Dynamics of small unilamellar vesicles

Abstract

In this paper, we investigate the dynamics of small unilamellar vesicles with the aid of neutron spin-echo spectroscopy. The purpose of this investigation is twofold. On the one hand, we investigate the influence of solubilised cosurfactant on the dynamics of the vesicle's surfactant bilayer. On the other hand, the small unilamellar vesicles used here have a size between larger vesicles, with dynamics being well described by the Zilman-Granek model and smaller microemulsion droplets which can be described by the Milner-Safran model. Therefore, we want to elucidate the question, which model is more suitable for the description of the membrane dynamics of small vesicles, where the finite curvature of the bilayer is felt by the contained amphiphilic molecules. This question is of substantial relevance for our understanding of membranes and how their dynamics is affected by curvature, a problem that is also of key importance in a number of biological questions. Our results indicate the even down to vesicle radii of 20 nm the Zilman-Granek model appears to be the more suitable one.

Phospholipid Bilayer Softening Due to Hydrophobic Gold Nanoparticle Inclusions

“…It has been previously shown that bending modulus is directly related to bilayer thickness. 80,81 However, in the present case, the average bilayer thickening is a result of membrane unzipping to situate the AuNP/AuNP cluster inclusion in the bilayer core. However, coupling between monolayers should be severely compromised on introducing isolated AuNP inclusions or cluster inclusions.…”

“…It has been shown previously that small alkyl chain additives at relatively low mole fractions can cause substantial reduction in bending modulus. 80,81 AuNP inclusions in the present research are functionalized with small alkyl chain dodecanethiol, which might substantially contribute toward disrupting conformational packing, leading to membrane softening.…”

Modeling the dynamics of phospholipids in the fluid phase of liposomes

“…However the MS model takes into account only the undulation for the length scale of the particle unlike the ZG prediction used in our model that results from the integration over all undulation wave vectors between the length scale of the particle and the lower cut-off molecular length scale. 48 While the MS model was successful in describing the dynamics of small microemulsion droplets for sizes on the order of 5 nm, it seems to fail for vesicles of radii > 20 nm. 48,49 Therefore, our model includes the ZG approach that yields more plausible values for bending rigidities.…”

“…48 While the MS model was successful in describing the dynamics of small microemulsion droplets for sizes on the order of 5 nm, it seems to fail for vesicles of radii > 20 nm. 48,49 Therefore, our model includes the ZG approach that yields more plausible values for bending rigidities.…”

Thermal fluctuations and osmotic stability of lipid vesicles

“…Motivated by this discrepancy, we here revisit the problem of the stability of spherical vesicles exposed to external osmotic stresses, taking into account the effect of thermal fluctuations of the lipid membrane. While not previously analysed in the context of osmotic stability, such thermal shape fluctuations have been extensively considered theoretically [13][14][15][16][17][18] and experimentally [19,20] and have, among other things, been shown to promote long-ranged repulsive interactions between fluctuating lipid bilayers [13,14]. Our analysis is based on the same basic formalism as that used in Ref.…”