Search results for "Microscopy"
showing 10 items of 3390 documents
Evaluating the microscopic effect of brushing stone tools as a cleaning procedure
2020
Cleaning stone tool surfaces is a common procedure in lithic studies. The first step widely applied at any archeological site (and/or at field laboratories) is the gross removal of sediment from the surfaces of artifacts. Lithic surface alterations due to mechanical action applied in wet or dry cleaning regimes have never been examined at a microscopic scale. This could have important implications in traceology, as any modern surface modifications inflicted on archeological artifacts might compromise their functional interpretations. The current trend toward quantification of use-wear traces makes the testing even more important, as even slight, apparently invisible surface alterations migh…
Adsorption and Conformation Behavior of Biotinylated Fibronectin on Streptavidin-Modified TiOX Surfaces Studied by SPR and AFM
2011
It is well-known that protein-modified implant surfaces such as TiO(2) show a higher bioconductivity. Fibronectin is a glycoprotein from the extracellular matrix (ECM) with a major role in cell adhesion. It can be applied on titanium oxide surfaces to accelerate implant integration. Not only the surface concentration but also the presentation of the protein plays an important role for the cellular response. We were able to show that TiO(X) surfaces modified with biotinylated fibronectin adsorbed on a streptavidin-silane self-assembly multilayer system are more effective regarding osteoblast adhesion than surfaces modified with nonspecifically bound fibronectin. The adsorption and conformati…
Defined-size DNA triple crossover construct for molecular electronics: modification, positioning and conductance properties.
2011
We present a novel, defined-size, small and rigid DNA template, a so-called B-A-B complex, based on DNA triple crossover motifs (TX tiles), which can be utilized in molecular scale patterning for nanoelectronics, plasmonics and sensing applications. The feasibility of the designed construct is demonstrated by functionalizing the TX tiles with one biotin-triethylene glycol (TEG) and efficiently decorating them with streptavidin, and furthermore by positioning and anchoring single thiol-modified B-A-B complexes to certain locations on a chip via dielectrophoretic trapping. Finally, we characterize the conductance properties of the non-functionalized construct, first by measuring DC conductivi…
Protein-membrane interaction probed by single plasmonic nanoparticles.
2008
We present a nanosized and addressable sensor platform based on membrane coated plasmonic particles and show unequivocally the covering with lipid bilayers as well as the subsequent detection of streptavidin binding to biotinylated lipids. The binding is detected on membrane covered gold nanorods by monitoring the spectral shift by fast single particle spectroscopy (fastSPS) on many particles in parallel. Our approach allows for local analysis of protein interaction with biological membranes as a function of the lateral composition of phase separated membranes.
Reactive Surface Coatings Based on Polysilsesquioxanes: Controlled Functionalization for Specific Protein Immobilization
2009
The key designing in reliable biosensors is the preparation of thin films in which biomolecular functions may be immobilized and addressed in a controlled and reproducible manner. This requires the controlled preparation of specific binding sites on planar surfaces. Poly(methylsilsesquioxane)-poly(pentafluorophenyl acrylates) (PMSSQ-PFPA) are promising materials to produce stable and adherent thin reactive coatings on various substrates. Those reactive surface coatings could be applied onto various materials, for example, gold, polycarbonate (PC), poly(tetrafluoroethylene) (PTFE), and glass. By dipping those substrates in a solution of a desired amine, specific binding sites for protein ads…
Streptavidin-coated TiO2 surfaces are biologically inert: Protein adsorption and osteoblast adhesion studies
2011
Non-fouling TiO2 surfaces are attractive for a wide range of applications such as biosensors and medical devices, where biologically inert surfaces are needed. Typically, this is achieved by controlled surface modifications which prevent protein adsorption. For example, polyethylene glycol (PEG) or PEG-derived polymers have been widely applied to render TiO2 surfaces biologically inert. These surfaces have been further modified in order to achieve specific bio-activation. Therefore, there have been efforts to specifically functionalize TiO2 surfaces with polymers with embedded biotin motives, which can be used to couple streptavidin for further functionalization. As an alternative, here a s…
Influence of surface chemistry on the structural organization of monomolecular protein layers adsorbed to functionalized aqueous interfaces.
1993
The molecular organization of streptavidin (SA) bound to aqueous surface monolayers of biotin-functionalized lipids and binary lipid mixtures has been investigated with neutron reflectivity and electron and fluorescence microscopy. The substitution of deuterons (2H) for protons (1H), both in subphase water molecules and in the alkyl chains of the lipid surface monolayer, was utilized to determine the interface structure on the molecular length scale. In all cases studied, the protein forms monomolecular layers underneath the interface with thickness values of approximately 40 A. A systematic dependence of the structural properties of such self-assembled SA monolayers on the surface chemistr…
Functionalized lipid tubules as tools for helical crystallization of proteins
1997
The development of functional supramolecular devices built by self-assembly of elementary molecules and with bioactive properties arouses considerable interest in the field of nanotechnology and new materials. We report here the formation of a new class of lipid tubules exhibiting both properties of molecular recognition and crystal formation for the protein streptavidin. These lipid tubules, made of biotin-containing dioctadecylamine molecules, are straight hollow cylinders with a constant diameter of 27 nm and variable length up to several micrometers. They are unilamellar with an inner diameter of about 16 nm, as shown by cryoelectron microscopy. Streptavidin binds to the biotinylated tu…
Piezospectroscopic study of mechanical stress in Al2O3:Cr under swift heavy ion irradiation
2009
Abstract The spatial distribution of mechanical stresses in Al2O3:Cr single crystal irradiated with (1 ÷ 3) MeV/amu Kr, Xe and Bi ions has been studied by using laser confocal scanning microscopy technique. The stress level as a function of the ion penetration depth has been evaluated from depth-resolved photostimulated R-line luminescence spectra exploiting the piezospectroscopic method. As it was found, the stress field generated by swift heavy ion irradiation is composed of stresses with maximal magnitude comparable with the ultimate stress limit of ruby crystals. Experimental data are discussed in the framework of a model considering the Cr3+ atoms as individual piezosensors.
Morphological and molecular redescription of the myxozoanUnicapsula pflugfelderiSchubert, Sprague & Reinboth 1975 from two teleost hosts in the M…
2009
Elongate plasmodia with myxosporean spores belonging to the genus Unicapsula, Davis, 1924 were found in the skeletal muscle of the striped seabream, Lithognathus mormyrus (L.), a candidate for the mediterranean aquaculture. The only species of Unicapsula described from the Mediterranean is Unicapsula pflugfelderi Schubert et al. 1975, which occurs in the picarel, Spicara smaris (L.). For morphological and molecular comparison of U. pflugfelderi from S. smaris with Unicapsula sp. from L. mormyrus measurements of plasmodia and spores, ultrastructural details and 18S and 28S rDNA sequences were analysed. Whereas plasmodia were 2-3 times larger in S. smaris than in L. mormyrus (length 2.47-0.81…