Enhancement of the transverse conductance in DNA nucleotides.

We theoretically study the electron transport properties of DNA nucleotides placed in the gap between two single-wall carbon nanotubes capped or terminated with H or N. We show that in the case of C-cap and H-termination the current at low electric bias is dominated by nonresonant tunneling, similarly to the cases of gold electrodes. In nitrogen-terminated nanotube electrodes, the nature of current is primarily quasiresonant tunneling and is increased by several orders of magnitude. We discuss the consequence of our result on the possibility of recognition at the level of single molecule.