Shear-Induced Deformation of Surfactant Multilamellar Vesicles

Abstract

Surfactant multilamellar vesicles (SMLVs) play a key role in the formulation of many industrial products, such as detergents, foodstuff, and cosmetics. In this Letter, we present the first quantitative investigation of the flow behavior of single SMLVs in a shearing parallel plate apparatus. We found that SMLVs are deformed and oriented by the action of shear flow while keeping constant volume and exhibit complex dynamic modes (i.e., tumbling, breathing, and tank treading). This behavior can be explained in terms of an excess area (as compared to a sphere of the same volume) and of microstructural defects, which were observed by 3D shape reconstruction through confocal microscopy. Furthermore, the deformation and orientation of SMLVs scale with radius R in analogy with emulsion droplets and elastic capsules (instead of R(3), such as in unilamellar vesicles). A possible application of the physical insight provided by this Letter is in the rationale design of processing methods of surfactant-based systems.

A methodology to study chemotaxis in 3‐D collagen gels

“…Cell trajectory was measured by means of a semiautomated image analysis macro based on standard software libraries [43][44][45] (Image Pro Plus) that allows the user to identify each cell on the best focus layer at each time step (i.e., every 2-10 min, depending on cell line). Cell position arrays were then processed by a Matlab script in order to calculate mean squared displacements, average velocities and the chemotactic index.…”

Dynamic behaviour of multilamellar vesicles under Poiseuille flow

“…The velocity U, normalized to the average flow velocity in the microcapillary Vm, is plotted as a function of the confinement parameter k for different values of the capillary number Ca =  Vm / eff, where we use the value of eff = 0.1 mN/m reported in a previous paper. 17 This is the classical scaling used for droplets and it appears to be valid for MLVs as well. In the case of unilamellar vesicles, a distinction needs to be made.…”

“…This value is in agreement with the value of  obtained from the deformation of MLVs under shear flow. 17 It is worth mentioning that a different value of the parameter n determines only a different value of the velocities ratio p in Eq. 3 without any influence on the trend of the curve.…”

“…16 We recently reported an experimental investigation on the dynamic behaviour of single MLVs under simple shear flow. 17,18 In this flow field, MLVs dynamics presents analogies with unilamellar vesicles and emulsion droplets. MLVs deform at constant volume under flow with a rich dynamic behaviour (i.e.…”

Drug Delivery Systems: Possibilities and Challenges

“…Vesicles can be described as lamellar phase lipid bilayers, which surround a drug or other payload core and can be unilamellar or multilamellar. 81,82 One such example is liposomes, where phosphatidylcholine is the main shell component and tends to accumulate in the stratum corneum. However, the mechanisms involved for effective penetration and enhancement of liposomes through the skin are still largely unknown.…”