Formation and Characterization of Lipopeptide Layers at Interfaces for the Molecular Recognition of Antibodies

A lipopeptide, carrying the antigenic peptide segment 135−154 of VP1, one of the capsid proteins of the picornavirus which causes foot-and-mouth disease in cattle, was investigated in lipid monolayers on the water surface and on hydrophobic solid supports. Such lipid monolayers, if present in the fluid state, can incorporate the lipopeptide at any given lipid/lipopeptide ratio. Circular dichroism and infrared spectroscopy show that, on the surface of the lipid layers, the peptidic portion of the lipopeptide adopts an average structure similar to that observed on the surface of the intact virus. The peptide is fully accessible to specific antibody binding as revealed by epifluorescence microscopy of lipid monolayers on the water surface and by surface plasmon resonance measurements of supported layers. In addition, the lipid monolayer surface prevents nonspecific protein binding. Since the lipopeptide-containing lipid monolayers can easily be formed by self-assembly on many transducer surfaces, we believe that this method is of general importance for the controlled presentation of antigens for the subsequent detection of antibody binding. More importantly, the findings open the way for simulating ligand−receptor interactions on biological cell surfaces in a reconstituted system using modern surface sensitive techniques which are equally interesting for basic research and biosensor applications.