ORDERED STRUCTURE FORMED BY BIOLOGICALLY RELATED MOLECULES

The two-dimensional arrangement of biologically related molecules was studied by means of scanning probe microscopy. For monolayers of fatty acid molecules with a saturated hydrocarbon chain adsorbed on a graph ite substrate, in the scanning tunneling microscope image, the positio n associated with the carbon atoms was clearly distinguished. In addit ion, based on the image for fatty acid molecules with an unsaturated h ydrocarbon chain, at the position of a double bond, local electrical c onductance was found to increase. Based on the images, it was pointed out that not the position of each carbon but the interaction between a graphite substrate and an alkyl chain plays an important role in imag ing. On the other hand, for the surface of Langmuir-Blodgett films com posed of phosphatidic acids with cations, the scanning force microscop e image shows, for the first time, evidence of the methyl ends in the arrangement of phospholipid molecules.