Structure and dynamics of DOPC vesicles: A transformation from unilamellar to multilamellar vesicles by n-alkyl-PEO polymer

TL;DR

This study explores how non-ionic polymers affect phospholipid vesicles, revealing their transformation from unilamellar to multilamellar structures and changes in membrane rigidity and dynamics, with potential biomedical applications.

Contribution

It introduces a generalized model to measure bending rigidity in multilayer vesicles and demonstrates polymer-induced vesicle transformation and membrane disruption.

Findings

Polymer presence increases vesicle size and induces multilamellar formation.

Polymers are trapped in the bilayer, reducing bending rigidity.

Polymer disrupts lipid tail motion, affecting membrane dynamics.

Abstract

We investigate the influence of a non-ionic surfactant like polymer on phospholipid vesicles. Our results from cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), small angle neutron and X-ray scattering (SANS/SAXS), identifies the existence of multilayer vesicles and an increase in size of the vesicles in presence of the polymers. We present a generalized model to obtain the bending rigidity from neutron spin echo spectroscopy (NSE) data for multilayer vesicles. We demonstrated that polymers are trapped in the lipid bilayer, causing a partial disruption in the vesicle, which is attributed to the reduction in bending rigidity per unit bilayer. We also observed substantial dampening of the trapped lipid tail motion in presence of the polymer. Our results highlighted the possibilities of using specialized polymers that can disrupt membrane and control their dynamics with possible application in topical drug or nutraceutical formulations.