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

Year: 2010

Authors: Becucci L., Martinuzzi S., Monetti E., Mercatelli R., Quercioli F., Battistel D., Guidelli R.

Autors Affiliation: Department of Chemistry, Florence University, Via della Lastruccia 3, 50019 Sesto Fiorentino Firenze, Italy; ISC, Istituto Dei Sistemi Complessi Del CNR, CNR, Via Madonna del Piano, 10, 50019 Sesto Fiorentino Firenze, Italy; Department of Physical Chemistry, Venice University, Calle Larga S. Marta 2137, 30123 Venezia, Italy

Abstract: 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).

Journal/Review: SOFT MATTER

Volume: 6 (12)      Pages from: 2733  to: 2741

More Information: The financial support by Ente Cassa di Risparmio di Firenze and by the Italian Ministero dell\’Istruzione, dell\’Universita e della Ricerca (MIUR) through PRIN 20079Y9578 are gratefully acknowledged.
KeyWords: Bi-layer; Coexistance; Differential capacity; Fluorescence lifetime imaging; Hydrocarbon tail; Lipid mixtures; Lipid monolayer; Low-transition temperature; Micro-domains; Microcap; Self-assembled; Solid ordered; Two-photon fluorescence lifetime, Binary mixtures; Cholesterol; Electrochemical corrosion; Electron energy levels; Fluorescence; Gels; Hydrocarbons; Lipid bilayers; Liquid metals; Mercury (metal); Phase transitions; Self assembled monolayers; Electrochemical impedance spectroscopy
DOI: 10.1039/b923895f

ImpactFactor: 4.457
Citations: 27
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