TY - JOUR A1 - Draude, F. A1 - Galla, S. A1 - Pelster, A. A1 - Tentschert, J. A1 - Jungnickel, H. A1 - Haase, A. A1 - Mantion, Alexandre A1 - Thünemann, Andreas A1 - Taubert, A. A1 - Luch, A. A1 - Arlinghaus, H. F. T1 - ToF-SIMS and laser-SNMS analysis of macrophages after exposure to silver nanoparticles N2 - Silver nanoparticles (SNPs) are among the most commercialized nanoparticles because of their antibacterial effects. Besides being employed, e.g. as a coating material for sterile surfaces in household articles and appliances, the particles are also used in a broad range of medical applications. Their antibacterial properties make SNPs especially useful for wound disinfection or as a coating material for prostheses and surgical instruments. Because of their optical characteristics, the particles are of increasing interest in biodetection as well. Despite the widespread use of SNPs, there is little knowledge of their toxicity. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and laser post-ionization secondary neutral mass spectrometry (Laser-SNMS) were used to investigate the effects of SNPs on human macrophages derived from THP-1 cells in vitro. For this purpose, macrophages were exposed to SNPs. The SNP concentration ranges were chosen with regard to functional impairments of the macrophages. To optimize the analysis of the macrophages, a special silicon wafer sandwich preparation technique was employed; ToF-SIMS was employed to characterize fragments originating from macrophage cell membranes. With the use of this optimized sample preparation method, the SNP-exposed macrophages were analyzed with ToF-SIMS and with Laser-SNMS. With Laser-SNMS, the three-dimensional distribution of SNPs in cells could be readily detected with very high efficiency, sensitivity, and submicron lateral resolution. We found an accumulation of SNPs directly beneath the cell membrane in a nanoparticular state as well as agglomerations of SNPs inside the cells. KW - Laser-SNMS KW - ToF-SIMS KW - Life sciences KW - Imaging KW - Nanoparticles KW - Three-dimensional depth profiling KW - Silver nanoparticle PY - 2013 DO - https://doi.org/10.1002/sia.4902 SN - 0142-2421 SN - 1096-9918 VL - 45 IS - 1 SP - 286 EP - 289 PB - Wiley CY - Chichester AN - OPUS4-27585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - López, J.P. A1 - Kraus, Werner A1 - Reck, Günter A1 - Thünemann, Andreas A1 - Kurth, D.G. T1 - Alternating perpendicular 1-D channels in the supramolecular structure of the copper(II) complex [Cu(pyterpy)2](PF6)2 . CH3OH . 0.5 CH2Cl2 (pyterpy = 4'-(4'''-pyridyl)-2,2':6',2''-terpyridine) KW - 4´-(4´´´-pyridyl)-2,2´:6´2´´-terpyridine KW - Copper complexes KW - Crystal structure KW - Supramolecular chemistry KW - Pi-pi stacking PY - 2005 SN - 1387-7003 VL - 8 SP - 281 EP - 284 PB - Elsevier CY - Amsterdam AN - OPUS4-6301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lichtenstein, D. A1 - Meyer, T. A1 - Böhmert, L. A1 - Juling, S. A1 - Fahrenson, C. A1 - Selve, S. A1 - Thünemann, Andreas A1 - Meijer, J. A1 - Estrela-Lopis, I. A1 - Braeuning, A. A1 - Lampen, A. T1 - Dosimetric quantification of coating-related uptake of silver nanoparticles N2 - The elucidation of mechanisms underlying the cellular uptake of nanoparticles (NPs) is an important topic in nanotoxicological research. Most studies dealing with silver NP uptake provide only qualitative data about internalization efficiency and do not consider NP-specific dosimetry. Therefore, we performed a comprehensive comparison of the cellular uptake of differently coated silver NPs of comparable size in different human intestinal Caco-2 cell-derived models to cover also the influence of the intestinal mucus barrier and uptake-specialized M-cells. We used a combination of the Transwell system, transmission electron microscopy, atomic absorption spectroscopy, and ion beam microscopy techniques. The computational in vitro sedimentation, diffusion, and dosimetry (ISDD) model was used to determine the effective dose of the particles in vitro based on their individual physicochemical characteristics. Data indicate that silver NPs with a similar size and shape show coating-dependent differences in their uptake into Caco-2 cells. The internalization of silver NPs was enhanced in uptake-specialized M-cells while the mucus did not provide a substantial barrier for NP internalization. ISDD modeling revealed a fivefold underestimation of dose–response relationships of NPs in in vitro assays. In summary, the present study provides dosimetry-adjusted quantitative data about the influence of NP coating materials in cellular uptake into human intestinal cells. Underestimation of particle effects in vitro might be prevented by using dosimetry models and by considering cell models with greater proximity to the in vivo situation, such as the M-cell model. KW - Silver nanoparticles KW - Small-angle X-ray scattering KW - Saxs PY - 2017 DO - https://doi.org/10.1021/acs.langmuir.7b01851 SN - 0743-7463 VL - 33 IS - 45 SP - 13087 EP - 13097 PB - Americal Chemical Society AN - OPUS4-42875 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, L. A1 - Saloga, Patrick E. J. A1 - Stock, V. A1 - Böhmert, L. A1 - Braeuning, A. A1 - Thünemann, Andreas A1 - Lampen, A. A1 - Sieg, H. T1 - Environmental impact of ZnO nanoparticles evaluated by in vitro simulated digestion N2 - ZnO nanoparticles are found in different food and consumer products, and their toxicological effects are still under investigation. It is therefore important to understand their behavior in the gastrointestinal tract. Here, we used an in vitro model to assess the physicochemical fate of ZnO nanoparticles during the digestive process in artificial saliva, stomach juice, and intestinal juice. Atomic absorption spectrometry and small-angle X-ray scattering were employed to investigate two ZnO nanomaterials, one intensively characterized reference material and soluble ZnCl2 in a broad range of concentrations between 25 and 1000 μg/mL in the intestinal fluid. Because food components may influence the behavior of nanomaterials in the gastrointestinal tract, starch, milk powder, and olive oil were used to mimic carbohydrates, protein, and fat, respectively. Additionally, ion release of all Zn species was assessed in cell culture media and compared to artificial intestinal juice to investigate relevance of typical cell culture conditions in ZnO nanotoxicology. ZnCl2 as well as the ZnO species were present as particles in artificial saliva but were solubilized completely in the acidic stomach juice. Interestingly, in the intestinal fluid a concentration-independent de novo formation of particles in the nanoscale range was shown. This was the case for all particles as well as for ZnCl2, regardless of the concentration used. Neither of the food components affected the behavior of any Zn species. On the contrary, all Zn species showed a Zn-concentration-dependent ion release in common cell culture medium. This questions the suitability of cell culture studies to investigate the effect of ZnO nanoparticles on intestinal cells. Our results show that Zn-containing nanoparticles reach the intestine. This underlines the importance of determining the influence of the test environment on nanoparticle fate. KW - SAXS KW - Digestion KW - Zinc oxide KW - Nanoparticles PY - 2020 DO - https://doi.org/10.1021/acsanm.9b02236 VL - 3 IS - 1 SP - 724 EP - 733 AN - OPUS4-50288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lutz, J.-F. A1 - Nehring, R. A1 - Thünemann, Andreas T1 - Solution Self-Assembly of Synthetic Copolymers bearing Complementary Nucleic Acid Funtionalities KW - DNA KW - Living polymerization KW - ATRP KW - Copolymers PY - 2005 SN - 0032-3934 VL - 46 IS - 2 SP - 397 EP - 398 PB - American Chemical Society CY - Newark, NJ AN - OPUS4-10535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schott, M. A1 - Szczerba, Wojciech A1 - Posset, U. A1 - Vuk, A.S. A1 - Beck, M. A1 - Riesemeier, Heinrich A1 - Thünemann, Andreas A1 - Kurth, D. G. T1 - In operando XAFS experiments on flexible electrochromic devices based on Fe(II)-metallo-supramolecular polyelectrolytes and vanadium oxides N2 - Flexible electrochromic devices (ECDs) based on Fe(II)-metallo-supramolecular polyelectrolytes (Fe-MEPE) and vanadium oxide are studied in operando by means of x-ray absorption fine structure (XAFS) spectroscopy. The ECDs are blue-purple in the colored state at 0.0 V and become light yellow when a voltage of 1.6 V is applied. The XAFS studies at the K-edge of Fe(II) reveals that the absorption edge is shifted toward higher energies by 1.8 eV in the transparent state. Comparison