Two-dimensional chiral crystals of phospholipid

Area of Science:

• Materials Science
• Biophysics
• Surface Chemistry

Background:

• Dipalmitoylphosphatidylcholine (DPPC) monolayers at the air-water interface form solid phase domains upon compression.
• These monolayers can form highly ordered two-dimensional crystals on solid substrates.
• Previous studies showed round crystal domains in hexagonal patterns.

Purpose of the Study:

• To investigate the effect of compression rate on DPPC monolayer domain formation.
• To characterize the morphology and properties of solid domains formed under rapid compression.
• To establish a link between lipid enantiomorphism and domain structure.

Main Methods:

• Epifluorescence optical microscopy for visualizing domain formation.
• Compression of DPPC monolayers at the air-water interface at controlled rates (approx. 2% area decrease/sec).
• Transfer of monolayers to solid substrates for potential X-ray diffraction analysis.

Main Results:

• Rapid compression (approx. 2% area decrease/sec) induces the formation of chiral solid domains.
• The handedness of these chiral domains is directly correlated with the enantiomorphic configuration of the constituent lipids.
• The observed domain shapes provide direct visual evidence of long-range orientational order in these two-dimensional crystalline structures.

Conclusions:

• Compression rate significantly influences the morphology of DPPC solid domains.
• Chiral domain formation in DPPC monolayers is a direct consequence of lipid enantiomorphism.
• The study visually confirms long-range orientational order in 2D lipid crystals.