Structural and Mechanical Response of Two-Component Photoswitchable Lipid Bilayer Vesicles

Area of Science:

• Biophysics
• Materials Science
• Photochemistry

Background:

• Phospholipids are key components of cell membranes.
• Optical control offers precise manipulation of membrane properties.
• Azo-PC is a photoresponsive lipid for dynamic membrane studies.

Purpose of the Study:

• Investigate how light-induced isomerization of Azo-PC affects membrane properties.
• Quantify changes in elastic modulus, water permeability, and toughness.
• Explore Azo-PC behavior in mixtures with other lipids.

Main Methods:

• Vesicle-scale micropipette measurements.
• Atomistic molecular dynamics simulations.
• Analysis of both dynamic and steady-state membrane properties.

Main Results:

• Azo-PC isomerization significantly altered membrane characteristics.
• Molecular area decreased by 16% in trans vs. cis state.
• Stretching modulus increased 2.5-fold, and water permeability decreased 3.5-fold.
• Simulations revealed changes in membrane thickness and chain order.

Conclusions:

• A single bond rotation in Azo-PC profoundly impacts molecular and membrane-scale properties.
• Light-triggered changes in lipid order are directly linked to macroscopic membrane behavior.
• Findings support applications in photopharmacology and switchable materials.