of two different ECDs and different charge cycles demonstrates the reversibility and repeatability of the process. We attribute the shift to a charge transfer and a change of oxidation state of the ions from Fe2+ to Fe3+. The transition is not accompanied by a noticeable structural change of the octahedral coordination geometry as confirmed by analysis of the extended x-ray absorption fine structure (EXAFS) data. (C) 2015 Elsevier B.V. All rights reserved. KW - Metallo-supramolecular polyelectrolytes KW - Vanadium oxide KW - Electrochromism KW - Electrochromic device KW - Cyclic voltammetry KW - XAFS PY - 2016 DO - https://doi.org/10.1016/j.solmat.2015.10.015 SN - 0927-0248 VL - 147 SP - 61 EP - 67 PB - Elsevier B.V. CY - Amsterdam [u.a.] AN - OPUS4-35251 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Juling, S. A1 - Böhmert, L. A1 - Lichtenstein, D. A1 - Oberemm, A. A1 - Creutzenberg, O. A1 - Thünemann, Andreas A1 - Braeuning, A. A1 - Lampen, A. T1 - Comparative proteomic analysis of hepatic effects induced by nanosilver, silver ions and nanoparticle coating in rats N2 - The presence of nano-scaled particles in food and food-related products has drawn attention to the oral uptake of nanoparticles and their interactions with biological systems. In the present study, we used a toxicoproteomics approach to allow for the untargeted experimental identification and comparative analysis of cellular Responses in rat liver after repeated-dose treatment with silver nanoparticles, ions, and the coating matrix used for particle stabilization. The proteomic analysis revealed treatment-related effects caused by exposure to silver in particulate and ionic form. Both silver species induced similar patterns of signaling and metabolic alterations. Silver-induced cellular alterations comprised, amongst others, proteins involved in metal homeostasis, oxidative stress response, and energy metabolism. However, we discovered that secondary nano-scaled structures were formed from ionic silver. Furthermore, also the coating matrix alone gave rise to the formation of nano-scaled particles. The present data confirm, complement, and extend previous knowledge on silver toxicity in rodent liver by providing a comprehensive proteomic data set. The observation of secondary particle formation from nonparticle controls underlines the difficulties in separating particle-, ion-, and matrix coating-related effects in biological systems. Awareness of this issue will support proper evaluation of nanotoxicology-related data in the future. KW - Silver nanoparticles KW - Small-angle X-ray scattering KW - SAXS PY - 2018 DO - https://doi.org/10.1016/j.fct.2018.01.056 SN - 0278-6915 SN - 1873-6351 VL - 113 SP - 255 EP - 266 PB - Elsevier AN - OPUS4-44563 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lutz, J.-F. A1 - Pfeifer, S. A1 - Chanana, M. A1 - Thünemann, Andreas A1 - Bienert, Ralf T1 - H-Bonding-Directed Self-Assembly of Synthetic Copolymers Containing Nucleobases: Organization and Colloidal Fusion in a Noncompetitive Solvent N2 - The self-organization of random copolymers composed of a nucleobase monomer (either 1-(4-vinylbenzyl)thymine or 9-(4-vinylbenzyl)adenine) and dodecyl methacrylate (DMA) was studied in dilute chloroform solutions. The balance between the molar fractions of the nucleobase monomer (leading to intermolecular H-bonding) and DMA (soluble moiety in chloroform) in the polymer chains was found to be the parameter that principally influences the self-organization. DMA-rich copolymers are molecularly soluble in chloroform, whereas nucleobase-rich copolymers are insoluble in this solvent. Copolymers possessing an equimolar comonomer composition self-assemble into micrometer-sized particles physically cross-linked by intermolecular H-bonds (either thymine-thymine or adenine-adenine interactions, depending on the studied copolymer). Nevertheless, when mixed together, thymine- and adenine-based colloids fuse into thermodynamically stable microspheres cross linked by adenine-thymine interactions. KW - Synthetic polymers KW - Self-organization KW - H-bonding KW - Nucleobases KW - Confocal fluorescence microscopy PY - 2006 DO - https://doi.org/10.1021/la061382a SN - 0743-7463 SN - 1520-5827 VL - 22 IS - 17 SP - 7411 EP - 7415 PB - American Chemical Society CY - Washington, DC