Developing design guidelines for controlling charge transport in DNA

Conceptual frameworks that describe the electronic structure of molecules are an integral part of understanding chemical structures and reaction mechanisms and designing organic compounds. Here we develop a preliminary set of design guidelines for controlling the electronic structure of DNA. Recent work indicates that charge delocalization occurs over several bases and results in coherence lengths greater than a single base pair. To examine the interactions between bases and their effects on delocalization, this study investigates the influence of nearest-neighbour base pair interactions on the charge transport properties of DNA duplexes that are predominantly composed of guanine-cytosine base pairs. Results show that, by manipulating the sequence, the conductance can be substantially modified without altering the molecular composition. The electronic density of states are then analysed to deduce a set of design guidelines aimed at maintaining high conductance values in long duplexes. Utilizing these rules, we demonstrate that 20-base-pair DNA sequences can exhibit conductance values surpassing 1 × 10^-3G₀.