Electrochemical and spectroelectrochemical characterization of lipid organization in an electric field

Bizzotto, Dan; Yang, Yanguo; Shepherd, Jeff L.; Stoodley, Robin; Agak, J.O; Stauffer, V; Lathuillière, Mike; Akhtar, Anisa S.; Chung, Emily

doi:10.1016/j.jelechem.2003.11.002

Cited by 43 publications

(58 citation statements)

References 108 publications

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“…31 Even a phospholipid monolayer self-assembled on a HMDE and incorporating a fluorophore in its polar head region yields fluorescence images for a long period of time over the potential region of minimum capacity of the monolayer. 37 Moreover, the fluorescent features of this mercurysupported monolayer, obtained by epi-fluorescence microscopy, are freely mobile, in contrast with those obtained on a gold support. Therefore, we found it interesting to obtain fluorescence lifetime images of a tethered bilayer lipid micromembrane (tBLmM) described in the materials and methods section.…”

Section: P-flim Measurementsmentioning

confidence: 86%

Electrochemical impedance spectroscopy and fluorescence lifetime imaging of lipid mixtures self-assembled on mercury

et al. 2010

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Monolayers and bilayers of lipid mixtures self-assembled on mercury form spontaneously gel-phase (solid ordered, s o ) and liquid-ordered (l o ) microdomains, thanks to the fluidity imparted to these films by the liquid metal support. The differential capacity of the hydrocarbon tail region of monolayers of mixtures of two lipid components of high and low transition temperature T m , increases during the transition from the liquid disordered (l d ) phase to the coexistence of l d and s o phases. Addition of cholesterol to this binary mixture causes a decrease in differential capacity. This behavior is explained by regarding the capacity as a measure of the total perimeter of the s o microdomains, due to the mismatch between these microdomains and the l d phase. Cholesterol removes this mismatch by converting the anisotropic s o microdomains into isotropic l o microdomains (rafts). This allows differential capacity measurements by electrochemical impedance spectroscopy to follow phase transitions in lipid mixtures. The coexistance of l d , l o and s o phases is confirmed by images of a distal lipid monolayer self-assembled on top of a thiolipid monolayer tethered to a mercury microcap, by using two-photon fluorescence lifetime imaging microscopy (2P-FLIM).

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Section: P-flim Measurementsmentioning

confidence: 86%

Electrochemical impedance spectroscopy and fluorescence lifetime imaging of lipid mixtures self-assembled on mercury

et al. 2010

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“…This procedure gives rise to a lipid monolayer with the hydrocarbon tails directed toward the mercury surface, thanks to its hydrophobic nature [20][21][22]. This lipid self-assembly is equivalent to a Langmuir-Blodgett transfer at the equilibrium spreading pressure [23]. In fact, by spreading an excess of the lipid at the nitrogen/solution interface, one obtains a monolayer at the characteristic spreading pressure (about 45 mN/m 2 ), in equilibrium with the bulk phase of the surfactant,…”

Section: Preparation Of Mercury-supported Self-assembled Monolayers (mentioning

confidence: 99%

“…i.e., a floating crystal of the surfactant [23][24][25]. The composition of the lipid monolayer self-assembled on a mercury drop through its passage across the lipid monolayer spread on the surface of the working solution is expected to be practically the same as that of the latter lipid monolayer, in analogy with Langmuir-Blodgett transfer.…”

Section: Preparation Of Mercury-supported Self-assembled Monolayers (mentioning

confidence: 99%

The GM1 Ganglioside Forms GM1-Rich Gel Phase Microdomains within Lipid Rafts

et al. 2014

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Mercury-supported, self-assembled monolayers (SAMs) of the sole dioleoylphosphatidylcholine (DOPC) and of a raft-forming mixture of DOPC, cholesterol (Chol) and palmitoylsphingomyelin (PSM) of (59:26:15) mol% composition, were investigated by electrochemical impedance spectroscopy (EIS), both in the absence and in the presence of the monosialoganglioside GM1. The impedance spectra of these four SAMs were fitted by a series of parallel combinations of a resistance and a capacitance (RC meshes) and displayed on plots of ωZ′ against −ωZ″, where Z′ and Z″ are the in-phase and quadrature components of the impedance and ω is the angular frequency. A comparison among these different impedance spectra points to the formation of GM1-rich gel phase microdomains within the lipid rafts of the DOPC/Chol/PSM mixture, thanks to the unique molecular-level smooth support provided by mercury, which allows EIS to detect the protruding gel phase microdomains by averaging them over a macroscopically large area.

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“…44,45 This desorption/re-adsorption process was imaged by using epi-fluorescence microscopy and including a small amount of an amphiphilic fluorescent dye molecule in the lipid monolayer. 46 On a Hg electrode, as distinct from a Au electrode, fluorescence can be detected even if the fluorophore is at a small distance from the electrode. In fact, the fluorescence quenching efficiency, due to nonradiative energy transfer to the electrode, is by two to three orders of magnitude lower on Hg than on Au.…”

Section: Mercury Supported Lipid Monolayersmentioning

confidence: 99%