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Phase coexistence in single-lipid membranes induced by buffering agents
Merrell A Johnson1, Soenke Seifert, Horia I Petrache
1Department of Physics, Indiana University-Purdue University Indianapolis , LD 154, 402 North Blackford Street, Indianapolis, Indiana 46202, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|August 8, 2014
Summary
Buffers induce phase coexistence in lipid bilayers, causing one phase to dehydrate and the other to swell with increasing buffer concentration. This challenges current theoretical models of lipid interactions.
Area of Science:
- Biophysics
- Materials Science
- Physical Chemistry
Background:
- Lipid bilayer interactions are influenced by buffers via van der Waals forces, electrostatics, hydration, and membrane bending rigidity.
- Previous studies have indicated buffer effects on lipid bilayer interactions.
Purpose of the Study:
- To investigate the peculiar effect of buffers on mixed chain 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayers.
- To explore buffer-induced phase coexistence in POPC lipid bilayers.
Main Methods:
- Experimental investigation of POPC lipid bilayers in the presence of varying buffer concentrations.
- Analysis of lipid bilayer phase behavior and hydration states.
Main Results:
- Observed phase coexistence in POPC lipid bilayers, analogous to alkali chloride effects.
- One lipid phase dehydrates, while the other swells as buffer concentration increases.
- The two coexisting phases remain in osmotic equilibrium.
Conclusions:
- Buffers can induce complex phase behaviors in lipid bilayers beyond known interaction mechanisms.
- The observed dehydration and swelling of coexisting lipid phases present a challenge to existing theoretical models of lipid interactions.
- Further theoretical development is needed to explain buffer-induced osmotic equilibrium in phase-separated lipid systems.
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