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

The mechanism for the formation of biomimetic model cell membranes consisting of bilayers composed of alkanethiols and phospholipids was probed with a kinetic study using surface plasmon resonance. The kinetics of formation of a monolayer of phospholipid from vesicles in solution onto a hydrophobic alkanethiol monolayer is described by a model that takes into account the lipid 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 this model describe the behavior of two distinct vesicle concentration conditions. At high concentrations of lipid vesicles the formation of the bilayer appears to be limited by the diffusion of vesicles to the surface; at lower concentrations of vesicles, the rate-limiting step is apparently the surface reorganization of lipid. This kinetic model can also be used to describe the formation of a biomimetic bilayer from an alkanethiol monolayer and cell membranes.