Search results for "LIPOSOMES"
showing 10 items of 221 documents
Functional response of novel bioprotective poloxamer-structured vesicles on inflamed skin
2017
[EN] Resveratrol and gallic acid, a lipophilic and a hydrophilic phenol, were co-loaded in innovative, biocompatible nanovesicles conceived for ensuring the protection of the skin from oxidative-and inflammatory-related affections. The basic vesicles, liposomes and glycerosomes, were produced by a simple, one-step method involving the dispersion of phospholipid and phenols in water or water/glycerol blend, respectively. Liposomes and glycerosomes were modified by the addition of poloxamer, a stabilizer and viscosity enhancer, thus obtaining viscous or semisolid dispersions of structured vesicles. The vesicles were spherical, unilamellar and small in size (similar to 70 nm in diameter). The …
In vitrouptake of lysozyme-loaded liposomes coated with chitosan biopolymer as model immunoadjuvants
2009
Chitosan binds to negatively charged soy lecithin liposomes by an electrostatic interaction driven by its cationic amino group. This interaction allows developing stable coated vesicles suitable as a targeted carrier and controlled release system for drugs and vaccines. In this work, we studied the effect of chitosan-coated liposomes on the uptake and antigen presentation of hen egg-white lysozyme (HEL) in Peyer's patches peritoneal macrophages isolated from mice. Chitosan-coated liposomes were characterized according to size, zeta potential, and antigen-loading and release properties. Results showed an increase in the positive net charge and size of the liposomes as the concentration of ch…
Light Scattering as an Easy Tool to Measure Vesicles Weight Concentration
2020
Over the last few decades, liposomes have emerged as promising drug delivery systems and effective membrane models for studying biophysical and biological processes. For all applications, knowing their concentration after preparation is crucial. Thus, the development of methods for easily controlling vesicles concentration would be of great utility. A new assay is presented here, based on a suitable analysis of light scattering intensity from liposome dispersions. The method, tested for extrusion preparations, is precise, easy, fast, non-destructive and uses a tiny amount of sample. Furthermore, the scattering intensity can be measured indifferently at different angles, or even by using the…
Membrane potential-dependent binding of polysialic acid to lipid monolayers and bilayers
2013
AbstractPolysialic acids are linear polysaccharides composed of sialic acid monomers. These polyanionic chains are usually membrane-bound, and are expressed on the surfaces of neural, tumor and neuroinvasive bacterial cells. We used toluidine blue spectroscopy, the Langmuir monolayer technique and fluorescence spectroscopy to study the effects of membrane surface potential and transmembrane potential on the binding of polysialic acids to lipid bilayers and monolayers. Polysialic acid free in solution was added to the bathing solution to assess the metachromatic shift in the absorption spectra of toluidine blue, the temperature dependence of the fluorescence anisotropy of DPH in liposomes, t…
Lipid dependence of diadinoxanthin solubilization and de-epoxidation in artificial membrane systems resembling the lipid composition of the natural t…
2006
In the present study, the solubility and enzymatic de-epoxidation of diadinoxanthin (Ddx) was investigated in three different artificial membrane systems: (1) Unilamellar liposomes composed of different concentrations of the bilayer forming lipid phosphatidylcholine (PC) and the inverted hexagonal phase (H(II) phase) forming lipid monogalactosyldiacylglycerol (MGDG), (2) liposomes composed of PC and the H(II) phase forming lipid phosphatidylethanolamine (PE), and (3) an artificial membrane system composed of digalactosyldiacylglycerol (DGDG) and MGDG, which resembles the lipid composition of the natural thylakoid membrane. Our results show that Ddx de-epoxidation strongly depends on the con…
Human tRNA(Sec) associates with HeLa membranes, cell lipid liposomes, and synthetic lipid bilayers.
2012
We have shown previously that simple RNA structures bind pure phospholipid liposomes. However, binding of bona fide cellular RNAs under physiological ionic conditions is shown here for the first time. Human tRNASec contains a hydrophobic anticodon-loop modification: N6-isopentenyladenosine (i6A) adjacent to its anticodon. Using a highly specific double-probe hybridization assay, we show mature human tRNASec specifically retained in HeLa intermediate-density membranes. Further, isolated human tRNASec rebinds to liposomes from isolated HeLa membrane lipids, to a much greater extent than an unmodified tRNASec transcript. To better define this affinity, experiments with pure lipids show that li…
Short-course treatment of visceral leishmaniasis with liposomal amphotericin B (AmBisome).
1996
We evaluated liposomal amphotericin B (AmBisome; Vestar, San Dimas, CA) administered to 88 immunocompetent patients (56 children) with visceral leishmaniasis (VL) caused by Leishmania infantum. Thirteen patients received 4 mg/kg on days 1-5 and 10 (total dose, 24 mg/kg), and all were cured; 42 received 3 mg/kg on days 1-5 and 10 (18 mg/kg), and 41 were cured; 32 received 3 mg/kg on days 1-4 and 10 (15 mg/kg), and 29 were cured (amastigotes were not cleared from 1 child, and 2 relapsed). One adult was cured with a total dose of 12mg/kg. The four children who were not cured received 3 mg/kg for 10 days; none had further relapses. There were no significant adverse events. For VL due to L. infa…
Peptides corresponding to helices 5 and 6 of Bax can independently form large lipid pores
2006
Proteins of the B-cell lymphoma protein 2 (Bcl2) family are key regulators of the apoptotic cascade, controlling the release of apoptotic factors from the mitochondrial intermembrane space. A helical hairpin found in the core of water-soluble folds of these proteins has been reported to be the pore- forming domain. Here we show that peptides including any of the two a-helix fragments of the hairpin of Bcl2 associated protein X (Bax) can independently induce release of large labelled dextrans from synthetic lipid vesicles. The permeability promoted by these peptides is influenced by intrinsic monolayer curvature and accompanied by fast transbilayer redis- tribution of lipids, supporting a to…
Pores Formed by Baxα5 Relax to a Smaller Size and Keep at Equilibrium
2010
AbstractPores made by amphipathic cationic peptides (e.g., antimicrobials and fragments of pore-forming proteins) are typically studied by examining the kinetics of vesicle leakage after peptide addition or obtaining structural measurements in reconstituted peptide-lipid systems. In the first case, the pores have been considered transient phenomena that allow the relaxation of the peptide-membrane system. In the second, they correspond to equilibrium structures at minimum free energy. Here we reconcile both approaches by investigating the pore activity of the α5 fragment from the proapoptotic protein Bax (Baxα5) before and after equilibrium of peptide/vesicle complexes. Quenching assays on …
Subphthalocyanines: addressing water-solubility, nano-encapsulation, and activation for optical imaging of B16 melanoma cells
2014
Water-soluble disulfonato-subphthalocyanines (SubPcs) or hydrophobic nano-encapsulated SubPcs are efficient probes for the fluorescence imaging of cells. 20 nm large liposomes (TEM and DLS) incorporated about 13% SubPc. Moreover, some of these fluorophores were found to be pH activatable.