical assay KW - IR spectroscopy KW - Fluorescence KW - Quantum yield KW - Quality assurance KW - Nano KW - Synthesis KW - Surface chemistry KW - Quantification KW - Method KW - Conductometry PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581502 DO - https://doi.org/10.1038/s41598-023-38518-7 SN - 2045-2322 VL - 13 IS - 1 SP - 1 EP - 15 PB - Springer Nature CY - London AN - OPUS4-58150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Solomun, Tihomir A1 - Cordsmeier, Leo A1 - Hallier, Dorothea C. A1 - Seitz, Harald A1 - Hahn, Marc Benjamin T1 - Interaction of a Dimeric Single-Stranded DNA-Binding Protein (G5P) with DNA Hairpins. A Molecular Beacon Study N2 - Gene-V protein (G5P/GVP) is a single-stranded (ss)DNA-binding protein (SBP) of bacteriophage f1 that is required for DNA synthesis and repair. In solution, it exists as a dimer that binds two antiparallel ssDNA strands with high affinity in a cooperative manner, forming a left-handed helical protein–DNA filament. Here, we report on fluorescence studies of the interaction of G5P with different DNA oligonucleotides having a hairpin structure (molecular beacon, MB) with a seven base-pair stem (dT24-stem7, dT18-stem7), as well as with DNA oligonucleotides (dT38, dT24) without a defined secondary structure. All oligonucleotides were end-labeled with a Cy3-fluorophore and a BHQ2-quencher. In the case of DNA oligonucleotides without a secondary structure, an almost complete quenching of their strong fluorescence (with about 5% residual intensity) was observed upon the binding of G5P. This implies an exact alignment of the ends of the DNA strand(s) in the saturated complex. The interaction of the DNA hairpins with G5P led to the unzipping of the base-paired stem, as revealed by fluorescence measurements, fluorescence microfluidic mixing experiments, and electrophoretic mobility shift assay data. Importantly, the disruption of ssDNA’s secondary structure agrees with the behavior of other single-stranded DNA-binding proteins (SBPs). In addition, substantial protein-induced fluorescence enhancement (PIFE) of the Cy3-fluorescence was observed. KW - DNA KW - Protein KW - ssDNA KW - Fluorescence KW - Raman KW - G5P KW - Hairpin KW - Molecular beacon KW - Quencher KW - Amino Acids KW - SBP KW - SSB KW - Cy3 KW - PIFE KW - Protein-induced fluorescence enhancement KW - Protein–DNA filament KW - Single-stranded DNA-binding protein KW - Bacteriophage f1 KW - Oligonucleotides PY - 2023 DO - https://doi.org/10.1021/acs.jpcb.3c03669 SN - 1520-6106 VL - 127 IS - 38 SP - 8131 EP - 8138 PB - ACS Publications AN - OPUS4-58295 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 - Maisuls, I. A1 - Wang, Cui A1 - Gutierrez Suburu, M. E. A1 - Wilde, S. A1 - Daniliuc, C.-G. A1 - Brunink, D. A1 - Doltsinis, N. L. A1 - Ostendorp, S. A1 - Kösters, J. A1 - Resch-Genger, Ute A1 - Strassert, C. A. T1 - Ligand-controlled and nanoconfinement-boosted luminescence employing Pt(II) and Pd(II) complexes: from color-tunable aggregation-enhanced dual emitters towards self-referenced oxygen reporters N2 - In this work, we describe the synthesis, structural and photophysical characterization of four novel Pd(II) and Pt(II) complexes bearing tetradentate luminophoric ligands with high photoluminescence quantum yields (FL) and long excited state lifetimes (s) at room temperature, where the results were interpreted by means of DFT calculations. Incorporation of fluorine atoms into the tetradentate ligand favors aggregation and thereby, a shortened average distance between the metal centers, which provides accessibility to metal–metal-to-ligand charge-transfer (3MMLCT) excimers acting as red-shifted Energy traps if compared with the monomeric entities. This supramolecular approach provides an elegant way to enable room-temperature phosphorescence from Pd(II) complexes, which are otherwise quenched by a thermal population of dissociative states due to a lower ligand field splitting. Encapsulation of These complexes in 100 nm-sized aminated polystyrene nanoparticles enables concentration-controlled aggregation-enhanced dual emission. This phenomenon facilitates the tunability of the absorption and emission colors while providing a rigidified environment supporting an enhanced FL up to about 80% and extended s exceeding 100 ms. Additionally, these nanoarrays constitute rare examples for selfreferenced oxygen reporters, since the phosphorescence of the aggregates is insensitive to external influences, whereas the monomeric species drop in luminescence lifetime and