(31c) The Fusion and Spreading of Liposome with Different Sizes: Molecular Dynamics Simulation with Dry-Martini Force Field

Liposome fusion is an essential phenomenon for cellular communication ^[1-2] and spreading of lipid vesicle is a potential way to build supported lipid bilayer membranes, which are of fundamental importance for many nano-devices ^[3-4]. Although great efforts have been applied to study the fusion and spreading of liposomes using both atomistic and coarse-grained simulation models ^[5-7], how the size of liposomes affects fusion and spreading process is still unknown due to the limited computing power. In this study, we conducted molecular dynamics simulations of the fusion and spreading of liposomes with different sizes based on dry-martini force field ^[8], which is recently developed for lipid membrane simulations. The effect of properties of liposome, including composition and size, and supported materials (charge, hydrophobicity) were investigated via molecular dynamics simulations. It is shown that a ringed structure composed of two identical sizes of liposomes occurs during the fusion of liposomes, and then the ranged structure transforms into the dumbbell-shaped structure. The mechanism and transient states were also investigated in term of the distribution of lipids, morphology analysis and energy analysis. It is also shown that the points with large curvature prefer to be the starting fusion sites. The simulation results reveal the important regulatory role of liposome size on fusion and spreading.

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