TY - GEN A1 - Maskos, Michael A1 - Berger, Georg A1 - Braun, Ulrike A1 - Heyn, Andreas A1 - Klinger, Christian A1 - Wachtendorf, Volker T1 - Schadensanalyse und Beständigkeit von Materialien in biomedizinischen Einsatzgebieten N2 - Der Anteil von Polymeren als Funktions- und Konstruktionswerkstoffe in dauerhaften medizinischen Anwendungen steigt beständig. Derartige Materialien müssen den mechanischen, biologischen und chemischen Bedingungen im Körper widerstehen (u.a. Abrieb, Hydrolyse, Degradation) und gleichzeitig gut verträglich sein. Der sichere Einsatz von polymeren Materialien erfordert die Kenntnisse über ihre Langzeitstabilität unter verschiedenen äußeren Bedingungen. Diese sind nicht nur beeinflusst durch die unmittelbare Umgebung in vivo, sondern auch durch die Historie der verwendeten Materialien. Dazu zählen u. a. erhöhte Temperaturen unter sauerstoffhaltiger Atmosphäre während der Verarbeitung oder die Exposition von ionisierender Strahlung oder reaktiven Radikalen während der Sterilisation. PY - 2011 SP - 83 EP - 85 CY - Berlin AN - OPUS4-23592 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Utech, S. A1 - Scherer, Christian A1 - Krohne, K. A1 - Carrella, L. A1 - Rentschler, E. A1 - Gasi, T. A1 - Ksenofontov, V. A1 - Felser, C. A1 - Maskos, Michael T1 - Magnetic polyorganosiloxane core-shell nanoparticles: Synthesis, characterization and magnetic fractionation N2 - Here, we present the synthesis, characterization and magnetic separation of magnetic polyorganosiloxane nanoparticles. Magnetic iron oxide nanoparticles with average particle radii of 3.2 nm had been synthesized by a simple coprecipitation process of iron(II) and iron(III) salt in basic solution. Afterwards, the particles were successfully incorporated into a polyorganosiloxane network via a polycondensation reaction of trimethoxymethylsilane (T), diethoxydimethylsilane (D) and the functional monomer (chloromethylphenyl)trimethoxysilane (ClBz-T) in aqueous dispersion. A core–shell system was chosen to increase the flexibility of the system concerning size, composition and functionalization possibilities. The magnetic nanocapsules with particle radii below 60 nm were separated from non-magnetic material with a high effectiveness by the use of commercially available separation columns which are commonly used for isolation of microbeads and subsequently characterized via transmission electron microscopy (TEM), asymmetrical flow field-flow fractionation (AF-FFF), superconducting quantum interference device (SQUID) and Mössbauer spectroscopy. KW - Nanoparticle KW - Magnetic KW - Encapsulation KW - Polyorganosiloxane KW - Magnetic separation PY - 2010 DO - https://doi.org/10.1016/j.jmmm.2010.06.056 SN - 0304-8853 VL - 322 IS - 21 SP - 3519 EP - 3526 PB - Elsevier CY - Amsterdam AN - OPUS4-22248 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tenzer, S. A1 - Docter, D. A1 - Rosfa, S. A1 - Wlodarski, A. A1 - Kuharev, J. A1 - Rekik, A. A1 - Knauer, S.K. A1 - Bantz, C. A1 - Nawroth, T. A1 - Bier, C. A1 - Sirirattanapan, J. A1 - Mann, W. A1 - Treuel, L. A1 - Zellner, R. A1 - Maskos, Michael A1 - Schild, H. A1 - Stauber, R.H. T1 - Nanoparticle size is a critical physico-chemical determinant of the human blood plasma corona: a comprehensive quantitative proteomic analysis N2 - In biological fluids, proteins associate with nanoparticles, leading to a protein 'corona' defining the biological identity of the particle. However, a comprehensive knowledge of particle-guided protein fingerprints and their dependence on nanomaterial properties is incomplete. We studied the long-lived ('hard') blood plasma derived corona on monodispersed amorphous silica nanoparticles differing in size (20, 30, and 100 nm). Employing label-free liquid chromatography mass spectrometry, one- and two-dimensional gel electrophoresis, and immunoblotting the composition of the protein corona was analyzed not only qualitatively but also quantitatively. Detected proteins were bioinformatically classified according to their physicochemical and biological properties. Binding of the 125 identified proteins did not simply reflect their relative abundance in the plasma but revealed an enrichment of specific lipoproteins as well as proteins involved in coagulation and the complement pathway. In contrast, immunoglobulins and acute phase response proteins displayed a lower affinity for the particles. Protein decoration of the negatively charged particles did not correlate with protein size or charge, demonstrating that electrostatic effects alone are not the major driving force regulating the nanoparticle–protein interaction. Remarkably, even differences in particle size of only 10 nm significantly determined the nanoparticle corona, although no clear correlation with particle surface volume, protein size, or charge was evident. Particle size quantitatively influenced the particle’s decoration with 37% of all identified proteins, including (patho)biologically relevant candidates. We demonstrate the complexity of the plasma corona and its still unresolved physicochemical regulation, which need to be considered in nanobioscience in the future. KW - Bionanoscience KW - Liquid chromatography mass spectrometry KW - Nanotoxicity KW - Nanomedicine KW - Immunology KW - Colloidal chemistry KW - Bioinformatics PY - 2011 DO - https://doi.org/10.1021/nn201950e SN - 1936-0851 VL - 5 IS - 9 SP - 7155 EP - 7167 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-25167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bleul, Regina A1 - Bachran, D. A1 - Thiermann, Raphael A1 - Bertin, Annabelle A1 - Fuchs, H. A1 - Maskos, Michael T1 - Probing polymersome-protein and -cell interactions: influence of different end-groups and environments N2 - Developing polymersomes for drug delivery purposes requires a deeper understanding of their behavior in physiological environment. We performed the self-assembly and in-situ loading of polybutadiene-block-polyethyleneoxide (PB-b-PEO) polymersomes in a continuous process using micromixers. Varying the length and end-groups of the starting block copolymer allows us to control the polymer membrane thickness and surface functionalities (hydroxyl or carboxylic acid), required to realize a further coupling with specific cell targeting ligands. To get a deeper understanding of these polymersomes in physiological environment, we studied the cellular response (HeLa cells) in presence of various polymersomes, and showed by cytotoxicity tests the relative biocompatibility of the systems. Flow cytometry experiments at 4?°C in PBS buffer showed a different behavior of hydroxyl-functionalized vesicles compared to carboxylic acid-functionalized vesicles. On the contrary cell binding in DMEM medium supplemented with 10% FCS was almost completely blocked with both kinds of polymersomes. Protein adsorption measurements by dynamic light scattering confirmed that protein binding occurs in all cases, which apparently influences the particle-cell interaction. This study contributes towards a deeper understanding of polymersomes in biological environment and further investigations will help us to design highly effective polymersomes for in vitro as well as in vivo applications. KW - Drug delivery KW - End-group functionality KW - Particle-cell interaction KW - Physiologic environment KW - Polymersomes KW - Protein adsorption PY - 2011 DO - https://doi.org/10.1002/masy.201100042 SN - 1022-1360 SN - 0258-0322 SN - 1521-3900 VL - 309/310 IS - 1 SP - 134 EP - 140 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25246 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ruthard, C. A1 - Maskos, Michael A1 - Yildiz, H. A1 - Gröhn, F. T1 - Association of a cylindrical polyelectrolyte brush with tetravalent counterions N2 - Cylindrical poly(styrene sulfonate) brushes were combined with a tetravalent double-DABCO based counterion. With increasing addition of counterion, hydrodynamic radius and radius of gyration decrease and AFM reveals a conformation change from wormlike to curled structures. Rg/Rh changes from 1.3 to 0.9. Above charge stoichiometry, brushes become interconnected into finite size assemblies, which are stable in aqueous solution for charge ratios (ratio of the molar concentration of charged counterion groups to the molar concentration of charged monomer units of the polymer brush) 1 < Ι < 1.2. They are compact and consist of the brushes in curled (bent) conformation, which is in difference to network-like aggregates from cylindrical poly(styrene sulfonate) brushes with tetravalent porphyrin counterions (Gröhn et al. Macromolecules 2009) and to a wormlike — bent conformation — helix transition found for another brush counterion system (Müller et al. Soft Matter 2009). KW - Bottle-brush KW - Electrostatic interaction KW - Macromonomers KW - Polyelectrolytes KW - Self-assembly PY - 2011 DO - https://doi.org/10.1002/marc.201000622 SN - 1022-1336 SN - 1521-3927 VL - 32 IS - 6 SP - 523 EP - 527 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Luty-Blocho, M. A1 - Fitzner, K. A1 - Hessel, V. A1 - Löb, P. A1 - Maskos, Michael A1 - Metzke, D. A1 - Paclawski, K. A1 - Wojnicki, M. T1 - Synthesis of gold nanoparticles in an interdigital micromixer using ascorbic acid and sodium borohydride as reducers N2 - Continuous-flow process conditions for the reduction to gold nanoparticles were varied following a variation scheme aiming at impacting each of the elementary steps–mixing, reaction, polymer diffusion and polymer binding. While the last three variations are done by proper material choice (reducer; polymeric stabilizer), flow processing using a multilamination micromixer intensified the mass transfer in all these steps and particularly improved the first mixing step of the reactants. As reducers L-ascorbic acid (H2Asc) and sodium borohydride (NaBH4) were used and as gold particle precursor chloroauric acid (HAuCl4). All processing runs were analysed by plasmon absorption and transmission electron microscopy to reveal size, shape and polydispersity. For the HAuCl4-H2Asc system, the smallest particles were 0.8–4 nm (7.5 mL/min) and 0.6–3 nm (10.0 mL/min) for the HAuCl4-NaBH4 system. This is at the upper edge of performance reported for batch systems in literature, i.e. among the smallest gold particles generated. While the particles made for the HAuCl4-H2Asc system were polydisperse and polyshaped for most process conditions (however being spherical and relatively uniform at the two largest flow rates investigated), processing with the HAuCl4-NaBH4 system resulted in particles sizes with small mean deviation and almost ideal spherical shape. With polyvinyl alcohol (PVA) as stabilizer, stable colloids were obtained for one week (violet coloured) up to at least 2 months (pink coloured) in case of reaction with ascorbic acid, and for at least 1 month in case of reaction with NaBH4. KW - Au nanoparticles KW - Kinetic of reduction reaction KW - Micromixer KW - Plasmon resonance PY - 2011 DO - https://doi.org/10.1016/j.cej.2011.03.104 SN - 1385-8947 SN - 0300-9467 SN - 0923-0467 SN - 0009-2487 VL - 171 IS - 1 SP - 279 EP - 290 PB - Elsevier CY - Amsterdam ; Boston, Mass. ; Jena ; London ; New York, NY ; Oxford ; Paris ; Philadelphia, PA ; San Diego, Calif. ; St. Louis, Mo. AN - OPUS4-25423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ruthard, C. A1 - Maskos, Michael A1 - Kolb, U. A1 - Gröhn, F. T1 - Polystyrene sulfonate - porphyrin assemblies: influence of polyelectrolyte and porphyrin structure N2 - In this study, electrostatic self-assembly of different polystyrene sulfonates and a set of tetravalent cationic porphyrins is investigated. It is shown that association of linear polystyrene sulfonates of different molar masses yields finite size nanoscale assemblies that are stable in aqueous solution. Aggregates are compared to the ones of cylindrical brushes, revealing that both form assemblies in the 100 nm range with the charge ratio (molar ratio of porphyrin charges to polyelectrolyte charges) being determining, while the morphology of the resulting network-like assemblies is different for both polyelectrolyte architectures. For the smallest 8k polystyrene sulfonate, in addition, stoichiometric conditions differ. The influence of the molecular porphyrin structure was investigated by comparing meso-tetrakis(4-(trimethyl-ammonium)phenyl)porphyrin (TAPP) with its Cu(II) and Zn(II) loaded analogues and meso-tetrakis(4-N-methylpyridinium)porphyrin (TMPyP), revealing differences in stacking tendency and geometry. Additionally, the TMPyP accumulates more in the inside of the brush than the other porphyrins, likely due to the different position of its charged groups. The supramolecular nanostructures formed were characterized by UV–vis spectroscopy, light scattering, atomic force microscopy, cryo transmission electron microscopy, and small-angle neutron scattering. Results may build a valuable basis for the use of polyelectrolyte–porphyrin assemblies in medicine, catalysis, or energy conversion. KW - Polyelectrolyte KW - Porphyrin KW - Self-assembly KW - Supramolecular nanostructures PY - 2011 DO - https://doi.org/10.1021/jp1078357 SN - 1520-6106 SN - 1520-5207 SN - 1089-5647 VL - 115 IS - 19 SP - 5716 EP - 5729 PB - Soc. CY - Washington, DC AN - OPUS4-25424 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bléger, D. A1 - Liebig, T. A1 - Thiermann, Raphael A1 - Maskos, Michael A1 - Rabe, J.P. A1 - Hecht, S. T1 - Light-orchestrated macromolecular 'accordions': reversible photoinduced shrinking of rigid-rod polymers N2 - Lichtspiele: Lichteinstrahlung verursacht drastische Änderungen der Form stabförmiger Polymere mit Azobenzol‐Photochromen in der Hauptkette. Die eingebetteten Photoschalter wirken als molekulare Scharniere, die bei lichtinduzierter Isomerisierung zur reversiblen Schrumpfung und Streckung des Polymerrückgrats führen (siehe Schema); das System erinnert an ein lichtorchestriertes makromolekulares Akkordeon. N2 - Synthetic molecular systems undergoing structure and property changes as a response to external stimuli offer a series of relevant functions. Their direct use in solution, immobilized at surfaces, or integrated into adequate matrices, allow for the elaboration of nano-carriers, molecular electronic memory circuits, adaptive systems, artificial muscles, or healable materials, among others. Reversible systems are commonly generated by utilizing molecular switches as responsive bi-stable molecules. Of particular interest are switches controlled by non-invasive triggers, especially light, which can display high spatial and temporal resolution. Photoswitches were used to change properties, such as conductance and basicity, based on light-induced alteration of the molecular geometry, that is, their dimensions and shape. In nature, light-induced geometrical modifications of molecular systems lead to primary biological functions, such as the visual perception in vertebrates, or proton pumping in some bacteria, two examples that nicely illustrate the potential of photo-inducing structural modifications in organic systems. KW - Aggregation KW - Azoverbindungen KW - Nanostrukturen KW - Photochromie KW - Polymere PY - 2011 DO - https://doi.org/10.1002/ange.201106879 SN - 0044-8249 SN - 0932-2140 SN - 1521-3757 VL - 123 IS - 52 SP - 12767 EP - 12771 PB - Wiley-VCH CY - Weinheim AN - OPUS4-25394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kasper, J. A1 - Herrmanns, M.I. A1 - Bantz, C. A1 - Utech, S. A1 - Koshkina, Olga A1 - Maskos, Michael A1 - Brochhausen, C. A1 - Pohl, C. A1 - Fuchs, S. A1 - Unger, R. E. A1 - Kirkpatrick, C.J. T1 - Flotillin-involved uptake of silica nanoparticles and responses of an alveolar-capillary barrier in vitro N2 - Drug and gene delivery via nanoparticles across biological barriers such as the alveolar-capillary barrier of the lung constitutes an interesting and increasingly relevant field in nanomedicine. Nevertheless, potential hazardous effects of nanoparticles (NPs) as well as their cellular and systemic fate should be thoroughly examined. Hence, this study was designed to evaluate the effects of amorphous silica NPs (Sicastar) and (poly)organosiloxane NPs (AmOrSil) on the viability and the inflammatory response as well as on the cellular uptake mechanisms and fate in cells of the alveolar barrier. For this purpose, the alveolar epithelial cell line (NCI H441) and microvascular endothelial cell line (ISO-HAS-1) were used in an experimental set up resembling the alveolar-capillary barrier of the lung. In terms of IL-8 and sICAM Sicastar resulted in harmful effects at higher concentrations (60 µg/ml) in conventional monocultures but not in the coculture, whereas AmOrSil showed no significant effects. Immunofluorescence counterstaining of endosomal structures in NP-incubated cells showed no evidence for a clathrin- or caveolae-mediated uptake mechanism. However, NPs were enclosed in flotillin-1 and -2 marked vesicles in both cell types. Flotillins appear to play a role in cellular uptake or trafficking mechanisms of NPs and are discussed as indicators for clathrin- or caveolae-independent uptake mechanisms. In addition, we examined the transport of NPs across this in vitro model of the alveolar-capillary barrier forming a tight barrier with a transepithelial electrical resistance of 560 ± 8 Ω cm². H441 in coculture with endothelial cells took up much less NPs compared to monocultures. Moreover, coculturing prevented the transport of NP from the epithelial compartment to the endothelial layer on the bottom of the filter insert. This supports the relevance of coculture models, which favour a differentiated and polarised epithelial layer as in vitro test systems for nanoparticle uptake. KW - Silica nanoparticles KW - Alveolar-capillary barrier KW - NP uptake KW - NP-transport KW - Endocytosis KW - Flotillin-1/-2-dependent uptake/trafficking PY - 2013 DO - https://doi.org/10.1016/j.ejpb.2012.10.011 SN - 0939-6411 SN - 1873-3441 VL - 84 IS - 2 SP - 275 EP - 287 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-28841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Maskos, Michael A1 - Stauber, R.H. ED - Ducheyne, P. ED - Healy, K.E. ED - Hutmacher, D.W. ED - Grainger, D.W. ED - Kirkpatrick, C.J. T1 - Characterization of nanoparticles in biological environments N2 - Deliberate and accidental exposure of the ecosystem including humans to nanoparticles becomes inevitable as nanomaterials are increasingly used. In biological fluids, biomolecules associate with nanoparticles, leading to the formation of a dynamic biomolecule “corona” that critically defines the biological identity of the particle. As the bio-physical properties of such a decorated particle often differ significantly from those of the formulated particle a detailed characterization of nanoparticles in biological environments becomes increasingly important though, nevertheless also technically challenging. Here, we introduce experimental methods currently employed for nanoparticle characterization, present examples underlining the complexity of the nano-bio interface, and discuss the need for further technical and conceptual developments. A deep and mechanistic bio-physical understanding of the nano-bio interface is a challenge but also fundamental prerequisite for future applications in nanobiology, nanomedicine and nano(eco)toxicology. KW - Amorphous silica nanoparticles KW - Dynamic light scattering DLS KW - Interparticle interactions KW - Field-flow fractionation FFF KW - Cryogenic transmission electron microscopy cryo-TEM PY - 2011 SN - 978-0-08-055302-3 VL - 3 IS - Chapter 3.319. SP - 329 EP - 339 PB - Elsevier AN - OPUS4-27283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eslahian, Kyriakos-Alexandros A1 - Maskos, Michael T1 - Hofmeister effect in thermal field-flow fractionation of colloidal aqueous dispersions N2 - In this study, the retention of colloidal polystyrene beads in aqueous dispersion in thermal field-flow fractionation (ThFFF) is investigated as function of various types and concentrations of electrolytes in the carrier liquid. A specific ion effect is observed and can be interpreted in terms of Hofmeister series. Addition of salt composed of chaotropic anions to the carrier liquid increases particle retention with increasing ionic strength up to several mM. This effect is less pronounced the more kosmotropic the anions are, up to a decrease of retention by increasing concentration of sulphate and citrate. It is demonstrated that the effect of varying cations is minor as compared to the one of anions with this model system. KW - Thermal field-flow fractionation KW - Hofmeister series KW - Specific ion effects KW - Thermophoresis KW - Soret coefficient PY - 2012 DO - https://doi.org/10.1016/j.colsurfa.2012.02.003 SN - 0927-7757 SN - 1873-4359 VL - 413 SP - 65 EP - 70 PB - Elsevier CY - Amsterdam AN - OPUS4-27432 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiermann, Raphael A1 - Mueller, W. A1 - Montesinos-Castellanos, A. A1 - Metzke, D. A1 - Löb, P. A1 - Hessel, V. A1 - Maskos, Michael T1 - Size controlled polymersomes by continous self-assembly in micromixers N2 - The formation of vesicles based on the self-assembly of amphiphilic poly(butadiene)-b-poly(ethylene oxide) (PB130-b-PEO66) block copolymer in water has been studied using THF as co-solvent. To obtain a highly controlled mixing process for the polymer/THF- and the water-phase, we employed micro mixers with different mixing geometries. The high impact of this preparation method on the self-assembling process was verified by TEM and DLS characterization of the obtained structures. Spherical micelles, vesicles and worm-like micelles were found depending on the parameters of mixing. By additional parameter adjustment in the vesicle regime, the size of the assembled vesicles was controlled between 45 and 100 nm. This demonstrates the continuous preparation of narrowly distributed vesicle structures with controlled sizes. KW - Vesicles KW - Polymersomes KW - Micromixers PY - 2012 DO - https://doi.org/10.1016/j.polymer.2012.03.058 SN - 0032-3861 SN - 1873-2291 VL - 53 IS - 11 SP - 2205 EP - 2210 PB - Springer CY - Berlin AN - OPUS4-25884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koshkina, Olga A1 - Bantz, C. A1 - Würth, Christian A1 - Lang, Thomas A1 - Resch-Genger, Ute A1 - Maskos, Michael T1 - Fluorophore-labeled siloxane-based nanoparticles for biomedical applications N2 - We present the synthesis and characterization of multifunctional fluorophore-labeled poly(organosiloxane) nanoparticles with core-shell architecture, where the fluorescent dye is incorporated into the core. Grafting of heterobifunctional poly(ethylene oxide) (PEO) onto the particle surface leads to water-soluble biocompatible nanoparticles. Two different strategies have been used for the synthesis: The encapsulation of dye-labeled monomers during the polycondensation with additional PEO coating and subsequent dye labeling by covalent attachment of the fluorescent dye rhodamine B to the (chloromethylphenyl)siloxane groups in the core after polymerization and grafting of PEO onto the surface. Comparison of the fluorescence quantum yields of the nanoparticles before and after PEO coating show a decrease in quantum yield after PEO coating. KW - Biocompatibility KW - Core-shell KW - Fluorescence KW - Fluorescence quantum yield KW - Nanoparticles KW - PEO PY - 2011 DO - https://doi.org/10.1002/masy.201100041 SN - 1022-1360 SN - 0258-0322 SN - 1521-3900 VL - 309/310 IS - 1 SP - 141 EP - 146 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-25143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Noskov, Sergey A1 - Scherer, Christian A1 - Maskos, Michael A1 - Thünemann, Andreas T1 - Determination of Hamaker constants of polymeric nanoparticles in organic solvents by asymmetrical flow field-flow fractionation N2 - Interaction forces between all objects are either of repulsive or attractive nature. Concerning attractive interactions, the determination of dispersion forces are of special interest since they appear in all colloidal systems and have a crucial influence on the properties and processes in these systems. One possibility to link theory and experiment is the description of the London–Van der Waals forces in terms of the Hamaker constant, which leads to the challenging problem of calculating the van der Waals interaction energies between colloidal particles. Hence, the determination of a Hamaker constant for a given material is needed when interfacial phenomena such as adhesion are discussed in terms of the total potential energy between particles and substrates. In this work, the asymmetrical flow field-flow fractionation (AF-FFF) in combination with a Newton algorithm based iteration process was used for the determination of Hamaker constants of different nanoparticles in toluene. KW - Hamaker constant KW - Asymmetrical flow field flow fractionation KW - Lifshitz KW - Van der Waals KW - London KW - Thermodynamic KW - Interaction PY - 2013 DO - https://doi.org/10.1016/j.chroma.2012.12.001 SN - 0021-9673 VL - 1274 SP - 151 EP - 158 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-27625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scherer, Christian A1 - Utech, S. A1 - Scholz, S. A1 - Noskov, S. A1 - Kindervater, P. A1 - Graf, R. A1 - Thünemann, Andreas A1 - Maskos, Michael T1 - Synthesis, characterization and fine-tuning of bimodal poly(organosiloxane) nanoparticles N2 - The acid catalyzed sol–gel type synthesis of polyorganosiloxane core-shell nanoparticles with removable PDMS core in aqueous dispersion leads to the inherent formation of a bimodal size distribution with smaller spheres having approximately 26 nm radii and larger nanoparticles with 60 nm in radius. The origin of the self-organized bimodality is investigated and finally attributed to a combination of stabilization of the growing particles due to i) a miniemulsion-type stabilization by the ultrahydrophobe PDMS and ii) by surface co-stabilization by the employed surfactant. The significant influence of temperature, pH, stirrer speed and amount of the surfactant on the particle sizes allows for the design and fine-tuning of different nanoparticles sizes and distributions. KW - Nanoparticles KW - Polyorganosiloxane KW - Field-flow fractionation (FFF) PY - 2010 DO - https://doi.org/10.1016/j.polymer.2010.09.065 SN - 0032-3861 SN - 1873-2291 VL - 51 IS - 23 SP - 5432 EP - 5439 PB - Springer CY - Berlin AN - OPUS4-22476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Thünemann, Andreas A1 - Eckelt, J. A1 - Maskos, Michael A1 - Wolf, B. A. ED - Matyjaszewski, K. ED - Möller, M. T1 - Fractionation N2 - The enormous diversity of polymers with respect to molecular weight, molecular architecture, and – in the case of copolymers – also the content and arrangement of dissimilar monomers requires well-targeted methods for the separation of the different species that are contained in a given sample. This chapter presents the most abundant fractionation procedures, which are either based on thermodynamic driving forces (like in the case of liquid–liquid phase separation) or on kinetic effects (as with field-flow fractionation). KW - Field-flow fractionation KW - Polymer science KW - Asymmetrical flow field-flow fractionation (AF-FFF) KW - Baker-Williams fractionation KW - Chemical composition distribution (CCD) KW - Circular asymmetrical flow field-flow eluation (CAFFFE) KW - Continuous polymer fractionation (CPF) KW - Crystallization analysis fractionation (CRYSTAF) KW - Crystallization–dissolution fractionation (CDF) KW - Liquid-liquid phase separation KW - Temperature rising elution fractionation (TREF) KW - Phase distribution chromatography (PDC) PY - 2012 SN - 978-0-444-53349-4 DO - https://doi.org/10.1016/B978-0-444-53349-4.00022-4 VL - 2 IS - Chapter 2.04 SP - 65 EP - 91 PB - Elsevier CY - Amsterdam AN - OPUS4-26265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kasper, J. A1 - Hermanns, M. A1 - Bantz, C. A1 - Maskos, Michael A1 - Stauber, R. A1 - Pohl, C. A1 - Unger, R. E. A1 - Kirkpatrick, J.C. T1 - Inflammatory and cytotoxic responses of an alveolar-capillary coculture model to silica nanoparticles: comparison with conventional monocultures N2 - To date silica nanoparticles (SNPs) play an important role in modern technology and nanomedicine. SNPs are present in various materials (tyres, electrical and thermal insulation material, photovoltaic facilities). They are also used in products that are directly exposed to humans such as cosmetics or toothpaste. For that reason it is of great concern to evaluate the possible hazards of these engineered particles for human health. Attention should primarily be focussed on SNP effects on biological barriers. Accidentally released SNP could, for example, encounter the alveolar-capillary barrier by inhalation. In this study we examined the inflammatory and cytotoxic responses of monodisperse amorphous silica nanoparticles (aSNPs) of 30 nm in size on an in vitro coculture model mimicking the alveolar-capillary barrier and compared these to conventional monocultures. Methods Thus, the epithelial cell line, H441, and the endothelial cell line, ISO-HAS-1, were used in monoculture and in coculture on opposite sides of a filter membrane. Cytotoxicity was evaluated by the MTS assay, detection of membrane integrity (LDH release), and TER (Transepithelial Electrical Resistance) measurement. Additionally, parameters of inflammation (sICAM-1, IL-6 and IL-8 release) and apoptosis markers were investigated. Results Regarding toxic effects (viability, membrane integrity, TER) the coculture model was less sensitive to apical aSNP exposure than the conventional monocultures of the appropriate cells. On the other hand, the in vitro coculture model responded with the release of inflammatory markers in a much more sensitive fashion than the conventional monoculture. At concentrations that were 10-100fold less than the toxic concentrations the apically exposed coculture showed a release of IL-6 and IL-8 to the basolateral side. This may mimic the early inflammatory events that take place in the pulmonary alveoli after aSNP inhalation. Furthermore, a number of apoptosis markers belonging to the intrinsic pathway were upregulated in the coculture following aSNP treatment. Analysis of the individual markers indicated that the cells suffered from DNA damage, hypoxia and ER-stress. Conclusion We present evidence that our in vitro coculture model of the alveolar-capillary barrier is clearly advantageous compared to conventional monocultures in evaluating the extent of damage caused by hazardous material encountering the principle biological barrier in the lower respiratory tract. KW - Silica nanoparticles KW - Alveolar-capillary coculture model KW - Cytotoxicity PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-254217 DO - https://doi.org/10.1186/1743-8977-8-6 SN - 1743-8977 VL - 8 IS - 6 SP - 1 EP - 16(?) PB - BioMed Central CY - London AN - OPUS4-25421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pretsch, Thorsten A1 - Ecker, Melanie A1 - Schildhauer, Markus A1 - Maskos, Michael T1 - Switchable information carriers based on shape memory polymer N2 - Herein we demonstrate the realization of a new technological concept, which enables the use of shape memory polymers (SMPs) as switchable information carriers. At first, we applied a surface-specific dyeing process based on 'guest-diffusion' on two sophisticated polymeric host materials, including a thermoplastic poly(ester urethane) SMP and a thermoset epoxy-based SMP. Upon drying, self-assembly of the dye molecules inside the polymer surfaces occurred, resulting in homogeneous color penetration depths of about 100 µm. Subsequently, the colored surfaces were patterned with quick response (QR) codes. For this purpose, laser ablation was used. The resulting cavity depth was exceeding the color penetration depth. This assured sufficient surface contrast and rendered the QR codes machine-readable. In a progressive approach, two thermo-mechanical functionalization protocols were designed in accordance with the thermal properties of the polymers. As a result of programming, the tag prototypes were converted into stable, temporary shapes with non-decodable QR code information. When thermally triggering the shape memory effect on the functionalized tags, we verified the mostly complete recovery of the polymer surface and the associated restoration into the almost original shape. As such, the QR code could again precisely be read out. We anticipate that tagging products with these information carriers is helpful for the purpose of secure one-time identification. KW - Shape memory polymer KW - Epoxy-based polymer KW - Poly(ester urethane) KW - Thermo-responsive polymer KW - Laser ablation KW - Laser marking KW - QR code KW - Functionalized tags KW - Tag technology KW - Smart tagging KW - Switchable information carrier KW - Authentification KW - Identification KW - Surface-specific dyeing KW - Guest diffusion PY - 2012 DO - https://doi.org/10.1039/c2jm16204k SN - 0959-9428 SN - 1364-5501 VL - 22 IS - 16 SP - 7757 EP - 7766 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-25737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kasper, J. A1 - Hermanns, M.I. A1 - Bantz, C. A1 - Koshkina, Olga A1 - Lang, Thomas A1 - Maskos, Michael A1 - Pohl, C. A1 - Unger, R. E. A1 - Kirkpatrick, C.J. T1 - Interactions of silica nanoparticles with lung epithelial cells and the association to flotillins N2 - Amorphous silica nanoparticles (aSNPs) gain increasing popularity for industrial and therapeutic claims. The lung with its surface area of 1006#8211;140 m² displays an ideal target for therapeutic approaches, but it represents also a serious area of attack for harmful nanomaterials. The exact nature of the cytotoxic effects of NPs is still unknown. Furthermore, cellular pathways and the destiny of internalized NPs are still poorly understood. Therefore, we examined the cytotoxicity (MTS, LDH) and inflammatory responses (IL-8) for different-sized aSNPs (30, 70, 300 nm) on our lung epithelial cells line NCI H441 and endothelial cell line ISO-HAS-1. Additionally, colocalization studies have been conducted via immunofluorescence staining for flotillin-1- and flotillin-2-bearing endocytic vesicles. Subsequently, the relevance of flotillins concerning the viability of aSNP-exposed epithelial cells has been evaluated using flotillin-1/2 depleted cells (siRNA). This study reveals the relevance of the nanoparticle size regarding cytotoxicity (MTS, LDH) and inflammatory responses (IL-8), whereat the smaller the size of the nanoparticle is, the more harmful are the effects. All different aSNP sizes have been incorporated in flotillin-1- and flotillin-2-labelled vesicles in lung epithelial and endothelial cells, which display a marker for late endosomal or lysosomal structures and appear to exhibit a clathrin- or caveolae-independent mode of endocytosis. Flotillin-depleted H441 showed a clearly decreased uptake of aSNPs. Additionally, the viability of aSNP-exposed cells was reduced in these cells. These findings indicate a contribution of flotillins in as yet unknown (clathrin or caveolae-independent) endocytosis mechanisms and (or) endosomal storage. KW - Silica nanoparticles KW - Alveolar-capillary barrier KW - Lung epithelial cells KW - Endothelial cells KW - Endocytosis KW - Flotillin-1 KW - Flotillin-2 KW - Cytotoxicity KW - Inflammatory response PY - 2012 DO - https://doi.org/10.1007/s00204-012-0876-5 SN - 0340-5761 SN - 1432-0738 SP - 1 EP - 13 PB - Springer CY - Berlin ; Heidelberg [u.a.] AN - OPUS4-26195 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lang, Thomas A1 - Eslahian, Kyriakos-Alexandros A1 - Maskos, Michael T1 - Ion effects in field-flow fractionation of aqueous colloidal polystyrene N2 - We discuss the effect of electrolytes on retention of aqueous colloidal polystyrene particles in asymmetrical flow (AF-FFF) and thermal field-flow fractionation (ThFFF). In both FFF subtechniques, interparticle interaction leads to non-ideal fractionation behavior, which can result in a sample load dependency. Electrostatic repulsion is reduced with increasing electrolyte concentration, resulting in a pronounced increase of retention. At higher salinities, hydrophobic interactions dominate, thus applications of AF-FFF under physiological conditions are limited. In ThFFF, also the separation mechanism of thermophoresis is affected by ionic shielding and experimental data are in accordance with recent theoretical models of thermophoresis. KW - Asymmetrical flow field-flow fractionation KW - Colloids KW - Interfaces KW - Ion effects KW - Thermal field-flow fractionation PY - 2012 DO - https://doi.org/10.1002/macp.201200132 SN - 1022-1352 SN - 1521-3935 VL - 213 IS - 22 SP - 2353 EP - 2361 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-27431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -