Modulated and spiral surface patterns on deformable lipid vesicles

Area of Science:

• Soft matter physics
• Biophysics
• Materials science

Background:

• Two-dimensional systems with spherical topology exhibit phase transitions.
• Lipid bilayer vesicles model cellular membranes and can separate into liquid-ordered and liquid-disordered phases.
• Phase separation in vesicles leads to complex spatial patterns beyond simple domain configurations.

Purpose of the Study:

• Investigate the behavior of two-dimensional systems with spherical topology and order-parameter-dependent mechanical properties.
• Analyze the interplay between phase coexistence, vesicle shape, and mechanical properties.
• Map the phase diagram of these systems, including novel spiral patterns.

Main Methods:

• Theoretical investigation of systems with spherical topology.
• Modeling multicomponent lipid bilayer vesicles.
• Analysis of phase transitions and surface morphology.

Main Results:

• Demonstrated a coupling between vesicle shape and local composition due to differing bending rigidities.
• Identified a rich phase diagram including homogeneous, separated, and axisymmetric modulated phases.
• Revealed regions of spiral patterns in surface morphology arising from phase coexistence.

Conclusions:

• The interplay of mechanical properties and phase separation in lipid vesicles leads to complex morphologies.
• A detailed phase diagram elucidates the transitions between different spatial patterns.
• Spiral surface patterns represent a novel outcome of phase coexistence in spherical systems.