Lipid vesicle adsorption versus formation of planar bilayers on solid surfaces

Area of Science:

• Biophysics
• Surface Science
• Lipid Bilayer Formation

Background:

• Lipid vesicles are crucial in biological systems and nanotechnology.
• Understanding their interaction with surfaces is key for developing new materials and drug delivery systems.
• Different lipid compositions exhibit unique behaviors upon surface contact.

Purpose of the Study:

• To investigate the adsorption and spreading behavior of palmitoyloleoylphosphatidylcholine (POPC) and Escherichia coli lipid vesicles on a glass surface.
• To characterize the resulting surface structures and their properties, including permeability and diffusion.
• To compare the formation of supported lipid bilayers versus supported vesicle layers.

Main Methods:

• Utilized fluorescence measurements with fluorescently labeled lipids.
• Quantified lipid adsorption, vesicle fusion, and lateral diffusion.
• Assessed the accessibility of adsorbed lipids to external water-soluble molecules.

Main Results:

• POPC vesicles spread to form supported planar bilayers.
• Escherichia coli lipid vesicles formed supported vesicle layers.
• Supported planar bilayers were permeable to small molecules.
• Supported vesicle layers were impermeable, forming immobilized compartments.

Conclusions:

• The lipid composition dictates the structure formed upon surface interaction (bilayer vs. vesicle layer).
• Supported planar bilayers offer pathways for molecular transport, unlike impermeable supported vesicle layers.
• These findings have implications for designing surfaces with controlled permeability and compartmentalization.