Abstract
Atomic force microscope (AFM) has been widely used as a tool, not only for the measurement of surface topography and the characterization of localized surface properties at nanometric scale, but also for nanolithography and nanostructure fabrication. In this paper, we propose a novel nanofabrication technique for a wide variety of polymer-based materials such as biomolecules (DNA, protein, etc.), living cells, and engineering plastics based on highly localized photochemical oxidation with a TiO_2-coated AFM tip. As a fundamental study, we optimized deposition conditions for preparing single phase anatase TiO_2 thin films by a sol-gel method and by anodic oxidation of sputtered Ti thin films. The photocatalytic decomposition of fluorescently labeled DNA molecules immobilized onto a TiO_2 substrate can be performed under UV irradiation. Moreover, the photocurrent originated from the photoelectrocatalytic oxidation of DNA molecules can be detected. We also demonstrate the ability of a TiO_2-coated AFM probe to perform highly localized photochemical oxidation of organic compounds.
