Search results for "Microscopy."

Porous Gelatin Hydrogels:  2. In Vitro Cell Interaction Study

2007

We report on the feasibility of applying porous gelatin hydrogels, prepared by a novel and controlled cryogenic treatment, as cell-interactive scaffolds for tissue engineering applications. Despite the large number of publications on gelatin as a biomaterial, a detailed study of screening a limited number of gelatin scaffolds for their interaction with a panel of human cells has, to the best of our knowledge, not yet been published. In the present work, we have evaluated two types of porous gelatin scaffolds that differ in their pore geometry and pore size. Type I hydrogels contained top-to-bottom transverse channels (i.e. cones) with a decreasing diameter from the top (330 microm) to the b…

Influence of low methoxyl pectin gel textures and in vitro release of rutin from calcium pectinate beads.

2013

This study described the preparation and characterization of low methoxyl pectin (LMP) gels and beads for controlled release applications. The rheological characterization of the various formulations was proposed. Then the mechanical and morphological characterizations of beads were determined. Finally, the controlled release studies taking rutin as a model drug was evaluated. The results showed that Young's modulus values of non-amidated LMP gels decrease when adding up to 15% sorbitol. Calcium pectinate beads loaded with rutin are about 600 μm, oblong shaped with dense matrix. Beads containing sodium bicarbonate showed about 80% lower rutin encapsulation efficiency by increasing the pH of…

The effect of heat treatment on the morphology and mobility of Au nanoparticles

2020

This work was supported by The Centre National de la Recherche Scientifique (CNRS) of France and the French Embassy Program. The authors are also grateful for partial support by COST Action CA15216, the Estonian Science Foundation (grants PUT1689 and PUT1372), the Estonian Centre of Excellence in Zero Energy and Resource Efficient Smart Buildings and Districts, ZEBE, grant 2014-2020.4.01.15.0016 and Latvian Science Council grant lzp-2018/2-0083.

Supramolecular Hydro- and Ionogels: A Study of Their Properties and Antibacterial Activity.

2017

Diimidazolium-based organic salts, bearing peptides or amino acids as anions have been synthesised and tested for their gelling ability in biocompatible solvents. These low molecular weight salts were successfully used as gelators in phosphate buffered saline (PBS) solution and ionic liquids. Then, the properties of the obtained soft materials were analysed in terms of melting temperature and gel strength as accounted for by rheological investigations. The gel-phase formation was studied by using UV/Vis and resonance light scattering measurements, whereas the morphology of the soft materials was analysed by using polarised optical microscopy and scanning electron microscopy. To get informat…

Distribution and Function of Gap Junction Coupling in Cortical GABAergic Neurons.

2013

Although gap junctions have been observed in GABAergic interneurons of several brain regions, this chapter focuses on the distribution and functions of gap junctions and connexins in inhibitory interneurons of the cerebral cortex and hippocampus. Evidence for interconnections mediated by electrical synapses is reported for at least eight cerebral cortex interneuron types, classified on the basis of morphology, electrophysiology and molecular markers. The main differences in the organization of these interneuronal networks are summarized in terms of homologous and heterologous electrical coupling and mutual chemical inhibition. The role of connexin36 (Cx36) in forming neuronal electrical syn…

Light-dependent CK2-mediated phosphorylation of centrins regulates complex formation with visual G-protein.

2008

AbstractCentrins are Ca2+-binding EF-hand proteins. All four known centrin isoforms are expressed in the ciliary apparatus of photoreceptor cells. Cen1p and Cen2p bind to the visual G-protein transducin in a strictly Ca2+-dependent way, which is thought to regulate light driven movements of transducin between photoreceptor cell compartments. These relatively slow motile processes represent a novel paradigm in light adaptation of photoreceptor cells.Here we validated specific phosphorylation as a novel regulator of centrins in photoreceptors. Centrins were differentially phosphorylated during photoreceptor dark adaptation. Inhibitor treatments revealed protein kinase CK2 as the major protein…

Optical illusions in scanning electron micrographs: the case of the eggshell of Acrosternum (Chinavia) marginatum (Hemiptera: Pentatomidae)

2003

Scanning electron microscopy revealed that-as is common in this family of the Hemiptera-the eggs of the green stink bug Acrosternum (Chinavia) marginatum are roughly barrel-shaped and possess at their apical pole a row of slender extensions, the aero-micropylar processes. The outer surface of the eggshell carries hexagonally arranged pits. The analysis of cross-fractured eggshells showed that the pits have slender basal extensions with transverse diaphragms. When scanning electron micrographs of the egg surface of A. marginatum are viewed upside down, the perception flips and the pits appear as elevations to all observers addressed. Thus, we are dealing with an optical illusion, which is kn…

Interactions of virus proteins within the host cell

2014

Revealing lattice disorder, oxygen incorporation and pore formation in laser induced two-photon oxidized graphene

2019

Abstract Laser induced two-photon oxidation has proven to be a reliable method to pattern and control the level of oxidation of single layer graphene, which in turn allows the development of graphene-based electronic and optoelectronic devices with an all-optical method. Here we provide a full structural and chemical description of modifications of air-suspended graphene during the oxidation process. By using different laser irradiation doses, we were able to show via transmission electron microscopy, electron energy loss spectroscopy, electron diffraction and Raman spectroscopy how graphene develops from its pristine form up to a completely oxidized, porous and amorphous carbon layer. Furt…

Metallic nanoparticles exhibit paradoxical effects on oxidative stress and pro-inflammatory response in endothelial cells in vitro

2007

Particulate matter is associated with different human diseases affecting organs such as the respiratory and cardiovascular systems. Very small particles (nanoparticles) have been shown to be rapidly internalized into the body. Since the sites of internalization and the location of the detected particles are often far apart, a distribution via the blood stream must have occurred. Thus, endothelial cells, which line the inner surface of blood vessels, must have had direct contact with the particles. In this study we tested the effects of metallic nanoparticles (Co and Ni) on oxidative stress and proinflammatory response in human endothelial cells in vitro. Exposure to both nanoparticle types…