Self assembly driven by hydrophobic interactions at alkanethiol monolayers: mechanism of formation of hybrid bilayer membranes

The mechanism for the formation of biomimetic model cell membranes consisti ng of bilayers composed of alkanethiols and phospholipids was probed with a kinetic study using surface plasmon resonance. The kinetics of formation o f a monolayer of phospholipid from vesicles in solution onto a hydrophobic alkanethiol monolayer is described by a model that takes into account the l ipid concentration, diffusion, and a surface reorganization rate constant. Monomer phospholipid apparently does not play a direct role in determining the kinetics of bilayer formation. Expressions for the limiting cases of th is model describe the behavior of two distinct vesicle concentration condit ions. At high concentrations of lipid vesicles the: formation of the bilaye r appears to be limited by the diffusion of vesicles to the surface; at low er concentrations of vesicles, the rate-limiting step is apparently the sur face reorganization of lipid. This kinetic model can also be used to descri be the formation of a biomimetic bilayer from an alkanethiol monolayer and cell membranes. (C) 1998 Elsevier Science B.V. All rights reserved.