Adhesion-induced phase behavior of two-component membranes and vesicles

Area of Science:

• Membrane biophysics
• Soft matter physics
• Physical chemistry

Background:

• Two-component membranes can spontaneously phase separate into distinct fluid phases, like liquid-ordered and liquid-disordered.
• Adhesion to substrates or other structures creates geometrically constrained environments for membranes.
• These constrained environments can lead to compartmentalization and altered phase behavior.

Purpose of the Study:

• To theoretically investigate the interplay between adhesion and phase separation in two-component membranes.
• To understand how different adhesion geometries influence membrane compartmentalization and phase behavior.
• To identify key parameters governing phase transitions in adhering membranes.

Main Methods:

• Generalization of a lattice model for binary mixtures to incorporate adhesion geometries.
• Theoretical analysis of phase diagrams in the composition/temperature plane.
• Investigation of parameters such as area fraction and affinity contrast.

Main Results:

• Adhering membranes exhibit phase behavior dependent on composition, temperature, area fraction, and affinity contrast.
• Non-vanishing affinity contrast leads to two distinct phase transitions and a specific phase diagram topology.
• Phase separation and domain formation occur independently in different membrane segments, not simultaneously.
• Adhesion can suppress phase separation in certain parameter regimes.

Conclusions:

• Adhesion-induced phase behavior in membranes is complex and tunable via geometric and compositional factors.
• The theoretical predictions offer insights into experimentally observable phenomena in adhering membrane systems.
• Understanding these principles is crucial for applications involving patterned or confined lipid bilayers.