Hexagonal phases in phospholipids with saturated chains: phosphatidylethanolamines and phosphatidic acids

Area of Science:

• Biochemistry
• Physical Chemistry
• Materials Science

Background:

• Phospholipids are essential components of cell membranes.
• Understanding phospholipid phase behavior is crucial for membrane biophysics and drug delivery systems.

Purpose of the Study:

• To investigate the structural properties of phospholipids with saturated acyl chains.
• To determine the phase transition behavior of phosphatidylethanolamines and phosphatidic acids.

Main Methods:

• Differential scanning calorimetry (DSC) was employed to analyze thermal transitions.
• X-ray diffraction was used to characterize the structural phases of phospholipids.

Main Results:

• Phosphatidylethanolamines and phosphatidic acids exhibit a hexagonal phase at elevated temperatures.
• The transition temperature to the hexagonal phase is influenced by acyl chain length and sodium salt concentration.
• Longer acyl chains and higher sodium salt concentrations decrease the hexagonal phase transition temperature.
• Some phospholipids displayed an additional low-temperature calorimetric transition.

Conclusions:

• Saturated phospholipids, specifically phosphatidylethanolamines and phosphatidic acids, can adopt a hexagonal phase.
• The phase behavior is tunable via lipid chain length and ionic strength.
• The findings contribute to understanding lipid polymorphism and phase transitions.