Planar Substrates (planar + substrate)

Distribution by Scientific Domains

Selected Abstracts

Caveolin-1 polarization in migrating endothelial cells is directed by substrate topology not chemoattractant gradient

CYTOSKELETON, Issue 11 2006
Virginie Santilman
Abstract Polarization is a hallmark of migrating cells, and an asymmetric distribution of proteins is essential to the migration process. Caveolin-1 is highly polarized in migrating endothelial cells (EC). Several studies have shown caveolin-1 accumulation in the front of migrating EC while others report its accumulation in the EC rear. In this paper we address these conflicting results on polarized localization of caveolin-1. We find evidence for the hypothesis that different modes of locomotion lead to differences in protein polarization. In particular, we show that caveolin-1 is primarily localized in the rear of cells migrating on a planar substrate, but in the front of cells traversing a three-dimensional pore. We also show that a chemoattractant, present either as a gradient or ubiquitously in the medium, does not alter caveolin-1 localization in cells in either mode of locomotion. Thus we conclude that substrate topology, and not the presence of a chemoattractant, directs the polarization of caveolin-1 in motile ECs. Cell Motil. Cytoskeleton 2006. 2006 Wiley-Liss, Inc. [source]

Equivalence between substrate-integrated (SIRW) rectangular waveguide short-circuit load and its equivalent rectangular waveguide short-circuit load

Wenquan Che
Abstract Substrate integrated rectangular waveguide (SIRW) is an artificial rectangular waveguide (RW) constructed in planar substrate with two rows of periodic metallized posts or slots. In this letter, the equivalence formula between the locations of the corresponding short circuits by cylinder walls and by the solid wall was derived, based on the former width equivalence formula of the SIRW and its equivalent RW [(11)]]. The theoretical and simulation results are given for the SIRW short load and RW short load, good agreements have been observed. Such equivalences are convenient for the design of small waveguides, of millimeter wave, in a multilayer circuit structure, such as the LTCC etc. 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1694,1698, 2006; Published online in Wiley InterScience ( DOI 10.1002/mop.21805 [source]

Hierarchical Gecko-Like Adhesives,

Christian Greiner
The role of hierarchy in gecko-like adhesive surfaces is presented. Experiments on two-level structured surfaces with micropillars of different dimensions demonstrate that hierarchy does not seem to positively influence adhesion of structured surfaces to planar substrates, but may be relevant when stiff materials or rough substrates come into play, where adaptability of the adhesive structure is required for successful contact. [source]

Cover Picture: Closing the Gap Between Self-Assembly and Microsystems Using Self-Assembly, Transfer, and Integration of Particles (Adv. Mater.

Abstract The cover shows 100 ,,m diameter glass spheres covered by a grid of hexagonally packed polystyrene beads. Wolf and co-workers placed the 500,nm diameter polystyrene beads onto the larger spheres using the self-assembly, transfer, and integration (SATI) process that they report on p.,2438. The cover illustrates the capability of SATI to process uneven surfaces in addition to the planar substrates discussed in the article. The carrier that holds the smaller beads deforms during their transfer onto the larger spheres, so that on the larger spheres patterned "caps" are formed. Using this process, which is compatible with standard microfabrication techniques, a variety of particle assemblies can be achieved. [source]

Design and in vitro Biodegradation of Novel Hepatocyte-Targetable (Galactose Polycation/Hemoglobin) Multilayers and Microcapsules

Fu Zhang
Abstract The formation of novel hepatocyte-targetable and biodegradable polycation/protein multilayers and hollow microcapsules by LbL assembly is reported, in which galactose residues allow for targetability and Hb acts as a main degradable component. The in vitro biodegradability of multilayers via proteases was evaluated in detail on both planar substrates and CaCO3 particles followed by UV-Vis, SEM, and AFM characterizations. The degradation approximately follows an exponential decay, and the relation between the kinetic constant k and the number n of deposited bilayers is well approximated by a power equation. Sustained release of the encapsulated model drug was attained by using enzymatic degradation of hollow capsules. [source]

Electrostatic Assembly of Poly(ethylene glycol) Nanotubes

Woo-Sik Jang
Abstract Poly(ethylene glycol) (PEG)-based films, nanotubes, and nanotube arrays were successfully made using layer-by-layer (LbL) assembly ion-containing PEO derivatives on porous templates and planar substrates. PEG nanotubes are challenging to produce because PEG dissolves into solutions and solvents used during nanotube processing, but our techniques circumvent the issue. Nanotube dimensions were verified using microscopy and the average observed diameter was 155,nm. The PEG-based structures showed remarkable stability in water, salt water, and sodium hydroxide solution. [source]

Probing Biomembrane Dynamics by Dual-Wavelength Reflection Interference Contrast Microscopy

CHEMPHYSCHEM, Issue 16 2009
Cornelia Monzel
Abstract We present an improved analysis of reflection interference contrast microscopy (RICM) images, recorded to investigate model membrane systems that mimic cell adhesion. The model systems were giant unilamellar vesicles (GUV) adhering via specific ligand,receptor interactions to supported lipid bilayers (SLB) or to patterns of receptors. Conventional RICM and dual-wavelength RICM (DW,RICM) were applied to measure absolute optical distances between the biomembranes and planar substrates. We developed algorithms for a straightforward implementation of an automated, time-resolved reconstruction of the membrane conformations from RICM/DW,RICM images, taking into account all the interfaces in the system and blurring of the data due to camera noise. Finally, we demonstrate the validity and usefulness of this new approach by analyzing the topography and fluctuations of a bound membrane in the steady state and its dynamic adaptation to osmotic pressure changes. These measurements clearly show that macroscopic membrane flow through tightly adhered area is possible in our system. [source]