TY - CONF A1 - Thünemann, Andreas T1 - Nanoparticle size analysis - Small-angle X-Ray scattering T2 - 32nd Meeting of the International Standard Organization ISO/TC24/SC4 CY - Stratford-upon-Avon, England DA - 2008-09-05 PY - 2008 AN - OPUS4-17952 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hansen, Ulf A1 - Thünemann, Andreas T1 - Considerations using silver nitrate as a reference for in vitro tests with silver nanoparticles N2 - Most in vitro tests regarding the cellular toxicology of nanoparticulate metals compare particle to associated metal ion exposure. However. it is also a fact. that for example silver ions are reduced by sugars or transformed to silver chloride by chloride salts which are abundant components of cell culture media. These reactions are likely to either complicate or even invalidate comparisons between effects of ions and particles. Here. we present a fast and quantitative method to determine particle formation and numbers in different cell culture media with non-destructive small-angle X-ray scattering (SAXS). Silver nitrate with a concentration of25 (.Jg Ag mL -I was dissolved for up to 24 h at 37 'C in Dulbeccos Modified Eagle Medium (DMEM) with and without 10% fetal bovine serum (FBS) and a solution ofO-glucose (4.5 (.Jg mL -1). respectively. Silver nanopartides were observed in all Solutions after 5 min. The cell culture media displayed a limited particle-growth. FBS showed an effect on the polydispersity of the generated particles but after 5 min the overall particle size was nearly equal in FBS and non FBS supplemented medium. Particles in D-glucose were precipitating after 10 min. Particulate silver concentration was between 3 and 4 (.Jg mL -1 in both cell culture media (CCM). These results should be taken into account when performing silver ion-toxicity experiments in relevant media. KW - Silver nanoparticles KW - In vitro tests KW - Silver nitrate KW - SAXS KW - DLS KW - SEM PY - 2016 DO - https://doi.org/10.1016/j.tiv.2016.03.014 SN - 0887-2333 VL - 34 SP - 120 EP - 122 PB - Elsevier AN - OPUS4-35844 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guitton-Spassky, Tiffany A1 - Schade, Boris A1 - Zoister, Christian A1 - Veronese, Eleonora A1 - Rosati, Marta A1 - Baldelli Bombelli, Francesca A1 - Cavallo, Gabriella A1 - Thünemann, Andreas A1 - Ghermezcheshme, Hassan A1 - Makki, Hesam A1 - Netz, Roland R. A1 - Ludwig, Kai A1 - Metrangolo, Pierangelo A1 - Singh, Abhishek Kumar A1 - Haag, Rainer T1 - Fluorinated Hexosome Carriers for Enhanced Solubility of Drugs N2 - Designing nanomaterials for drug encapsulation is a crucial, yet challenging, aspect for pharmaceutical development. An important step is synthesizing amphiphiles that form stable supramolecular systems for efficient drug loading. In the case of fluorinated drugs, these have superior properties and also a tendency toward reduced water solubility. For the first time, we report here fluorinated hexosome carriers made from nonionic dendritic amphiphiles, capable of encapsulating the fluorinated drug Leflunomide with high efficiency (62 ± 3%) and increasing its solubility by 12-fold. We synthesized amphiphiles with varying tail groups (fluorinated/alkylated), and their supramolecular self-assembly was investigated using cryogenic transmission electron microscopy and small-angle X-ray scattering. Furthermore, Leflunomide and its equivalent nonfluorinated counterpart were encapsulated within fluorinated and nonfluorinated assemblies. Self-assembly and encapsulation mechanisms were well supported by coarse-grained molecular simulations, yielding a fundamental understanding of the new systems. KW - PEFAS KW - Small-angle X-ray scattering KW - SAXS KW - Reference method PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-632002 DO - https://doi.org/10.1021/jacsau.5c00198 SN - 2691-3704 VL - 5 IS - 5 SP - 2223 EP - 2236 PB - American Chemical Society (ACS) CY - Washington, DC AN - OPUS4-63200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Qiang A1 - Heuchel, Matthias A1 - Thünemann, Andreas A1 - Machatscheck, Rainhard T1 - The role of diffusion in the hydrolytic degradation of poly(lactic-co-glycolic acid): A molecular perspective N2 - This research emphasizes the importance of internal surface erosion as a key factor in the hydrolytic degradation of PLGA (poly(D,L-lactic-co-glycolic acid)) providing an alternative view of the established surface and bulk erosion degradation modes. Using molecular dynamics (MD) simulations, this study reveals the role of water and oligomer diffusion during the degradation of PLGA and highlights the importance of water channels formed as the overall water content increases. We found that these continuous water channels play a crucial role in accelerating the transport of water and the release of degradation products from the polymer matrix, as the diffusion coefficients of water and small oligomers exhibit significant differences spanning 2 to 3 orders of magnitude between the water and polymer phases. Water follows a different diffusion mechanism than polymer fragments. The diffusion rate of the fragments up to a size of octamers was found to be size-dependent and reasonably well approximated by a 1/N behavior, in line with the Rouse model. KW - Small-angle X-ray scattering KW - SAXS KW - Nanostructure KW - PLGA PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621250 DO - https://doi.org/10.1016/j.polymdegradstab.2024.111119 VL - 232 SP - 1 EP - 12 PB - Elsevier Ltd. AN - OPUS4-62125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kieserling, Helena A1 - Sieg, Holger A1 - Heilscher, Jasmin A1 - Drusch, Stephan A1 - Braeuning, Albert A1 - Thünemann, Andreas A1 - Rohn, Sascha T1 - Towards Understanding Particle-Protein Complexes: Physicochemical, Structural, and Cellbiological Characterization of β-Lactoglobulin Interactions with Silica, Polylactic Acid, and Polyethylene Terephthalate Nanoparticles N2 - Nanoplastic particles and their additives are increasingly present in the food chain, interacting with biomacromolecules with not yet known consequences. A protein corona forms around the particles in these usually complex matrices, primarily with a first contact at surface-active proteins. However, systematic studies on the interactions between the particles and proteins –especially regarding protein affinity and structural changes due to surface properties like polarity – are limited. It is also unclear whether the protein corona can "mask" the particles, mimic protein properties, and induce cytotoxic effects when internalized by mammalian cells. This study aimed at investigating the physicochemical properties of model particle-protein complexes, the structural changes of adsorbed proteins, and their effects on Caco-2 cells. Whey protein β-lactoglobulin (β-Lg) was used as a well-characterized model protein and studied in a mixture with nanoparticles of varying polarity, specifically silica, polylactic acid (PLA), and polyethylene terephthalate (PET). The physicochemical analyses included measurements of the hydrodynamic diameter and the zeta potential, while the protein conformational changes were analyzed using Fourier-transform-infrared spectroscopy (FTIR) and intrinsic fluorescence. Cellular uptake in Caco-2 cells was assessed through flow cytometry, cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay, and cellular impedance was analyzed with xCELLigence® technology. The results indicated that β-Lg had the highest affinity for hydrophilic silica particles, forming silica-β-Lg complexes and large aggregates through electrostatic interactions. The affinity decreased for PLA and was lowest for hydrophobic PET, which formed smaller complexes. Adsorption onto silica caused partial unfolding and refolding of β-Lg. The silica-β-Lg complexes were internalized by Caco-2 cells, impairing cell proliferation. In contrast, PLA- and PET-protein complexes were not internalized, though PLA complexes slightly reduced cell viability. This study enhances our understanding of protein adsorption on nanoparticles and its potential biological effects. KW - Nanoplastics KW - Microplastics KW - Reference materials KW - Scattering KW - DLS PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630093 DO - https://doi.org/10.1016/j.colsurfb.2025.114702 SN - 1873-4367 VL - 253 SP - 1 EP - 12 PB - Elsevier BV CY - Amsterdam AN - OPUS4-63009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mikhlin, Yuri A1 - Muzikansky, Anya A1 - Zysler, Melina A1 - Thünemann, Andreas A1 - Zitoun, David T1 - Emerging electrochemistry of high-concentration colloids: Redox-activity, wide potential window and electrophoretic transport of iron oxide nanoparticles N2 - High-concentration, steric stabilizer free colloids and particularly their electrochemical behavior remains almost unexplored. Herein, we report on the electrochemistry (cyclic voltammetry, impedance spectroscopy, etc.) of highly concentrated aqueous colloidal dispersion up to 800 g/L of citrate-capped ∼11 nm Fe3-xO4 nanoparticles (NPs) without background electrolyte on glassy carbon electrodes. X-ray photoelectron spectroscopy was applied to analyze the reaction products. Solid-state Fe(II)/Fe(III) conversion was concluded to determine the cathodic and anodic faradaic reactions of the particles, with the currents depending on approximately square root of the concentration. The electrochemical reactions are coupled with the electrophoretic transfer of the negatively charged NPs on toward the anode, with the ohmic-type behavior in the bulk demonstrated by the nearly linear voltametric cathodic curves and frequency-independent impedance above ∼10–100 Hz. Accumulation and clogging of the NPs retards diffusion near anode. Hydrogen and especially oxygen evolution are arrested, and very large oxidation overpotentials result in extraordinary wide, up to 12 V, electrochemical window of water stability. The findings shed light onto basic features of the electrochemistry of high-concentration colloids without added electrolyte and their potential applications in redox flow batteries, electrophoretic deposition and beyond. KW - Nanoplastics KW - SAXS KW - Small-angle X-ray scattering PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644340 DO - https://doi.org/10.1016/j.jcis.2025.139247 SN - 0021-9797 VL - 703 SP - 1 EP - 18 PB - Elsevier Inc. AN - OPUS4-64434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mandel, K. A1 - Szczerba, Wojciech A1 - Thünemann, Andreas A1 - Riesemeier, Heinrich A1 - Girod, Matthias A1 - Sextl, G. T1 - Nitric acid-stabilized superparamagnetic iron oxide nanoparticles studied with X-rays N2 - Agglomerated superparamagnetic iron oxide nanoparticles can easily and in large scale be precipitated from iron salt solutions. Although the process is well known, it is ambiguously either assumed that magnetite or maghemite is obtained. The first part of our study clarifies this question using X-ray absorption spectroscopy. For further processing of the nanoparticles, i.e., for giving them a surface functionality or incorporating them into composites, it is important to break the agglomerates and individualize the particles at first. This can effectively be done with nitric acid treatment. The influence of this process on the particles chemistry and structure was analyzed in great detail using X-ray diffraction, X-ray absorption, and smallangle X-ray scattering. In contrast to our expectation, no oxidation from magnetite (Fe3O4) to maghemite (γ- Fe2O3) was found; the formal valence of the particles in any case is magnetite (Fe3O4). Instead, an increase in the particles' surface disorder was discovered from X-ray absorption analyses and high-resolution transmission electron microscopy. The acid treatment roughens and distorts the surface of the nanoparticles which is connected with an increased spin disorder. KW - XANES KW - EXAFS KW - SAXS KW - Coprecipitation KW - Iron oxide spectra KW - Ferrofluid PY - 2012 DO - https://doi.org/10.1007/s11051-012-1066-3 SN - 1388-0764 SN - 1572-896X VL - 14 IS - 8 SP - 1 EP - 9 PB - Kluwer CY - Dordrecht AN - OPUS4-26357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hansen, Ulf A1 - Thünemann, Andreas T1 - Characterization of silver nanoparticles in cell culture medium containing fetal bovine serum N2 - Nanoparticles are being increasingly used in consumer products worldwide, and their toxicological effects are currently being intensely debated. In vitro tests play a significant role in nanoparticle risk assessment, but reliable particle characterization in the cell culture medium with added fetal bovine serum (CCM) used in these tests is not available. As a step toward filling this gap, we report on silver ion release by silver nanoparticles and on changes in the particle radii and in their protein corona when incubated in CCM. Particles of a certified reference material, p1, and particles of a commercial silver nanoparticle material, p2, were investigated. The colloidal stability of p1 is provided by the surfactants polyethylene glycol-25 glyceryl trioleate and polyethylene glycol-20 sorbitan monolaurate, whereas p2 is stabilized by polyvinylpyrrolidone. Dialyses of p1 and p2 reveal that their silver ion release rates in CCM are much larger than in water. Particle characterization was performed with asymmetrical flow field-flow fractionation, small-angle X-ray scattering, dynamic light scattering, and electron microscopy. p1 and p2 have similar hydrodynamic radii of 15 and 16 nm, respectively. The silver core radii are 9.2 and 10.2 nm. Gel electrophoresis and subsequent peptide identification reveal that albumin is the main corona component of p1 and p2 after incubation in CCM that consists of Dulbecco's modified Eagle medium with 10% fetal bovine serum added. PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-335510 DO - https://doi.org/10.1021/acs.langmuir.5b00687 SN - 0743-7463 SN - 1520-5827 VL - 31 IS - 24 SP - 6842 EP - 6852 PB - American Chemical Society CY - Washington, DC AN - OPUS4-33551 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neffe, A.T. A1 - Von Ruesten-Lange, M. A1 - Braune, S. A1 - Lützow, K. A1 - Roch, T. A1 - Richau, K. A1 - Krüger, A. A1 - Becherer, T. A1 - Thünemann, Andreas A1 - Jung, F. A1 - Haag, R. A1 - Lendlein, A. T1 - Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility N2 - Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and thrombocyte adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and thrombocyte adhesion as well as thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo- and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials. KW - Nanotechnology KW - thrombocyte adhesion KW - biomedical applications PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-308196 DO - https://doi.org/10.1039/c4tb00184b SN - 2050-750X SN - 2050-7518 VL - 2 IS - 23 SP - 3626 EP - 3635 PB - Royal Soc. of Chemistry CY - Cambridge AN - OPUS4-30819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kästner, Claudia A1 - Thünemann, Andreas T1 - Catalytic reduction of 4-nitrophenol using silver nanoparticles with adjustable activity N2 - We report on the development of ultra-small core-shell silver nanoparticles synthesized by an up-scaled modification of the polyol process. It is foreseen to use these thoroughly characterized particles as reference material to compare the catalytic and biological properties of functionalized silver nanoparticles. Small-angle X-ray scattering (SAXS) analysis reveal a narrow size distribution of the silver cores with a mean radius of RC = 3.0 nm and a distribution width of 0.6 nm. Dynamic light scattering (DLS) provides a hydrodynamic radius of RH = 10.0 nm and a PDI of 0.09. The particles’ surface is covered with poly(acrylic acid) (PAA) forming a shell with a thickness of 7.0 nm, which provides colloidal stability lasting for more than six months at ambient conditions. The PAA can be easily exchanged by biomolecules to modify the surface functionality. Replacements of PAA with glutathione (GSH) and bovine serum albumin (BSA) have been performed as examples. We demonstrate that the particles effectively catalyze the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride. With PAA as stabilizer, the catalytic activity of 436 ± 24 L g⁻¹ s⁻¹ is the highest reported in literature for silver nanoparticles. GSH and BSA passivate the surface substantially resulting in a catalytic activity of 77.6 ± 0.9 and 3.47 ± 0.50 L g⁻¹ s⁻¹, respectively. KW - Silver nanoparticles KW - Catalysis KW - Reference material KW - Protein coating PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-370655 DO - https://doi.org/10.1021/acs.langmuir.6b01477 SN - 0743-7463 SN - 1520-5827 VL - 32 IS - 29 SP - 7383 EP - 7391 AN - OPUS4-37065 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szczerba, Wojciech A1 - Schott, M. A1 - Riesemeier, Heinrich A1 - Thünemann, Andreas A1 - Kurth, D.G. T1 - Thermally induced structural rearrangement of the Fe(II) coordination geometry in metallo-supramolecular polyelectrolytes N2 - Rigid rod-type metallo-supramolecular coordination polyelectrolytes with Fe(II) centres (Fe-MEPEs) are produced via the self-assembly of the ditopic ligand 1,4-bis(2,2':6',2''-terpyridine-4'-yl)benzene (tpy-ph-tpy) and Fe(II) acetate. Fe-MEPEs exhibit remarkable electrochromic properties; they change colour from blue to transparent when an electric potential is applied. This electrochemical process is generally reversible. The blue colour in the ground state is a result of a metal-to-ligand charge transfer at the Fe(II) centre ion in a quasi-octahedral geometry. When annealed at temperatures above 100 °C, the blue colour turns into green and the formerly reversible electrochromic properties are lost, even after cooling down to room temperature. The thermally induced changes in the Fe(II) coordination sphere are investigated in situ during annealing of a solid Fe-MEPE using X-ray absorption fine structure (XAFS) spectroscopy. The study reveals that the thermally induced transition is not accompanied by a redox process at the Fe(II) centre. From the detailed analysis of the XAFS spectra, the changes are attributed to structural changes in the coordination sphere of the Fe(II) site. In the low temperature state, the Fe(II) ion rests in a quasi-octahedral coordination environment surrounded by six nitrogen atoms of the pyridine rings. The axial Fe–N bond length is 1.94 Å, while the equatorial bond length amounts to 1.98 Å. In the high temperature state, the FeN6-site exhibits a distortion with the axial Fe–N bonds being shortened to 1.88 Å and the equatorial Fe–N bonds being elongated to 2.01 Å. KW - Metallo-supramolecular polyelectrolytes KW - Electrochromism KW - XANES KW - EXAFS KW - Local structure KW - Thermal stability PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-317331 DO - https://doi.org/10.1039/c4cp01187b SN - 1463-9076 SN - 1463-9084 VL - 16 IS - 36 SP - 19694 EP - 19701 PB - The Royal Soc. of Chemistry CY - Cambridge AN - OPUS4-31733 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -