title: Resonance-mode electrochemical impedance measurements of silicon dioxide supported lipid bilayer formation and ion channel mediated charge transport.
abstract: A single-chip electrochemical method based on impedance measurements in resonance mode has been employed to study lipid monolayer and bilayer formation on hydrophobic alkanethiolate and SiO(2) substrates, respectively. The processes were monitored by temporally resolving changes in interfacial capacitance and resistance, revealing information about the rate of formation, coverage, and defect density (quality) of the layers at saturation. The resonance-based impedance measurements were shown to reveal significant differences in the layer formation process of bilayers made from (i) positively charged lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-ethylphosphocholine (POEPC), (ii) neutral lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) on SiO(2), and (iii) monolayers made from POEPC on hydrophobic alkanethiolate substrates. The observed responses were represented with an equivalent circuit, suggesting that the differences primarily originate from the presence of a conductive aqueous layer between the lipid bilayers and the SiO(2). In addition, by adding the ion channel gramicidin D to bilayers supported on SiO(2), channel-mediated charge transport could be measured with high sensitivity (resolution around 1 pA).
authors.affiliation: Department of Cell and Molecular Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Lundgren
authors.forename: Julia
authors.initials: J
authors.lastname: Hedlund
authors.forename: Olof
authors.initials: O
authors.lastname: Andersson
authors.forename: Magnus
authors.initials: M
authors.lastname: Brändén
authors.forename: Angelika
authors.initials: A
authors.lastname: Kunze
authors.forename: Hans
authors.initials: H
authors.lastname: Elwing
authors.forename: Fredrik
authors.initials: F
authors.lastname: Höök
mesh_terms: D058266:Dielectric Spectroscopy; D006096:Gramicidin / Q000737:chemistry; D007473:Ion Channels / Q000378:metabolism*; D017136:Ion Transport; D008051:Lipid Bilayers / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D007473:Ion Channels; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D006096:Gramicidin; D012822:Silicon Dioxide; C028694:1-palmitoyl-2-oleoylphosphatidylcholine