Single molecular layer of avidin is fabricated on an atomically flat SiO2 surface and characterized by atomic force microscopy (AFM) and infrared reflection absorption spectroscopy. Immobilization of avidin is performed as follows; i) ester-modification of the surface by silane-coupling agent, ii) carboxylation by hydrolysis in HCl and iii) amide bonding between the surface-COOH and-NH2 in avidin molecules. Large dome structures (∼60 nm height) are formed after the ester-modification, but an atomically flat surface is obtained after the hydrolysis reaction. AFM topographs and function-recognizing images show that the each of avidin molecules adsorbs as a single molecule and retains the biotin-binding activity. Formation of a tethered bilayer membrane of a biotinylated phospholipid on the avidin layer is also described.
Dy@C 82 and Dy@C 60 adsorbed on Si(111)-(7ϫ7) surface are investigated by scanning tunneling microscopy ͑STM͒ at 295 K. The Dy@C 82 molecules in the first layer are adsorbed on the Si(111)-(7ϫ7) surface without formation of islands and nucleation, and the internal structure of the Dy@C 82 molecule is first observed on the surface at 295 K. The average heights of the Dy@C 82 molecules in the first and second layers are estimated to be 7.2 and 10.8 Å, respectively, by STM. These results suggest strong interactions between the Si atoms and the Dy@C 82 molecules in the first layer. The STM image reveals that the Dy@C 60 molecule is nearly spherical, showing that the metal endohedral C 60 possesses a cage-form structure.
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