AN - OPUS4-12637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thünemann, Andreas T1 - The investigation of supramolecular structures using synchrotron radiation: small-angle X-ray scattering T2 - School of Chemistry and Center of Exellence in Chemistry, University of Bristol CY - Bristol, England DA - 2007-04-04 PY - 2007 AN - OPUS4-14666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thünemann, Andreas A1 - Bienert, Ralf A1 - Appelhans, Dietmar A1 - Voit, B. T1 - Core-shell structures of oligosaccharide-functionalized hyperbranched poly(ethylene imines) N2 - Hyperbranched poly(ethylene imine)s (PEIs) functionalized with maltose, maltotriose, and maltoheptaose form distinct core-shell globular nanoparticles as revealed by small-angle X-ray scattering (SAXS). The solution structures are quantified using the Beaucage unified exponential/power-law approach. SAXS results were confirmed with dynamic light scattering (DLS). We found that all PEI structures are completely insensitive to changes of temperature (5 °C < T < 80 °C) and pH (1 < pH < 10). This remarkable stability of a compact spherical polymeric structure makes the modified PEIs promising for a wide range of biomedical applications. KW - Colloids KW - Core-shell polymers KW - Nanoparticles KW - Polyamines KW - Small-angle X-ray scattering (SAXS) PY - 2012 DO - https://doi.org/10.1002/macp.201100490 SN - 1022-1352 SN - 1521-3935 VL - 213 IS - 22 SP - 2362 EP - 2369 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-26975 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thünemann, Andreas A1 - Klobes, Peter A1 - Wieland, Christoph A1 - Bruzzano, S. T1 - On the nanostructure of micrometer-sized cellulose beads N2 - The analysis of the porosity of materials is an important and challenging field in analytical chemistry. The gas adsorption and mercury intrusion methods are the most established techniques for quantification of specific surface areas, but unfortunately, dry materials are mandatory for their applicability. All porous materials that contain water and other solvents in their functional state must be dried before analysis. In this process, care has to be taken since the removal of solvent bears the risk of an incalculable alteration of the pore structure, especially for soft materials. In the present paper, we report on the use of small-angle X-ray scattering (SAXS) as an alternative analysis method for the investigation of the micro and mesopores within cellulose beads in their native, i.e., water-swollen state; in this context, they represent a typical soft material. We show that even gentle removal of the bound water reduces the specific surface area dramatically from 161 to 109 m² g-1 in cellulose bead sample type MT50 and from 417 to 220 m² g-1 in MT100. Simulation of the SAXS curves with a bimodal pore size distribution model reveals that the smallest pores with radii up to 10 nm are greatly affected by drying, whereas pores with sizes in the range of 10 to 70 nm are barely affected. The SAXS results were compared with Brunauer–Emmett–Teller results from nitrogen sorption measurements and with mercury intrusion experiments. KW - Small-angle X-ray scattering KW - Cellulose KW - Mesopores KW - Micropores KW - Porosimetry PY - 2011 DO - https://doi.org/10.1007/s00216-011-5176-z SN - 1618-2642 SN - 1618-2650 VL - 401 IS - 4 SP - 1101 EP - 1108 PB - Springer CY - Berlin AN - OPUS4-24251 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thünemann, Andreas T1 - Characterization of multicore superparamagnetic iron oxide nanoparticles using XAFS and SAXS T2 - 10th International Conference on the Scientific and Clinical Applications of Magnetic Carriers CY - Dresden, Germany DA - 2014-06-10 PY - 2014 AN - OPUS4-31019 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thünemann, Andreas A1 - Schütt, D. A1 - Kaufner, L. A1 - Pison, U. A1 - Möhwald, H. T1 - Maghemite Nanoparticles Protectively Coated with Poly(ethylene imine) and Poly(ethylene oxide)-block-poly(glutamic acid) N2 - Superparamagnetic iron oxide particles (SPIO) of maghemite were prepared in aqueous solution and subsequently stabilized with polymers in two layer-by-layer deposition steps. The first layer around the maghemite core is formed by poly(ethylene imine) (PEI), and the second one is formed by poly(ethylene