Solid Domain Patterns on Giant Lipid Vesicles: Vesicle size controls domain shape at fixed composition*

Stimulated by the requirements of industry, there is growing interest in mechanisms to control and exploit the growth of two-dimensional crystals on curved surfaces. Giant Lipid Vesicles are a versatile platform for studies and implementation of crystallization strategies because they provide controllable confinement, stress, and curvature. In this study, we investigated how solid lipid domains grow in the nanometrically-thin curved 2D bilayer membrane and how the growth pattern depends on the key variables. By carefully controlling the thermal history and the composition of the bicomponent vesicles, we can produce vesicles containing a single solid domain. We found that the domain shape has a dependence on the overall vesicle size. Compact domains are found on small vesicles; however, as the vesicle diameter increases, the solid domain pattern becomes increasingly elaborate and flower-like. Theory as well as micropipette experiments further suggests that the diverse domain morphology is caused by variation in membrane tension imposing out of plane stresses during nucleation and growth in vesicles of different sizes.