intensity with increasing triplet molecular dioxygen concentrations (diffusion-controlled quenching). KW - Fluorescence KW - Multiplexing KW - Lifetime KW - Bead KW - Particle KW - Dye KW - Barcoding KW - Encoding KW - Quantum yield KW - Label KW - Reporter KW - Pd(II) KW - Pt(II) KW - Complex KW - NMR KW - X-ray KW - Sythesis KW - Aggregation KW - Monomer KW - Color PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525288 DO - https://doi.org/10.1039/d0sc06126c VL - 12 IS - 9 SP - 3270 EP - 3281 PB - Royal Society of Chemistry AN - OPUS4-52528 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 - Scholtz, Lena A1 - Eckert, J. G. A1 - Elahi, T. A1 - Lübkemann, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Luminescence encoding of polymer microbeads with organic dyes and semiconductor quantum dots during polymerization N2 - Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5–2.5 μm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate. KW - Polymerization KW - Quantum dots KW - Microbeads KW - Fluorescence PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-553430 DO - https://doi.org/10.1038/s41598-022-16065-x SN - 2045-2322 VL - 12 SP - 1 EP - 16 PB - Nature Publishing Group CY - London AN - OPUS4-55343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - 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 - Wen, Keqing A1 - Gorbushina, Anna A1 - Schwibbert, Karin A1 - Bell, Jérémy T1 - Microfluidic platform with precisely controlled hydrodynamic parameters and integrated features for generation of microvortices to accurately form and monitor biofilms in flow N2 - Microorganisms often live in habitats characterized by fluid flow, and their adhesion to surfaces in industrial systems or clinical settings may lead to pipe clogging, microbially influenced corrosion, material deterioration, food spoilage, infections, and human illness. Here, a novel microfluidic platform was developed to investigate biofilm formation under precisely controlled (i) cell concentration, (ii) temperature, and (iii) flow conditions. The developed platform central unit is a single-channel microfluidic flow cell designed to ensure ultrahomogeneous flow and condition in its central area, where features, e.g., with trapping properties, can be incorporated. In comparison to static and macroflow chamber assays for biofilm studies, microfluidic chips allow in situ monitoring of biofilm formation under various flow regimes and have better environment control and smaller sample requirements. Flow simulations and experiments with fluorescent particles were used to simulate bacteria flow in the platform cell for calculating flow velocity and direction at the microscale level. The combination of flow analysis and fluorescent strain injection in the cell showed that microtraps placed at the center of the channel were efficient in capturing bacteria at determined positions and to study how flow conditions, especially microvortices, can affect biofilm formation. The microfluidic platform exhibited improved performances in terms of homogeneity and robustness for in vitro biofilm formation. We anticipate the presented platform to be suitable for broad, versatile, and high-throughput biofilm studies at the microscale level. KW - Topographical pattern KW - E. coli KW - Fluorescence KW - Bacteria trapping KW - Particle velocimetry PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610450 DO - https://doi.org/10.1021/acsbiomaterials.4c00101 SN - 2373-9878 VL - 10 IS - 7 SP - 4626 EP - 4634 PB - ACS Publ. CY - Washington, DC AN - OPUS4-61045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromer, C. A1 - Schwibbert, Karin A1 - Gadicherla, A. K. A1 - Thiele, Dorothea A1 - Nirmalananthan-Budau, Nithiya A1 - Laux, P. A1 - Resch-Genger, Ute A1 - Luch, A. A1 - Tschiche, H. R. T1 - Monitoring and imaging pH in biofilms utilizing a fluorescent polymeric nanosensor N2 - Biofilms are ubiquitous in nature and in the man-made environment. Given their harmful effects on human health, an in-depth understanding of biofilms and the monitoring of their formation and growth are important. Particularly relevant for many metabolic processes and survival strategies of biofilms is their extracellular pH. However, most conventional techniques are not suited for minimally invasive pH measurements of living biofilms. Here, a fluorescent nanosensor is presented for ratiometric measurements of pH in biofilms in the range of pH 4.5–9.5 using confocal laser scanning microscopy. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with pH-inert dye Nile Red and is surface functionalized with a pH-responsive fluorescein dye. Its performance was validated by fluorometrically monitoring the time-dependent changes in pH in E. coli biofilms after glucose inoculation at 37 °C and 4 °C. This revealed a temperature-dependent decrease in pH over a 4-h period caused by the acidifying glucose metabolism of E. coli. These studies demonstrate the applicability of this nanosensor to characterize the chemical microenvironment in biofilms with fluorescence methods. KW - Dye KW - Fluorescence KW - Signal enhancement KW - Sensor KW - Quantum yield KW - Synthesis KW - Nanoparticle KW - Nano KW - Polymer KW - Ph KW - Biofilm KW - MIC KW - Corrosion KW - Microorganism KW - Bacteria PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550751 DO - https://doi.org/10.1038/s41598-022-13518-1 SN - 2045-2322 VL - 12 IS - 1 SP - 1 EP - 10 PB - Nature Publishing Group CY - London AN - OPUS4-55075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - 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 - Climent Terol, Estela A1 - Biyikal, Mustafa A1 - Gröninger, Delia A1 - Weller, Michael G. A1 - Martínez Mánez, R. A1 - Rurack, Knut ED - Climent Terol, Estela T1 - Multiplexed Detection of Analytes on Single Test Strips with Antibody-Gated Indicator-Releasing Mesoporous Nanoparticles N2 - Rapid testing methods for the use directly at apointof need are expected to unfold their true potential especiallywhen offering adequate capabilities for the simultaneousmeasurement of multiple analytes of interest. Considering theunique modularity,high sensitivity,and selectivity of antibody-gated indicator delivery (gAID) systems,amultiplexed assayfor three small-molecule explosives (TATP, TNT,PETN) wasthus developed, allowing to detect the analytes simultaneouslywith asingle test strip at lower ppb concentrations in the liquidphase in < 5min using afluorescence reader or asmartphonefor readout. While the TNT and PETN systems were newlydeveloped here,all the three systems also tolerated harshermatrices than buffered aqueous model solutions.Besidesasingle-track strip,the outstanding modularity of the hybridbiosensor materials in combination with strip-patterningtechnologies allowed us to obtain amultichannel strip inastraightforwardmanner,offering comparable analyticalperformance while allowing to be tailored even more to theusersneed. KW - Multiplexing KW - Explosives detection KW - Gated materials KW - Fluorescence PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518424 DO - https://doi.org/10.1002/anie.202009000 SN - 1433-7851 SN - 1521-3773 VL - 59 IS - 52 SP - 23862 EP - 23869 PB - Wiley-VCH CY - Weinheim AN - OPUS4-51842 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 - Liu, Y. A1 - Qiao, X. A1 - Wen, J. A1 - Resch-Genger, Ute A1 - Long, W. A1 - Ou, J. T1 - NaYF4:Yb3+/Tm3+@NaYF4:Yb3+ Upconversion Nanoparticles for Optical Temperature Monitoring and Self-Heating in Photothermal Therapy N2 - The core−shell NaYF4:Yb3+/Tm3+@NaYF4:Yb3+ upconversion nanoparticles were successfully prepared by a solvothermal method, and a layer of mesoporous silica (mSiO2) was successfully coated on the periphery of the core−shell nanoparticles to transform their surface from lipophilic to hydrophilic, further expanding their applications in biological tissues. The physical phase, morphology, structure, and fluorescence properties were characterized by X-ray diffraction (XRD), field emission transmission electron microscopy (TEM), Fourier infrared spectroscopy (FT-IR), ζ potential analysis, and fluorescence spectroscopy. It was found that the material has a hexagonal structure with good hydrophilicity and emits intense fluorescence under 980 nm pump laser excitation. The non-contact temperature sensing performance of nanoparticles was evaluated by analyzing the upconversion fluorescence of Tm3+ (1G4 → 3F4 and 3F3 → 3H6) in the temperature range of 284−344 K. The absolute and relative sensitivities were found to be 0.0067 K−1 and 1.08 % K−1, respectively, with high-temperature measurement reliability and good temperature cycling performance. More importantly, its temperature measurement in phosphate-buffered saline (PBS) solution is accurate. In addition, the temperature of the cells can be increased by adjusting the laser power density and laser irradiation time. Therefore, an optical temperature sensing platform was built to realize the application of real-time monitoring of cancer cell temperature and the dual function of photothermal therapy. KW - Sensor KW - Temperature KW - Lanthanide KW - Tag KW - Fluorescence KW - Nanoparticles KW - Synthesis KW - Environment KW - Monitoring KW - Sensing KW - Nano KW - Life sciences KW - Upconversion PY - 2023 DO - https://doi.org/10.1021/acsanm.2c05110 VL - 6 IS - 1 SP - 759 EP - 771 PB - ACS Publications AN - OPUS4-57081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chazeau, E. A1 - Pipier, A. A1 - Wegner, Karl David A1 - Ghiringhelli, F. A1 - Sancey, L. A1 - Paul, C. A1 - Goze, C. T1 - NIR-II aza-BODIPY Platform for the Development of a Fluorescent Antibody Drug Conjugate N2 - Real-time imaging of antibody-drug conjugates (ADCs) offers valuable insights for assessing tumor targeting specificity, monitoring therapeutic efficacy, and detecting off-target accumulation that may cause adverse effects. To enable precise tracking, we developed a versatile fluorescent platform based on an NIR-II emitting aza-BODIPY dye, which can be site-specifically grafted onto an IgG1 antibody to generate well-defined fluorescent ADCs. As a proof of concept, we synthesized an HER2-targeting trastuzumab immunoconjugate bearing a NIR-II aza-BODIPY fluorophore. The cytotoxic monomethyl auristatin E (MMAE) payload was introduced in the final step, resulting in a trackable and homogeneous ADC suitable for both in vitro and in vivo investigations. The resulting Trastu-azaNIRII-MMAE selectively accumulated in HER2-positive subcutaneous tumors, significantly reducing the tumor growth. Using NIR-II optical imaging, a single injection of the NIR-II-ADC allowed for the detection of the conjugate over a period of more than one month, highlighting its potential for long-term tracking and therapeutic applications. KW - NIR-II KW - Fluorescence KW - Quality assurance KW - Antibody drug conjugate KW - In vivo imaging PY - 2025 DO - https://doi.org/10.1021/acs.jmedchem.4c02777 VL - 68 IS - 7 SP - 7232 EP - 7242 PB - ACS Publications AN - OPUS4-63025 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mansurova, Maria A1 - Johann, Sergej A1 - Kohlhoff, Harald A1 - Rurack, Knut A1 - Bartholmai, Matthias A1 - Bell, Jérémy T1 - On-Site Analytical Tool Based on Crude Oil Fluorescence and Chemometrics for the Rapid Determination of the Nature and Essential Properties of Oil Spills N2 - With the reduction of large oil spills because of stricter regulations and safety measures, the question of how to manage smaller oil spills arises. Few on-site analytical tools are available for first responders or other law enforcement personnel to rapidly test for crude oil in the early management of localized polluted areas. The approach reported here relies on well-described computer-assisted multivariate data analysis of the intrinsic fluorescence fingerprints of crude oils to build a multivariate model for the rapid classification of crude oils and the prediction of their properties. Thanks to a dedicated robust portable reader, the method allowed classification and accurate prediction of various properties of crude oil samples like density (according to API, the American Petroleum Institute and viscosity as well as composition parameters such as volume fractions of paraffins or aromatics. In this way, autonomous operation in on-site or in-the-field applications becomes possible based on the direct (undiluted and untreated) measurement of samples and a rapid, tablet-operated readout system to yield a robust and simple analytical test with superior performance. Testing in real-life scenarios allowed the successful classification and prediction of a number of oil spill samples as well as weathered samples that closely resemble samples collected by first responders. KW - Oil spills KW - Fluorescence KW - PCA KW - Petroleum KW - Rapid test KW - Portable PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595442 DO - https://doi.org/10.1021/acsestwater.3c00648 VL - 4 IS - 2 SP - 621 EP - 627 PB - American Chemical Society (ACS) AN - OPUS4-59544 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 - 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 - Wang, Z. A1 - Wegner, Karl David A1 - Stiegler, L. M. S. A1 - Zhou, X. A1 - Rezvani, A. A1 - Odungat, A. S. A1 - Zubiri, B. A. A1 - Wu, M. A1 - Spiecker, E. A1 - Walter, J. A1 - Resch-Genger, Ute A1 - Segets, D. T1 - Optimizing the Shelling Process of InP/ZnS Quantum Dots Using a Single-Source Shell Precursor: Implications for Lighting and Display Applications N2 - InP/ZnS core/shell quantum dots (QDs), recognized as highly promising heavy-metal-free emitters, are increasingly