TY - JOUR A1 - Giannakopoulos, Antonios E. A1 - Zisis, Athanasios A1 - Zervaki, Anna D. A1 - Dimopoulos, Christos D. A1 - Platypodis, Efstathios A1 - Eberwein, Robert T1 - Effective elastic moduli and failure mechanisms of a random assembly of thin walled glass microbubbles N2 - In this work a methodology is presented to estimate the elastic properties and failure mechanisms of an assembly of random, brittle microbubbles. The approach is based on the mechanics of frictionless micro-contact between hollow spherical shells by employing relations from classical shell theory and verified by two dimensional axisymmetric Finite Elements. The estimated values are in agreement with available experimental values. Moreover, a granular type analytical homogenization model provides an isotropic elastic constitutive law to be used for the macroscopic deformation of an assembly of glass micro-bubbles when it is compressed by external loads. In addition, approximate estimates are also proposed for two important micro-failure mechanisms of such assemblies that relate either to the splitting or to the buckling of a brittle spherical shell, prior its complete crushing. The results are novel and are expected to enhance the application of glass microbubbles directly in acute thermal insulation problems such as liquid hydrogen storage. KW - LH2 KW - Cryogenic Vessels KW - Insulation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634354 DO - https://doi.org/10.1016/j.ijsolstr.2025.113528 SN - 0020-7683 VL - 320 SP - 1 EP - 11 PB - Elsevier BV CY - Amsterdam AN - OPUS4-63435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hildebrandt, Jana T1 - Aqueous Dispersions of polypropylene as possible reference material for nanoplastics N2 - Plastic debris in micron and nanometer scale pollutes the nature all over the world. The potential dangers of these pollutants remain unpredictable. While risk assessment studies on microplastics are already popular, nanoplastic has not yet reached the same focus of investigation. The reason for this difference is simple: There is a "methodological gap" in the analytics of plastic particles with a diameter smaller than 1 µm. Submicron and nanoplastic particles are currently not detectable in environmental matrices. Therefore, it is important for researchers to have a well-characterized nanoplastic material, that serves as a reference for nanoplastics found in nature. Our aim was to synthesize nanoplastics made from the most common used plastics such as polypropylene (PP). We found an easy way to form nanoparticles consisting of PP (nano-PP), adapting and improving the method presented for polystyrene (PS). Nano-PP was formed via a top-down method where the polymer was dispersed to acetone and then transferred to water. No additional surfactant is needed to obtain a dispersion which is stable for more than 35 weeks. The success of forming nanoplastics and their size was detected via scattering methods, predominantly dynamic light scattering (DLS). The chemical analysis of the nanoplastics was performed via Fourier Transform Infrared spectroscopy. To examine the good stability of the nanoparticles, zeta potential measurements were performed, which revealed zeta potentials of -30 to -40 mV. T2 - European Polymer Congress 2022 CY - Prag, Czechia DA - 26.06.2022 KW - Nanoplastic PY - 2022 AN - OPUS4-55960 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sieg, H. A1 - Klusmann, L. A1 - Ellermann, A. L. A1 - Böhmert, L. A1 - Thünemann, Andreas A1 - Braeuning, A. T1 - Counterions determine uptake and effects of aluminum in human intestinal and liver cells N2 - Aluminum (Al) is highly abundant in the biosphere and can occur in different physico-chemical states. It is present in human food and undergoes transitions between dissolved and particulate species during the passage of the gastrointestinal tract. Moreover, in a complex matrix such as food different inorganic and organic counterions can affect the chemical behavior of Al following oral uptake. In this work, the effects of different counterions, namely chloride, citrate, sulfate, lactate and acetylacetonate, on Al uptake and toxicity in the human intestine are studied. The respective Al salts showed different dissolution behavior in biological media and formed nanoscaled particles correlating in reverse with the amount of their dissolved fraction. The passage through the