Influence of backbone on the charge transport properties of G4-DNA molecules: a model-based calculation

We put forward a model Hamiltonian to describe the influence of backbone energetics on charge transport through guanine-quadruplex DNA (G4-DNA) molecules. Our analytical results show that an energy gap can be produced in the energy spectrum of G4-DNA by hybridization effects between the backbone and the base and by on-site energy difference of the backbone from the base. The environmental effects are investigated by introducing different types of disorder into the backbone sites. Our numerical results suggest that the localization length of G4-DNA can be significantly enhanced by increasing the backbone disorder degree when the environment-induced disorder is sufficiently large. There exists a backbone disorder-induced semiconducting-metallic transition in short G4-DNA molecules, where G4-DNA behaves as a semiconductor if the backbone disorder is weak and behaves as a conductor if the backbone disorder degree surpasses a critical value.