Pathways connecting two opposed bilayers with a fusion pore: a molecularly-informed phase field approach

Abstract

A phase field model with two phase fields, representing the concentration and the head–tail separation of amphiphilic molecules, respectively, has been constructed using an extension of the Ohta–Kawasaki model (Macromolecules, 1986, 19, 2621–2632). It is shown that this molecularly-informed phase field model is capable of producing various self-assembled amphiphilic aggregates, such as bilayers, vesicles and micelles. Furthermore, pathways connecting two opposed bilayers with a fusion pore are obtained by using a combination of the phase field model and the string method. Multiple fusion pathways, including a classical pathway and a leaky pathway, have been obtained depending on the initial separation of the two bilayers. The study shed light on the understanding of the membrane fusion pathways and, more importantly, laid a foundation for further investigation of more complex membrane morphologies and transitions.