Characterization of solid-supported dipalmitoylphosphatidylcholine membranes containing cholesterol

Area of Science:

• Biophysics
• Materials Science

Background:

• Cholesterol significantly alters lipid membrane properties.
• Dipalmitoylphosphatidylcholine (DPPC) is a common model membrane system.

Purpose of the Study:

• To investigate the effect of cholesterol on DPPC membrane adhesion and structure.
• To correlate membrane defects with adhesion forces.

Main Methods:

• Surface force apparatus (SFA) for force-distance profiles.
• Atomic force microscopy (AFM) for high-resolution structural imaging.
• Neutron reflectometry for structural characterization.

Main Results:

• Adhesion between cholesterol-DPPC membranes was higher than pure DPPC membranes.
• Membrane adhesion varied with the number of defects in the outer leaflet.
• Defects, averaging 230 nm, were detectable by AFM and correlated with increased adhesion.
• Adhesion increased as membrane thickness decreased, linked to exposed hydrophobic groups.

Conclusions:

• Cholesterol incorporation enhances DPPC membrane adhesion.
• Membrane defects play a crucial role in modulating adhesion forces.
• AFM is vital for identifying nanoscale defects influencing macroscopic properties.