Hydrophobic Mismatch Triggering Texture Defects in Membrane Gel Domains

Area of Science:

• Biophysics
• Materials Science
• Cell Biology

Background:

• The orientational texture of gel-phase lipid bilayers influences membrane domain structure.
• Understanding lipid orientation within domains is crucial for membrane biophysics.

Purpose of the Study:

• To map the lateral variation of lipid orientation within single membrane domains.
• To investigate the lipid-induced transition between vortex and uniform textures in binary phospholipid bilayers.
• To correlate domain texture with lipid composition and hydrophobic mismatch.

Main Methods:

• Two-photon polarized fluorescence microscopy for imaging lipid orientation.
• Image analysis techniques to quantify texture variations.
• Atomic Force Microscopy (AFM) to monitor hydrophobic mismatch.

Main Results:

• A transition between vortex and uniform textures was observed, induced by lipid composition.
• Low hydrophobic mismatch correlated with uniform textures, while higher mismatch correlated with vortex textures.
• Early growth defect patterns persisted in larger domains, explained by anisotropic line tension and vortex energy.

Conclusions:

• Lipid composition and domain nucleation are critical factors determining membrane domain texture.
• Hydrophobic mismatch at domain boundaries plays a key role in texture formation.
• The findings provide insights into the self-assembly and structural organization of lipid membranes.