Research on the Electrical Properties of Drug-DNA Complexes Takes Into Account Na⁺ Ions and the Solvent Environment

Counterions and the solvent environment are critical factors determining the electrical properties of DNA. Previous studies have reported the effects of Na⁺ ion concentration variations and solvent environments on the electrical conductivity of B-DNA. However, the mechanism by which they exert their influence on the drug-DNA complex remains unclear. This model integrates density functional theory and the nonequilibrium Green's function formalism to explore the impact of Na⁺ ions on the electrical properties of three drug-DNA complexes in both aqueous and vacuum environments. By minimizing the energy, Na⁺ ions are added to the drug-DNA complexes to render them electrically neutral. Subsequently, the electrical properties of the three DNA molecules are calculated under neutral conditions and after randomly removing one Na⁺ ion in different solvent environments to investigate the effects of the solvent environment and Na⁺ ions. The results show that the presence of Na⁺ hinders charge transport at the HOMO level both in aqueous solvent and vacuum. The removal of one Na⁺ ion from each of the three complexes leads to an increase in molecular conductivity and charge transfer efficiency, among which the Noga-DNA complex is particularly significantly affected by Na⁺ ions in the aqueous environment.