A computational model for capturing the distinct in- and out-of-plane response of lipid membranes

A computational framework was developed to capture the combined fluid- and solid-like behavior of lipid membranes in a unified manner. Specifically, the in-plane diffusion of lipid molecules and the associated evolution of membrane tension were explicitly taken into account in the model. In addition, the out-of-plane movement induced bending and shearing of membrane, along with its thermal undulations caused by bombardment of medium molecules, were also considered. The capability and validity of this approach were demonstrated by simulating the enforced deformation and shape fluctuations of a lipid vesicle under a variety of testing conditions as well as their comparison with corresponding theoretical predictions. Our model could serve a useful platform for investigating processes such as cell spreading and division where morphology evolution of the membrane and transport of lipids/transmembrane proteins are known to play key roles. In this paper, we presented a novel computational framework to capture the combined fluid- and solid-like response of lipid membranes and then used it to investigate the enforced deformation and spontaneous shape fluctuation of lipid vesicles under a variety of experimental conditions. Specifically, the in-plane diffusion of lipid molecules and the associated evolution of membrane tension were explicitly taken into account in the model. In addition, the out-of-plane movement induced bending and shearing of membrane, along with its thermal undulations caused by bombardment of medium molecules, were also considered.