title: Structure and dynamics of highly PEG-ylated sterically stabilized micelles in aqueous media.
abstract: Molecular assemblies of highly PEG-ylated phospholipids are important in many biomedical applications. We have studied sterically stabilized micelles (SSMs) of self-assembled DSPE–PEG2000 in pure water and isotonic HEPES-buffered saline solution. The observed SSM sizes of 2–15 nm largely depend on the solvent and the lipid concentration used. The critical micelle concentration of DSPE–PEG2000 is 10 times higher in water than in buffer, and the viscosity of the dispersion dramatically increases with the lipid concentration. To explain the experimentally observed results, we performed atomistic molecular dynamics simulations of solvated SSMs. Our modeling revealed that the observed assemblies have very different aggregation numbers (N(agg) ≈ 90 in saline solution and N(agg) < 8 in water) because of very different screening of their charged PO4(–) groups. We also demonstrate that the micelle cores can inflate and their coronas can fluctuate strongly, thus allowing storage and delivery of molecules with different chemistries.
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States.
authors.forename: Lela
authors.initials: L
authors.lastname: Vuković
authors.forename: Fatima A
authors.initials: FA
authors.lastname: Khatib
authors.forename: Stephanie P
authors.initials: SP
authors.lastname: Drake
authors.forename: Antonett
authors.initials: A
authors.lastname: Madriaga
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Brandenburg
authors.forename: Petr
authors.initials: P
authors.lastname: Král
authors.forename: Hayat
authors.initials: H
authors.lastname: Onyuksel
mesh_terms: D008823:Micelles; D008958:Models, Molecular; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry
chemical_list: C519184:1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy-poly(ethylene glycol 2000); D008823:Micelles; D010714:Phosphatidylethanolamines; D014867:Water; D011092:Polyethylene Glycols