Vesicular layer

McFadden L.D., McDonald E.V., Wells S.G., Anderson K., Quade J., Forman S.L. The vesicular layer and carbonate collars of desert soils and pavements formation, age and relation to climate change. Geomorphology 1998 24 101-145. 

Reviakine, F. F. Rossetti, A. N. Morozov, and M. Textor, Investigating the properties of supported vesicular layers on titanium dioxide by quartz crystal microbalance with dissipation measurements, J. Chem. Phys., 122, 204711 (2005). 

In the first step, lipid model membranes have been generated (Fig. 15) on the air/liquid interface, on a glass micropipette (see Section VIII.A.1), and on an aperture that separates two cells filled with subphase (see Section VIII.A.2). Further, amphiphilic lipid molecules have been self-assembled in an aqueous medium surrounding unilamellar vesicles (see Section VIII.A.3). Subsequently, the S-layer protein of B. coagulans E38/vl, B. stearother-mophilus PV72/p2, or B. sphaericus CCM 2177 have been injected into the aqueous subphase (Fig. 15). As on solid supports, crystal growth of S-layer lattices on planar or vesicular lipid films is initiated simultaneously at many randomly distributed nucleation... 

The majority of CYP enzymes are located in a hydrophobic environment in the endoplasmic reticulum of cells, although cytosolic enzymes also exist, such as CYP101. In order to mimic the physiological environment of CYP enzymes, a number of groups have used phospholipids to construct biosensors such as DDAB, dimeristoyl-L-a-phosphatidylcholine (DMPC), dilauroylphosphatidylethanolamine (DLPE) and distearoylphosphatidylethanolamine (DSPE). Phospholipid layers form stable vesicular dispersions that bear structural relationship with the phospholipid components of biologically important membranes. By this way a membranous environment is created that facilitates electron transfer between the enzyme s redox center and the electrode. 

With some molecules, a high concentration results in a lamellar phase but no additional mesophases are formed if the concentration is reduced. The lamellar phase is dispersed in the form of concentric layered particles in an excess of solvent (water or aqueous solution). This results in a vesicular dispersion. If the mesogenic material eonsists of phospholipids, the vesicular dispersion is called a liposomal dispersion... 

Intriguingly, it has recently been found that even nonionic surfactants accumulate OH at the vesicular surface, an effect that has been attributed to the molecular orientation of water molecules in the first two hydration layers of hydro-phobic surfaces. ... 

Additional evidence for a role of 5-HT in the development of neonatal rodent SSC derives from the transient barrel-Hke distribution of 5-HT, 5-HTib, and 5-HT2A receptors, and of the 5-HT transporter (Lebrand et al. 1996 Mansour-Robaey et al. 1998).The transient barrel-Hke 5-HT pattern visualized in layer IV of the SSC of neonatal rodents stems from 5-HT uptake and vesicifiar storage in thalamocortical neurons, transiently expressing at this developmental stage both 5-HT transporter and the vesicular monoamine transporter (VMAT2) despite their later glutamatergic phenotype (Lebrand et al. 1996). 

Persico AM, Revay RS, MOssner R, Conciatori M, Marino R, Baldi A, Cabib S, Pascucci T, Sora I, Uhl GR, Murphy DL, Lesch KP, Keller P (2001) Barrel pattern formation in somatosensory cortical layer IV requires serotonin uptake by thalamocortical endings, while vesicular monoamine release is necessary for development of supragranular layers. J Neurosci 21 6862-6873... 

Figure 9.29 Membrane formation by meteoritic amphiphilic compounds (courtesy of David Deamer). A sample of the Murchison meteorite was extracted with the chloroform-methanol-water solvent described by Deamer and Pashley, 1989. Amphiphilic compounds were isolated chromatographically on thin-layer chromatography plates (fraction 1), and a small aliquot ( 1 p,g) was dried on a glass microscope slide. Alkaline carbonate buffer (15 p,l, 10 mM, pH 9.0) was added to the dried sample, followed by a cover slip, and the interaction of the aqueous phase with the sample was followed by phase-contrast and fluorescence microscopy, (a) The sample-buffer interface was 1 min. The aqueous phase penetrated the viscous sample, causing spherical structures to appear at the interface and fall away into the medium, (b) After 30 min, large numbers of vesicular structures are produced as the buffer further penetrates the sample, (c) The vesicular nature of the structures in (b) is clearly demonstrated by fluorescence microscopy. Original magnification in (a) is x 160 in (b) and (c) x 400.

At low concentrations, a hollow vesicle results with usually just one double layer and, as the concentration is increased, the number of double layers can increase in a transition from unilamellar vesicles to multilamellar structures. Since the hydro-plilic head groups are exposed on the inside as well as the outside of the vesicular structure this provides an opportunity to entrap hydrophilic guest drug molecules both inside the center of the vesicle and, if multilamellar, between the phospholipid bilayers as well. On the other hand, hydrophobic molecules can become incorporated in the hydrophobic regions of the bilayers where the hydrophobic tails overlap. 

A number of works investigated the interaction between niosomes and human skin. With niosomes prepared from Ci2 alcohol polyoxyethylene ether and cholesterol, vesicular structures of about 100 nm size have been observed between the first and second layers of human corneocytes 48 h after incubation as well as in the deeper strata of the skin [37], The authors concluded that the structures visualized in the deeper regions could be vesicles reorganized from individual molecules that penetrated the skin. In another study, electron micrographs illustrated that niosomes containing surfactants and cholesterol affected only the most superficial corneocytes. Moreover, two-photon fluorescence microscopy confirmed that fluorescent probe encapsulated in niosomes was confined to the intercellular spaces within the apical stratum corneum layers [56]. 

The superficial two to three cell layers of the corneal and conjunctival epithelium are the main barrier for the permeation of topically applied compounds. In this rate-limiting cell layer, the transcellular permeation is dictated by the lipophilicity of the cell membrane whereas the paracellular permeation is limited by the paracellular pore size and density. Vesicular penetration (e.g., receptor- or endocytosis-mediated) of macromolecules across surface epithelium is possible [33], However, the proposed mechanism is energy consuming (e.g., incorporation into pinocytotic vesicles and phagosomes) and thus more feasible in cell lines with abundant intracellular energy sources like corneal endothelium and RPE [34-37]. 

Harkany T, Holmgren C, Hartig W, Qureshi T, Chaudhry FA, Storm-Mathisen J, Dobszay MB, Berghuis P, Schulte G, Sousa KM, Fremeau RT, Jr., Edwards RH, Mackie K, Ernfors P, Zilberter Y (2004) Endocannabinoid-Independent Retrograde Signaling at Inhibitory Synapses in Layer 2/3 of Neocortex Involvement of Vesicular Glutamate Transporter 3. J Neurosci 24 4978 1988. 

Katagiri K, Hamasaki R, Ariga K et al (2002) Layered paving of vesicular nanoparticles formed with cerasome as a bioinspired organic-inorganic hybrid. J Am Chem Soc 124 7892-7893... 

The vesicular particle morphology of a typical MSU-G silica is shown in the TEM micrograph of Figure 4. The size of the vesicles varies over a wide range (20-1500 nm). The vesicle shells may consist of a single silica nanolayer, or they may be composed of several nanolayers. Each silica layer is 3 nm in thickness. Mesopores oriented both parallel and orthogonal to the lamellae are apparent in the image. 

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