Cationic Lipid Modulates Phospholipid Adsorption on Silica

Abstract

At 2 % cationic lipid and 98 % phospholipid, pH 6.3, in pure water, high affinity adsorption isotherms with limiting adsorption indicative of one bilayer deposition on each silica particle were obtained whereas for the other molar proportions tested, limiting lipid adsorption was either above or below the level expected for bilayer deposition. This suggested a modulating role for cationic lipid allowing control of total amount of lipid adsorbed on silica. Silica sedimentation documented from photographs was almost absent over a range of lipid concentrations where bilayer deposition was achieved.

Biomimetic Particles: Optimization of Phospholipid Bilayer Coverage on Silica and Colloid Stabilization

“…Mornet and co-workers recently provided beautiful cryo transmission electron microscopy images for the dioleoylphosphatidylcholine (DOPC)/silica interaction. Vesicle adhesion was often observed after deposition of the bilayer onto the particles in close association with quantitative data for lipid adsorption previously provided by our laboratory 7,10 which indicated either low affinity and mere vesicle adhesion or uncontrollable vesicle adsorption going beyond bilayer deposition. , Recently, the adequacy of the optimal experimental conditions for bilayer deposition described here (150 mM ionic strength, pH 7.4, 0.3 mM PC, 1 mg/mL silica) was further checked against quantitative reconstitution of biomolecular recognition between cholera toxin (CT) and its monosyaloganglioside (GM1) receptor . At the root of the optimal recognition achieved at 1:5 molar ratio (CT:GM1) 31 was the increase in affinity between the PC bilayer and silica obtained upon increasing the ionic strength and thereby van der Waals attraction between the PC bilayer and silica particles.…”

“…7,10 Recently, the adequacy of the optimal experimental conditions for bilayer deposition described here (150 mM ionic strength, pH 7.4, 0.3 mM PC, 1 mg/mL silica) was further checked against quantitative reconstitution of biomolecular recognition between cholera toxin (CT) and its monosyaloganglioside (GM1) receptor. 31 At the root of the optimal recognition achieved at 1:5 molar ratio (CT:GM1) 31 was the increase in affinity between the PC bilayer and silica obtained upon increasing the ionic strength and thereby van der Waals attraction between the PC bilayer and silica particles.…”

“…The large surface area on biomimetic particles and the simplicity of the analytical methods employed for both protein 31 and lipid analysis (this work) will certainly facilitate qualitative and quantitative studies for a variety of receptor-ligand pairs in the future.…”

Assembly of a model hydrophobic drug into cationic bilayer fragments

“…Vesicles and other bilayer assemblies, such as bilayer fragments or disks, though ephemeral, produced useful devices by depositing onto polymeric [7,8], mineral [9,10], or drug particles [3,11] or cell surfaces [12][13][14] or by acting as templates for direction of inorganic matter deposition, redox processes, or polymerization reactions [15][16][17]. In biology and medicine, they offered a suitable matrix to solubilize and/or carry drugs [18][19][20], either as entire entities, as complexes with the drug to be carried, or as bilayer capsules surrounding the hydrophobic drug granule [21].…”

Highly Efficient Microscale Purification of Glycerophospholipids by Microfluidic Cell Lysis and Lipid Extraction for Lipidomics Profiling

“…At higher ionic strength, the negative potential of silica surfaces is reduced, thereby decreasing the electrostatic repulsion between the negatively charged phospholipid molecules and the bead surface. However, high concentrations of salt reduce the water activity due to the formation of hydrated ions, which facilitates the dehydration of phospholipids and silica surfaces and drives the lipid to the extraction bed . The electrostatic repulsion can be further reduced if the phospholipid is dissolved in a loading buffer below the p K a of the silica (p K a ≈ 8), due to the fact that increasing protonation of the surface silanol groups reduces the surface charge. − In addition, extremely acidic loading buffer conditions could affect the solubility of lipids and may induce precipitation, which could ultimately lead to a failure of the microfluidic device.…”