title: Effects of imidazolium-based ionic surfactants on the size and dynamics of phosphatidylcholine bilayers with saturated and unsaturated chains.
abstract: Imidazolium-based ionic surfactants of different sizes were simulated with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. Regardless of the phospholipid type, larger surfactants at higher concentrations more significantly insert into the bilayer and increase the bilayer-surface size, in agreement with experiments and previous simulations. Insertion of surfactants only slightly decreases the bilayer thickness, as also observed in experiments. Although the surfactant insertion and its effect on the bilayer size and thickness are similar in different types of bilayers, the volume fractions of surfactants in the bilayer are higher for DMPC bilayers than for POPC and DOPC bilayers. In particular, ionic surfactants with four hydrocarbons yield their volume fractions of 4.6% and 8.7%, respectively, in POPC and DMPC bilayers, in quantitative agreement with experimental values of ∼5% and ∼10%. Also, the inserted surfactants increase the lateral diffusivity of the bilayer, which depends on the bilayer type. These findings indicate that although the surfactant insertion does not depend on the bilayer type, the effects of surfactants on the volume fraction and bilayer dynamics occur more significantly in the DMPC bilayer because of the smaller area per lipid and shorter saturated tails, which helps explain the experimental observations regarding different volume fractions of surfactants in POPC and DMPC bilayers.
authors.affiliation: Department of Chemical Engineering, Dankook University, Yongin 448-701, South Korea. Electronic address: leeh@dankook.ac.kr.
authors.forename: Hwankyu
authors.initials: H
authors.lastname: Lee
mesh_terms: D001881:Borates / Q000494:pharmacology*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D007093:Imidazoles / Q000494:pharmacology*; D052578:Ionic Liquids / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010713:Phosphatidylcholines / Q000737:chemistry*; D012997:Solvents; D013501:Surface-Active Agents / Q000494:pharmacology*; D013816:Thermodynamics
chemical_list: C525963:1-butyl-3-methylimidazolium; C528767:1-hexyl-3-methylimidazolium; D001881:Borates; D007093:Imidazoles; D052578:Ionic Liquids; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D012997:Solvents; D013501:Surface-Active Agents; C017251:1,2-oleoylphosphatidylcholine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine; C518739:1-ethyl-3-methylimidazolium; D004134:Dimyristoylphosphatidylcholine
keywords: Imidazolium-based ionic surfactant; Lipid bilayer; MD simulation