Domain formation in thin lipid films probed with near-field scanning optical microscopy

High-resolution near-field scanning optical microscopy (NSOM) fluorescence and topographic images of L-alpha-dipalmitoylphosphatidylcholine (DPPC) mon olayers doped with a fluorescent dye are presented, DPPC monolayers are dep osited onto mica substrates from the air-water interface at several surface pressures using the Langmuir-Blodgett technique, Sub-diffraction limit pha se domain structures are observed in both fluorescence and topographic NSOM images of the lipid films. The morphology of the resulting monolayers depe nds strongly on the surface pressure and composition of the subphase used i n the film transfer, Mechanisms for lipid domain formation and growth are d iscussed.