Search results for "LIPOSOMES"

Biopolymer coating of soybean lecithin liposomes via layer-by-layer self-assembly as novel delivery system for ellagic acid

2010

Abstract The formulation of a novel delivery system for ellagic acid formulated via layer-by-layer (L-b-L) electrostatic deposition of biopolymers onto soybean lecithin liposomes was achieved. Optimization of parameters affecting the formulation of biopolymer-coated liposomes was carried out by monitoring changes on its size, surface charge and morphology. Ellagic acid was loaded into the liposome core and loading properties were analyzed. Release profiles for ellagic acid from optimized biopolymer-coated liposomes were evaluated as a function of time, temperature and pH of the media. The L-b-L electrostatic deposition of biopolymers succeeded in building nanosized, spherical and stable lip…

Electrically induced deformation of giant liposomes monitored by thickness shear mode resonators.

2006

Thickness shear mode resonators are capable of registering small changes in the thickness and viscoelastic properties of ultrathin films attached to their surface. It was found that it is possible to monitor the deformation of surface-bound giant liposomes by applying an electric field with small amplitudes. Changes in the apparent height of attached vesicles in the nanometer range were easily detected as a function of lipid composition. Increasing the bending modulus by adding cholesterol results in a significantly reduced deformation from 16.8 nm (5% cholesterol) down to 3.2 nm (20% cholesterol), rendering this new method a robust and sensitive tool to detect the bending elasticity of lip…

Coreconstitution of bacterial ATP synthase with monomeric bacteriorhodopsin into liposomes. A comparison between the efficiency of monomeric bacterio…

1987

The conditions for coreconstitution of a bacterial ATP synthase and bacteriorhodopsin into lecithin liposomes and for light driven ATP synthesis have been optimized. A rate of maximally 280 nmol ATP min-1 mg ATP synthase-1 was achieved with monomerized bacteriorhodopsin compared with a rate of up to 45 nmol ATP min-1 mg-1 found for proteoliposomes containing bacteriorhodopsin in the form of purple membrane patches. The different rates are explained by the finding that monomeric bacteriorhodopsin is more homogeneously distributed among the liposomes than the purple membrane patches. The final activities depended on both the purification method for the two proteins and the coreconstitution pr…

Predicting the in vivo release from a liposomal formulation by IVIVC and non-invasive positron emission tomography imaging

2010

This study aimed to predict the in vivo performance from the in vitro release of a low-molecular weight model compound, [(18)F]-2-fluoro-2-deoxy-d-glucose ([(18)F]FDG), from liposomes and by means of positron emission tomography (PET). Liposomes composed of hydrogenated phosphatidylcholine (HPC) were prepared by a freeze-thaw method. Particle size distribution was measured by dynamic light scattering (DLS). In vitro release was examined with a dispersion method detecting the radioactivity of [(18)F]FDG. In vivo release of [(18)F]FDG, following i.p. injection of the liposomes in rats, was determined by using a Micro-PET scanner. Convolution was performed to predict the in vivo profiles from …

Heparin modulates the cellular uptake of nanomedicines

2021

Liposomal formulations are used to improve the safety and cellular absorption of conventional drugs by limiting their interaction with phagocytes. The uptake behaviour of these nanocarriers is affected by the blood composition, and accordingly the presence of an anticoagulant in the blood could have a critical impact on the efficiency of nanomedicines. For the negatively charged liposomes, such as AmBisome®, no significant change in the uptake could be observed when co-incubated with heparin and primary phagocytes. Yet, we observed that a peak of the uptake extent of cationic liposomes was reached at a clinically relevant concentration of heparin for phagocytes and cancer cells. Hence, we r…

A physicist friendly method to control extruded-liposome concentration by using static light scattering

Preliminary Studies for the Preparation of Casein-loaded Liposomes to Inhibit Aβ1-40 Fibrillogenesis

2018

αs1-Casein is a natural protein which constitutes the most prevalent form of casein in bovine milk. αs1-Casein is amphiphilic, almost unfolded, and consist of two highly hydrophobic zones separated by an hydrophilic region. Previous studies have demonstrated the ability of αs1-Casein to inhibit in vitro the nucleation phase of amyloid β-peptide (Aβ) fibrillogenesis by sequestering Aβ species on its surface. One of the main hallmark for Alzheimer Disease (AD) is the extracellular deposition in brain tissues of proteinaceous plaques, rich of well-ordered Aβ peptide amyloid aggregates. Although such an evidence, oligomeric intermediates in the fibrillogenesis have been discovered to be the mos…

Scrutiny of the Failure of Lipid Membranes As A Function of Headgroups, Chain Length, and Lamellarity Measured by Scanning Force Microscopy

2004

AbstractA fast, quantitative, and unambiguous screening of material properties of biomembranes using scanning force microscopy in pulsed force mode on lipid membranes is presented. The spatially resolved study of breakthrough force, breakthrough distance, adhesion, stiffness, and topography of lipid membranes as determined simultaneously by digitalized pulsed force mode provides new insight into the structure-function relationship of model membranes, which are systematically analyzed by varying chain length, lipid headgroup, and lamellarity. For this purpose, a novel unbiased analysis method is presented. A strong correlation between adhesion and breakthrough events is found on lipid bilaye…

Partitioning of Pyrene-Labeled Phospho- and Sphingolipids between Ordered and Disordered Bilayer Domains

2004

AbstractHere we have studied how the length of the pyrene-labeled acyl chain (n) of a phosphatidylcholine, sphingomyelin, or galactosylceramide affects the partitioning of these lipids between 1), gel and fluid domains coexisting in bovine brain sphingomyelin (BB-SM) or BB-SM/spin-labeled phosphatidylcholine (PC) bilayers or 2), between liquid-disordered and liquid-ordered domains in BB-SM/spin-labeled PC/cholesterol bilayers. The partitioning behavior was deduced either from modeling of pyrene excimer/monomer ratio versus temperature plots, or from quenching of the pyrene monomer fluorescence by spin-labeled PC. New methods were developed to model excimer formation and pyrene lipid quenchi…

An in vitro and in vivo study of peptide-functionalized nanoparticles for brain targeting: The importance of selective blood-brain barrier uptake

2017

Targeted delivery of drugs across endothelial barriers remains a formidable challenge, especially in the case of the brain, where the blood-brain barrier severely limits entry of drugs into the central nervous system. Nanoparticle-mediated transport of peptide/protein-based drugs across endothelial barriers shows great potential as a therapeutic strategy in a wide variety of diseases. Functionalizing nanoparticles with peptides allows for more efficient targeting to specific organs. We have evaluated the hemocompatibilty, cytotoxicity, endothelial uptake, efficacy of delivery and safety of liposome, hyperbranched polyester, poly(glycidol) and acrylamide-based nanoparticles functionalized wi…