Dipolar interactions between domains in lipid monolayers at the air-water interface

TL;DR

This paper introduces a passive imaging method to estimate dipolar interactions between lipid domains in monolayers, combining experimental image analysis with Brownian dynamics simulations for improved understanding of domain behavior.

Contribution

It presents a novel approach to quantify dipolar repulsion in lipid monolayers through image analysis and simulation comparison, advancing the study of domain interactions.

Findings

Method successfully estimates dipolar density differences.

Results align with surface potential measurements.

Provides a systematic analysis for various parameters.

Abstract

A great variety of biologically relevant monolayers present phase coexistence characterized by domains formed by lipids in an ordered phase state dispersed in a continuous, disordered phase. The difference in surface densities between these phases originates inter-domain dipolar interactions, which are relevant for the determination of the spacial distribution of domains, as well as their dynamics. In this work, we propose a novel manner of estimating the dipolar repulsion using a passive method that involves the analysis of images of the monolayer with phase coexistence. The method is based on the comparison of the pair correlation function obtained from experiments with that obtained from Brownian dynamics simulations of a model system. As an example, we determined the difference in dipolar density of a binary monolayer of DSPC/DMPC at the air-water interface from the analysis of the radial distribution of domains, and the results are compared with those obtained by surface potential determinations. A systematic analysis for experimentally relevant parameter range is given, which may be used as a working curve for obtaining the dipolar repulsion in different systems.