intestinal barrier was studied using a Caco-2 Transwell® system, showing counterion-dependent variance in cellular uptake and transport. In addition, Al toxicity was investigated using Al species (Al3+, metallic Al0 and oxidic γAl2O3 nanoparticles) and counterions individually or in mixtures on Caco-2 and HepG2 cells. The strongest toxicity was observed using a combination of Al species, depending on solubility, and the lipophilic counterion acetylacetonate. Notably, only the combination of both led to toxicity, while both substances individually did not show toxic effects. A toxification of previously non-toxic Al-species by the presence of acetylacetonate is shown here for the first time. The dependency on the concentration of free Al ions was demonstrated using sodium hydrogen phosphate, which was able to counteract the toxic effects by complexing free Al ions. These findings, using Al salts as an example for a common food contaminant, underline the importance of a consideration of the chemical properties of human nutrition, especially dissolution and hydrophobicity, which can significantly influence the cellular uptake and effects of xenobiotic substances. KW - SAXS KW - Small-angle X-ray scattering KW - Nanoparticle PY - 2022 DO - https://doi.org/10.1016/j.tiv.2021.105295 VL - 79 SP - 1 EP - 7 PB - Elsevier AN - OPUS4-54110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hörmann, Anja Franziska T1 - Next Level Grazing Incidence, Part I: Standardization of Calibration and Alignment for Grazing Incidence Small-Angle (X-ray) Scattering N2 - We present initial results of our survey on grazing incidence methods which focuses on hardware, software, sample alignment and instrument calibration. We illustrate both sample alignment and sample-to-detector distance calibration with data recorded at the MOUSE and conclude with promising results from our Bayesian beam optimization procedure based on Gaussian Process regression. T2 - XIX edition of the International Small-Angle Scattering Conference (SAS2024) CY - Taipei, Taiwan DA - 04.11.2024 KW - Standardisation KW - Grazing incidence KW - Sample alignment KW - Instrument calibration PY - 2024 AN - OPUS4-62775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ihlenburg, R. B. J. A1 - Mai, T. A1 - Thünemann, Andreas A1 - Baerenwald, R. A1 - Saalwächter, K. A1 - Koetz, J. A1 - Taubert, A. T1 - Sulfobetaine Hydrogels with a Complex Multilength-Scale Hierarchical Structure N2 - Hydrogels with a hierarchical structure were prepared from a new highly water-soluble crosslinker N,N,N′,N′-tetramethyl-N,N′-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and from the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The free radical polymerization of the two compounds is rapid and yields near-transparent hydrogels with sizes up to 5 cm in diameter. Rheology shows a clear correlation between the monomer-to-crosslinker ratio and the storage and loss moduli of the hydrogels. Cryo-scanning electron microscopy, low-field nuclear magnetic resonance (NMR) spectroscopy, and small-angle X-ray scattering show that the gels have a hierarchical structure with features spanning the nanometer to the sub-millimeter scale. The NMR study is challenged by the marked inhomogeneity of the gels and the complex chemical structure of the sulfobetaine monomer. NMR spectroscopy shows how these complications can be addressed via a novel fitting approach that considers the mobility gradient along the side chain of methacrylate-based monomers. KW - Small-angle X-ray scattering KW - SAXS KW - Gel PY - 2021 DO - https://doi.org/10.1021/acs.jpcb.0c10601 SN - 1520-6106 VL - 125 IS - 13 SP - 3398 EP - 3408 PB - American Chemical Society AN - OPUS4-52403 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hildebrandt, Jana T1 - PP Nanoplastics Dispersed In Water As Reference Materials N2 - Plastic debris in micron and nanometer scale pollutes the nature all over the world. The potential dangers of these pollutants remain unpredictable. While risk assessment studies on microplastic are already popular, nanoplastic has not yet reached the same focus of investigation. The reason for this difference is simple: There is a “methodological gap” in the analytics of plastic particles with a diameter smaller than 1 µm. Submicron and nano plastic particles are currently not detectable in environmental matrices. Therefore, it is