Temperature gating and competing temperature-dependent effects in DNA molecular wires

Abstract

While recent research in electron-transport mechanism on a double strands DNA seems to converge into a consensus, experiments in direct electrical measurements on a long DNA molecules still lead to a conflicting result This study is the continuation of our previous research in electrical characterization of DNA molecular wires, where we furtherly investigate the effects of temperature on the electrical conductivity of DNA molecular wires by measuring its impedance response. We found that at higher temperatures, the expected increase in charge hopping mechanism may account for the decrease in impedance (and hence increase in conductivity) supporting the ’charge hopping mechanism’ theory. UV light exposure, on the other hand, causes damage to GC base pairs reducing the path available for hopping mechanism and hence resulting in increased impedance - this again supporting the ’charge hopping mechanism’ theory. We also report that λ-DNA molecular wires have differing impedance responses at two temperature regimes: impedance increases between 4 °C - 40 °C and then decreases between 40 °C - melting point (∼110 °C), after which λ-DNA denatures resulting in no current transduction. We submit that the low impedance of λ-DNA molecular wires observed at moderate to high frequencies may have significant implications to the field of DNA-based bionanoelectronics.