Solubilization kinetics determines the pulsatory dynamics of lipid vesicles exposed to surfactant

TL;DR

This study presents a biophysical model linking surfactant-induced solubilization kinetics to the pulsatory pore dynamics in lipid vesicles, providing insights into membrane stability and potential applications in drug delivery.

Contribution

The paper introduces a novel biophysical model that connects solubilization kinetics to pore dynamics in lipid vesicles, validated with experimental data and offering a new method to measure solubilization rates.

Findings

Pore dynamics depend on solubilization rate, with regimes of short-lived and long-lived pores.

The model accurately predicts pore behavior validated by experimental data.

A phase diagram maps pore regimes based on membrane and surfactant properties.

Abstract

We establish a biophysical model for the dynamics of lipid vesicles exposed to surfactants. The solubilization of the lipid membrane due to the insertion of surfactant molecules induces a reduction of membrane surface area at almost constant vesicle volume. This results in a rate-dependent increase of membrane tension and leads to the opening of a micron-sized pore. We show that solubilization kinetics due to surfactants can determine the regimes of pore dynamics: either the pores open and reseal within a second (short-lived pore), or the pore stays open up to a few minutes (long-lived pore). First, we validate our model with previously published experimental measurements of pore dynamics. Then, we investigate how the solubilization kinetics and membrane properties affect the dynamics of the pore and construct a phase diagram for short and long-lived pores. Finally, we examine the dynamics of sequential pore openings and show that cyclic short-lived pores occur at a period inversely proportional to the solubilization rate. By deriving a theoretical expression for the cycle period, we provide an analytic tool to measure the solubilization rate of lipid vesicles by surfactants. Our findings shed light on some fundamental biophysical mechanisms that allow simple cell-like structures to sustain their integrity against environmental stresses, and have the potential to aid the design of vesicle-based drug delivery systems.