Kinetics of the Unrolling of Small Unilamellar Phospholipid Vesicles onto Self-Assembled Monolayers

Abstract

Self-assembled monolayers (SAMs) comprised of a mixture of a cholesterol functionalized thiol derivative and a short chain ethyleneoxythiol derivative have been used to attach phospholipid bilayers to gold surfaces. The cholesterol derivatives serve as “anchoring units” and are inserted into the lower leaflet of the attached bilayer. The short chain ethyleneoxy derivatives are present to promote a disordered hydrophilic region beneath the bilayer. The bilayers were formed by incubation of the SAMs with small unilamellar vesicles. On single component hydrophobic surfaces a single lipid layer was adsorbed, while on mixed SAMs containing the cholesterol anchoring units, and single component hydrophilic surfaces, a lipid bilayer was adsorbed. The kinetics of bilayer formation was followed using surface plasmon resonance spectroscopy, and showed dramatic differences depending on the SAM composition.