Charge Transfer and Charge Transport on the Double Helix

TL;DR

This paper reviews experiments on charge transfer and transport in DNA, highlighting the role of water in AC conductivity and comparing different measurement approaches.

Contribution

It provides new insights into DNA's AC conductivity, emphasizing water's dissipation role over photon-assisted hopping, and compares chemistry and physics measurement methods.

Findings

AC conductivity of DNA is mainly due to water dipole dissipation.

Different measurement methods probe distinct aspects of charge transfer.

Water environment significantly influences DNA charge transport properties.

Abstract

We present a short review of various experiments that measure charge transfer and charge transport in DNA. Some general comments are made on the possible connection between 'chemistry-style' charge transfer experiments that probe fluorescence quenching and remote oxidative damage and 'physics-style' measurements that measure transport properties as defined typically in the solid-state. We then describe measurements performed by our group on the millimeter wave response of DNA. By measuring over a wide range of humidity conditions and comparing the response of single strand DNA and double strand DNA, we show that the appreciable AC conductivity of DNA is not due to photon assisted hopping between localized states, but instead due to dissipation from dipole motion in the surrounding water helix.