title: Infrared and fluorescence spectroscopic studies of a phospholipid bilayer supported by a soft cationic hydrogel scaffold.
abstract: Polarized attenuated total reflection (ATR-IR) spectroscopy and fluorescence microscopy techniques were used to characterize a 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) membrane supported on porous, cationic hydrogel beads. Fluorescence microscopy images showed that the DPhPC coated the external surface of the hydrogel scaffold. In addition, a fluorescence assay of the emission intensity of the Tb(3+)/dipicolinic acid complex demonstrated that the DPhPC coating acted as a barrier to Tb(3+) efflux from the scaffolded vesicle and successfully sealed the porous hydrogel bead. Fluorescence quenching and ATR-IR spectroscopic measurements revealed that the lipid coating has a bilayer structure. The phytanoyl chains were found to exhibit significant trans-gauche isomerization, characteristic of the fluid liquid phase. However, no lipid lateral mobility was observed by fluorescence recovery after photobleaching (FRAP) measurements. The phosphocholine headgroup was found to be well hydrated and oriented such that the cationic choline group tucked in behind the anionic phosphate group, consistent with an electrostatic attraction between the cationic scaffold and zwitterionic lipid. The absence of lipid lateral mobility may be due to the strength of this attraction.
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Grossutti
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: Seenath
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: John A
authors.initials: JA
authors.lastname: Noël
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada. Electronic address: jlipkows@uoguelph.ca.
authors.forename: Jacek
authors.initials: J
authors.lastname: Lipkowski
keywords: ATR-IR spectroscopy; Fluorescence recovery after photobleaching (FRAP); Giant scaffolded vesicles; Soft cationic hydrogels; Supported phospholipid bilayers