being utilized in lighting and display applications. Their synthesis in a tubular flow reactor enables production in a highly efficient, scalable, and reproducible manner, particularly when combined with a single-source shell precursor, such as zinc diethyldithiocarbamate (Zn(S2CNEt2)2). However, the photoluminescence quantum yield (PLQY) of QDs synthesized with this route remains significantly lower compared with those synthesized in batch reactors involving multiple steps for the shell growth. Our study identifies the formation of absorbing, yet nonemissive ZnS nanoparticles during the ZnS shell formation process as a main contributing factor to this discrepancy. By varying the shelling conditions, especially the shelling reaction temperature and InP core concentration, we investigated the formation of pure ZnS nanoparticles and their impact on the optical properties, particularly PLQY, of the resultant InP/ZnS QDs through ultraviolet−visible (UV−vis) absorption, steady-state and time-resolved photoluminescence (PL) spectroscopy, scanning transmission electron microscopy (STEM), and analytical ultracentrifugation (AUC) measurements. Our results suggest that process conditions, such as lower shelling temperatures or reduced InP core concentrations (resulting in a lower external surface area), encourage homogeneous nucleation of ZnS. This reduces the availability of shell precursors necessary for effective passivation of the InP core surfaces, ultimately resulting in lower PLQYs. These findings explain the origin of persistently underperforming PLQY of InP/ZnS QDs synthesized from this synthesis route and suggest further optimization strategies to improve their emission for lighting and display applications. KW - Nano KW - Particle KW - Synthesis KW - InP KW - Shell KW - Fluorescence KW - Quantum yield KW - ZnS KW - Semiconductor KW - Quantum dot KW - Flow reactor KW - Method KW - AUC KW - Size KW - Automation KW - Sensor PY - 2024 DO - https://doi.org/10.1021/acsanm.4c05265 SN - 2574-0970 VL - 7 IS - 20 SP - 24262 EP - 24273 PB - ACS Publications AN - OPUS4-61518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Gawlitza, Kornelia A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Polymerizable BODIPY probe crosslinker for the molecularly imprinted polymer-based detection of organic carboxylates via fluorescence N2 - This contribution reports the development of a polymerizable BODIPY-type fluorescent probe targeting small-molecule carboxylates for incorporation into molecularly imprinted polymers (MIPs). The design of the probe crosslinker includes a urea recognition site p-conjugated to the 3-position of the BODIPY core and two methacrylate moieties. Titration experiments with a carboxylate-expressing antibiotic, levofloxacin (LEVO), showed a blue shift of the absorption band as well as a broadening and decrease in emission, attributed to hydrogen bonding between the probe’s urea group and the carboxylate group of the antibiotic. Using this probe crosslinker, core–shell particles with a silica core and a thin MIP shell were prepared for the detection of LEVO. The MIP exhibited highly selective recognition of LEVO, with an imprinting factor of 18.1 compared to the non-imprinted polymer. Transmission electron microscopy confirmed the core–shell structure and spectroscopic studies revealed that the receptor’s positioning leads to a unique perturbation of the polymethinic character of the BODIPY chromophore, entailing the favourable responses. These features are fully preserved in the MIP, whereas no such response was observed for competitors such as ampicillin. The sensory particles allowed to detect LEVO down to submicromolar concentrations in dioxane. We have developed here for the first time a BODIPY probe for organic carboxylates and incorporated it into polymers using the imprinting technique, paving the way for BODIPY-type fluorescent MIP sensors. KW - Fluorescence KW - BODIPY probe KW - Molecularly Imprinted Polymers KW - Sensor Materials KW - Dyes KW - Water analysis KW - Advanced materials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598629 DO - https://doi.org/10.1039/D3MA00476G SP - 1 EP - 11 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tavernaro, Isabella A1 - Rajotte, Isabelle A1 - Thibeault, Marie-Pier A1 - Sander, Philipp C. A1 - Kodra, Oltion A1 - Lopinski, Gregory A1 - Radnik, Jörg A1 - Johnston, Linda J. A1 - Brinkmann, Andreas A1 - Resch-Genger, Ute T1 - Quantifying surface groups on aminated silica nanoparticles of different size, surface