Transmission electron microscopy and light scattering studies on the interaction of a nonionic/anionic surfactant mixture with phosphatidylcholine liposomes

Maza, Alfons de la; Coderch, L.; López, Olga; Parra, J. L.

doi:10.1002/(sici)1097-0029(19980101)40:1<63::aid-jemt9>3.0.co;2-y

Cited by 15 publications

(4 citation statements)

References 30 publications

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“…However, whereas in that system the time-dependent component rapidly reaches (on the order of 1−5 min) steady-state values, in the NaPAA−DOTAP complexes, the growing kinetics extends over large time intervals (on the order of 10 3 min or more). A bimodal distribution, in which both the two components are stable upon time, has been observed in zwitterionic liposome−surfactant mixtures, where small closed particles and open structures with formation of tubular aggregates coexist 2 Hydrodynamic diameter 〈2 R H 〉 of NaPAA−DOTAP structures in the high polyion concentration regime.…”

Section: Resultsmentioning

confidence: 99%

“…To properly interpret the morphology of the various complexes formed between NaPAA and cationic liposomes and to reveal their structural features, we employed TEM measurements. The TEM technique applied to negatively stained liposome structures has been shown , to be appropriate to study the formation and the morphology of liposomal aggregates (complexes) of different sizes, formed during the interactions with different surfactants and charged micelles.…”

Section: Resultsmentioning

confidence: 99%

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Complexation of Anionic Polyelectrolytes with Cationic Liposomes: Evidence of Reentrant Condensation and Lipoplex Formation

et al. 2004

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We have studied the complexation process taking place in cationic liposomes in the presence of anionic polyelectrolytes, in the polyion concentration range from the dilute to the concentrated regime, by combining dynamic light scattering and transmission electron microscopy techniques. We employed as the cationic lipid a two-chained amphiphile (Dioleoyltrimethylammoniumpropane) and sodium polyacrylate salt as the flexible anionic polyelectrolyte. The results evidence a variety of different structures, mainly depending on the liposome-polyion charge ratio, whose peculiar dynamical and structural features are briefly described. In particular, three different polyion concentration regions are found, within which a monomodal or bimodal distribution of aggregates, with a well-defined time evolution, is present. At low polyion content, close to the isoelectric point, large aggregates are formed, deriving from the collapse of the liposomal bilayers into extended charged surfaces, where adsorbed polyions form a two-dimensional strongly correlated array and organize into a two-dimensional Wigner liquid. At high polyion content, above a critical concentration, the size distributions of the complexes are clearly bimodal and a large-component aggregate, continuously increasing with time, coexists with a population of smaller-size aggregates. At an intermediate polyion concentration, spherical, small-size vesicular structures are reformed, connected in a network by polymer chains. A brief discussion tries to summarize our results into a consistent picture.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Complexation of Anionic Polyelectrolytes with Cationic Liposomes: Evidence of Reentrant Condensation and Lipoplex Formation

et al. 2004

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“…The liposome suspensions were subjected to a transmission electron microscopic study after negative staining with uranyl acetate by the method of de la Maza et al [8]. Liposomes treated with anti-cancer dietary factors of 10 µM were found to retain the same membrane structures as those of control liposomes (treated with DMSO alone) both before and after labeling with a fluorescent probe.…”

Section: Measurement Of Fluorescence Polarizationmentioning

confidence: 99%

Membrane‐rigidifying effects of anti‐cancer dietary factors

et al. 2002

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Since several anti-cancer drugs interact with cell membrane lipids, the effects of anti-cancer dietary factors on liposomal membranes with different lipid composition were comparatively studied by measuring fluorescence polarization. Fluidity was imparted on both hydrophobic and hydrophilic regions of lipid bilayers by decreasing cholesterol and increasing unsaturated phosphatidylcholine in membranes. At 0.625-10 microM, (-)-epigallocatechin gallate, genistein, apigenin, resveratrol and a reference anti-cancer drug, doxorubicin, rigidified the tumor cell model membranes consisting of 20 mol% cholesterol and 80 mol% phosphatidylcholine with the acyl chain 18:1/16:0 ratio of 1.0, but not daidzein. They were more effective on the membrane core than the membrane surface. Quercetin showed a biphasic effect on the hydrophobic regions of membrane lipid bilayers to rigidify above 5 microM and fluidize below 2.5 microM. In contrast, anti-cancer dietary factors and doxorubicin were not or much less effective in rigidifying the normal cell model membranes consisting of 40 mol% cholesterol and 60 mol% phosphatidylcholine with the acyl chain 18:1/16:0 ratio of 0.5. The membrane-rigidifying effects were greater depending on a decrease of the cholesterol/phosphatidylcholine ratio and an increase of the phosphatidylcholine unsaturation degree. Membrane-active dietary factors and doxorubicin inhibited the growth of mouse myeloma cells at 10-100 microM, while the growth inhibition by membrane-inactive daidzein was relatively weak. Anti-cancer dietary factors appear to act on more fluid membranes like tumor cells as well as doxorubicin to induce rigidification, especially in the hydrocarbon core of membrane lipids, which is determined by the composition of cholesterol and unsaturated phospholipids.

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“…Liposomes were studied by means of transmission electron microscopy and changes in the mean particle size and in the static light scattering of the system during liposome solubilization [5]. Transmission electron microscope is often used to determine the size and morphological characteristics of liposomes [6].…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural Characterization of Liposomes Using Transmission Electron Microscope

Chetanachan¹,

Akarachalanon

Worawirunwong³

et al. 2008

AMR

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A liposome is a spherical vesicle composed of phospholipids and cholesterol bilayer membrane and contains a core of aqueous solution. Liposomes are polymeric nanoparticles used for drug delivery due to their unique properties. It can carry both hydrophobic and hydrophilic molecules. In this study, we showed the benefit of using transmission electron microscope (TEM) with negative staining technique to investigate the morphology of liposomes produced by thin film method. At the same magnification of micrograph results, we could see the multilamellar vesicles of liposomes in various figures and different sizes.

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Transmission electron microscopy and light scattering studies on the interaction of a nonionic/anionic surfactant mixture with phosphatidylcholine liposomes

Cited by 15 publications

References 30 publications

Complexation of Anionic Polyelectrolytes with Cationic Liposomes: Evidence of Reentrant Condensation and Lipoplex Formation

Complexation of Anionic Polyelectrolytes with Cationic Liposomes: Evidence of Reentrant Condensation and Lipoplex Formation

Membrane‐rigidifying effects of anti‐cancer dietary factors

Ultrastructural Characterization of Liposomes Using Transmission Electron Microscope

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