Electrochemical Characterization of Synthetic Hybrid DNA Molecular Wires

As a viable solution to long-term stability problems associate with DNA molecular wires along with the additional benefits of tuning their conductivity, hybrid DNA molecular wires made of natural base-pairs and synthetic base-pairs, which have lower ionization potentials and a more pi orbital overlapping, offer an attractive option. A strong synthetic nucleotide candidate is tricyclic cytosine analogue (such as (8-MeO) tC), which we show has (i) a lower ionization potential (similar to 0.65V) compared to natural nucleotides, G (1.29V), C (1.6V), A (1.42V), T (1.7V) and (ii) more p-orbital stacking due to its tricyclic structure. Moreover, to illuminate the importance of the pi orbital stack to the conductivity of DNA molecular wires, in this paper, we compared the conductivity of wild-type DNA and DNA sequences containing mismatched base-pairs that perturb the pi orbital stack. Lower conductivity was obtained when modifying the surface of the gold electrodes with both wild-type and mismatched DNA. Further, chips functionalized with DNA sequences with mismatched base-pairs were observed to have lower conductivity than those functionalized with wild-type DNA sequences.