important for researchers to have a well-characterized nanoplastic material, that serves as a reference for nanoplastic found in nature. Our aim was to synthesize nanoplastics made from the most common used plastics, starting with polypropylene (PP). We found an easy way to form nanoparticles consisting of PP (nano-PP), adapting and improving the method presented for polystyrene (PS). PP was dispersed to acetone and then transferred to water. No additional surfactant is needed to obtain a dispersion which is stable for more than 35 weeks. The The success of forming nanoplastics and their size was detected via scattering methods, predominantly dynamic light scattering (DLS). To examine the good stability of the nanoparticles, zeta potential measurements were performed, which revealed zeta potentials of -30 to -40 mV. This method is repeatable and well suited to produce reference material, as which we propose our prepared particles, based on a homogeneity study, that we performed, following the ISO Guide 35 for reference materials. T2 - Prague Meeting on Macromolecules 2022 CY - Prag, Czechia DA - 24.07.2022 KW - Nanoplastic KW - Reference material PY - 2022 AN - OPUS4-55961 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hildebrandt, Jana T1 - Aqueous dispersions of polypropylene: towards referencematerials for nanoplastics characterization N2 - Plastic pollution in the environment is a rising concern for the health of our planet. The plastic litter that pollutes our environment leads to microplastic particles. They can be found (nearly) everywhere. The processes that lead to microplastic can also form nanoplastic particles, which have a size below 1 µm. Because of the small size they can penetrate tissue more easily. Only few risk assessment studies of nanoplastics were carried out so far. Using polystyrene (PS) nanoparticles to test effects on organisms is easy because it is commercially available. However, this falls a little short, as the polyolefins i.e., polypropylene (PP) and polyethylene (PE), are produced in a larger proportion than PS. Moreover, these plastics are mainly used for disposable products, which means that they also account for a large proportion of plastic waste. Therefore, the percentage of polyolefins in environmental nanoplastic is presumably high. It is important to test the toxicological effects also with nanoplastics made of PP and PE to have more realistic results. Herein, we present an easy and repeatable method to prepare an aqueous dispersion of polypropylene nanoplastics (nano-PP). They are stabilized electrostatically, resulting in a strongly negative zeta potential of -43 mV (± 2 mV) and making no surfactant necessary to keep the dispersion stable. The size and the size distribution were determined via Dynamic Light Scattering (DLS) and gives a hydrodynamic diameter of 180.5 nm (± 5.8 nm) and a PDI of 0.084 (± 0.023). Finally, ca. 480 bottles of the dispersion with a volume of 10 mL each were prepared to serve as a potential reference material for further testing of detection methods or risk assessments. T2 - International Conference on Microplastic Pollution in the Mediterranean Sea CY - Neapel, Italy DA - 25.09.2022 KW - Nanoplastic PY - 2022 AN - OPUS4-55963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hildebrandt, Jana T1 - Polypropylene and polyethylene nanoplastics in water N2 - Considering the huge amount of plastics, that is produced and thrown away all over the world every day, an increasing part of the society became aware of microplastic and its possible impact on the environment. Polymer particles smaller than 1 µm are called nanoplastic. Due to their small size they form a special group within particulate waste. Their high specific surface makes it easier for them to penetrate tissue and pose potential harm. On the other hand, the size and the chemical structure make it difficult to detect and analyze nanoplastics in nature. Furthermore, the concentrations in environmental samples are very low. Therefore, there is a need for a well-characterized nanoplastic material, that serves as a reference for nanoplastic found in nature. T2 - Tag der Chemie 2021 Uni Potsdam CY - Online meeting DA - 06.07.2021 KW - Nanoplastic PY - 2021 AN - OPUS4-53775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Kulow, Anicó A1 - Kabelitz, Anke A1 - Grunewald, C. A1 - Seidel, R. A1 - Chapartegui-Arias, Ander A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Beyer, S. T1 - Observation of early ZIF-8 crystallization stages with X-ray absorption spectroscopy N2 - The present study investigates early stages of ZIF-8 crystallization up to 5 minutes post mixing of precursor solutions. Dispersive X-ray Absorption Spectroscopy (DXAS) provides a refined understanding of the evolution of the coordination environment during ZIF-8 crystallization. Linear Combination Fiting (LCF) suggests tetrakis(1-methylimidazole)zinc2+ to be a suitable and stable mononuclear structure analogue for some early stage ZIF-8 intermediates. Our results pave the way for more detailed studies on physico-chemical aspects of ZIF-8 crystallization to better control tailoring ZIF-8 materials for specific applications. KW - In-situ KW - XANES KW - ZIF-8 KW - Crystallization PY - 2020 DO - https://doi.org/10.1039/D0SM01356K SN - 1744-6848 VL - 17 IS - 2 SP - 331 EP - 334 PB - Royal Scociety of Chemistry AN - OPUS4-51723 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinekamp, Christian A1 - Kneiske, Sönke A1 - de Oliveira Guilherme Buzanich, Ana A1 - Ahrens, Mike A1 - Braun, Thomas A1 - Emmerling, Franziska T1 - A fluorolytic sol-gel route to access an amorphous Zr fluoride catalyst: A useful tool for C-F bond activation N2 - A route to a ZrF4 catalyst active in room temperature Friedel–Crafts and dehydrofluorination reactions was developed via a fluorolytic sol–gel route, which was followed by a postfluorination step using a stream of CHClF2. The behaviour of different Zr(IV) precursors in a sol–gel reaction with anhydrous isopropanol/HF solution was investigated. The subsequent post-fluorination step was optimised in its temperature ramp and confirmed the necessity of a fluorination of the generated xerogels to obtain catalytic activity. The process is discussed in the context of the analysis of the materials using Brunauer–Emmett–Teller analysis (BET), powder X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The local structure of the amorphous catalyst was elucidated by extended X-ray absorption fine structure spectroscopy (EXAFS). KW - Catalysis KW - Heterogeneous catalysis KW - C-F bond activation KW - Postfluorination PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593433 DO - https://doi.org/10.1039/D3CY01439H SN - 2044-4761 SP - 1 EP - 8 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shasmal, Nilanjana T1 - Effects of Direct femtosecond laser writing on chloroborosilicate glasses doped with Eu3+/Eu2+ and CdS quantum dots N2 - Femtosecond (fs) direct laser writing (DLW) is a promising technique for developing nano-inhomogeneous materials with advanced optical properties and for fabricating novel photonic devices such as integrated waveguides, ultrafast optical switches, phase plates, and 3D optical memory. In this study, DLW was applied to chloroborosilicate glasses that were singly and co-doped with Eu and CdS quantum dots (QDs). The glasses were laser-treated within a very narrow range of experimental conditions, resulting in laser-inscribed sites exhibiting enhanced emission, similar to the glass-ceramics crystallized from the as-prepared glass. In the regions crystalized by DLW a significant reduction of Eu3+ to Eu2+ was verified by photoluminescence spectroscopy. However, the characteristics of the emission bands of Eu2+ changed markedly in the laser-treated sites as compared to the emission spectra of the same glass crystallized by heat treatment. A considerable redshift and splitting of the emission band were observed, attributed to changes in the surrounding environment of the rare earth (RE) ions which was, in turn, attributed to an alteration in the coordination number of Ba2 + and/or Eu2+ as a result of the high-power laser treatment. Although there was an issue with homogeneity of the glass in the micro-level, which restricts some of the aspects of the DLW, these findings suggest the potential for structural modifications through laser treatment, which could be harnessed to create new functionalities for advanced optical applications. T2 - ICG 2025 (27th International Congress on Glass) CY - Kolkata, India DA - 20.01.2025 KW - Femtosecond direct laser writing KW - DLW KW - CdS quantum dots KW - Eu/CdS co-doped glass PY - 2025 AN - OPUS4-65285 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fortes Martin, R. A1 - Thünemann, Andreas A1 - Stockmann, Jörg Manfred A1 - Radnik, Jörg A1 - Koetz, J. T1 - From Nanoparticle Heteroclusters to Filament Networks by Self-Assembly at the Water–Oil Interface of Reverse Microemulsions N2 - Surface self-assembly of spherical nanoparticles of sizes below 10 nm into hierarchical heterostructures is under arising development despite the inherent difficulties of obtaining complex ordering patterns on a larger scale. Due to template-mediated interactions between oil-dispersible superparamagnetic nanoparticles (MNPs) and polyethylenimine-stabilized gold nanoparticles (Au(PEI)NPs) at the water–oil interface of microemulsions, complex nanostructured films can be formed. Characterization of the reverse microemulsion phase by UV–vis absorption revealed the formation of heteroclusters from Winsor type II phases (WPII) using Aerosol-OT (AOT) as the surfactant. SAXS measurements verify the mechanism of initial nanoparticle clustering in defined dimensions. XPS suggested an influence of AOT at the MNP surface. Further, cryo-SEM and TEM visualization demonstrated the elongation of the reverse microemulsions into cylindrical, wormlike structures, which subsequently build up larger nanoparticle superstructure arrangements. Such WPII phases are thus proven to be a new form of soft template, mediating the self-assembly of different nanoparticles in hierarchical network-like filaments over a substrate during solvent evaporation. KW - Small-angle X-ray scattering KW - SAXS KW - Nanoparticle KW - Nano structure PY - 2021 DO - https://doi.org/10.1021/acs.langmuir.1c01348 VL - 37 IS - 29 SP - 8876 EP - 8885 PB - American Chemical Society AN - OPUS4-53034 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tu, Z. A1 - Donskyi, Ievgen A1 - Qiao, H. A1 - Zhu, Z. A1 - Unger, Wolfgang A1 - Hackenberger, C. P. R. A1 - Chen, W. A1 - Adeli, M. A1 - Haag, R. T1 - Graphene Oxide-Cyclic R10 Peptide Nuclear Translocation Nanoplatforms for the Surmounting of Multiple-Drug Resistance N2 - Multidrug resistance resulting from a variety of defensive pathways in Cancer has become a global concern with a considerable impact on the mortality associated with the failure of traditional chemotherapy. Therefore, further research and new therapies are required to overcome this challenge. In this work, a cyclic R10 peptide (cR10) is conjugated to polyglycerol-covered nanographene oxide to engineer a nanoplatform for the surmounting of multidrug resistance. The nuclear translocation of the nanoplatform, facilitated by cR10 peptide, and subsequently, a laser-triggered release of the loaded doxorubicin result in efficient anticancer activity confirmed by both in vitro and in vivo experiments. The synthesized nanoplatform with a combination of different features, including active nucleus-targeting, highloading capacity, controlled release of cargo, and photothermal property, provides a new strategy for circumventing multidrug resistant cancers. KW - Graphen Oxide KW - Nanoplatform KW - Cancer PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510061 DO - https://doi.org/10.1002/adfm.202000933 VL - 30 IS - 35 SP - 2000933 PB - Wiley VCH AN - OPUS4-51006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulka, M.W. A1 - Nie, C. A1 - Nickl, P. A1 - Kerkhoff, Y. A1 - Garg, A. A1 - Salz, D. A1 - Radnik, Jörg A1 - Grunwald, I. A1 - Haag, R. T1 - Surface-Initiated Grafting of Dendritic Polyglycerol from Mussel-Inspired Adhesion-Layers for the Creation of Cell-Repelling Coatings N2 - Biofouling is a major challenge in the application of textiles, biosensors, and biomedical implants. In the current work, a straightforward method for the solvent-free polymerization of antifouling dendritic polyglycerol (dPG) from mussel-inspired dendritic polyglycerol (MI-dPG) coatings on hydrophilic titanium dioxide (TiO2) and hydrophobic polydimethylsiloxane (PDMS) is reported. Surface characterization is performed by static water contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Significant lower CA values are obtained after dPG grafting from MI-dPG-coated TiO2 and MI-dPG coated PDMS. Furthermore, XPS shows a time-dependent increase of the CO bond content upon dPG grafting from MI-dPG-coated TiO2 and MI-dPG-coated PDMS. Analysis of the surface morphology by SEM shows a clear time-dependent increase in the surface roughness upon dPG grafting from MI-dPG-coated TiO2 and MIdPG-coated PDMS. When the viability of two adhesive cell types is studied via LIVE/DEAD staining, a strong reduction in the cell density is observed after the dPG grafting from MI-dPG-coated TiO2 and MI-dPG-coated PDMS (a decrease of >95% in all cases). The combined results show that biocompatible but highly cell-repelling surfaces are efficiently constructed via the grafting of dPG from MI-dPG-coated TiO2 and MI-dPG-coated PDMS. KW - Repelling surface coatings KW - Dendritic polyglycerol KW - Mussel-inspired adhesives KW - Surface-initated grafting PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516590 DO - https://doi.org/10.1002/admi.202000931 SN - 2196-7350 VL - 7 IS - 24 SP - 931 PB - Wiley VCH AN - OPUS4-51659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weigert, Florian A1 - Müller, A. A1 - Häusler, I. A1 - Geißler, Daniel A1 - Skroblin, D. A1 - Unger, Wolfgang A1 - Radnik, Jörg A1 - Resch-Genger, Ute T1 - Combining HR‑TEM and XPS to elucidate the core–shell structure of ultrabright CdSe/CdS semiconductor quantum dots N2 - Controlling thickness and tightness of surface passivation shells is crucial for many applications of core–shell nanoparticles (NP). Usually, to determine shell thickness, core and core/shell particle are measured individually requiring the availability of both nanoobjects. This is often not fulfilled for functional nanomaterials such as many photoluminescent semiconductor quantum dots (QD) used for bioimaging, solid state lighting, and display technologies as the core does not show the applicationrelevant functionality like a high photoluminescence (PL) quantum yield, calling for a whole nanoobject approach. By combining high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), a novel whole nanoobject approach is developed representatively for an ultrabright oleic acid-stabilized, thick shell CdSe/CdS QD with a PL quantum yield close to unity. The size of this spectroscopically assessed QD, is in the range of the information depth of usual laboratory XPS. Information on particle size and monodispersity were validated with dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) and compared to data derived from optical measurements. In addition to demonstrating the potential of this novel whole nanoobject approach for determining architectures of small nanoparticles, the presented results also highlight challenges faced by different sizing and structural analysis methods and method-inherent uncertainties. KW - Photoluminescence KW - Single particle KW - Microscopy KW - Particle architecture KW - Thickness KW - SAXS KW - Shell KW - XPS KW - TEM KW - Semiconductor KW - Quantum dot KW - Photophysics KW - Quantum yield PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517911 DO - https://doi.org/10.1038/s41598-020-77530-z VL - 10 IS - 1 SP - 20712 PB - Springer Nature AN - OPUS4-51791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Anja A1 - Krahl, T. A1 - Radnik, Jörg A1 - Wagner, Andreas A1 - Werner, W. S. M. A1 - Ritter, B. A1 - Kemnitz, E. A1 - Unger, Wolfgang T1 - Chemical in-depth analysis of (Ca/Sr)F2 core–shell like nanoparticles by X-ray photoelectron spectroscopy with tunable excitation energy N2 - The fluorolytic sol–gel synthesis is applied with the intention to obtain two different types of core–shell nanoparticles, namely, SrF2–CaF2 and CaF2–SrF2. In two separate fluorination steps for core and shell formation, the corresponding metal lactates are reacted with anhydrous HF in ethylene glycol. Scanning transmission electron microscopy (STEM) and dynamic light scattering (DLS) confirm the formation of particles with mean dimensions between 6.4 and 11.5 nm. The overall chemical composition of the particles during the different reaction steps is monitored by quantitative Al Kα excitation X-ray photoelectron spectroscopy (XPS). Here, the formation of stoichiometric metal fluorides (MF2) is confirmed, both for the core and the final core–shell particles. Furthermore, an in-depth analysis by synchrotron radiation XPS (SR-XPS) with tunable excitation energy is performed to confirm the core–Shell character of the nanoparticles. Additionally, Ca2p/Sr3d XPS intensity ratio in-Depth profiles are simulated using the software Simulation of Electron Spectra for Surface Analysis (SESSA). In principle, core–shell like particle morphologies are formed but without a sharp interface between calcium and strontium containing phases. Surprisingly, the in-depth chemical distribution of the two types of nanoparticles is equal within the error of the experiment. Both comprise a SrF2-rich core domain and CaF2-rich shell domain with an intermixing zone between them. Consequently, the internal morphology of the final nanoparticles seems to be independent from the synthesis chronology. KW - Metal fluorides KW - Sol-gel synthesis KW - Synchrotron radiation KW - X-ray photoelectron spectroscopy PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522284 DO - https://doi.org/10.1002/sia.6937 SN - 0142-2421 VL - 53 IS - 5 SP - 494 EP - 508 PB - Wiley VCH AN - OPUS4-52228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bennet, Francesca A1 - Müller, Anja A1 - Radnik, Jörg A1 - Hachenberger, Y. A1 - Jungnickel, H. A1 - Laue, P. A1 - Luch, A. A1 - Tentschert, J. T1 - Preparation of Nanoparticles for ToF-SIMS and XPS Analysis N2 - Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, chemistry, and their potential to enable advanced materials. To effectively understand and regulate the physico-chemical properties and potential adverse effects of nanoparticles, validated measurement procedures for the various properties of nanoparticles need to be developed. While procedures for measuring nanoparticle size and size Distribution are already established, standardized methods for analysis of their surface chemistry are not yet in place, although the influence of the surface chemistry on nanoparticle properties is undisputed. In particular, storage and preparation of nanoparticles for surface analysis strongly influences the analytical results from various methods, and in order to obtain consistent results, sample preparation must be both optimized and standardized. In this contribution, we present, in detail, some standard procedures for preparing nanoparticles for surface analytics. In principle, nanoparticles can be deposited on a suitable substrate from suspension or as a powder. Silicon (Si) Wafers are commonly used as substrate, however, their cleaning is critical to the process. For sample preparation from suspension, we will discuss drop-casting and spin-coating, where not only the cleanliness of the substrate and purity of the suspension but also its concentration play important roles for the success of the preparation methodology. For nanoparticles with sensitive ligand shells or coatings, deposition as powders is more suitable, although this method requires particular care in fixing the sample. KW - Titania nanoparticles KW - X-ray photoelectron spectroscopy KW - Secondary ion mass spectrometry KW - Surface chemisttry PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520103 UR - https://www.jove.com/video/61758 DO - https://doi.org/10.3791/61758 VL - 163 SP - e61758 AN - OPUS4-52010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Nie, C. A1 - Ludwig, K. A1 - Trimpert, J. A1 - Ahmed, R. A1 - Quaas, E. A1 - Achazi, K. A1 - Radnik, Jörg A1 - Adeli, M. A1 - Haag, R. A1 - Osterrieder, K. T1 - Graphene Sheets with Defined Dual Functionalities for the Strong SARS-CoV-2 Interactions N2 - Search of new strategies for the inhibition of respiratory viruses is one of the urgent health challenges worldwide, as most of the current therapeutic agents and treatments are inefficient. Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) has caused a pandemic and has taken lives of approximately two Million people to date. Even though various vaccines are currently under development, virus, and especially its spike glycoprotein can mutate, which highlights a Need for a broad-spectrum inhibitor. In this work, inhibition of SARS-CoV-2 by graphene platforms with precise dual sulfate/alkyl functionalities is investigated. A series of graphene derivatives with different lengths of aliphatic chains is synthesized and is investigated for their ability to inhibit SARS-CoV-2 and feline coronavirus. Graphene derivatives with long alkyl chains (>C9) inhibit coronavirus replication by virtue of disrupting viral envelope. The ability of these graphene platforms to rupture viruses is visualized by atomic force microscopy and cryogenic electron microscopy. A large concentration window (10 to 100-fold) where graphene platforms display strongly antiviral activity against native SARS-CoV-2 without significant toxicity against human cells is found. In this concentration range, the