title: Characterization of phospholipid bilayer formation on a thin film of porous SiO2 by reflective interferometric Fourier transform spectroscopy (RIFTS).
abstract: Classical methods for characterizing supported artificial phospholipid bilayers include imaging techniques such as atomic force microscopy and fluorescence microscopy. The use in the past decade of surface-sensitive methods such as surface plasmon resonance and ellipsometry, and acoustic sensors such as the quartz crystal microbalance, coupled to the imaging methods, have expanded our understanding of the formation mechanisms of phospholipid bilayers. In the present work, reflective interferometric Fourier transform spectrocopy (RIFTS) is employed to monitor the formation of a planar phospholipid bilayer on an oxidized mesoporous Si (pSiO(2)) thin film. The pSiO(2) substrates are prepared as thin films (3 μm thick) with pore dimensions of a few nanometers in diameter by the electrochemical etching of crystalline silicon, and they are passivated with a thin thermal oxide layer. A thin film of mica is used as a control. Interferometric optical measurements are used to quantify the behavior of the phospholipids at the internal (pores) and external surfaces of the substrates. The optical measurements indicate that vesicles initially adsorb to the pSiO(2) surface as a monolayer, followed by vesicle fusion and conversion to a surface-adsorbed lipid bilayer. The timescale of the process is consistent with prior measurements of vesicle fusion onto mica surfaces. Reflectance spectra calculated using a simple double-layer Fabry-Perot interference model verify the experimental results. The method provides a simple, real-time, nondestructive approach to characterizing the growth and evolution of lipid vesicle layers on the surface of an optical thin film.
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-ENSCM-UM2-UM1, Matériaux Avancés pour la Catalyse et la Santé, Ecole Nationale Supérieure de Chimie de Montpellier, Montpellier, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Pace
authors.forename: Bastien
authors.initials: B
authors.lastname: Seantier
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Belamie
authors.forename: Nicole
authors.initials: N
authors.lastname: Lautrédou
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sailor
authors.forename: Pierre-Emmanuel
authors.initials: PE
authors.lastname: Milhiet
authors.forename: Frédérique
authors.initials: F
authors.lastname: Cunin
mesh_terms: D000327:Adsorption; D005583:Fourier Analysis; D007368:Interferometry; D008051:Lipid Bilayers / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013057:Spectrum Analysis; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D010743:Phospholipids; D053835:Unilamellar Liposomes; D012822:Silicon Dioxide