oxide)-block-poly(glutamic acid) (PEO-PGA). The hydrodynamic diameter of the particles increases stepwise from Dh = 25 nm (parent) via 35 nm (PEI) to 46 nm (PEI plus PEO-PGA) due to stabilization. This is accompanied by a switching of their -potentials from moderately positive (+28 mV) to highly positive (+50 mV) and finally slightly negative (-3 mV). By contrast, the polydispersity indexes of the particles remain constant (ca. 0.15). Mössbauer spectroscopy revealed that the iron oxide, which forms the core of the particles, is only present as Fe(III) in the form of superparamagnetic maghemite nanocrystals. The magnetic domains and the maghemite crystallites were found to be identical with a size of 12.0 ± 0.5 nm. The coated maghemite nanoparticles were tested to be stable in water and in physiological salt solution for longer than 6 months. In contrast to novel methods for magnetic nanoparticle production, where organic solvents are necessary, the procedure proposed here can dispense with organic solvents. Magnetic resonance imaging (MRI) experiments on living rats indicate that the nanoparticles are useful as an MRI contrast agent. KW - Polymer KW - Polyelectrolyte KW - Mössbauer PY - 2006 DO - https://doi.org/10.1021/la052990d SN - 0743-7463 SN - 1520-5827 VL - 22 IS - 5 SP - 2351 EP - 2357 PB - American Chemical Society CY - Washington, DC AN - OPUS4-12119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thünemann, Andreas T1 - Small-angle X-Ray scattering (SAXS): Investigation of self-assembled nanoparticles T2 - Kolloquium des Instituts für Chemie, Humboldt-Universität Berlin CY - Berlin, Germany DA - 2007-06-04 PY - 2007 AN - OPUS4-14662 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meister, A. A1 - Förster, G. A1 - Thünemann, Andreas A1 - Kurth, D. T1 - Nanoscopic Structure of a Metallo-supramolecular Polyelectrolyte - Amphiphile Complex, Elucidated by X-ray Scattering and Molecular Modeling N2 - A combination of molecular modeling and X-ray scattering was used to elucidate the structure of the metallosupramolecular polyelectrolyte-amphiphile complex (PAC) self-assembled from FeII, 1,4-bis(2,2:6,2-terpyridin-4-yl)benzene, and dihexadecyl phosphate (DHP). An approximate structure of the semi-ordered material was derived from the analysis of the X-ray scattering data. The experimental data provided sufficient input for obtaining a useful starting configuration for molecular modeling. Various models of the supramolecular architecture are presented and discussed in terms of their total energies and scattering patterns. In an iterative approach each level of the structural hierarchy was refined until satisfactory agreement of calculated and experimental scattering patterns was reached. The remarkable sensitivity of the simulated scattering curves to even the smallest structural changes at all length scales restricts the arbitrariness of modeling. The final model of PAC consists of flat lamellae of alternating strata of interdigitated DHP monolayers and nematically ordered polyelectrolyte chains. PY - 2003 DO - https://doi.org/10.1002/cphc.200300702 SN - 1439-4235 SN - 1439-7641 VL - 4 SP - 1095 EP - 1100 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-2692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heinke, D. A1 - Gehrke, N. A1 - Ludwig, F. A1 - Steinhoff, U. A1 - Pankhurst, Q. A. A1 - Lüdtke-Buzug, K. A1 - Thünemann, Andreas A1 - Johansson, Ch. T1 - NanoMag - Standardization of Analysis Methods for Magnetic Nanoparticles N2 - The NanoMag project brings together various leading experts in magnetic nanoparticle synthesis as well as nanoparticle analysis and characterization from research institutes, companies, universities and metrology institutes that will perform cutting-edge research and develop applications in the field of magnetic particles. This work is supported by the European Commission Framework Programme7 under the NanoMag project [grant agreement no 604448]. T2 - 2015 5th International Workshop on Magnetic Particle Imaging (IWMPI) CY - Istanbul, Turkey DA - 26.03.2015 KW - nanoparticles PY - 2015 UR - http://www.nanomag-project.eu/ SN - 978-1-4799-7269-2 SN - 978-1-4799-7271-5 DO - https://doi.org/10.1109/IWMPI.2015.7107065 VL - 2015 SP - P39 PB - IEEE AN - OPUS4-37324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lutz, J.