A new approach supporting the possibility of cluster buckling during the main phase transition in the lipid bilayer is presented. The elastic energy is calculated via harmonic approximation which yields the potential minimum in the case of buckling cluster, if critical cluster size is achieved. The significance of this event for interbilayer interaction in multilamellar vesicles is discussed.

Depletion-attraction induced adhesion of two giant (∼ 40 μm), charged multilamellar vesicles is studied using a new Cantilevered-Capillary Force Apparatus, developed in this laboratory. The specific goal of this work is to investigate the role of dynamics in the adhesion and de-adhesion processes when the vesicles come together or are pulled apart at a constant velocity. Hydrodynamic effects ar...

It was found for the first time that rich lamellar structures are formed by a single-tailed amphiphilic ionic liquid (IL), 1-dodecyl-3-methylimidazolium β-naphthalene sulfonate ([C12mim][Nsa]), in aqueous solutions without any additives. With increasing IL concentration, spontaneous transition from micelles to unilamellar and multilamellar vesicles, planar bilayers, and then to lamellar liquid ...

The effects of ionic liquids on model phospholipid membranes were studied by small-angle X-ray scattering, dynamic light scattering (DLS) and zeta potential measurements. Multilamellar 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes and large unilamellar vesicles composed of l-α-phosphatidylcholine (eggPC) and l-α-phosphatidylglycerol (eggPG) (80:20mol%) or eggPC, eggPG, and choleste...

Dilute ( ~10% w/v) unsonicated phosphatidylserine dispersions in Hz0 contain spherical particles of a wide size distribution (0.1 to 15 q). The majority have diameters between 0.1 to 2 pm and lack the multilamellar arrangement of bilayers typical of unsonicated lecithin dispersions. Sonication uroduces small thermodynamically unstable vesicles surrounded by a single closed bilayer with an avera...

Aqueous dispersions of 50 mM dimyristoylphosphatidylglycerol (DMPG) in the presence of increasing salt concentrations (2-500 mM NaCl) were studied by small angle X-ray scattering (SAXS) and optical microscopy between 15 and 35 degrees C. SAXS data show the presence of a broad peak around q approximately 0.12 A(-1) at all temperatures and conditions, arising from the electron density contrasts w...

As a prerequisite for the use of liposomes for delivery of biologically active agents, techniques are required for the efficient and rapid entrapment of such agents in liposomes. Here we review the variety of procedures available for trapping hydrophilic and hydrophobic compounds. Considerations which are addressed include factors influencing the choice of a particular liposomal system and tech...

We explore the interplay of membrane curvature and nonspecific binding due to excluded-volume effects among colloidal particles inside lipid bilayer vesicles. We trapped submicron spheres of two different sizes inside a pear-shaped, multilamellar vesicle and found the larger spheres to be pinned to the vesicle’s surface and pushed in the direction of increasing curvature. A simple model predict...

A simple thermodynamic model of the main transition in pure lipid bilayers is presented. The basic relations for cooperativity, aggregation degree and fractional number of molecules are derived. The experimental heat capacity measurements of uni- and multilamellar phospholipid vesicles are analysed within the context of this model, and the transition characteristics are obtained. It is demonstr...