Molecular dynamics study of changes in physico-chemical properties of DMPC lipid bilayers by addition of nonionic surfactant C₁₂E₁₀

Abstract

Changes in physico-chemical properties of dimyristoyl phosphatidylcholine (DMPC) lipid bilayers caused by the addition of 9.4 mol% nonionic surfactant decaoxyethylene monododecyl ethers (C₁₂E₁₀) have been investigated by molecular dynamics calculations. In spite of addition of single chain C₁₂E₁₀, the lipid bilayers showed an increase of membrane area. Isothermal area compressibility, which is a measure of membrane softness in lateral direction, also increased by 50% for DMPC/C₁₂E₁₀ mixed bilayers. Furthermore, the order parameter of C–H vector for DMPC acyl tails decreased. We found that these changes are caused by the hydrophilic head groups of C₁₂E₁₀ which are located near the glycerol backbone of the DMPC molecules and have bulky random coil conformation without any preferential ordered structures.

Keywords::

• molecular dynamics calculation
• lipid bilayer
• DMPC
• C₁₂E₁₀

Acknowledgements

The authors would like to thank Prof. R. Ueoka for useful discussions. This work was supported by TCCI/CMSI in the Strategic Programs for Innovative Research, MEXT, Japan [Proposal number: hp120292, hp120293 and hp130011]. The calculations were partly performed at the Research Center for Computational Science, Okazaki, Japan, the Center for Computational Sciences, the Supercomputer Center, the Institute for Solid State Physics, the University of Tokyo and the Research Institute for Information Technology, Kyushu University.