title: PM-IRRAS Studies of DMPC Bilayers Supported on Au(111) Electrodes Modified with Hydrophilic Monolayers of Thioglucose.
abstract: A phospholipid bilayer composed of 1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine (d54-DMPC) was deposited onto the Au(111) electrode modified with a self-assembled monolayer of 1-thio-β-d-glucose (β-Tg) via the Langmuir-Blodgett and Langmuir-Schaefer (LB-LS) techniques. Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) measurements were used to characterize structural and orientational changes in this model biological membrane on a hydrophilic surface modified gold electrode. The results of the spectroscopic measurements showed that the tilt angle of acyl chains obtained for deuterated DMPC bilayers supported on the β-Tg-modified gold is significantly lower than that reported previously for DMPC bilayers deposited directly on Au(111) electrodes. Moreover, tilt angles of ∼18° were obtained for d54-DMPC bilayers on β-Tg self-assembled monolayers (SAMs) at positive potentials, which are similar to the values calculated for h-DMPC deposited on bare gold in the desorbed state and to those observed for a stack of hydrated DMPC bilayers. This data confirms that the β-thioglucose SAM promotes the formation of a water cushion that separates the phospholipid bilayer from the metal surface. As a result, the DMPC polar heads are not in direct contact with the electrode and can adopt a zigzag configuration, which strengthens the chain-chain interactions and allows for an overall decrease in the tilt of the acyl chains. These novel supported model membranes may be especially useful in studies pertaining to the incorporation of peptides and proteins into phospholipid bilayers.
authors.affiliation: Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw , Żwirki i Wigury 101, 02089 Warsaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Matyszewska
authors.affiliation: Faculty of Chemistry, University of Warsaw , ul. Pasteura 1, 02093 Warsaw, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Bilewicz
authors.affiliation: Department of Chemistry, University of Guelph , Guelph, Ontario N1G 2W1, Canada.
authors.forename: ZhangFei
authors.initials: Z
authors.lastname: Su
authors.affiliation: Department of Chemistry, University of Guelph , Guelph, Ontario N1G 2W1, Canada.
authors.forename: Fatemah
authors.initials: F
authors.lastname: Abbasi
authors.affiliation: Department of Chemistry, University of Guelph , Guelph, Ontario N1G 2W1, Canada.
authors.forename: J Jay
authors.initials: JJ
authors.lastname: Leitch
authors.affiliation: Department of Chemistry, University of Guelph , Guelph, Ontario N1G 2W1, Canada.
authors.forename: Jacek
authors.initials: J
authors.lastname: Lipkowski
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D004566:Electrodes; D005947:Glucose / Q000031:analogs & derivatives* / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D008051:Lipid Bilayers; D006046:Gold; C018399:1-thioglucose; D005947:Glucose; D004134:Dimyristoylphosphatidylcholine