ABSTRACT
There has been no general consensus on the electrical conduc-
tivity of deoxyribonucleic acid (DNA). Kasumov et al. [6] directly measured the electrical resistivity of double-stranded DNA with
rhenium/carbon (Re/C) bilayer electrodes and found that DNA
was metallic down to 50 mK and reported a proximity effect of
the superconductivity of metallic rhenium. On the other hand,
Porath et al. [4] have directly measured the electrical conductivity of synthetic DNA [poly(G)–poly(C)] with a length of 10 nm to
find a semiconducting behavior with the temperature-dependent
energy gap of 2-4 eV. Such controversial interpretations of the
electronic states in DNAs can be considered to arise from the
Figure 5.1 [Left] Comparison of the theoretical DOS (solid curve) and the photoemission spectrum (dashed curve) of poly(dA)–poly(dT). The
hatched area corresponds to the unoccupied part of the calculated DOS.
[Right] Schematic band diagram of poly(dA)–poly(dT) DNA on the Si/SiO2 substrate. Reprinted with permission from Ref. [166], Copyright 2005, AIP
Publishing LLC.
