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PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions
Published on: July 27, 2017
Interaction energies between oxide surfaces and multiple phosphatidylcholine bilayers from extended-DLVO theory
1Department of Geoscience, 1215 West Dayton Street, University of Wisconsin, Madison, WI 53706, USA. toleson@geology.wisc.edu
Journal of Colloid and Interface Science
|September 28, 2010
Summary
Dipalmitoylphosphatidylcholine (DPPC) bilayer adsorption on corundum and quartz surfaces depends on ionic strength. Extended DLVO theory explains how electrostatic interactions influence multiple bilayer formation, impacting proto-cell membrane self-assembly.
Area of Science:
- Surface Science
- Physical Chemistry
- Biophysics
Background:
- Dipalmitoylphosphatidylcholine (DPPC) bilayers are model systems for cell membranes.
- Understanding interactions between lipid bilayers and mineral surfaces is crucial for applications in biomedicine and origins of life research.
Purpose of the Study:
- To investigate oxide-dependent multiple bilayer adsorption of DPPC on corundum and quartz.
- To examine the influence of ionic strength on these interactions using extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory.
Main Methods:
- Calculated interaction energies between DPPC bilayers and corundum (α-Al(2)O(3)) or quartz (α-SiO(2)) using extended DLVO theory.
- Investigated interactions at two ionic strengths (17 mM and 217 mM).
- Compared theoretical calculations with experimental DPPC adsorption data on corundum and quartz particles.
Main Results:
- Repulsive hydration interaction diminishes with distance; electrostatic and van der Waals forces dominate beyond ~3 nm.
- Revised electrostatic interaction model accounts for bilayer solution exclusion, extending interaction range.
- Calculated energies explain experimental findings: three DPPC bilayers on corundum vs. two on quartz at low ionic strength, and two on both at high ionic strength.
- Observed adsorption is consistent with electric double-layer extension at low ionic strength facilitating DPPC bilayer deposition at large separations (~14 nm).
Conclusions:
- Extended DLVO theory accurately predicts oxide-dependent DPPC bilayer adsorption.
- Electrostatic interactions, modified by bilayer properties and ionic strength, are key drivers of multiple bilayer formation.
- Kinetic factors, not just thermodynamic predictions, limit the formation of theoretically possible infinite bilayer stacks.
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