title: Infrared and Fluorescence Spectroscopic Investigations of the Acyl Surface Modification of Hydrogel Beads for the Deposition of a Phospholipid Coating.
abstract: The scaffolded vesicle has been employed as an alternative means of developing natural model membranes and envisioned as a potential nutraceutical transporter. Furthering the research of the scaffolded vesicle system, a nucleophilic substitution reaction was implemented to form an ester linkage between palmitate and terminal hydroxyl groups of dextran in order to hydrophobically modify the hydrogel scaffold. An average tilt angle of 38° of the hydrophobic palmitate modifying layer on the surface of the hydrogel was determined from dichroic ratios obtained from infrared spectra collected in the attenuated total reflection (ATR) configuration. ATR-IR studies of the DMPC-coated acylated hydrogel demonstrated that the hydrocarbon chains of the DMPC coating was similar to those of the DMPC bilayers and that the underlying palmitate layer had a negligible effect on the average tilt angle (26°) of the DMPC coating. The permeability of this acylated hydrogel was investigated with fluorescence spectroscopy and the terbium/dipicolinic acid assay. The hydrophobic modification on the surface of the hydrogel bead allowed for an efficient deposition of a DMPC layer that served as an impermeable barrier to terbium efflux. About 72% of DMPC-coated acylated hydrogel beads showed ideal barrier properties. The remaining 28% were leaking, but the half-life of terbium efflux of the DMPC-coated acylated hydrogel was increasing, and the total amount of leaked terbium was decreasing with the incubation time. The half-life time and the retention were considered a marked improvement relative to past scaffolded vesicle preparations. The process of acylating hydrogel beads for efficient DMPC deposition has been identified as another viable method for controlling the permeability of the scaffolded vesicle.
authors.affiliation: Department of Chemistry, University of Guelph , Guelph, ON, Canada N1G 2W1.
authors.forename: Michael
authors.initials: M
authors.lastname: Grossutti
authors.affiliation: Department of Chemistry, University of Guelph , Guelph, ON, Canada N1G 2W1.
authors.forename: Ryan
authors.initials: R
authors.lastname: Seenath
authors.affiliation: Department of Chemistry, University of Guelph , Guelph, ON, Canada N1G 2W1.
authors.forename: Jacek
authors.initials: J
authors.lastname: Lipkowski
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013055:Spectrophotometry, Infrared
chemical_list: D008051:Lipid Bilayers; D010743:Phospholipids; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D004134:Dimyristoylphosphatidylcholine