Search results for "Dipalmitoylphosphatidylcholine"
showing 10 items of 33 documents
Effect of cholesterol on the physical properties of pulmonary surfactant films: Atomic force measurements study
2006
International audience; Atomic force measurements were performed on supported pulmonary surfactant (PS) films to address the effect of cholesterol on the physical properties of lung surfactant films. We recently found that cholesterol in excess of a physiological proportion abolishes surfactant function, and is the reason that surfactant fails to lower the surface tension upon compression. In this study, we investigated how the loss of mechanical stability observed earlier is related to the local mechanical properties of the film by local force measurements. The presence of 20% of cholesterol in bovine lipid extract surfactant (BLES) resulted in a decrease of the observed adhesive interacti…
Metalloporphyrin intercalation in liposome membranes: ESR study
2010
Liposomes characterized by membranes featuring diverse fluidity (liquid-crystalline and/or gel phase), prepared from egg yolk lecithin (EYL) and dipalmitoylphosphatidylcholine (DPPC), were doped with selected metalloporphyrins and the time-related structural and dynamic changes within the lipid double layer were investigated. Porphyrin complexes of Mg(II), Mn(III), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and the metal-free base were embedded into the particular liposome systems and tested for 350 h at 24°C using the electron spin resonance (ESR) spin probe technique. 5-DOXYL, 12-DOXYL, and 16-DOXYL stearic acid methyl ester spin labels were applied to explore the interior of the lipid bila…
Dynamics of surface of lipid membranes: theoretical considerations and the ESR experiment.
2016
The effect of the surface layer of model membranes on their physical properties was discussed in this paper. The research involved a physical ESR experiment with the use of spin probes and computer simulation based on the Monte Carlo technique. Liposomes formed during the process of sonication of lecithin were scanned in an ESR spectrometer. The membrane surface layer model, represented by the system of electric dipoles arranged in rectangular or hexagonal matrices, was studied. The final states of computer simulations were presented as textures. It was found that in the gel phase some ordered domain structures are formed, while in the liquid–crystal phase we got complex textures comprising…
Interfacial behavior of recombinant forms of human pulmonary surfactant protein SP-C.
2012
The behavior at air-liquid interfaces of two recombinant versions of human surfactant protein SP-C has been characterized in comparison with that of native palmitoylated SP-C purified from porcine lungs. Both native and recombinant proteins promoted interfacial adsorption of dipalmitoylphosphatidylcholine bilayers to a limited extent, but catalyzed very rapid formation of films from different lipid mixtures containing both zwitterionic and anionic phospholipids. Once at the interface, the recombinant variants exhibited compression-driven structural transitions, consistent with changes in the orientation of the deacylated N-terminal segment, which were not observed in the native protein. Com…
Hydrolytic action of phospholipase A2 in monolayers in the phase transition region: direct observation of enzyme domain formation using fluorescence …
1990
Phospholipase A2, a ubiquitous lipolytic enzyme highly active in the hydrolysis of organized phospholipid substrates, has been characterized optically in its action against a variety of phospholipid monolayers using fluorescence microscopy. By labeling the enzyme with a fluorescent marker and introducing it into the subphase of a Langmuir film balance, the hydrolysis of lipid monolayers in their liquid-solid phase transition region could be directly observed with the assistance of an epifluorescence microscope. Visual observation of hydrolysis of different phospholipid monolayers in the phase transition region in real-time could differentiate various mechanisms of hydrolytic action against …
Self-assembly mechanism of nanoparticles of Ni-based Prussian Blue analogues at the air/liquid interface: a synchrotron X-ray reflectivity study.
2015
Prussian Blue analogue (PBA) nanoparticles can be self-assembled at air/liquid interfaces to build novel materials with interesting magnetic features. Herein, we study the influence of the size of PBA Cs0.4 Ni[Cr(CN)6 ]0.9 and K0.25 Ni[Fe(CN)6 ]0.75 nanoparticles on the self-assembly behavior by synchrotron X-ray reflectivity. Both nanoparticles show similar Z-potential values. The phospholipid dipalmitoylphosphatidylcholine and the amino surfactant dimethyldioctadecylammonium have been used as Langmuir monolayers to anchor the PBA nanoparticles and study the interplay of forces directing the self-assembly of the nanoparticles at the surfactant/liquid interface. Whereas Cs0.4 Ni[Cr(CN)6 ]0.…
Liposomes as nonspecific nanocarriers for 5-Fluorouracil in the presence of cyclodextrins
2021
Abstract 5-Fluorouracil (5-FU) is one of anticancer drugs with broad activity. Due to its severe side effects, recent studies concentrate on new ways of directed 5-FU delivery and its release in ill tissue. One of selective carriers could be cyclodextrins and liposomes. The combination of novel methods, leading to formation of inclusion complexes (IC) between host molecule of β-cyclodextrin (β-CD) or 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and 5-FU guest and its subsequent encapsulation in dipalmitoylphosphatidylcholine (DPPC) liposomes is studied experimentally in the present work. Several methods are applied to proof the encapsulation of the analysed drug and its release over time at 37 …
Investigation of Temperature-Induced Phase Transitions in DOPC and DPPC Phospholipid Bilayers Using Temperature-Controlled Scanning Force Microscopy
2004
Under physiological conditions, multicomponent biological membranes undergo structural changes which help define how the membrane functions. An understanding of biomembrane structure-function relations can be based on knowledge of the physical and chemical properties of pure phospholipid bilayers. Here, we have investigated phase transitions in dipalmitoylphosphatidylcholine (DPPC) and dioleoylphosphatidylcholine (DOPC) bilayers. We demonstrated the existence of several phase transitions in DPPC and DOPC mica-supported bilayers by both atomic force microscopy imaging and force measurements. Supported DPPC bilayers show a broad L(beta)-L(alpha) transition. In addition to the main transition …
Fluorescence microscopy studies of layer/substrate interaction during the Langmuir-Blodgett transfer: Fractional condensation and local layer modific…
1991
Transfer fluorescence microscopy reveals the substrate-mediated fractional condensation and phase-selective deposition of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylethanolamine (DMPE) monolayers during the LB-transfer. Preferentially the higher ordered liquid-condensed (LC) state is transferred onto the substrate during the transfer of a monolayer in the LC/LE (liquid/expanded) coexistence state on the water subphase. This is manifested in the directly observable attraction of LC-domains towards the three-phase line and observation of a domain-free gap as consequence of the segregation of the fluorescent probe into the floating monolayer adjacent to the three-phase li…
Size influences the effect of hydrophobic nanoparticles on lung surfactant model systems
2013
Item does not contain fulltext The alveolar lung surfactant (LS) is a complex lipid protein mixture that forms an interfacial monolayer reducing the surface tension to near zero values and thus preventing the lungs from collapse. Due to the expanding field of nanotechnology and the corresponding unavoidable exposure of human beings from the air, it is crucial to study the potential effects of nanoparticles (NPs) on the structural organization of the lung surfactant system. In the present study, we investigated both, the domain structure in pure DPPC monolayers as well as in lung surfactant model systems. In the pure lipid system we found that two different sized hydrophobic polymeric nanopa…