Relationship between the Structure and Electrical Conductivity of 12-Mer Single-Stranded Polyadenine Studied by Scanning Tunnelling Microscope

Abstract: In order to investigate the structure and electrical conductivity of (DNA), Scanning Tunnelling Microscopy (STM) studies were carried out on a model of DNA which was composed of a 12-mer single-stranded polyadenine connected via sugar-phosphate backbone. The 12-mer single-stranded polyadenine molecules were found to be aligned in parallel to each other at a separation 25±7.5 Å. This alignment formed a one-dimensional chain structure, which indicated that the side-by-side coupling among the molecules was strong. The STM measurements with constant current mode and fixed bias voltage, demonstrate that, the electrical conductivity of DNA bases could be deduced by monitoring the size of the structure of 12-mer single-stranded polyadenine.