Effect of temperature and UV illumination on charge transport mechanisms in DNA

Research into the use of DNA molecules as building blocks for nanoelectronics as well as nanosystems continues. Recently, our group has reported significant electrical conductivity in λ-DNA through direct and in-direct measurements involving high-aspect ratio electrodes that eliminate the effect of the substrate. Our results demonstrate that, at moderate to high frequencies, λ-DNA molecular wires show low impedance. In addition, to prove that the conductivity is indeed from DNA bridge, we studied the effect of temperature and UV irradiation on DNA molecular wires. The temperature results indicate that λ-DNA molecular wires have differing impedance responses at two temperature regimes: impedance increases between 4°C - 40°C, then decreases from 40°C to the melting point (~110°C) at which λ-DNA denatures resulting in a complete loss of current transduction. This hysteric and bi-model behavior makes DNA a candidate for nanoelectronics components such as thermal transistors and switches. The data from UV exposure experiments indicates decreased conductivity of λ-DNA molecular wires after UV exposure, due to damage to GC base pairs and phosphate groups reducing the path available for both charge hopping and short-range electron tunneling mechanisms. The lessons learned from these conductivity experiments along with our knowledge of different charge transport mechanisms within DNA can be applied to the design of synthetic molecular wires for the construction of nanoelectronic devices.