Subtle changes in pH affect the packing and robustness of fatty acid bilayers

Area of Science:

• Physical chemistry
• Self-assembly science
• Soft matter science

Background:

• Connecting molecular interactions to emergent properties is a key goal in physical chemistry, self-assembly, and soft matter science.
• Fatty acid bilayers are fundamental structures with implications for early life and biological systems.

Purpose of the Study:

• To investigate the coupling between pH and the physical properties of fatty acid bilayers, specifically vesicle rupture tension and permeability.
• To elucidate the molecular mechanisms by which pH influences lipid packing and membrane characteristics.

Main Methods:

• Experimental studies on fatty acid membranes.
• Molecular dynamics simulations to analyze membrane behavior at a molecular level.

Main Results:

• A minor pH change can drastically reduce membrane rupture tension, comparable to effects of lipid unsaturation.
• Increased pH leads to enhanced water penetration, ion permeability, pore formation, and membrane disorder.
• Oleic acid membranes exhibit extreme sensitivity to protons compared to sodium ions.

Conclusions:

• pH is a critical regulator of fatty acid bilayer physical properties, influencing membrane integrity and transport.
• The findings have significant implications for understanding primitive cell membranes, biological processes like digestion, and biomaterials.