Current–voltage characteristics of λ- and poly-DNA

We have studied the current–voltage characteristics of λ- and poly-DNA molecules attached on the gap formed between two Au metal electrodes. Under high humidity condition, all types of deoxyribonucleic acid (DNA) show a similar shape in I–V curves, as well as a comparable magnitude in current level at the given voltage. The conductivity of DNA molecules, however, was drastically changed after minimizing the humidity level in a vacuum chamber, causing a rectifying property in I–V characteristics. More important, the G–C content in DNA molecules decides the conductivity level at the given voltage, suggesting that the electrical conductions of DNA molecules are strongly dependent on both humidity in a measurement chamber and intrinsic properties of DNA itself.