title: Properties of Poloxamer Molecules and Poloxamer Micelles Dissolved in Water and Next to Lipid Bilayers: Results from Computer Simulations.
abstract: To study the properties of poloxamer molecules P85 and P188 and micelles containing these poloxamers in bulk water and also next to lipid bilayers, we performed coarse-grained molecular dynamics computer simulations. We used MARTINI force-field and adjusted Lennard-Jones nonbonded interaction strength parameters for poloxamer beads to take into account the presence of polarizable water. Simulations of systems containing poloxamer molecules or micelles solvated in bulk water showed that structural properties, such as radii of gyration of the molecules and micelles, agree with the ones inferred from experiments. We observed that P85 micelle is almost spherical in shape, whereas the P188 micelle is distorted from being spherical. Simulations containing systems with the water-lipid bilayer interface showed that hydrophilic blocks of poloxamers interact with lipid headgroups of the bilayer and remain at the interface, whereas hydrophobic blocks prefer to insert into the central hydrophobic region of the bilayer. Simulations containing poloxamer micelles next to lipid bilayer showed no permeation of these micelles into the bilayer. To study the "healing" properties of P188 poloxamer, we performed simulations on a system containing a P188 micelle next to "damaged" lipid bilayer containing a pore. We observed that hydrophobic chains of poloxamers got inserted into the bilayer through the pore region, ultimately closing the pore.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: Upendra
authors.initials: U
authors.lastname: Adhikari
authors.affiliation: Department of Biochemistry and Biophysics and Program in Molecular and Cellular Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: Ardeshir
authors.initials: A
authors.lastname: Goliaei
authors.affiliation: Theory and Bio-Systems, Max Planck Institute for Colloids and Interfaces , 14424 Potsdam, Germany.
authors.forename: Levan
authors.initials: L
authors.lastname: Tsereteli
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: Max L
authors.initials: ML
authors.lastname: Berkowitz
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D008823:Micelles; D056004:Molecular Dynamics Simulation; D020442:Poloxamer / Q000737:chemistry*; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D008823:Micelles; D012996:Solutions; D014867:Water; D020442:Poloxamer; D004134:Dimyristoylphosphatidylcholine