DNA is an important and promising molecule, not only due to its genetic function, but also as a molecular scaffold for nanotechnology and nanostructure. DNA has the special double helix structure with p-electron cores of well-stacking bases, which may be a good candidate for long-distance(e.g., 200Å) and one-dimensional charge transport. These investigations have significant implications for the study of DNA damage and repair in biological systems, the application of DNA in electronic devices and DNA-based electrochemical biosensors. The nature of this electronic interaction is vigorously debated and dependent on the base-sequence, dynamic structure and base stacking, etc.
Herein we report the direct measurements of electrical characteristics of DNA bundles and single DNA molecule, i.e. polyd(A)-polyd(T) and polyd(G)-polyd(C). Three different methods have been applied for the stretching and alignment of DNA on the freshly cleaved mica or modified-mica surface by APS and Mg ions. A gold electrode is fabricated on DNA/mica surface by shadow-mask deposition in high vacuum. The electrical properties of DNA are measured using an AFM equipped with a gold-coated conductive tip under vacuum.
Fig.1. Three elongated polyd(A)-polyd(T) molecules attached on gold electrode.
Kawai Lab., ISIR-Sanken, Osaka University
Ibaraki, Osaka 567-0047, Japan