Liquid-Ordered/Liquid-Crystalline Phase Separation at a Lipid Bilayer Suspended over Microwells

Area of Science:

• Biophysics
• Materials Science
• Surface Chemistry

Background:

• Lipid membranes exhibit phase separation into liquid-ordered (L_o) and liquid-crystalline (L_α) domains.
• Domain stability and lipid diffusion are influenced by membrane stiffness and lateral tension.
• Supported lipid bilayers on patterned substrates allow investigation of phase behavior.

Purpose of the Study:

• To investigate the localization of L_o and L_α lipid domains on silicon microwell arrays.
• To understand how micropatterning influences lipid membrane phase separation and domain arrangement.
• To examine lipid domain behavior in membranes suspended over microwells.

Main Methods:

• Fabrication of silicon substrates with microwell arrays.
• Formation of lipid membranes (giant unilamellar vesicles and supported membranes) on patterned substrates.
• Microscopy and diffusion measurements to observe phase separation and domain dynamics.

Main Results:

• Phase separation into L_o and L_α domains is observed and rearranged by micropatterning.
• In membranes suspended over microwells, the L_α phase is preferred, excluding lipids to the periphery.
• Anisotropic diffusion leads to a slow, linear reduction in L_o domain area.

Conclusions:

• Micropatterned substrates effectively control lipid membrane domain localization and arrangement.
• Suspended membranes over microwells exhibit unique phase behavior, favoring L_α domains.
• The study demonstrates localized L_α domains within L_o supported membranes in microwell structures.