title: Insertion mechanism of a poly(ethylene oxide)-poly(butylene oxide) block copolymer into a DPPC monolayer.
abstract: Interactions between amphiphilic block copolymers and lipids are of medical interest for applications such as drug delivery and the restoration of damaged cell membranes. A series of monodisperse poly(ethylene oxide)-poly(butylene oxide) (EOBO) block copolymers were obtained with two ratios of hydrophilic/hydrophobic block lengths. We have explored the surface activity of EOBO at a clean interface and under 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers as a simple cell membrane model. At the same subphase concentration, EOBO achieved higher equilibrium surface pressures under DPPC compared to a bare interface, and the surface activity was improved with longer poly(butylene oxide) blocks. Further investigation of the DPPC/EOBO monolayers showed that combined films exhibited similar surface rheology compared to pure DPPC at the same surface pressures. DPPC/EOBO phase separation was observed in fluorescently doped monolayers, and within the liquid-expanded liquid-condensed coexistence region for DPPC, EOBO did not drastically alter the liquid-condensed domain shapes. Grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XRR) quantitatively confirmed that the lattice spacings and tilt of DPPC in lipid-rich regions of the monolayer were nearly equivalent to those of a pure DPPC monolayer at the same surface pressures.
authors.affiliation: Chemical Engineering Department, Stanford University, Stanford, California 94305, USA.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: Leiske
authors.forename: Brian
authors.initials: B
authors.lastname: Meckes
authors.forename: Chad E
authors.initials: CE
authors.lastname: Miller
authors.forename: Cynthia
authors.initials: C
authors.lastname: Wu
authors.forename: Travis W
authors.initials: TW
authors.lastname: Walker
authors.forename: Binhua
authors.initials: B
authors.lastname: Lin
authors.forename: Mati
authors.initials: M
authors.lastname: Meron
authors.forename: Howard A
authors.initials: HA
authors.lastname: Ketelson
authors.forename: Michael F
authors.initials: MF
authors.lastname: Toney
authors.forename: Gerald G
authors.initials: GG
authors.lastname: Fuller
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D011092:Polyethylene Glycols / Q000737:chemistry*; D012212:Rheology; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D004852:Epoxy Compounds; C087757:poly(ethylene oxide)-poly(butylene oxide) copolymer; D015060:1,2-Dipalmitoylphosphatidylcholine; D011092:Polyethylene Glycols