Molecular Conductance of Nicked Nucleic Acid Duplexes

This work investigates how the conductance of a nucleic acid duplex with a “nick” in its backbone compares with that of a duplex with a fully covalent backbone. Statistical analyses of the single-molecule conductance properties reveal that molecular junctions with a nicked duplex have an average conductance close to that found for non-nicked structures but exhibit greater variability in the molecular conductance. This effect is shown for both DNA homoduplexes and DNA/PNA heteroduplexes, with the heteroduplexes showing a greater average molecular conductance and a smaller degree of variability. The average molecular conductance of the heteroduplexes is also shown to be affected by their PNA content; the conductance of duplexes increases as the ratio of PNA to DNA increases. These observations suggest that the charge-transfer properties of nucleic acid-based assemblies can support complex functions.