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- ItemNanoparticles Can Wrap Epithelial Cell Membranes and Relocate Them Across the Epithelial Cell Layer(Washington, DC : ACS Publ., 2018-7-24) Urbančič, Iztok; Garvas, Maja; Kokot, Boštjan; Majaron, Hana; Umek, Polona; Cassidy, Hilary; Škarabot, Miha; Schneider, Falk; Galiani, Silvia; Arsov, Zoran; Koklic, Tilen; Matallanas, David; Čeh, Miran; Muševič, Igor; Eggeling, Christian; Štrancar, JanezAlthough the link between the inhalation of nanoparticles and cardiovascular disease is well established, the causal pathway between nanoparticle exposure and increased activity of blood coagulation factors remains unexplained. To initiate coagulation tissue factor bearing epithelial cell membranes should be exposed to blood, on the other side of the less than a micrometre thin air-blood barrier. For the inhaled nanoparticles to promote coagulation, they need to bind lung epithelial-cell membrane parts and relocate them into the blood. To assess this hypothesis, we use advanced microscopy and spectroscopy techniques to show that the nanoparticles wrap themselves with epithelial-cell membranes, leading to the membrane’s disruption. The membrane-wrapped nanoparticles are then observed to freely diffuse across the damaged epithelial cell layer relocating epithelial cell membrane parts over the epithelial layer. Proteomic analysis of the protein content in the nanoparticles wraps/corona finally reveals the presence of the coagulation-initiating factors, supporting the proposed causal link between the inhalation of nanoparticles and cardiovascular disease.
- ItemNanoscale Spatiotemporal Diffusion Modes Measured by Simultaneous Confocal and Stimulated Emission Depletion Nanoscopy Imaging(Washington, DC : ACS Publ., 2018-6-12) Schneider, Falk; Waithe, Dominic; Galiani, Silvia; Bernardino de la Serna, Jorge; Sezgin, Erdinc; Eggeling, ChristianThe diffusion dynamics in the cellular plasma membrane provide crucial insights into molecular interactions, organization, and bioactivity. Beam-scanning fluorescence correlation spectroscopy combined with super-resolution stimulated emission depletion nanoscopy (scanning STED–FCS) measures such dynamics with high spatial and temporal resolution. It reveals nanoscale diffusion characteristics by measuring the molecular diffusion in conventional confocal mode and super-resolved STED mode sequentially for each pixel along the scanned line. However, to directly link the spatial and the temporal information, a method that simultaneously measures the diffusion in confocal and STED modes is needed. Here, to overcome this problem, we establish an advanced STED–FCS measurement method, line interleaved excitation scanning STED–FCS (LIESS–FCS), that discloses the molecular diffusion modes at different spatial positions with a single measurement. It relies on fast beam-scanning along a line with alternating laser illumination that yields, for each pixel, the apparent diffusion coefficients for two different observation spot sizes (conventional confocal and super-resolved STED). We demonstrate the potential of the LIESS–FCS approach with simulations and experiments on lipid diffusion in model and live cell plasma membranes. We also apply LIESS–FCS to investigate the spatiotemporal organization of glycosylphosphatidylinositol-anchored proteins in the plasma membrane of live cells, which, interestingly, show multiple diffusion modes at different spatial positions.
- ItemPlasticity, crack initiation and defect resistance in alkali-borosilicate glasses: From normal to anomalous behavior(Amsterdam [u.a.] : Elsevier Science, 2015) Limbach, R.; Winterstein-Beckmann, A.; Dellith, J.; Möncke, D.; Wondraczek, L.We provide a comprehensive description of the defect tolerance of sodium-borosilicate glasses upon sharp contact loading. This is motivated by the key role which is taken by this particular glass system in a wide variety of applications, ranging from electronic substrates, display covers and substrates for biomedical imaging and sensing to, e.g., radioactive waste vitrification. The present report covers the mechanical properties of glasses in the Na2O–B2O3–SiO2 ternary over the broad range of compositions from pure SiO2 to binary sodium-borates, and crossing the regions of various commercially relevant specialty borosilicate glasses, such as the multi-component Duran-, Pyrex- and BK7-type compositions and typical soda-lime silicate glasses, which are also included in this study. In terms of structure, the considered glasses may be separated into two groups, that is, one series which contains only bridging oxygen atoms, and another series which is designed with an increasing number of non-bridging oxygen ions. Elastic moduli, Poisson ratio, hardness as well as creep and crack resistance were evaluated, as well as the contribution of densification to the overall amount of indentation deformation. Correlations between the mechanical properties and structural characteristics of near- and mid-range order are discussed, from which we obtain a mechanistic view at the molecular reactions which govern the overall deformation reaction and, ultimately, contact cracking.
- ItemRapid Colorimetric Detection of Pseudomonas aeruginosa in Clinical Isolates Using a Magnetic Nanoparticle Biosensor(Washington, DC : ACS Publications, 2019) Alhogail, Sahar; Suaifan, Ghadeer A.R.Y; Bikker, Floris J.; Kaman, Wendy E.; Weber, Karina; Cialla-May, Dana; Popp, Jürgen; Zourob, Mohammed M.A rapid, sensitive, and specific colorimetric biosensor based on the use of magnetic nanoparticles (MNPs) was designed for the detection of Pseudomonas aeruginosa in clinical samples. The biosensing platform was based on the measurement of P. aeruginosa proteolytic activity using a specific protease substrate. At the N-terminus, this substrate was covalently bound to MNPs and was linked to a gold sensor surface via cystine at the C-terminus of the substrates. The golden sensor appears black to naked eyes because of the coverage of the MNPs. However, upon proteolysis, the cleaved peptide–MNP moieties will be attracted by an external magnet, revealing the golden color of the sensor surface, which can be observed by the naked eye. In vitro, the biosensor was able to detect specifically and quantitatively the presence of P. aeruginosa with a detection limit of 102 cfu/mL in less than 1 min. The colorimetric biosensor was used to test its ability to detect in situ P. aeruginosa in clinical isolates from patients. This biochip is anticipated to be useful as a rapid point-of-care device for the diagnosis of P. aeruginosa-related infections.
- ItemSilicon Powder-Based Wafers for Low-Cost Photovoltaics: Laser Treatments and Nanowire Etching(New York, NY [u.a.] : Hindawi Publ. Corp., 2018) Jia, G.; Plentz, J.; Gawlik, A.; Azar, A.S.; Stokkan, G.; Syvertsen, M.; Carvalho, P.A.; Dellith, J.; Dellith, A.; Andrä, G.; Ulyashin, A.In this study, laser-treated polycrystalline Si (pc-Si) wafers, fabricated by wire sawing of hot-pressed ingots sintered from Si powder, have been investigated. As-cut wafers and those with high-quality thin Si layers deposited on top of them by e-beam have been subjected to laser irradiation to clarify typical trends of structural modifications caused by laser treatments. Moreover, possibility to use laser-treated Si powder-based substrates for fabrication of advanced Si structures has been analysed. It is established that (i) Si powder-based wafers with thicknesses 180 μm can be fully (from the front to back side) or partly (subsurface region) remelted by a diode laser and grain sizes in laser-treated regions can be increased; (ii) a high-quality top layer can be fabricated by crystallization of an additional a-Si layer deposited by e-beam evaporation on top of the pc-Si; and (iii) silicon nanowires can be formed by metal-assisted wet chemical etching (MAWCE) of polished Si powder-based wafers and as-cut wafers irradiated with medium laser power, while a surface texturing on the as-cut pc-Si wafers occur, and no nanowires can form in the region subject to a liquid phase crystallization (LPC) caused by high-power laser treatments.
- ItemTowards on-site testing of Phytophthora species(Cambridge : RSC Publ., 2014) Schwenkbier, Lydia; Pollok, Sibyll; König, Stephan; Urban, Matthias; Werres, Sabine; Cialla-May, Dana; Weber, Karina; Popp, JürgenRapid detection and accurate identification of plant pathogens in the field is an ongoing challenge. In this study, we report for the first time on the development of a helicase-dependent isothermal amplification (HDA) in combination with on-chip hybridization for the detection of selected Phytophthora species. The HDA approach allows efficient amplification of the yeast GTP-binding protein (Ypt1) target gene region at one constant temperature in a miniaturized heating device. The assay's specificity was determined by on-chip DNA hybridization and subsequent silver nanoparticle deposition. The silver deposits serve as stable endpoint signals that enable the visual as well as the electrical readout. Our promising results point to the direction of a near future on-site application of the combined techniques for a reliable detection of Phytophthora species.
- ItemRadiofrequency Hyperthermia of Cancer Cells Enhanced by Silicic Acid Ions Released during the Biodegradation of Porous Silicon Nanowires(Washington, DC : ACS Publications, 2019) Gongalsky, Maxim; Gvindzhiliia, Georgii; Tamarov, Konstantin; Shalygina, Olga; Pavlikov, Alexander; Solovyev, Valery; Kudryavtsev, Andrey; Sivakov, Vladimir; Osminkina, Liubov A.The radiofrequency (RF) mild hyperthermia effect sensitized by biodegradable nanoparticles is a promising approach for therapy and diagnostics of numerous human diseases including cancer. Herein, we report the significant enhancement of local destruction of cancer cells induced by RF hyperthermia in the presence of degraded low-toxic porous silicon (PSi) nanowires (NWs). Proper selection of RF irradiation time (10 min), intensity, concentration of PSi NWs, and incubation time (24 h) decreased cell viability to 10%, which can be potentially used for cancer treatment. The incubation for 24 h is critical for degradation of PSi NWs and the formation of silicic acid ions H+ and H3SiO4- in abundance. The ions drastically change the solution conductivity in the vicinity of PSi NWs, which enhances the absorption of RF radiation and increases the hyperthermia effect. The high biodegradability and efficient photoluminescence of PSi NWs were governed by their mesoporous structure. The average size of pores was 10 nm, and the sizes of silicon nanocrystals (quantum dots) were 3-5 nm. Degradation of PSi NWs was observed as a significant decrease of optical absorbance, photoluminescence, and Raman signals of PSi NW suspensions after 24 h of incubation. Localization of PSi NWs at cell membranes revealed by confocal microscopy suggested that thermal poration of membranes could cause cell death. Thus, efficient photoluminescence in combination with RF-induced cell membrane breakdown indicates promising opportunities for theranostic applications of PSi NWs. © 2019 American Chemical Society.
- ItemPolymeric Photoacids Based on Naphthols—Design Criteria, Photostability, and Light-Mediated Release(Weinheim : Wiley-VCH, 2019) Wendler, Felix; Sittig, Maria; Tom, Jessica C.; Dietzek, Benjamin; Schacher, Felix H.The implementation of photoswitches within polymers offers an exciting toolbox in the design of light-responsive materials as irradiation can be controlled both spatially and temporally. Herein, we introduce a range of water-soluble copolymers featuring naphthol-based chromophores as photoacids in the side chain. With that, the resulting materials experience a drastic increase in acidity upon stimulation with UV light and we systematically studied how structure and distance of the photoacid from the copolymer backbone determines polymerizability, photo-response, and photostability. Briefly, we used RAFT (reversible addition–fragmentation chain transfer) polymerization to prepare copolymers consisting of nona(ethylene glycol) methyl ether methacrylate (MEO9MA) as water-soluble comonomer in combination with six different 1-naphthol-based (“N”) monomers. Thereby, we distinguish between methacrylates (NMA, NOeMA), methacrylamides (NMAm, NOeMAm), vinyl naphthol (VN), and post-polymerization modification based on [(1-hydroxynaphthalen-2-amido)ethyl]amine (NOeMAm, NAmeMAm). These P(MEO9MAx-co-“N”y) copolymers typically feature a 4:1 MEO9MA to “N” ratio and molar masses in the range of 10 kg mol−1. After synthesis and characterization by using NMR spectroscopy and size exclusion chromatography (SEC), we investigated how potential photo-cleavage or photo-degradation during irradiation depends on the type and distance of the linker to the copolymeric backbone and whether reversible excited state proton transfer (ESPT) occurs under these conditions. In our opinion, such materials will be strong assets as light-mediated proton sources in nanostructured environments, for example, for the site-specific creation of proton gradients. We therefore exemplarily incorporated NMA into an amphiphilic block copolymer and could demonstrate the light-mediated release of Nile red from micelles formed in water as selective solvent. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
- ItemLinear and nonlinear absorption of titanium dioxide films produced by plasma ion-assisted electron beam evaporation: Modeling and experiments(Basel : MDPI, 2019) Stenzel, Olaf; Wilbrandt, Steffen; Mühlig, Christian; Schröder, SvenTitanium dioxide films were prepared by plasma ion-assisted electron beam evaporation. Linear optical properties were investigated in terms of spectrophotometry using the beta-distributed oscillator (ss_do) model as a parametrized dispersion law. The nonlinear two-photon absorption coecient of titanium dioxide was determined by means of the laser-induced deflection technique at a wavelength of 800 nm. The obtained values of (2-5) x 10-11 cm/W were consistent with published experimental values for rutile as well as for simulations performed in the frames of the ss_do and Sheik-Bahae models. © 2020 by the authors.