SCANNING FORCE MICROSCOPY CHARACTERIZATION OF THIN LIPID FILMS ON A SUBSTRATE

The surface morphology and frictional property of self-assembled domai ns of ultrathin organic films adsorbed on a solid substrate have been studied by a commercially available scanning probe microscopy with an operation mode of simultaneous atomic force microscopy and lateral for ce microscopy measurements. Two lipid film systems have been studied; one is a film system formed from synthetic dialkyl lipid, N,N-dioctade cylsuccinamic acid, and the other is films formed from biological phos pholipids such as dipalmitoylphosphatidylcholine (DPPC), phosphatidylc holine, and phosphatidylethanolamine. The characteristic self-assemble d domain structures as well as the local friction behaviors of the lip id films are presented. A preliminary result is also shown which sugge sts the hydrophobic alkyl tail groups appeared on multilamellar surfac es of DPPC film can be distinguished from the other hydrophilic polar headgroups.