Electric field induced charge transfer through single- and double-stranded DNA polymer molecules

Abstract

The charge transfer through single-stranded and double-stranded DNA polymer molecules has been the subject of numerous experimental and theoretical studies concerning their applications in molecular electronics. However, the underlying mechanisms responsible for their different electrical conductivity observed in the experiments are poorly understood. Here we use a self-consistent quantum molecular dynamics method to study the effect of an applied electric field along the molecular axis on charge transfer through single-stranded and double-stranded DNA polymer molecules with an injected electron or hole and assess the consequences for electronic applications. Charge transfer through both single-stranded and double-stranded DNA polymer molecules is predicted, regardless of the sign of the injected charge, the molecular structure and the base sequence. The amount of charge transfer through a double-stranded DNA polymer molecule is slightly lower than through the corresponding two isolated single-strands as a result of the lower charge transport through the purine–pyrimidine base-stacking as compared with through DNA nucleobase-stacking. These results suggest that each DNA polymer strand can act as a molecular wire with both the sugar–phosphate backbone and the bases playing an important role in charge transfer, which opens new perspectives for molecular electronics applications.