Resonance-Mode Electrochemical Impedance Measurements of Silicon Dioxide Supported Lipid Bilayer Formation and Ion Channel Mediated Charge Transport

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• 作者：Anders Lundgren ; Julia Hedlund ; Olof Andersson ; Magnus Br盲nd茅n ; Angelika Kunze ; Hans Elwing ; Fredrik H枚枚k
• 刊名：Analytical Chemistry
• 出版年：2011
• 出版时间：October 15, 2011
• 年：2011
• 卷：83
• 期：20
• 页码：7800-7806
• 全文大小：894K
• 年卷期：v.83,no.20(October 15, 2011)
• ISSN：1520-6882

文摘

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 SiO₂ 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 SiO₂, 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 SiO₂. In addition, by adding the ion channel gramicidin D to bilayers supported on SiO₂, channel-mediated charge transport could be measured with high sensitivity (resolution around 1 pA).