A New Method for Measuring Edge Tensions and Stability of Lipid Bilayers: Effect of Membrane Composition

TL;DR

This paper introduces a new method using electroporation to measure edge tensions in lipid bilayers, revealing how membrane composition affects stability and tension, with implications for understanding membrane mechanics.

Contribution

The study presents a novel, simple approach for measuring edge tension and explores how different lipid compositions influence membrane stability and tension.

Findings

Cholesterol increases edge tension in DOPC membranes.

DOPE decreases edge tension, contrary to expectations.

Cholesterol lowers the lysis tension of DOPC bilayers.

Abstract

We report a new and facile method for measuring edge tensions of lipid membranes. The approach is based on electroporation of giant unilamellar vesicles and analysis of the pore closure dynamics. We applied this method to evaluate the edge tension in membranes with four different compositions: egg phosphatidylcholine (EggPC), dioleoylphosphatidylcholine (DOPC), and mixtures of the latter with cholesterol and dioleoylphosphatidylethanolamine (DOPE). Our data confirm previous results for EggPC and DOPC. The addition of 17 mol % cholesterol to the DOPC membrane causes an increase in the membrane edge tension. On the contrary, when the same fraction of DOPE is added to the membrane, a decrease in the edge tension is observed, which is an unexpected result considering the inverted-cone shape geometry of the molecule. Presumably, interlipid hydrogen bonding lies in the origin of this behavior. Furthermore, cholesterol was found to lower the lysis tension of DOPC bilayers. This behavior differs from that observed on bilayers made of stearoyloleoylphosphatidylcholine, suggesting that cholesterol influences the membrane mechanical stability in a lipid-specific manner.