Nanoscale Substrate Roughness Hinders Domain Formation in Supported Lipid Bilayers

Area of Science:

• Biophysics
• Materials Science
• Surface Science

Background:

• Supported lipid bilayers (SLBs) are crucial model membranes for studying membrane properties using surface-sensitive techniques.
• Their integration with technology offers potential for applications like drug screening.
• Substrate choice is recognized to influence SLB behavior, but this effect is not well understood.

Purpose of the Study:

• To investigate the influence of different substrates on the phase separation behavior of a simple model bilayer.
• To understand the mechanisms by which substrates affect domain formation in SLBs.

Main Methods:

• Phase separation of a model lipid bilayer on various substrates (glass, mica, silicon, quartz).
• Characterization of domain morphology using microscopy techniques.
• Analysis of surface properties and their correlation with bilayer behavior.

Main Results:

• Distinct micron-scale domains were observed on mica, similar to free-floating vesicles.
• Domain size was reduced to nanometers on glass and quartz substrates.
• Nanoscale surface roughness was identified as a likely factor inhibiting domain formation.
• Physicochemical surface properties, potentially via the interstitial water layer, mediate this effect.

Conclusions:

• Substrate properties, particularly nanoscale roughness and surface chemistry, critically influence supported lipid bilayer organization.
• Understanding these substrate effects is essential for designing reliable SLB experiments and biotechnological applications.
• The findings provide insights into controlling membrane behavior on solid supports.