A hybrid SAM phospholipid approach to fabricating a 'free' supported lipid bilayer

Using a combination of self assembly, Langmuir-Blodgett and Langmuir-Schaeffer techniques, we have produced a multilayered film of dimyristoylphosphatidylcholine ( DMPC) intended for use as a biomembrane mimic. Neutron reflectivity measurements have revealed that the upper two layers of phospholipid are separated from the silicon substrate and the lower layers by a hydration region approximately 30 A thick. This layer limits the tethering effect of the substrate such that the phospholipid molecules within the upper bilayer have significant freedom. This freedom is evidenced by the fact that the upper bilayer shows a transition to the P-beta' ripple phase. This phase could not be observed if the phospholipid molecules were significantly constrained by the substrate.