chemistry, and porosity with solution NMR, XPS, optical assays, and potentiometric titration N2 - We assessed the quantification of surface amino functional groups (FGs) for a large set of commercial and custom-made aminated silica nanoparticles (SiO2 NPs) with sizes of 20–100 nm, prepared with different sol–gel routes, different amounts of surface amino FGs, and different porosity with four methods providing different, yet connected measurands in a bilateral study of two laboratories, BAM and NRC, with the overall aim to develop standardizable measurements for surface FG quantification. Special emphasis was dedicated to traceable quantitative magnetic resonance spectroscopy (qNMR) performed with dissolved SiO2 NPs. For the cost efficient and automatable screening of the amount of surface amino FGs done in a first step of this study, the optical fluorescamine assay and a potentiometric titration method were utilized by one partner, i.e., BAM, yielding the amount of primary amino FGs accessible for the reaction with a dye precursor and the total amount of (de)protonatable FGs. These measurements, which give estimates of the minimum and maximum number of surface amino FGs, laid the basis for quantifying the amount of amino silane molecules with chemo-selective qNMR with stepwise fine-tuned workflows, involving centrifugation, drying, weighting, dissolution, measurement, and data evaluation steps jointly performed by BAM and NRC. Data comparability and relative standard deviations (RSDs) obtained by both labs were used as quality measures for method optimization and as prerequisites to identify method-inherent limitations to be later considered for standardized measurement protocols. Additionally, the nitrogen (N) to silicon (Si) ratio in the near-surface region of the SiO2 NPs was determined by both labs using X-ray photoelectron spectroscopy (XPS), a well established surface sensitive analytical method increasingly utilized for microparticles and nano-objects which is currently also in the focus of international standardization activities. Overall, our results underline the importance of multi-method characterization studies for quantifying FGs on NMs involving at least two expert laboratories for effectively identifying sources of uncertainty, validating analytical methods, and deriving NM structure–property relationships. KW - Advanced Materials KW - Amino Groups KW - Calibration KW - Characterization KW - Functional groups KW - Method Comparison KW - Nano Particle KW - Validation KW - XPS KW - Optical Assay KW - Quantification KW - Surface Analysis KW - Reference Materials KW - Synthesis KW - Fluorescence PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-649992 DO - https://doi.org/10.1039/d5na00794a VL - 7 IS - 21 SP - 6888 EP - 6900 PB - Royal Society of Chemistry AN - OPUS4-64999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kang, Y. A1 - Nack, L. M. A1 - Liu, Y. A1 - Qi, B. A1 - Huang, Y. A1 - Liu, Z. A1 - Chakraborty, I. A1 - Schulz, F. A1 - Ahmed, A. A. A. A1 - Poveda, M. C. A1 - Hafizi, F. A1 - Roy, S. A1 - Mutas, M. A1 - Holzapfel, M. A1 - Sanchez-Cano, C. A1 - Wegner, Karl David A1 - Feliu, N. A1 - Parak, W. J. T1 - Quantitative considerations about the size dependence of cellular entry and excretion of colloidal nanoparticles for different cell types N2 - Most studies about the interaction of nanoparticles (NPs) with cells have focused on how the physicochemical properties of NPs will influence their uptake by cells. However, much less is known about their potential excretion from cells. However, to control and manipulate the number of NPs in a cell, both cellular uptake and excretion must be studied quantitatively. Monitoring the intracellular and extracellular amount of NPs over time (after residual noninternalized NPs have been removed) enables one to disentangle the influences of cell proliferation and exocytosis, the major pathways for the reduction of NPs per cell. Proliferation depends on the type of cells, while exocytosis depends in addition on properties of the NPs, such as their size. Examples are given herein on the role of these two different processes for different cells and NPs. KW - Cell proliferation KW - Exocytosis KW - Gold nanoparticles KW - Quantum dots KW - Fluorescence KW - Uptake studies PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543476 DO - https://doi.org/10.1007/s40828-021-00159-6 SN - 2199-3793 VL - 8 IS - 1 SP - 1 EP - 8 PB - Springer CY - Berlin AN - OPUS4-54347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -