TY - JOUR A1 - Roloff, Alexander A1 - Nirmalananthan-Budau, Nithiya A1 - Rühle, Bastian A1 - Borcherding, H. A1 - Thiele, T. A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Quantification of Aldehydes on Polymeric Microbead Surfaces via Catch and Release of Reporter Chromophores N2 - Aldehyde moieties on 2D-supports or microand nanoparticles can function as anchor groups for the attachment of biomolecules or as reversible binding sites for proteins on cell surfaces. The use of aldehyde-based materials in bioanalytical and medical settings calls for reliable methods to detect and quantify this functionality. We report here on a versatile concept to quantify the accessible aldehyde moieties on particle surfaces through the specific binding and subsequent release of small reporter molecules such as fluorescent dyes and nonfluorescent chromophores utilizing acylhydrazone formation as a reversible covalent labeling strategy. This is representatively demonstrated for a set of polymer microparticles with different aldehyde labeling densities. Excess reporter molecules can be easily removed by washing, eliminating inaccuracies caused by unspecific adsorption to hydrophobic surfaces. Cleavage of hydrazones at acidic pH assisted by a carbonyl trap releases the fluorescent reporters rapidly and quasi-quantitatively and allows for their fluorometric detection at low concentration. Importantly, this strategy separates the signal-generating molecules from the bead surface. This circumvents common issues associated with light scattering and signal distortions that are caused by binding-induced changes in reporter fluorescence as well as quenching dye− dye interactions on crowded particle surfaces. In addition, we demonstrate that the release of a nonfluorescent chromophore via disulfide cleavage and subsequent quantification by absorption spectroscopy gives comparable results, verifying that both assays are capable of rapid and sensitive quantification of aldehydes on microbead surfaces. These strategies enable a quantitative comparison of bead batches with different functionalization densities, and a qualitative prediction of their coupling efficiencies in bioconjugations, as demonstrated in reductive amination reactions with Streptavidin. KW - Fluorescent label KW - Surface group quantification KW - Polymer particle KW - Cleavable linker KW - Catch and release assay PY - 2019 DO - https://doi.org/10.1021/acs.analchem.8b05515 SN - 0003-2700 SN - 1520-6882 VL - 91 IS - 14 SP - 8827 EP - 8834 PB - ACS Publications AN - OPUS4-48284 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schoenhals, Andreas T1 - Dielectric and flash DSC investigations on an epoxy based nanocomposite system with MgAl layered double hydroxide as nanofiller N2 - Nanocomposites based on MgAL layered double hydroxides (LDH) and an epoxy resin were prepared and investigated by a combination of complementary methods. As epoxy resin Bisphenol A diglycidyl ether (DGEBA) was used with Diethylenetriamine as curing agent. The LDH was modified with taurine, which acts as an additional crosslinking agent due to its amine groups. The epoxy resin was cured in a presence of the nanofiller, which was added to the system in various concentrations. X-ray scattering, by combination of SAXS and WAXS was used to characterize the morphology of the obtained nanocomposites. These investigations show that the filler is distributed in the matrix as small stacks of ca. 10 layers. The molecular dynamics of the system, as probe for structure, was investigated by broadband dielectric spectroscopy. In addition to the - and -relaxation (dynamic glass transition), characteristic for the unfilled materials, a further process was found which was assigned to localized fluctuations of segments physically adsorbed or chemically bonded to the nanoparticles. The dielectric -relaxation is shifted to higher temperatures for the nanocomposites in comparison to the pure material but depends weakly on the content of nanoparticles. Further, for the first time Flash DSC was employed to a thermosetting system to investigate the glass transition behavior of the nanocomposites. The heating rates were converted in to relaxation rates. For low concentrations of the nanofiller the thermal data overlap more or less with that of the pure epoxy. For higher concentrations the thermal data are shifted significantly to higher temperatures. This is discussed in terms the cooperativity approach to the glass transition. KW - Nanocomposites KW - Broadband dielectric spectroscopy KW - Flash DSC PY - 2019 DO - https://doi.org/10.1016/j.tca.2019.01.010 SN - 0040-6031 VL - 677 SP - 151 EP - 161 PB - Elsevier AN - OPUS4-48218 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Elert, Anna Maria A1 - Kanerva, M A1 - Puolakka, A A1 - Takala, T.M. A1 - Mylläri, V A1 - Jönkkäri, I A1 - Sarlin, E A1 - Seitsonen, J A1 - Ruokolainen, J A1 - Saris, P A1 - Vuorinen, J T1 - Antibacterial polymer fibres by rosin compounding and melt-spinning N2 - The antibacterial features of natural pine/spruce rosin are well established, yet the functionality in various thermoplastics has not been surveyed. This work focuses on the processing of industrial grade purified rosin mixed with polyethylene (PE), polypropylene (PP), polylactic acid (PLA), polyamide (PA) and corn starch based biopolymer (CS). Homopolymer masterbatches were extrusion-compounded and melt-spun to form fibres for a wide range of products, such as filters, reinforcements, clothing and medical textiles. Due to the versatile chemical structure of rosin, it was observed compatible with all the selected polymers. In general, the rosin-blended systems were shear-thinning in a molten condition. The doped fibres spun of PE and PP indicated adequate melt-spinning capability and proper mechanical properties in terms of ultimate strength and Young's modulus. The antibacterial response was found dependent on the selected polymer. Especially PE with a 10 wt% rosin content showed significant antibacterial effects against Escherichia coli DH5α and Staphylococcus aureus ATCC 12598 when analysed in the Ringer's solution for 24 h. KW - Rosin KW - Antibacterial KW - Thermoplastics PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481785 DO - https://doi.org/10.1016/j.mtcomm.2019.05.003 SN - 2352-4928 VL - 20 SP - 527 EP - 527 PB - Elsevier AN - OPUS4-48178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martynenko, Irina V. ED - Baimuratov, A. S. ED - Weigert, Florian ED - Soares, J. X. ED - Dhamo, Lorena ED - Nickl, Philip ED - Doerfel, I. ED - Pauli, Jutta ED - Rukhlenko, I. D. ED - Baranov, A. V. ED - Resch-Genger, Ute T1 - Photoluminescence of Ag–In–S/ZnS quantum dots: Excitation energy dependence and low-energy electronic structure N2 - Cd-free I–III–VI group semiconductor quantum dots (QDs) like Ag–In–S and Cu–In–S show unstructured absorption spectra with a pronounced Urbach tail, rendering the determination of their band gap energy (Eg) and the energy structure of the exciton difficult. Additionally, the origin of the broad photoluminescence (PL) band with lifetimes of several hundred nanoseconds is still debated. This encouraged us to study the excitation energy dependence (EED) of the PL maxima, PL spectral band widths, quantum yields (QYs), and decay kinetics of AIS/ZnS QDs of different size, composition, and surface capping ligands. These results were then correlated with the second derivatives of the corresponding absorption spectra. The excellent match between the onset of changes in PL band position and spectral width with the minima found for the second derivatives of the absorption spectra underlines the potential of the EED approach for deriving Eg values of these ternary QDs from PL data. The PL QY is, however, independent of excitation energy in the energy range studied. From the EED of the PL features of the AIS/ZnS QDs we could also derive a mechanism of the formation of the low-energy electronic structure. This was additionally confirmed by a comparison of the EED of PL data of as-synthesized and size-selected QD ensembles and the comparison of these PL data with PL spectra of single QDs. These results indicate a strong contribution of intrinsic inhomogeneous PL broadening to the overall emission features of AIS/ZnS QDs originating from radiative transitions from a set of energy states of defects localized at different positions within the quantum dot volume, in addition to contributions from dimensional and chemical broadening. This mechanism was confirmed by numerically modelling the absorption and PL energies with a simple mass approximation for spherical QDs and a modified donor–acceptor model, thereby utilizing the advantages of previously proposed PL mechanisms of ternary QDs. These findings will pave the road to a deeper understanding of the nature of PL in quantum confined I–III–VI group semiconductor nanomaterials. KW - Core/shell quantum dot KW - Silver indium sulfide KW - Defect photoluminescence KW - Photoluminescence quantum yield KW - Single-dot spectroscopy PY - 2019 DO - https://doi.org/10.1007/s12274-019-2398-4 SN - 1998-0124 SN - 1998-0000 VL - 12 IS - 7 SP - 1595 EP - 1603 PB - Springer Nature AN - OPUS4-48503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ghasem Zadeh Khorasani, Media A1 - Elert, Anna Maria A1 - Hodoroaba, Vasile-Dan A1 - Agudo Jácome, Leonardo A1 - Altmann, Korinna A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - Short- and long-range mechanical and chemical interphases caused by interaction of Boehmite (γ-AlOOH) with anhydride-cured epoxy resins N2 - Understanding the interaction between boehmite and epoxy and the formation of their interphases with different mechanical and chemical structures is crucial to predict and optimize the properties of epoxy-boehmite nanocomposites. Probing the interfacial properties with atomic force microscopy (AFM)-based methods, especially particle-matrix long-range interactions, is challenging. This is due to size limitations of various analytical methods in resolving nanoparticles and their interphases, the overlap of interphases, and the effect of buried particles that prevent the accurate interphase property measurement. Here, we develop a layered model system in which the epoxy is cured in contact with a thin layer of hydrothermally synthesized boehmite. Different microscopy methods are employed to evaluate the interfacial properties. With intermodulation atomic force microscopy (ImAFM) and amplitude dependence force spectroscopy (ADFS), which contain information about stiffness, electrostatic, and van der Waals forces, a soft interphase was detected between the epoxy and boehmite. Surface potential maps obtained by scanning Kelvin probe microscopy (SKPM) revealed another interphase about one order of magnitude larger than the mechanical interphase. The AFM-infrared spectroscopy (AFM-IR) technique reveals that the soft interphase consists of unreacted curing agent. The long-range electrical interphase is attributed to the chemical alteration of the bulk epoxy and the formation of new absorption bands. KW - Nanocomposites KW - Interphase KW - Intermodulation AFM KW - Electron microscopy KW - Infrared nano AFM PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483672 UR - https://www.mdpi.com/2079-4991/9/6/853/htm DO - https://doi.org/10.3390/nano9060853 SN - 2079-4991 VL - 9 IS - 6 SP - 853, 1 EP - 20 PB - MDPI AN - OPUS4-48367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Musnier, B. A1 - Wegner, Karl David A1 - Comby-Zerbino, C. A1 - Trouillet, V. A1 - Jourdan, M. A1 - Häusler, I. A1 - Antoine, R. A1 - Coll, J.-L. A1 - Resch-Genger, Ute A1 - Le Guevel, X. T1 - High photoluminescence of shortwave infrared-emitting anisotropic surface charged gold nanoclusters N2 - Incorporating anisotropic surface charges on atomically precise gold nanoclusters (Au NCs) led to a strong absorption in the nearinfrared region and could enable the formation of self-assembled Au NCs xhibiting an intense absorption band at ∼1000 nm. This surface modification showed a striking enhancement of the photoluminescence in the Shortwave Infrared (SWIR) region with a quantum yield as high as 6.1% in water. KW - Gold nanoclusters KW - SWIR photoluminescence KW - Self-assembly PY - 2019 DO - https://doi.org/10.1039/C9NR04120F VL - 11 IS - 25 SP - 12092 EP - 12096 PB - Royal Society of Chemistry AN - OPUS4-48305 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wegner, Karl David A1 - Pouget, S. A1 - Ling, W. L. A1 - Carriere, M. A1 - Reiss, P. T1 - Gallium – a versatile element for tuning the photoluminescence properties of InP quantum dots N2 - With the goal to tune the emission properties of colloidal InP quantum dots, the incorporation of Ga was explored. Unexpectedly, depending on the nature of the gallium precursor, the photoluminescence shifted either to the red (gallium oleate) or to the blue (gallium acetylacetonate). In the first case, larger-sized InP/GaP core/shell nanocrystals were formed, while in the second case the formation of an InGaP alloy structure enabled the blue range of emission (475 nm) to be accessed. KW - Indium phosphide KW - Quantum dots KW - Gallium doping PY - 2019 DO - https://doi.org/10.1039/C8CC09740B VL - 55 IS - 11 SP - 1663 EP - 1666 PB - Royal Society of Chemistry AN - OPUS4-48306 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tarantini, A. A1 - Wegner, Karl David A1 - Dussert, F. A1 - Sarret, G. A1 - Beal, D. A1 - Mattera, L. A1 - Lincheneau, C. A1 - Proux, O. A1 - Truffier-Boutry, D. A1 - Moriscot, C. A1 - Gallet, B. A1 - Jouneau, P.-H. A1 - Reiss, P. A1 - Carriere, M. T1 - Physicochemical alterations and toxicity of InP alloyed quantum dots aged in environmental conditions: A safer by design evaluation N2 - Due to their unique optical properties, quantum dots (QDs) are used in a number of optoelectronic devices and are forecasted to be used in the near future for biomedical applications. The most popular QD composition consists of cadmium selenide (CdSe) or cadmium telluride (CdTe), which has been shown to pose health risks due to the release of toxic cadmium (Cd) ions. Due to similar optical properties but lower intrinsic toxicity, indium phosphide (InP) QDs have been proposed as a safer alternative. Nevertheless, investigations regarding their safety and possible toxicological effects are still in their infancy. The fate and toxicity of seven different water-dispersible indium (In) based QDs, either pristine or after ageing in a climatic chamber, was evaluated. The core of these QDs was composed of indium, zinc and phosphorus (InZnP) or indium, zinc, phosphorus and sulfur (InZnPS). They were assessed either as core-only or as core-shell QDs, for which the core was capped with a shell of zinc, selenium and sulfur (Zn(Se,S)). Their Surface was functionalized using either penicillamine or glutathione. In their pristine form, these QDs showed essentially no cytotoxicity. The particular case of InZnPS QD showed that core-shell QDs were less cytotoxic than core-only QDs. Moreover, surface functionalization with either penicillamine or glutathione did not appreciably influence cytotoxicity but affected QD stability. These QDs did not lead to over-accumulation of reactive oxygen species in exposed cells, or to any oxidative damage to cellular DNA. However, accelerated weathering in a climatic chamber led to QD precipitation and degradation, together with significant cytotoxic effects. Ageing led to dissociation of IneP and ZneS bonds, and to complexation of In Zn ions with carboxylate and/or phosphate moieties. These results show that InZnP and InZnPS alloyed QDs are safer alternatives to CdSe QDs. They underline the necessity to preserve as much as possible the structural integrity of QDs, for instance by developing more robust shells, in order to ensure their safety for future applications. KW - Indium phosphide KW - Safe by design KW - Toxicity KW - EXAFS PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483070 DO - https://doi.org/10.1016/j.impact.2019.100168 VL - 14 SP - 100168-1 EP - 100168-13 PB - Elsevier AN - OPUS4-48307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, J. A1 - Tarábek, J. A1 - Kulkarni, R. A1 - Wang, Cui A1 - Dračínský, M. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Resch-Genger, Ute A1 - Bojdys, M. J. T1 - A π-conjugated, covalent phosphinine framework N2 - Structural modularity of polymer frameworks is a key advantage of covalent organic polymers, however, only C, N, O, Si and S have found their way into their building blocks so far. Here, we expand the toolbox available to polymer and materials chemists by one additional nonmetal, phosphorus. Starting with a building block that contains a λ⁵‐phosphinine (C₅P) moiety, we evaluate a number of polymerisation protocols, finally obtaining a π‐conjugated, covalent phosphinine‐based framework (CPF‐1) via Suzuki‐Miyaura coupling. CPF‐1 is a weakly porous polymer glass (72.4 m2 g‐1 N2 BET at 77 K) with green fluorescence (λmax 546 nm) and extremely high thermal stability. The polymer catalyzes hydrogen evolution from water under UV and visible light irradiation without the need for additional co‐catalyst at a rate of 33.3 μmol h‐¹ g‐¹. Our results demonstrate for the first time the incorporation of the phosphinine motif into a complex polymer framework. Phosphinine‐based frameworks show promising electronic and optical properties that might spark future interest in their applications in light‐emitting devices and heterogeneous catalysis. KW - Phosphinine KW - Fully aromatic frameworks KW - Suzuki-Miyaura coupling KW - Polymers KW - Fluorescence KW - Small-angle scattering PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485330 DO - https://doi.org/10.1002/chem.201900281 SP - 2 EP - 10 PB - Wiley VCH-Verlag CY - Weinheim AN - OPUS4-48533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin T1 - Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation N2 - The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model. KW - Micromagnetism KW - LLG KW - LL equation KW - Landau Lifshitz equation KW - Landau Lifshitz Gilbert equation KW - Stochastic Landau Lifshitz equation KW - Stochastic Landau Lifshitz Gilbert equation KW - Curie temperature KW - Magnetic Nanoparticles KW - Thin film systems KW - Temeprature scaling KW - Phase transition KW - Magnet coupling KW - Ferromagnetism KW - Superparamagnetism KW - Paramagnetism KW - Ni KW - Co KW - Fe KW - Steel KW - Nickel KW - Cobalt KW - Iron KW - Temperature effects KW - Cell size KW - Damping factor KW - Gamma KW - Alpha KW - Spin KW - Magnetic moment KW - Magnetic interacion KW - Magnetization dynamics KW - Domain wall KW - Exchange length KW - temeprature dependent exchange length KW - Bloch wall KW - Neel wall KW - Exchange interaction KW - Magnetic anisotropy KW - Simulation KW - OOMMF KW - Object oriented micromagnetic framework PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-484610 DO - https://doi.org/10.1088/2399-6528/ab31e6 VL - 3 IS - 7 SP - 075009-1 EP - 075009-8 PB - IOPscience CY - England AN - OPUS4-48461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rühle, Bastian A1 - Virmani, E. A1 - Engelke, H. A1 - Hinterholzinger, F. M. A1 - von Zons, T. A1 - Brosent, B. A1 - Bein, T. A1 - Godt, A. A1 - Wuttke, S. T1 - A Chemiluminescent Metal–Organic Framework N2 - The synthesis and characterization of a chemiluminescent metal–organic framework with high porosity is reported. It consists of Zr6O6(OH)4 nodes connected by 4,4′‐(anthracene‐9,10‐diyl)dibenzoate as the linker and luminophore. It shows the topology known for UiO‐66 and is therefore denoted PAP‐UiO. The MOF was not only obtained as bulk material but also as a thin film. Exposure of PAP‐UiO as bulk or film to a mixture of bis‐(2,4,6‐trichlorophenyl) oxalate, hydrogen peroxide, and sodium salicylate in a mixture of dimethyl and dibutyl phthalate evoked strong and long lasting chemiluminescence of the PAP‐UiO crystals. Time dependent fluorescence spectroscopy on bulk PAP‐UiO and, for comparison, on dimethyl 4,4′‐(anthracene‐9,10‐diyl)dibenzoate provided evidence that the chemiluminescence originates from luminophores being part of the PAP‐UiO, including the luminophores inside the crystals. KW - Chemiluminescence KW - Metal–organic framework KW - MOF KW - Thin film KW - UiO PY - 2019 DO - https://doi.org/10.1002/chem.201806041 SN - 0947-6539 VL - 25 IS - 25 SP - 6349 EP - 6354 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-48338 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gao, S. A1 - Hou, J. A1 - Deng, Z. A1 - Wang, T. A1 - Beyer, Sebastian A1 - de Oliveira Guilherme Buzanich, Ana A1 - Richardson, J. J. A1 - Rawal, A. A1 - Seidel, R. A1 - Zulkifli, M. Y. A1 - Li, W. A1 - Bennett, T. D. A1 - Cheetham, A. K. A1 - Liang, K. T1 - Improving the Acidic Stability of Zeolitic Imidazolate Frameworks by Biofunctional Molecules N2 - Zeolitic imidazolate frameworks (ZIFs) have been widely investigated for their use in separation, gas adsorption, catalysis, and biotechnology. Their practical applications, however, can be hampered by their structural instability in humid acidic conditions. Here, guided by density functional theory calculations, we demonstrate that the acidic stability of two polymorphic ZIFs (i.e., ZIF-8 and ZIF-L) can be enhanced by the incorporation of functional groups on polypeptides or DNA. A range of complementary synchrotron investigations into the local chemical structure and bonding environment suggest that the enhanced acidic stability arises from the newly established coordinative interactions between the Zn centers and the inserted carboxylate (for polypeptides) or phosphate (for DNA) groups, both of which have lower pKas than the imidazolate ligand. With functional biomolecular homologs (i.e., enzymes), we demonstrate a symbiotic stability reinforcement effect, i.e., the encapsulated biomolecules stabilize the ZIF matrix while the ZIF exoskeleton protects the enzyme from denaturation. KW - Zeolitic Imidazolate Frameworks KW - Biofunctional Molecules KW - X-ray Absorption Spectroscopy PY - 2019 DO - https://doi.org/10.1016/j.chempr.2019.03.025 VL - 5 IS - 6 SP - 1597 EP - 1608 PB - Elsevier Inc. AN - OPUS4-48702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Azab, W. A1 - Cuellar-Camach, J.L. A1 - Guday, G. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Osterrieder, K. A1 - Adeli, M. A1 - Haag, R. T1 - Functionalized nanographene sheets with high antiviral activity through synergistic electrostatic and hydrophobic interactions N2 - As resistance to traditional drugs emerges for treatment of Virus infections, the need for new methods for virus inhibition increases. Graphene derivatives with large surface areas have shown strong activity against different viruses. However, the inability of current synthetic protocols to accurately manipulate the structure of graphene sheets in order to control their antiviral activity remains a major challenge. In this work, a series of graphene derivatives with defined polyglycerol sulfate and fatty amine functionalities have been synthesized and their interactions with herpes simplex Virus type 1 (HSV-1) are investigated. While electrostatic interactions between polyglycerol sulfate and virus particles trigger the binding of graphene to virus, alkyl chains induce a high antiviral activity by secondary hydrophobic interactions. Among graphene sheets with a broad range of alkyl chains, (C3–C18), the C12-functionalized sheets showed the highest antiviral activity, indicating the optimum synergistic effect between electrostatic and hydrophobic interactions, but this derivative was toxic against the Vero cell line. In contrast, sheets functionalized with C6- and C9-alkyl chains showed low toxicity against Vero cells and a synergistic Inhibition of HSV-1. This study shows that antiviral agents against HSV-1 can be obtained by controlled and stepwise functionalization of graphene sheets and may be developed into antiviral agents for future biomedical applications. KW - Functionalized nanographene KW - X-ray Photoelectron Spectroscopy (XPS) KW - NEXAFS KW - Antiviral activity PY - 2019 DO - https://doi.org/10.1039/c9nr05273a SN - 2040-3364 VL - 11 IS - 34 SP - 15804 EP - 15809 PB - The Royal Society of Chemistry AN - OPUS4-48807 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Modena, Mario M. A1 - Rühle, Bastian A1 - Burg, Thomas P. A1 - Wuttke, Steffan T1 - Nanoparticle characterization: What to measure? N2 - What to measure? is a key question in nanoscience, and it is not straightforward to address as different physicochemical properties define a nanoparticle sample. Most prominent among these properties are size, shape, surface charge, and porosity. Today researchers have an unprecedented variety of measurement techniques at their disposal to assign precise numerical values to those parameters. However, methods based on different physical principles probe different aspects, not only of the particles themselves, but also of their preparation history and their environment at the time of measurement. Understanding these connections can be of great value for interpreting characterization results and ultimately controlling the nanoparticle structure–function relationship. Here, the current techniques that enable the precise measurement of these fundamental nanoparticle properties are presented and their practical advantages and disadvantages are discussed. Some recommendations of how the physicochemical parameters of nanoparticles should be investigated and how to fully characterize these properties in different environments according to the intended nanoparticle use are proposed. The intention is to improve comparability of nanoparticle properties and performance to ensure the successful transfer of scientific knowledge to industrial real‐world applications. KW - Nanoparticle characterization KW - Nanoparticles KW - Porosity KW - Shape KW - Size PY - 2019 DO - https://doi.org/10.1002/adma.201901556 SN - 0935-9648 SN - 1521-4095 VL - 31 IS - 32 SP - 1901556, 1 EP - 26 PB - Wiley AN - OPUS4-49129 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, X. A1 - Schmidt, Franziska A1 - Gurlo, A. T1 - Fabrication of polymer-derived ceramics with hierarchical porosities by freeze casting assisted by thiol-ene click chemistry and HF etching N2 - The freeze casting technique assisted with cryo thiol-ene photopolymerization is successfully employed for the fabrication of macroporous polymer-derived silicon oxycarbide with highly aligned porosity. It is demonstrated that the free radical initiated thiol-ene click reaction effectively cross-linked the vinyl-containing liquid polysiloxanes into infusible thermosets even at low temperatures. Furthermore, mixed solution- and suspension-based freeze casting is employed by adding silica nanopowders. SiOC/SiO2 foams with almost perfect cylindrical shapes are obtained, demonstrating that the presence of nano-SiO2 does not restrict the complete photoinduced cross-linking. The post-pyrolysis HF acid treatments of produced SiOC monoliths yields hierarchical porosities, with SiOC/SiO2 nanocomposites after etching demonstrating the highest specific surface area of 494 m2/g and pore sizes across the macro-, meso- and micropores ranges. The newly developed approach gives a versatile solution for the fabrication of bulk polymer-derived ceramics with controlled porosity. KW - Freeze casting KW - Preceramic polymer KW - Hierarchical porosities KW - Thiol-ene click chemistry KW - Frozen state photopolymerization PY - 2019 DO - https://doi.org/10.1016/j.jeurceramsoc.2019.09.038 SN - 0955-2219 VL - 40 IS - 2 SP - 315 EP - 323 PB - Elsevier AN - OPUS4-49172 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Saloga, Patrick E. J. A1 - Thünemann, Andreas T1 - Microwave-Assisted Synthesis of Ultrasmall Zinc Oxide Nanoparticles N2 - We report on ultrasmall zinc oxide single-crystalline nanoparticles of narrow size distribution and long-term colloidal stability. These oleate-stabilized nanoparticles were synthesized using microwave-assisted synthesis for 5 min, corresponding to a 99% decrease in synthesis time, when compared to the conventional synthesis method. It was observed that the average particle radius increases from 2.6 ± 0.1 to 3.8 ± 0.1 nm upon increasing synthesis temperature from 125 to 200 °C. This change also corresponded to observed changes in the optical band gap and the fluorescence energy of the particles, from 3.44 ± 0.01 to 3.36 ± 0.01 eV and from 2.20 ± 0.01 to 2.04 ± 0.01 eV, respectively. Small-angle X-ray scattering, dynamic light scattering, and UV–vis and fluorescence spectroscopy were employed for particle characterization. Debye–Scherrer analysis of the X-ray diffraction (XRD) pattern reveals a linear increase of the crystallite size with synthesis temperature. The consideration of the convolution of a Lorentz function with a Gaussian function for data correction of the instrumental peak broadening has a considerable influence on the values for the crystallite size. Williamson–Hall XRD analyses in the form of the uniform deformation model, uniform stress deformation model, and uniform deformation energy density model revealed a substantial increase of strain, stress, and deformation energy density of the crystallites with decreasing size. Exponential and power law models were utilized for quantification of strain, stress, and deformation energy density. KW - SAXS KW - Zinc oxide KW - Microwave synthesis KW - Nanoparticles PY - 2019 DO - https://doi.org/10.1021/acs.langmuir.9b01921 SN - 0743-7463 VL - 35 IS - 38 SP - 12469 EP - 12482 PB - American Chemical Society CY - Washington, D.C., USA AN - OPUS4-49136 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwibbert, Karin A1 - Menzel, F. A1 - Epperlein, N. A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Bacterial adhesion on femtosecond laser-modified polyethylene N2 - In this study, femtosecond laser-induced sub-micrometer structures are generated to modify polyethylene (PE) surface topographies. These surfaces were subjected to bacterial colonization studies with Escherichia coli and Staphylococcus aureus as test strains. The results reveal that the nanostructures do not influence S. aureus coverage, while the adhesion of E. coli is reduced. KW - Bacterial adhesion KW - Laser-modified surface KW - Polyethylene KW - Laser-induced nanostructures KW - Biofilm PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492280 DO - https://doi.org/10.3390/ma12193107 VL - 12 IS - 19 SP - 3107 PB - MDPI CY - Basel, Schweiz AN - OPUS4-49228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wegner, Karl David A1 - Dussert, F. A1 - Truffier-Boutry, D. A1 - Benayad, A. A1 - Beal, D. A1 - Mattera, L. A1 - Ling, W. L. A1 - Carrière, M. A1 - Reiss, P. T1 - Influence of the Core/Shell Structure of Indium Phosphide Based Quantum Dots on Their Photostability and Cytotoxicity N2 - With the goal to improve their photostability, InP-based QDs are passivated with three types of inorganic shells, namely (i) a gradient ZnSexS1−x shell, (ii) an additional ZnS shell on top of the gradient shell with two different thicknesses (core/shell/shell, CSS), (iii) an alumina coating on top of ZnS. All three systems have photoluminescence Quantum yields (PLQY) > 50%and similar PL decay times (64–67 ns). To assess their photostability they are incorporated into a transparent poly (methyl methacrylate) (PMMA) matrix and exposed to continuous irradiation with simulated sunlight in a climate chamber. The alumina coated core/shell system exhibits the highest stability in terms of PLQY Retention as well as the lowest shift of the PL maximum and lowest increase of the PL linewidth, followed by the CSS QDs and finally the gradient shell system. By means of XPS studies we identify the degradation of the ZnS outer layer and concomitant xidation of the emissive InZnP core as the main origins of degradation in the gradient structure. These modifications do not occur in the case of the alumina-capped sample, which exhibits excellent chemical stability. The gradient shell and CSS systems could be transferred to the aqueous phase using surface ligand exchange with penicillamine. Cytotoxicity studies on human primary keratinocytes revealed that exposure for 24 h to 6.25–100 nM of QDs did not affect cell viability. However, a trend toward reduced cell proliferation is observed for higher concentrations of gradient shell and CSS QDs with a thin ZnS shell, while CSS QDs with a thicker ZnS shell do not exhibit any impact. KW - Indium phosphide KW - Quantum dots KW - Cytotoxicity KW - Photostability PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494249 DO - https://doi.org/10.3389/fchem.2019.00466 VL - 7 SP - Article Number: 466 PB - Frontiers Media SA AN - OPUS4-49424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wegner, Karl David A1 - Moros, M. A1 - Castillo-Michel, H. A1 - Materra, L. A1 - Onorato, G. A1 - Ling, W. L. A1 - Reiss, P. A1 - Tortiglione, C. T1 - In Vivo Biotransformations of Indium Phosphide Quantum Dots Revealed by X‑Ray Microspectroscopy N2 - Many attempts have been made to synthesize cadmium-free quantum dots (QDs), using nontoxic materials, while preserving their unique optical properties. Despite impressive advances, gaps in knowledge of their intracellular fate, persistence, and excretion from the targeted cell or organism still exist, precluding clinical applications. In this study, we used a simple model organism (Hydra vulgaris) presenting a tissue grade of organization to determine the biodistribution of indium phosphide (InP)-based QDs by X-ray fluorescence imaging. By complementing elemental imaging with In L-edge X-ray absorption near edge structure, unique information on in situ chemical speciation was obtained. Unexpectedly, spectral profiles indicated the appearance of In−O species within the first hour post-treatment, suggesting a fast degradation of the InP QD core in vivo, induced mainly by carboxylate groups. Moreover, no significant difference in the behavior of bare core QDs and QDs capped with an inorganic Zn(Se,S) gradient shell was observed. The results paralleled those achieved by treating animals with an equivalent dose of indium salts, confirming the preferred bonding type of In3+ ions in Hydra tissues. In conclusion, by focusing on the chemical identity of indium along a 48 h long journey of QDs in Hydra, we describe a fast degradation process, in the absence of evident toxicity. These data pave the way to new paradigms to be considered in the biocompatibility assessment of QD-based biomedical applications, with greater emphasis on the dynamics of in vivo biotransformations, and suggest strategies to drive the design of future applied materials for nanotechnology-based diagnosis and therapeutics. KW - Indium phosphide KW - Quantum dots KW - Cytotoxicity KW - X-ray microspectroscopy PY - 2019 DO - https://doi.org/10.1021/acsami.9b15433 VL - 11 IS - 39 SP - 35630 EP - 35640 PB - ACS Publications AN - OPUS4-49425 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Harris, J. A1 - Mey, I. P. A1 - Böhm, C. F. A1 - Trinh, T. T. H. A1 - Fink, A. A1 - Bayer, F. A1 - Leupold, S. A1 - Prinz, Carsten A1 - Tripal, P. A1 - Palmisano, R. A1 - Wolf, S. E. T1 - Ultra-smooth and space-filling mineral films generated via particle accretion processes N2 - Nonclassical crystallization typically occurs via the attachment of individual nanoparticles. Intuitively, materials synthesized via this route should exhibit pronounced surface roughness and porosity as a hallmark of the formation process via particle accretion. Here, we demonstrate that nonclassical mineralization of calcium carbonate allows synthesis of ultra-smooth and dense surfaces with unprece-dented root-mean-square roughness of 0.285 nm, simply by con-trolling the hydration state of the nanosized building blocks using Mg doping. High fidelity coating of corrugated substrates can even be achieved. Nonclassical crystallization can thus lead to space-filling inorganic solid-state materials transgressing the implicit porosity commonly expected for particle-driven self-organization processes. KW - Nonclassical crystallization KW - Hydration KW - Particle accretion PY - 2019 DO - https://doi.org/10.1039/c9nh00175a VL - 4 IS - 6 SP - 1388 EP - 1393 PB - Royal Society of Chemistry AN - OPUS4-49488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -