TY - JOUR A1 - Niehoff, A. A1 - Mantion, Alexandre A1 - McAloney, R. A1 - Huber, Alexandra A1 - Falkenhagen, Jana A1 - Goh, C.M. A1 - Thünemann, Andreas A1 - Winnik, M. A. A1 - Menzel, H. T1 - Elucidation of the structure of poly(gamma-benzyl-L-glutamate) nanofibers and gel networks in a helicogenic solvent JF - Colloid and polymer science N2 - The synthesis, characterization, self-assembly, and gel formation of poly(γ-benzyl-L-glutamate) (PBLG) in a molecular weight range from ca. 7,000–100,000 g/mol and with narrow molecular weight distribution are described. The PBLG is synthesized by the nickel-mediated ring-opening polymerization and is characterized by size-exclusion chromatography coupled with multiple-angle laser light scattering, NMR, and Fourier transform infrared spectroscopy. The self-assembly and thermoreversible gel formation in the helicogenic solvent toluene is investigated by transmission electron microscopy, atomic force microscopy, small-angle X-ray scattering, and synchrotron powder X-ray diffraction. At concentrations significantly below the minimum gelation concentration, spherical aggregates are observed. At higher concentrations, gels are formed, which show a 3D network structure composed of nanofibers. The proposed self-assembly mechanism is based on a distorted hexagonal packing of PBLG helices parallel to the axis of the nanofiber. The gel network forms due to branching and rejoining of bundles of PBLG nanofibers. The network exhibits uniform domains with a length of 200±42 nm composed of densely packed PBLG helices. KW - Poly(gamma-benzyl-L-glutamate) (PBLG) KW - Nickel-mediated NCA polymerization KW - Thermoreversible gel formation KW - Physical/supramolecular organogel KW - Nanofiber KW - Self-assembly KW - Alpha-helix KW - Nanotechnology KW - Small-angle X-ray scatering KW - SAXS PY - 2013 DO - https://doi.org/10.1007/s00396-012-2866-9 SN - 0303-402X SN - 1435-1536 VL - 291 IS - 6 SP - 1353 EP - 1363 PB - Springer CY - Berlin AN - OPUS4-28615 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tentschert, J. A1 - Draude, F. A1 - Jungnickel, H. A1 - Haase, A. A1 - Mantion, Alexandre A1 - Galla, S. A1 - Thünemann, Andreas A1 - Taubert, A. A1 - Luch, A. A1 - Arlinghaus, H. F. T1 - TOF-SIMS analysis of cell membrane changes in functional impaired human macrophages upon nanosilver treatment JF - Surface and interface analysis N2 - Silver nanoparticles (SNP) are among the most commercialized nanoparticles. Here, we show that peptide-coated SNP cause functional impairment of human macrophages. A dose-dependent inhibition of phagocytosis is observed after nanoparticle treatment, and pretreatment of cells with N-acetyl cysteine (NAC) can counteract the phagocytosis disturbances caused by SNP. Using the surface-sensitive mode of time-of-flight secondary ion mass spectrometry, in combination with multivariate statistical methods, we studied the composition of cell membranes in human macrophages upon exposure to SNP with and without NAC preconditioning. This method revealed characteristic changes in the lipid pattern of the cellular membrane outer leaflet in those cells challenged by SNP. Statistical analyses resulted in 19 characteristic ions, which can be used to distinguish between NAC pretreated and untreated macrophages. The present study discusses the assignments of surface cell membrane phospholipids for the identified ions and the resulting changes in the phospholipid pattern of treated cells. We conclude that the adverse effects in human macrophages caused by SNP can be partially reversed through NAC administration. Some alterations, however, remained. KW - Silver nanoparticles KW - Lipidomics KW - N-acetyl cysteine KW - Phagocytosis KW - Oxidative stress KW - Reference material PY - 2013 DO - https://doi.org/10.1002/sia.5155 SN - 0142-2421 SN - 1096-9918 VL - 45 IS - 1 SP - 483 EP - 485 PB - Wiley CY - Chichester AN - OPUS4-27586 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 JF - Surface and interface analysis 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 - Haase, A. A1 - Rott, S. A1 - Mantion, Alexandre A1 - Graf, P. A1 - Plendl, J. A1 - Thünemann, Andreas A1 - Meier, W.P. A1 - Taubert, A. A1 - Luch, A. A1 - Reiser, G T1 - Effects of silver nanoparticles on primary mixed neural cell cultures: uptake, oxidative stress and acute calcium responses JF - Toxicological sciences N2 - In the body, nanoparticles can be systemically distributed and then may affect secondary target organs, such as the central nervous system (CNS). Putative adverse effects on the CNS are rarely investigated to date. Here, we used a mixed primary cell model consisting mainly of neurons and astrocytes and a minor proportion of oligodendrocytes to analyze the effects of well-characterized 20 and 40 nm silver nanoparticles (SNP). Similar gold nanoparticles served as control and proved inert for all endpoints tested. SNP induced a strong size-dependent cytotoxicity. Additionally, in the low concentration range (up to 10 µg/ml of SNP), the further differentiated cultures were more sensitive to SNP treatment. For detailed studies, we used low/medium dose concentrations (up to 20 µg/ml) and found strong oxidative stress responses. Reactive oxygen species (ROS) were detected along with the formation of protein carbonyls and the induction of heme oxygenase-1. We observed an acute calcium response, which clearly preceded oxidative stress responses. ROS formation was reduced by antioxidants, whereas the calcium response could not be alleviated by antioxidants. Finally, we looked into the responses of neurons and astrocytes separately. Astrocytes were much more vulnerable to SNP treatment compared with neurons. Consistently, SNP were mainly taken up by astrocytes and not by neurons. Immunofluorescence studies of mixed cell cultures indicated stronger effects on astrocyte morphology. Altogether, we can demonstrate strong effects of SNP associated with calcium dysregulation and ROS formation in primary neural cells, which were detectable already at moderate dosages. KW - Silver nanoparticles KW - Neurons KW - Oxidative stress KW - Protein carbonyls KW - Calcium KW - Reference material KW - Nanoparticle KW - Small-angle X-ray scattering KW - SAXS PY - 2012 DO - https://doi.org/10.1093/toxsci/kfs003 SN - 1096-6080 SN - 1096-0929 VL - 126 IS - 2 SP - 457 EP - 468 PB - Oxford University Press CY - Oxford AN - OPUS4-25633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haase, A. A1 - Mantion, Alexandre A1 - Graf, P. A1 - Plendl, J. A1 - Thünemann, Andreas A1 - Meier, W. A1 - Taubert, A. A1 - Luch, A. T1 - A novel type of silver nanoparticles and their advantages in toxicity testing in cell culture systems JF - Archives of toxicology N2 - Silver nanoparticles (SNPs) are among the most commercialized nanoparticles worldwide. Often SNP are used because of their antibacterial properties. Besides that they possess unique optic and catalytic features, making them highly interesting for the creation of novel and advanced functional materials. Despite its widespread use only little data exist in terms of possible adverse effects of SNP on human health. Conventional synthesis routes usually yield products of varying quality and property. It thus may become puzzling to compare biological data from different studies due to the great variety in sizes, coatings or shapes of the particles applied. Here, we applied a novel synthesis approach to obtain SNP of well-defined colloidal and structural properties. Being stabilized by a covalently linked small peptide, these particles are nicely homogenous, with narrow size distribution, and form monodisperse suspensions in aqueous solutions. We applied these peptide- coated SNP in two different sizes of 20 or 40 nm (Ag20Pep and Ag40Pep) and analyzed responses of THP- 1-derived human macrophages while being exposed against these particles. Gold nanoparticles of similar size and coating (Au20Pep) were used for comparison. The cytotoxicity of particles was assessed by WST-1 and LDH assays, and the uptake into the cells was confirmed via transmission electron microscopy. In summary, our data demonstrate that this novel type of SNP is well suited to serve as model system for nanoparticles to be tested in toxicological studies in vitro. KW - Silver nanoparticles KW - Peptide coating KW - Nanotoxicity PY - 2012 DO - https://doi.org/10.1007/s00204-012-0836-0 SN - 0340-5761 SN - 1432-0738 VL - 86 IS - 7 SP - 1089 EP - 1098 PB - Springer CY - Berlin ; Heidelberg [u.a.] AN - OPUS4-26269 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vila-Comamala, J. A1 - Diaz, A. A1 - Guizar-Sicairos, M. A1 - Gorelick, S. A1 - Guzenko, V.A. A1 - Karvinen, P. A1 - Kewish, C.M. A1 - Färm, E. A1 - Ritala, M. A1 - Mantion, Alexandre A1 - Bunk, O. A1 - Menzel, A. A1 - David, C. ED - Morawe, C. ED - Khounsary, A.M. ED - Goto, S. T1 - Characterization of a 20-nm hard X-ray focus by ptychographic coherent diffractive imaging T2 - Advances in X-Ray/EUV optics and components VI (Proceedings of SPIE) N2 - Recent advances in the fabrication of diffractive X-ray optics have boosted hard X-ray microscopy into spatial resolutions of 30 nm and below. Here, we demonstrate the fabrication of zone-doubled Fresnel zone plates for multi-keV photon energies (4-12 keV) with outermost zone widths down to 20 nm. However, the characterization of such elements is not straightforward using conventional methods such as knife edge scans on well-characterized test objects. To overcome this limitation, we have used ptychographic coherent diffractive imaging to characterize a 20 nm-wide X-ray focus produced by a zone-doubled Fresnel zone plate at a photon energy of 6.2 keV. An ordinary scanning transmission X-ray microscope was modified to acquire the ptychographic data from a strongly scattering test object. The ptychographic algorithms allowed for the reconstruction of the image of the test object as well as for the reconstruction of the focused hard X-ray beam waist, with high spatial resolution and dynamic range. This method yields a full description of the focusing performance of the Fresnel zone plate and we demonstrate the usefulness ptychographic coherent diffractive imaging for metrology and alignment of nanofocusing diffractive X-ray lenses. T2 - SPIE Optics and photonics CY - San Diego, USA DA - 20.08.2011 KW - X-ray imaging KW - Diffractive X-ray optics KW - Electron beam lithography KW - Ptychographic coherent diffractive imaging PY - 2011 DO - https://doi.org/10.1117/12.893235 SN - 0277-786X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 8139 SP - 81390E-1 EP - 81390E-7 AN - OPUS4-24613 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vila-Comamala, J. A1 - Diaz, A. A1 - Guizar-Sicairos, M. A1 - Mantion, Alexandre A1 - Kewish, C.M. A1 - Menzel, A. A1 - Bunk, O. A1 - David, C. T1 - Characterization of high-resolution diffractive X-ray optics by ptychographic coherent diffractive imaging JF - Optics express N2 - We have employed ptychographic coherent diffractive imaging to completely characterize the focal spot wavefield and wavefront aberrations of a high-resolution diffractive X-ray lens. The ptychographic data from a strongly scattering object was acquired using the radiation cone emanating from a coherently illuminated Fresnel zone plate at a photon energy of 6.2 keV. Reconstructed images of the object were retrieved with a spatial resolution of 8 nm by combining the difference-map phase retrieval algorithm with a non-linear optimization refinement. By numerically propagating the reconstructed illumination function, we have obtained the X-ray wavefield profile of the 23 nm round focus of the Fresnel zone plate (outermost zone width, Δr = 20 nm) as well as the X-ray wavefront at the exit pupil of the lens. The measurements of the wavefront aberrations were repeatable to within a root mean square error of 0.006 waves, and we demonstrate that they can be related to manufacturing aspects of the diffractive optical element and to errors on the incident X-ray wavefront introduced by the upstream beamline optics. KW - Fourier zone plate KW - Coherent diffraction imaging KW - Ptychography PY - 2011 DO - https://doi.org/10.1364/OE.19.021333 SN - 1094-4087 VL - 19 IS - 22 SP - 21333 EP - 21344 PB - Optical Society of America CY - Washington, DC AN - OPUS4-24615 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Orts Gil, Guillermo A1 - Natte, Kishore A1 - Drescher, Daniela A1 - Bresch, Harald A1 - Mantion, Alexandre A1 - Kneipp, J. A1 - Österle, Werner T1 - Characterisation of silica nanoparticles prior to in vitro studies: from primary particles to agglomerates JF - Journal of nanoparticle research N2 - The size, surface charge and agglomeration state of nanoparticles under physiological conditions are fundamental parameters to be determined prior to their application in toxicological studies. Although silica-based materials are among the most promising candidates for biomedical applications, more systematic studies concerning the characterisation before performing toxicological studies are necessary. This interest is based on the necessity to elucidate the mechanisms affecting its toxicity. We present here TEM, SAXS and SMPS as a combination of methods allowing an accurate determination of single nanoparticle sizes. For the commercial material, Ludox TM50 single particle sizes around 30 nm were found in solution. DLS measurements of single particles are rather affected by polydispersity and particles concentration but this technique is useful to monitor their agglomeration state. Here, the influence of nanoparticle concentration, ionic strength (IS), pH and bath sonication on the agglomeration behaviour of silica particles in solution has been systematically investigated. Moreover, the colloidal stability of silica particles in the presence of BSA has been investigated showing a correlation between silica and protein concentrations and the formation of agglomerates. Finally, the colloidal stability of silica particles in standard cell culture medium has been tested, concluding the necessity of surface modification in order to preserve silica as primary particles in the presence of serum. The results presented here have major implications on toxicity investigations because silica agglomeration will change the probability and uptake mechanisms and thereby may affect toxicity. KW - Silica KW - Toxicology KW - Agglomeration KW - BSA KW - Nanoparticles KW - Characterisation PY - 2011 DO - https://doi.org/10.1007/s11051-010-9910-9 SN - 1388-0764 SN - 1572-896X VL - 13 IS - 4 SP - 1593 EP - 1604 PB - Springer AN - OPUS4-21179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - De Bruyn Ouboter, D. A1 - Schuster, T.B. A1 - Mantion, Alexandre A1 - Meier, W. T1 - Hierarchical organization of purely peptidic amphiphiles into peptide beads JF - The journal of physical chemistry / C N2 - A broad range of new properties is emerging from supramolecular aggregates as they pass beyond the limitations of simple molecules. Self-assembled structures of purely peptidic amphiphiles may exploit such properties to produce biocompatible, smart materials for drug administration. In aqueous media, the solid-phase derived amphiphilic undecapeptide described herein (Ac-X3-gT) forms self-assembled particles of spherical shape with diameters between 200 and 1500 nm, termed 'peptide beads'. The beads result from hierarchical organization of micellar-like structures, a fact determined by a combination of investigations carried out by electron and atomic force microscopy (AFM), static and dynamic light scattering, and small-angle X-ray scattering. These highly ordered structures agree with the concept of multicompartmentization and represent the first example of supramicellar assemblies based purely on peptides. New structural insights, as presented here, allow a better understanding of the beads' capacity to embed hydrophobic and hydrophilic payloads and therefore provide new perspectives for drug delivery applications that may result from this new class of material. KW - Peptide beads KW - Spherical peptide particles KW - Hierarchical self-assembly KW - Multicompartment micelles KW - Purely peptidic amphiphiles PY - 2011 DO - https://doi.org/10.1021/jp203048h SN - 1932-7447 SN - 1089-5639 VL - 115 IS - 30 SP - 14583 EP - 14590 PB - Soc. CY - Washington, DC AN - OPUS4-24212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, P. A1 - Mantion, Alexandre A1 - Haase, A. A1 - Thünemann, Andreas A1 - Masic, A. A1 - Meier, W. A1 - Luch, A. A1 - Taubert, A. T1 - Silicification of peptide-coated silver nanoparticles - a biomimetic soft chemistry approach toward chiral hybrid core-shell materials JF - ACS nano N2 - Silica and silver nanoparticles are relevant materials for new applications in optics, medicine, and analytical chemistry. We have previously reported the synthesis of pH responsive, peptide-templated, chiral silver nanoparticles. The current report shows that peptide-stabilized nanoparticles can easily be coated with a silica shell by exploiting the ability of the peptide coating to hydrolyze silica precursors such as TEOS or TMOS. The resulting silica layer protects the nanoparticles from chemical etching, allows their inclusion in other materials, and renders them biocompatible. Using electron and atomic force microscopy, we show that the silica shell thickness and the particle aggregation can be controlled simply by the reaction time. Small-angle X ray scattering confirms the Ag/peptide@silica core–shell structure. UV–vis and circular dichroism spectroscopy prove the conservation of the silver nanoparticle chirality upon silicification. Biological tests show that the biocompatibility in simple bacterial systems is significantly improved once a silica layer is deposited on the silver particles. KW - Peptide-templated materials KW - Silver nanoparticles KW - Chiral nanoparticles KW - Ag/peptide@SiO2 nanostructures KW - Core-shell structures PY - 2011 DO - https://doi.org/10.1021/nn102969p SN - 1936-0851 VL - 5 IS - 2 SP - 820 EP - 833 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-23207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -