Dynamics of fatty acid vesicles in response to pH stimuli

Abstract

We investigate the dynamics of decanoic acid/decanoate (DA) vesicles in response to pH stimuli. Two types of dynamic processes induced by the micro-injection of NaOH solutions are sequentially observed: deformations and topological transitions. In the deformation stage, DA vesicles show a series of shape deformations, i.e., prolate-oblate-stomatocyte-sphere. In the topological transition stage, spherical DA vesicles follow either of the two pathways, pore formation and vesicle fusion. The pH stimuli modify a critical aggregation concentration of DA molecules, which causes the solubilization of DA molecules in the outer leaflet of the vesicle bilayers. This solubilization decreases the outer surface area of the vesicle, thereby increasing surface tension. A kinetic model based on area difference elasticity theory can accurately describe the dynamics of DA vesicles triggered by pH stimuli.

Shape changes and budding of giant vesicles induced by an internal chemical trigger: an interplay between osmosis and pH change

“…Both the pH and the osmotic pressure were previously exploited to control the shape transformation of GUVs. For example, a large variation of the external pH (5-6 units) was found to induce shape changes in pure fatty acid vesicles 37 or changes of the preferred curvature of SOPC (1-stearoyl-2-oleoyl-phosphatidylcholine) membranes. 64 In recent work, the proper control of the osmotic pressure induced the total division (two vesicles completely separated) in heterogeneous GUVs.…”

“…30 The average cross section at pH 6 is comparable with the values of average area per head group simulated at pH 5.5 (0.54 AE 0.01 nm 2 ) and pH 7.5 (0.66 AE 0.01 nm 2 ) for mixed vesicles Lyso-PC : oleic acid = 50% : 50%. 60 The diffusion constant k f and the solubilisation constant k off were chosen in line with previous works 37 and slightly changed to match the timescale of our experiments, i.e. k f = 0.4 s À1 and k off = 0.008 s À1 .…”

“…36 The ADE model has been successfully applied to investigate, among the others, shape changes in binary vesicles of DLPE (1,2-dilauroyl-sn-glycero-3-phosphoethanolamine) and DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) during heating-cooling cycles 21 and shape changes in pure fatty acid vesicles fed externally with NaOH. 37 Herein, we propose a model that integrate the pH changes due to the enzymatic reaction with the chemistry of fatty acids and takes into account the osmotic shock to explain the n and Da 0 changes which cause the vesicles shape transformations.…”

Cooperative formation of porous silica and peptides on the prebiotic Earth

“…Indeed, many prebiotic systems may require an evaporative environment to drive condensation reactions (67,68). Fatty acids form micelles and vesicles, and they have been considered as the fundamental building blocks of prebiotic membranes in that they are chemically simpler than phospholipids (69,70). Amphiphilic molecules have been isolated from meteorites and synthesized under simulated prebiotic conditions (71,72).…”

Encapsulation of hydrophobic components in dendrimersomes and decoration of their surface with proteins and nucleic acids

“…Liposomes are lipid bilayer membranes formed from natural and synthetic lipids that accurately mimic the thickness, flexibility, and 2D dynamics of natural membranes (1, 15, 16). Nonetheless, they lack stability to environmental conditions, severely limiting their use for advance functions (7, 17). Stealth liposomes are stable vesicles containing a mixture of phospholipids, phospholipid conjugated with poly(ethyleneglycol) (PEG), and cholesterol (18).…”