Effective creases and contact angles between membrane domains with high spontaneous curvature

TL;DR

This paper demonstrates that elastic distortions at membrane domain boundaries can create creases with finite contact angles, modeled as slope discontinuities, especially in domains with high spontaneous curvature like biological rafts.

Contribution

It introduces a model accounting for creases and contact angles in membrane domains through an effective line tension with angular dependence, highlighting the role of spontaneous curvature.

Findings

Creases can be modeled as slope discontinuities in membranes.

High spontaneous curvature domains exhibit finite contact angles.

Impurities can induce similar creases in symmetric membranes.

Abstract

We show that the short-scale elastic distortions that are excited in the vicinity of the joint between different lipidic membrane domains (at a scale of \~10 nm) may produce a "crease" from the point of view of the standard elastic description of membranes, i.e., an effective discontinuity in the membrane slope at the level of Helfrich's theory. This "discontinuity" may be accounted for by introducing a line tension with an effective angular dependence. We show that domains bearing strong spontaneous curvatures, such as biological rafts, should exhibit creases with a finite contact-angle, almost prescribed, corresponding to a steep extremum of the line energy. Finite contact-angles might also occur in symmetric membranes from the recruitment of impurities at the boundary.