Dioleoyl phosphocholine

Fig. 19 Left) Schematic representation of the proposed mechanism for topological changes in dioleoyl phosphoethanolamine (DOPE) based liposomal membranes upon ultrasound irradiation. Right) (a) Giant DOPE-based unilamellar vesicle, before sonication, which shows an inhomogeneous membrane DOPE-rich domains of negative curvature are marked in red, embedded in zones rich in dioleoyl phosphocholine (DOPC) of zero mean curvature, (b) Illustration of shape changes upon ultrasound stimuli. Reproduced with permission from [99]. Copyright 2014 The Royal Society of Chemistry...

Fig. 3 (a) Structure of cationic phosphatidylcholines (PCs) (b) l,2-Dioleoyl-s -glycero-3-ethyl-phosphocholine (diC18 l-EPC EDOPC), the best studied, (c) l,2-Dimyristoleoyl-. i-glycero-3-ethylphosphocholine (diC14 l-EPC, EDMoPC), the most efficient representative of the cationic PCs... 

L-a-Dioleoyl Phosphatidylethanolamine (DOPE), and 1,2-Dipalmitoyl-OT-Glycero-3-Phosphocholine (DPPC) were purchased from Avanti Polar Lipids. The chol-PEGjj was obtained in one step from the reaction of cholesteryl chloroformate and a-amino-co-methoxy-PEG. The luciferase encoding gene was obtained as reported (22). Picogreen was purchased from Molecular Probes, USA, Baftlomycin from Sigma, France, the BCA kit from Pierce and the luciferase kit from Promega. 

DOPE l,2-Dioleoyl-sn-glycero-3-phosphoethanolamine DPPC l,2-Dipalmitoyl-SM-glycero-3-phosphocholine DPPS l,2-Dipalmitoyl-s -glycero-3-phosphoserine LB Langmuir-Blodgett MC Monte Carlo... 

Another assay that has gained popularity and acceptance for the evaluation of permeability is the parallel artificial membrane permeability assay (PAMPA). Earlier versions of this system coated polyvinylidene fluoride (PVDF) filter plates with artificial membrane using dioleoyl-sn-glycerol-3-phosphocholine (Chen et al., 2008). Several companies attempted to develop this technology in the late 1990s with limited success (Kansy et al., 1998). These earlier versions suffered poor correlation to cell models, poor correlation to human absorption, and poor reproducibility. More modem systems have been developed with different lipid formulations and solvation techniques that seem to correlate better with Caco-2 and human data and are more reproducible (Chan et al., 2005). Some companies use the PAMPA as a tier 1 prescreen discovery... 

Figure 14 Structures of zwitterionic phospholipids commonly used in the formation of liposomes and lipid bilayers. Shown are l-palmitoyl-2-oleoyl-in-glycero-3-phosphocholine (POPC), l,2-ipalmitoyl-in-glycero-3-phosphocholine (DPPC), and 1,2-dioleoyl-iw-glycero-3-phosphoethanolamine (DOPE). As is the case with POPC and DPPC, the acyl chains attached to the polar phosphatidylcholine head group may correspond to various fatty acids, which can be interchanged. DOPE, on the other hand, is comprised of the same acyl chains as DPPC and POPC but differs in the headgroup.

Vesicles were swollen from 1,2-dioleoyl-s/i-glycero-3-phosphocholine (Avanti Polar Lipids, USA) and V- (6-(biotinoyl)amino)hexanoyl)-l,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (biotin-X DHPE, Molecular Probes, The Netherlands) at a ratio of 99 1. Tubes were grown out of lipid globules in shear flow and cut to the desired length with a pipette. Streptavidin-coated beads (Dynal, Germany) were used... 

FIGURE 3.1 Some examples of common surfactant molecules, from top anionic surfactant SDS (sodium dodecyl sulfate, also commonly known as sodium lauryl sulfate) cationic surfactants CTAB (hexadecyltrimethylammonium bromide), DDAB (didecyidimethylammonium bromide) commercial nonionic detergent Triton X-100 and zwitterionic lipid DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine). 

FIGURE 3.7 Bilayer tubules prepared in solution from the lipid DOPC (l,2-dioleoyl-sn-glycero-3-phosphocholine, a biological surfactant) and imaged using fluorescence microscopy. 

FIGURE 6.24 Examples of SAXS data collected in two different lipid lamellar phases, (a) The gel phase Lp. on a sample of pure DPPC (l,2-dlpalmltoyl-sn-glycero-3-phosphocholine) and (b) in the liquid crystalline lipid phase on a sample of pure DOPE (l,2-dioleoyl-sn-glycero-3-phosphoethanolamine. Both sets of data were collected using a synchrotron x-ray source at Brookhaven National Laboratory. 

Calculate the average bilayer spacing in this lipid phase and compare your answer with the expected bilayer thickness based on an approximation for the lipid DOPC (1,2-dioleoyl-sw-glycero-3-phosphocholine). What fraction of the phase is water In the gel phase, a WAXS peak is detected at 14.8 nm use this value to estimate the average area taken up by each lipid head group. 

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