Impacts of Chlorine Counterions on Electronic Properties of Metal-Modified DNA

Understanding the impact of the solvent environment on the electronic properties of modified DNA is essential for their use in nanoelectronics and in medicine. We modeled the impact of counterions in metal modified DNA (mmDNA) using ab-initio density functional theory to model wet and dry conditions. The orbital wavefunctions and charge transport properties were compared for a variety of test conditions, looking at effects for a single basepair as well as a longer DNA chain, using the Thymine-Mercury-Thymine mmDNA basepair as a case study.

Preliminary results from single base pair calculations indicate that chlorine counterions in wet DNA do not significantly affect the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, while in dry cases, orbital wavefunctions are more localized and at lower energies, albeit with a similar bandgap. In most calculations, the LUMO localizes on the central metal atom. These findings suggest that longer DNA molecules could potentially form a channel for electron transport along the metal atoms, effectively functioning as a nanowire with a conductance dependent on solvation and counterion presence. With a more accurate model of DNA as a nanomaterial for bioelectronics, it will be possible to develop smaller, more efficient devices operable in biomolecule-friendly environments.