-F. A1 - Thünemann, Andreas A1 - Rurack, Knut T1 - DNA-like "Melting" of Adenine- and Thymine-Functionalized Synthetic Copolymers KW - Polymers KW - Micelles KW - Amyloid beta-peptide KW - Proteins KW - Secondary structure PY - 2005 SN - 0024-9297 SN - 1520-5835 VL - 38 IS - 20 SP - 8124 EP - 8126 PB - American Chemical Society CY - Washington, DC AN - OPUS4-11068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Löwa, N. A1 - Knappe, Patrick A1 - Wiekhorst, F. A1 - Eberbeck, D. A1 - Thünemann, Andreas A1 - Trahms, L. T1 - Hydrodynamic and magnetic fractionation of superparamagnetic nanoparticles for magnetic particle imaging N2 - Resovist® originally developed as a clinical liver contrast agent for Magnetic Resonance Imaging exhibits also an outstanding performance as a tracer in Magnetic Particle Imaging (MPI). In order to study the physical mechanism of the high MPI performance of Resovist®, we applied asymmetric flow field–flow fractionation (A4F) and static magnetic fractionation (SMF) to separate Resovist® into a set of fractions with defined size classes. As A4F based on an elution method separates MNP according to their hydrodynamic size, SMF fractionates a particle distribution by its magnetic moment. The obtained fractions of both separation techniques were then magnetically characterized by magnetorelaxometry measurements to extract the corresponding effective magnetic anisotropy and hydrodynamic size distribution parameters. Additionally, the MPI performance of each fraction was assessed using magnetic particle spectroscopy. With both separation techniques fractions (normalized to their iron amount) an MPI signal gain of a factor of two could be obtained, even though the distribution of effective anisotropy and hydrodynamic size were significantly different. Relating these findings to the results from magnetic characterization allows for a better understanding of the underlying mechanisms of MPI performance of Resovist®. This knowledge may help to improve the design of novel MPI tracers and development of separation methods. KW - Superparamagnetic nanoparticles KW - Asymmetric flow field–flow fractionation KW - Magnetic particle spectroscopy KW - Magnetorelaxometry KW - Magnetic separation KW - Magnetic particle imaging KW - Resovist® KW - Nanotechnology KW - SAXS KW - Nanoparticles PY - 2015 DO - https://doi.org/10.1016/j.jmmm.2014.08.057 SN - 0304-8853 VL - 380 SP - 266 EP - 270 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-32562 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rocha, S. A1 - Krastev, R. A1 - Thünemann, Andreas A1 - Carmo Pereira, M. A1 - Möhwald, H. A1 - Brezesinski, G. T1 - Adsorption of Amyloid beta-Peptide at Polymer Surfaces: A Neutron Reflectivity Study KW - Beta amyloid KW - Neutron reflectivity PY - 2005 SN - 1439-4235 SN - 1439-7641 IS - 6 SP - 2527 EP - 2534 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-11562 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thünemann, Andreas T1 - Investigation of Nanostructures using Small-Angle X-Ray Scattering T2 - ICYS Special Seminar Nanotechnology (National Institute for Materials Science) CY - Tsukuba, Japan DA - 2014-03-26 PY - 2014 AN - OPUS4-30533 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thünemann, Andreas T1 - Small-Angle X-Ray Scattering for Nanomedicine T2 - International Conference on Biological Barriers CY - Saarbrücken, Germany DA - 2014-02-16 PY - 2014 AN - OPUS4-30551 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khare, V. A1 - Li, Z. A1 - Mantion, Alexandre A1 - Ayi, A. A. A1 - Sonkaria, S. A1 - Voelkl, A. A1 - Thünemann, Andreas A1 - Taubert, A. T1 - Strong anion effects on gold nanoparticle formation in ionic liquids N2 - Ionic liquids (ILs) have attracted tremendous interest in the recent past for their potential in many chemical fields. The current report explores the effects of a set of ILs based on the 1-ethyl-3-methyl-imidazolium cation and different anions on the formation of gold nanoparticles. X-Ray diffraction finds face-centered cubic gold in all cases, but transmission electron microscopy (TEM) shows that there are distinct differences in particle formation and stabilization with the ethyl sulfate (ES), trifluoromethanesulfonate (TfO) and methanesulfonate (MS) anions. With the MS anion, nanoparticles with diameters between 5 and 7 nm form, which increasingly aggregate at higher reaction temperatures. With TfO, also small 5 to 7 nm particles form, but only at low temperatures. Above ca. 160 °C, large, ill-defined and aggregated particles form. With ES, polydisperse samples form at all temperatures except 160 °C. In this case the nanoparticles appear often surrounded by an IL film, which appears to stabilize individual, ca. 15 to 20 nm particles. Dynamic light scattering and UV/Vis spectroscopy further show that in suspension the particles are, much like seen in the TEM, more strongly aggregated with higher reaction temperatures. In summary, the results suggest that there are very specific IL-gold interactions that are responsible for the formation of gold particles with an IL-specific shape, size, and aggregation behavior. KW - Ionic liquid templating KW - Gold nanoparticle KW - Ionic liquid PY - 2010 DO - https://doi.org/10.1039/b917467b SN - 0959-9428 SN - 1364-5501 VL - 20 SP - 1332 EP - 1339 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-20872 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khare, V. A1 - Kraupner, A. A1 - Mantion, Alexandre A1 - Jelicic, A. A1 - Thünemann, Andreas A1 - Giordano, C. A1 - Taubert, A. T1 - Stable iron carbide nanoparticle dispersions in [Emim][SCN] and [Emim][N(CN)2] ionic liquids N2 - Dispersions of Fe3C nanoparticles in several ionic liquids (ILs) have been investigated. The ILs are based on 1-ethyl-3-methylimidazolium [Emim] and 1-butyl-3-methylimidazolium [Bmim] cations. Anions are ethylsulfate [ES], methanesulfonate [MS], trifluoromethylsulfonate (triflate) [TfO], tetrafluoroborate [BF4], dicyanamide [N(CN)2], and thiocyanate [SCN]. Among the ILs studied, [Emim][SCN] and [Emim][N(CN)2] stand out because only in these ILs have stable and transparent nanoparticle dispersions been obtained. All other ILs lead to blackish, slightly turbid dispersions or to completely nontransparent suspensions, which often contain undispersed sediment. UV/vis spectroscopy, transmission electron microscopy, and X-ray scattering suggest that the reason for the stabilization of the Fe3C nanoparticles in [Emim][SCN] is the leaching of traces of iron from the particles (without affecting the crystal structure of the Fe3C particles). The resulting particle surface is thus carbon-rich, which presumably favors the stabilization of the particles. A similar explanation can be postulated for [Emim][N(CN)2], with the dicyanamide anion also being a good ligand for iron. KW - Ionic liquid KW - Iron carbide PY - 2010 DO - https://doi.org/10.1021/la100775m SN - 0743-7463 SN - 1520-5827 VL - 26 IS - 13 SP - 10600 EP - 10605 PB - American Chemical Society CY - Washington, DC AN - OPUS4-21624 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, P. A1 - Mantion, Alexandre A1 - Foelske, A. A1 - Shkilnyy, A. A1 - Masic, A. A1 - Thünemann, Andreas A1 - Taubert, A. T1 - Peptide-coated silver nanoparticles: Synthesis, surface chemistry, and pH-triggered, reversible assembly into particle assemblies N2 - Simple tripeptides are scaffolds for the synthesis and further assembly of peptide/silver nanoparticle composites. Herein, we further explore peptide-controlled silver nanoparticle assembly processes. Silver nanoparticles with a pH-responsive peptide coating have been synthesized by using a one-step precipitation/coating route. The nature of the peptide/silver interaction and the effect of the peptide on the formation of the silver particles have been studied via UV/Vis, X-ray photoelectron, and surface-enhanced Raman spectroscopies as well as through electron microscopy, small angle X-ray scattering and powder X-ray diffraction with Rietveld refinement. The particles reversibly form aggregates of different sizes in aqueous solution. The state of aggregation can be controlled by the solution pH value. At low pH values, individual particles are present. At neutral pH values, small clusters form and at high pH values, large precipitates are observed. KW - Hybrid materials KW - Nano-particles KW - Oligopeptides KW - pH KW - Silver PY - 2009 DO - https://doi.org/10.1002/chem.200802329 SN - 0947-6539 SN - 1521-3765 VL - 15 IS - 23 SP - 5831 EP - 5844 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-19514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -