Polyelectrolyte-induced peeling of charged multilamellar vesicles

TL;DR

This study investigates how oppositely charged polyelectrolytes interact with charged multilamellar vesicles, revealing a peeling mechanism driven by PE-induced tension and pore formation, with implications for understanding vesicle stability and complex formation.

Contribution

It introduces the novel observation of PE-induced peeling of bilayers in charged vesicles and analyzes the underlying mechanisms involved.

Findings

PE induces peeling of bilayers in charged vesicles

Peeling involves shape fluctuations and pore formation

Aggregate formation depends on charge ratio and isoelectric point

Abstract

We study mixtures of charged surfactants, which alone in solution form uni- and multilamellar vesicles, and oppositely charged polyelectrolytes (PEs). The phase behavior is investigated at fixed surfactant concentration as a function of the PE-to-surfactant charge ratio $x$. We find that, for $x>0$, aggregates form. Light microscopy and X-ray scattering experiments show that the isoelectric point plays a crucial role since the morphology and the microscopic structure of the aggregates are different before ($x\leq1$) and after the isoelectric point ($x>1$). To better understand the dynamics for the formation of PE/surfactant complexes, we perform light microscopy experiments where we follow in real-time the effect of a PE solution on one multilamellar vesicle (MLV). We find that the PE induces a peeling of the bilayers of the MLV one by one. The peeling is accompanied by strong shape fluctuations of the MLV and leads ultimately to a pile of small aggregates. This novel phenomenon is analyzed in detail and discussed in terms of PE-induced tension, and pore formation and growth in a surfactant bilayer.