TY - JOUR A1 - Prinz, J. A1 - Schreiber, B. A1 - Olejko, L. A1 - Oertel, J. A1 - Rackwitz, J. A1 - Keller, A. A1 - Bald, Ilko T1 - DNA origami substrates for highly sensitive surface-enhanced Raman scattering N2 - DNA nanotechnology holds great promise for the fabrication of novel plasmonic nanostructures and the potential to carry out single-molecule measurements using optical spectroscopy. Here, we demonstrate for the first time that DNA origami nanostructures can be exploited as substrates for surface-enhanced Raman scattering (SERS). Gold nanoparticles (AuNPs) have been arranged into dimers to create intense Raman scattering hot spots in the interparticle gaps. AuNPs (15 nm) covered with TAMRA-modified DNA have been placed at a nominal distance of 25 nm to demonstrate the formation of Raman hot spots. To control the plasmonic coupling between the nanoparticles and thus the field enhancement in the hot spot, the size of AuNPs has been varied from 5 to 28 nm by electroless Au deposition. By the precise positioning of a specific number of TAMRA molecules in these hot spots, SERS with the highest sensitivity down to the few-molecule level is obtained. KW - DANN Origami KW - Surface-enhanced Raman scattering KW - Nanoparticles KW - TAMRA PY - 2013 DO - https://doi.org/10.1021/jz402076b SN - 1948-7185 VL - 4 IS - 23 SP - 4140 EP - 4145 PB - ACS CY - Washington, DC AN - OPUS4-29907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Svoboda, S. A1 - Oertel, B. T1 - Wear resistant alumina coatings produced by a sol-gel process N2 - Aluminium oxide films were prepared by a dip-coating procedure from solutions of hydrolysed aluminium-tri-sec-butoxide in methoxyethanol on austenitic steel as well as hard metal tools. The heat treatment was performed in an argon atmosphere or vacuum at temperatures up to 1100 °C. Characterisation of the coatings by SEM, showed nearly crack free coatings with a dense morphology which completely cover the substrate. The chemical composition of the coatings was investigated by ESCA, GD-OES and XRD measurements. This analysis detected a multi-layered arrangement of spinel phases, ?- and ?-alumina in the coatings. The scratch test showed sufficient adhesion of the coatings comparable to CVD layers. Pin-on-disc and oscillating sliding tests were carried out on sol–gel coated samples and also on uncovered reference samples. The determined wear rates and friction coefficients showed significant improvement in wear resistance of sol–gel coatings containing a corundum phase. The strong adhesion to the substrates is due to a layered assembly formation and gradient composition of the coating caused by an interdiffusion of metal cations and oxygen in the metal/oxide interface during heat treatment. KW - Oxide film formation KW - Film analysis KW - Wear resistance PY - 2006 DO - https://doi.org/10.1016/j.surfcoat.2005.11.014 SN - 0257-8972 VL - 201 IS - 1-2 SP - 487 EP - 491 PB - Elsevier Science CY - Lausanne AN - OPUS4-18583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Bauroth, F. A1 - Oertel, B. A1 - Svoboda, S. T1 - Aluminiumoxid-Sol/Gel-Schutzschichten auf Metallen PY - 1995 SN - 0173-9913 SN - 0196-6219 VL - 10 IS - 4 SP - 60 EP - 66 PB - Göller CY - Baden-Baden AN - OPUS4-5680 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hübert, Thomas A1 - Oertel, B. A1 - Heinze, D. ED - Kunzmann, H. T1 - Kapazitive Sensorsysteme zur Ermittlung prozeßnaher Größen (Temperatur und Feuchte) T2 - Abschlußkolloquium CY - Braunschweig, Deutschland DA - 1994-04-13 PY - 1994 SN - 3-89429-454-X SN - 0179-0609 N1 - Serientitel: PTB-Bericht: PTB-F – Series title: PTB-Bericht: PTB-F IS - 12 SP - 1 EP - 11 CY - Braunschweig AN - OPUS4-5681 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Schwarz, J. A1 - Oertel, B. T1 - Sol-gel alumina coatings on stainless steel for wear protection N2 - The aluminium oxide films on austenitic steel are prepared from sols of re-dispersed boehmite nano powders in water. After dip-coating of the sol, a heat treatment including drying, calcination and annealing in vacuum at temperatures up to 1100°C is performed to obtain crack-free coatings of a thickness up to 6 µm. XRD measurements detect α- and γ-alumina, a TiOx-phase at the metal/coating interface and a gradient of phase formation in the coating. The strong adhesion on the substrates is due to the layered assembly and gradient composition of the coating caused by an inter-diffusion of metal cations and oxygen in the metal/oxide interface during heat treatment. Residual stress measurements by X-rays result in compressive stresses of 2–4 GPa in the alumina coatings. The pin-on-disc test shows a remarkable improvement of wear resistance obtained by sol-gel coatings. The α-alumina content and the compressive stress of the coatings correlate with wear resistance of the coatings. KW - Alumina KW - Sol-gel KW - Coating KW - Wear protection KW - Residual stress PY - 2006 DO - https://doi.org/10.1007/s10971-006-6470-7 SN - 0928-0707 SN - 1573-4846 VL - 38 IS - 2 SP - 179 EP - 184 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-12435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oertel, J. A1 - Keller, A. A1 - Prinz, J. A1 - Schreiber, B. A1 - Hübner, R. A1 - Kerbusch, J. A1 - Bald, Ilko A1 - Fahmy, K. T1 - Anisotropic metal growth on phospholipid nanodiscs via lipid bilayer expansion N2 - Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the “outer shape” of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials. KW - Lipid Nanodiscs KW - Metal nanoparticles KW - Infrared spectroscopy KW - Surface-enhanced Raman scattering PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-364303 UR - http://www.nature.com/articles/srep26718 DO - https://doi.org/10.1038/srep26718 SN - 2045-2322 VL - 6 SP - 26718-1 EP - 26718-9 PB - Nature Publishing Group CY - London, UK AN - OPUS4-36430 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -