Structural Properties of Asymmetric Mixed-Chain Phosphatidylethanolamine Films

Saulnier, Patrick; Foussard, Françoise; Boury, Frank; Proust, J. E.

doi:10.1006/jcis.1999.6409

Cited by 13 publications

(19 citation statements)

References 18 publications

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“…The pressure increase after vesicle injection in the unsaturated POPC and POPG monolayers at 10 mN/m and 20 mN/m and in the saturated and negatively charged DPPG surface layers at 10 mN/m is indicative of a considerate material insertion. It may be a consequence of the conical shape of DPPG, POPC, and POPG (4,41,42), which could lead to the formation of defects in the monolayer. Fig.…”

Section: Molecular Packing and Vesicle Insertionmentioning

confidence: 99%

Influence of Lipid Saturation Grade and Headgroup Charge: A Refined Lung Surfactant Adsorption Model

Klenz

Saleem

Meyer

et al. 2008

Biophysical Journal

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Rapid adsorption of surfactant material to the air/liquid interface of the lung is essential for maintaining normal lung function. The detailed mechanism of this process, however, remains unclear. In this study, we elucidate the influence of lipid saturation grade and headgroup charge of surface layer lipids on surfactant protein (SP)-induced vesicle insertion into monolayers spread at the air/water interface of a film balance. We used dipalmitoylphosphatidlycholine (DPPC),1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) as monolayer lipids doped with either hydrophobic surfactant-specific protein SP-B or SP-C (0.2 and 0.4 mol %, respectively). Vesicles consisting of DPPC/DPPG (4:1, mol ratio) were injected into a stirred subphase to quantify adsorption kinetics. Based on kinetic film balance and fluorescence measurements, a refined model describing distinct steps of vesicle adsorption to surfactant monolayers is presented. First, in a protein-independent step, lipids from vesicles bridged to the interfacial film by Ca(2+) ions are inserted into defects of a disordered monolayer at low surface pressures. Second, in a SP-facilitated step, active material insertion involving an SP-B- or SP-C-induced flip-flop of lipids occurs at higher surface pressures. Negatively charged lipids obviously influence the threshold pressures at which this second protein-mediated adsorption mechanism takes place.

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Section: Molecular Packing and Vesicle Insertionmentioning

confidence: 99%

Influence of Lipid Saturation Grade and Headgroup Charge: A Refined Lung Surfactant Adsorption Model

Klenz

Saleem

Meyer

et al. 2008

Biophysical Journal

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“…The formulation of LNCs was based on a phase inversion process and was thoroughly described [5,23,32]. Briefly, an emulsion composed by Lipoid  S75-3, Lipophilic Labrafac  WL 1349, Solutol  HS-15, NaCl, and water was prepared and inverted several times across its phase inversion zone by temperature variations before a rapid cooling-dilution process in cold water which led to a suspension of nanocapsules in water.…”

Section: Formulationmentioning

confidence: 99%

Electrokinetic properties of noncharged lipid nanocapsules: Influence of the dipolar distribution at the interface

et al. 2005

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Lipid nanocapsules (LNCs) containing poly(ethylene glycol) (PEG) were developed according to a phase inversion process without organic solvent. The distribution of PEG chains at the surface was determined due to electrokinetic properties, in order to correlate it with protein adsorption potentiality. In this aim, electrophoretic mobilities were measured as a function of ionic strength and pH, for particles differing by their size, dialysis effects, and the presence or not of lecithin in their shell. The study allowed the determination of the isoelectric point (pI) as well as the charge density (ZN) in relation with the dipolar distribution in the polyelectrolyte accessible layer (depth = 1/lambda), by using soft-particle electrophoresis analysis. These parameters pointed out that the PEG surface organization was dependent on the particle size. Moreover, this organization could be modified by dialyzing particles and/or by formulating them with or without lecithin. Lecithin was found to be present in the inner part of the polyelectrolyte layer and to play a role in the outer part disorganization. Dialyzing LNCs formulated with lecithin allowed to obtain stable and well-structured nanocapsules, ready to an in vivo use as drug delivery system.

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“…26 It is also interesting to notice that there is a subtle slope change in the isotherm at 45 mN‚m -1 (see Figure 1) that had not been reported in previous works. 15 the BAM images is too small at this high lateral pressure to be able to distinguish any changes in the mesoscopic structure. However, absence of new bright spots (which would imply the onset of monolayer collapse) suggests that there is a transition into a different condensed phase.…”

Section: Resultsmentioning

confidence: 97%

Unveiling a Complex Phase Transition in Monolayers of a Phospholipid from the Annular Region of Transmembrane Proteins

et al. 2007

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The lateral packing properties of phospholipids that surround transmembrane proteins are fundamental in the biological activity of these proteins. In this work, Langmuir monolayers of one such lipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), are studied with a combination of pressure-area isotherm analysis, Brewster angle microscopy, and atomic force microscopy of extracted films. The analysis reveals a sequence of phase transitions LE-LC-LC' occurring in a narrow packing range. The lateral pressures and area densities of these phases provided meanings for the packing requirements in the annular lipid region of typical transmembrane proteins.

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Structural Properties of Asymmetric Mixed-Chain Phosphatidylethanolamine Films

Cited by 13 publications

References 18 publications

Influence of Lipid Saturation Grade and Headgroup Charge: A Refined Lung Surfactant Adsorption Model

Influence of Lipid Saturation Grade and Headgroup Charge: A Refined Lung Surfactant Adsorption Model

Electrokinetic properties of noncharged lipid nanocapsules: Influence of the dipolar distribution at the interface

Unveiling a Complex Phase Transition in Monolayers of a Phospholipid from the Annular Region of Transmembrane Proteins

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