title: A neutron reflectivity study of polymer-modified phospholipid monolayers at the solid-solution interface: polyethylene glycol-lipids on silane-modified substrates.
abstract: The structure of polymer-decorated phospholipid monolayers at the solid-solution interface was investigated using neutron reflectometry. The monolayers were composed of distearoylphosphatidylethanolamine (DSPE) matrixed with varying amounts of DSPE-PEG (DSPE with polyethylene glycol covalently grafted to its headgroup). Mixed lipid monolayers were Langmuir-Blodgett deposited onto hydrophobic quartz or silicon substrates, previously hydrophobized by chemically grafting a robust monolayer of octadecyltrichlorosilane (OTS). We show that this method results in homogeneous and continuous phospholipid monolayers on the silanated substrates and determine that the grafted PEG chains extend away from the monolayers into the solvent phase as a function of their density, as expected from scaling theories. In addition, ligands were coupled to the end of the PEG chains and selective binding was demonstrated using fluorescence microscopy. Our results demonstrate that these constructs are ideal for further characterization and studies with well-defined monomolecular films.
authors.affiliation: Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: T L
authors.initials: TL
authors.lastname: Kuhl
authors.forename: J
authors.initials: J
authors.lastname: Majewski
authors.forename: J Y
authors.initials: JY
authors.lastname: Wong
authors.forename: S
authors.initials: S
authors.lastname: Steinberg
authors.forename: D E
authors.initials: DE
authors.lastname: Leckband
authors.forename: J N
authors.initials: JN
authors.lastname: Israelachvili
authors.forename: G S
authors.initials: GS
authors.lastname: Smith
mesh_terms: D000327:Adsorption; D008081:Liposomes / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D009502:Neutrons; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011791:Quartz / Q000378:metabolism; D012542:Scattering, Radiation; D012825:Silicon / Q000378:metabolism; D013499:Surface Properties; D014965:X-Rays
chemical_list: D008081:Liposomes; D010714:Phosphatidylethanolamines; D010743:Phospholipids; D011791:Quartz; C038089:1,2-distearoylphosphatidylethanolamine; D011092:Polyethylene Glycols; D012825:Silicon