synthesized graphene platforms inhibit the infection of enveloped viruses efficiently, opening new therapeutic and metaphylactic avenues against SARS-CoV-2. KW - Graphene KW - Graphene-based polyglycerol sulfates KW - SARS-CoV2 inhibitor KW - Virucidality PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520858 DO - https://doi.org/10.1002/smll.202007091 VL - 17 IS - 11 SP - 7091 PB - Wiley VCH AN - OPUS4-52085 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radnik, Jörg A1 - Knigge, Xenia A1 - Andresen, Elina A1 - Resch-Genger, Ute A1 - Cant, D.J.H. A1 - Shard, A.G. A1 - Clifford, C.A. T1 - Composition, thickness, and homogeneity of the coating of core–shell nanoparticles—possibilities, limits, and challenges of X-ray photoelectron spectroscopy N2 - Core–shell nanoparticles have attracted much attention in recent years due to their unique properties and their increasing importance in many technological and consumer products. However, the chemistry of nanoparticles is still rarely investigated in comparison to their size and morphology. In this review, the possibilities, limits, and challenges of X-ray photoelectron spectroscopy (XPS) for obtaining more insights into the composition, thickness, and homogeneity of nanoparticle coatings are discussed with four examples: CdSe/CdS quantum dots with a thick coating and a small core; NaYF4-based upconverting nanoparticles with a large Yb-doped core and a thin Er-doped coating; and two types of polymer nanoparticles with a poly(tetrafluoroethylene) core with either a poly(methyl methacrylate) or polystyrene coating. Different approaches for calculating the thickness of the coating are presented, like a simple numerical modelling or a more complex simulation of the photoelectron peaks. Additionally, modelling of the XPS background for the investigation of coating is discussed. Furthermore, the new possibilities to measure with varying excitation energies or with hard-energy X-ray sources (hard-energy X-ray photoelectron spectroscopy) are described. A discussion about the sources of uncertainty for the determination of the thickness of the coating completes this review. KW - X-ray spectroscopy KW - Nanoparticles KW - Spectroscopy / Instrumentation KW - Spectroscopy / Theory PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548305 DO - https://doi.org/10.1007/s00216-022-04057-9 VL - 414 IS - 15 SP - 4331 EP - 4345 PB - SpringerNature AN - OPUS4-54830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Page, T.M. A1 - Nie, C. A1 - Neander, L. A1 - Povolotsky, T.L. A1 - Sahoo, A.K. A1 - Nickl, Philip A1 - Adler, J.M. A1 - Bawadkji, O. A1 - Radnik, Jörg A1 - Achazi, K. A1 - Ludwig, K. A1 - Lauster, D. A1 - Netz, R.R. A1 - Trimpert, J. A1 - Kaufer, B. A1 - Haag, R. A1 - Donskyi, Ievgen T1 - Functionalized Fullerene for Inhibition of SARS-CoV-2 Variants N2 - As virus outbreaks continue to pose a challenge, a nonspecific viral inhibitor can provide significant benefits, especially against respiratory viruses. Polyglycerol sulfates recently emerge as promising agents that mediate interactions between cells and viruses through electrostatics, leading to virus inhibition. Similarly, hydrophobic C60 fullerene can prevent virus infection via interactions with hydrophobic cavities of surface proteins. Here, two strategies are combined to inhibit infection of SARS-CoV-2 variants in vitro. Effective inhibitory concentrations in the millimolar range highlight the significance of bare fullerene’s hydrophobic moiety and electrostatic interactions of polysulfates with surface proteins of SARS-CoV-2. Furthermore, microscale thermophoresis measurements support that fullerene linear polyglycerol sulfates interact with the SARS-CoV-2 virus via its spike protein, and highlight importance of electrostatic interactions within it. All-atom molecular dynamics simulations reveal that the fullerene binding site is situated close to the receptor binding domain, within 4 nm of polyglycerol sulfate binding sites, feasibly allowing both portions of the material to interact simultaneously. KW - Covalent functionalization KW - Fullerene KW - SARS-CoV 2 KW - Sulfated materials KW - Virus inhibition PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568672 DO - https://doi.org/10.1002/smll.202206154 SN - 1613-6810 SP - 1 EP - 8 PB - Wiley VCH AN - OPUS4-56867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -