Adsorbed and free lipid bilayers at the solid-liquid interface

Single and double phosphocholine (DPPC and DSPC) bilayers adsorbed at the s ilicon-water interface have been prepared and characterised. The second bil ayer, called "free bilayer", is a novel highly hydrated system floating at 20 to 30 Angstrom above the first one. Robust and reproducible preparation has been possible thanks to a combination of Langmuir-Blodgett and Langmuir -Schaeffer techniques. Carefully optimised neutron reflectivity measurement s have allowed a precise non-destructive characterisation of the structure, hydration and roughness of the layers. This work opens new possibilities f or the investigation of the interaction between membrane lipids and soluble proteins, in particular peptides too small to be Visible with other techni ques.