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DNA drug molecules are not only widely used in gene therapy, but also play an important role in controlling the electrical properties for molecular electronics. Covalent binding, groove binding, and intercalation are all important forms of drug DNA interaction. But its applications are limited due to a lack of understanding of the electron transport mechanisms after different drug-DNA interaction modes. Here, we used a combination of density functional theory (DFT) calculations and non-equilibrium Green’s function formulation with decoherence to study the effect of drug molecules on the charge transport property of DNA under three different binding modes. Conductance of DNA is found to decrease from 2.35E-5 G0 to 1.95E-6 G0 upon doxorubicin intercalation due to modifications of the density of states in the near-HOMO region, δG = 1105.13%. Additionally, the conductance of DNA after cDPCP covalent binding increases from 1.02E-6 G0 to 5.25E-5 G0, δG = 5047.06%. While in the case of pentamidine groove binding, because there is no direct change in DNA molecular structure during drug binding, the conductance changes before and after drug binding is much smaller than the two above cases, δG = 90.43%. Our theoretical calculations suggest that the conductance of DNA can be regulated by different drug molecules or switching the interaction modes between small molecules and DNA. Which opens new possibilities for their potential applications in controllable modulation of the electron transport property of DNA.

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Based on the first-principles calculation method of density functional theory, the influence of different directions and concentrations of Sn doping on V2O5 was discussed. The doping formation energy, electronic density of states, and isosurface charge density of different Sn doping directions and doping concentration structures are calculated. The calculation results of five different crystal orientation doping models show that the doped structure along the [111] crystal orientation has a smaller doping formation energy of 1.879 eV, which has the best electrical properties and the largest charge density. And the charge distribution is the most concentrated. It is most conducive to the formation of conductive filaments. In addition, as the doping concentration increases, the charge density gradually increases. When the doping concentration is 3.174%, the peak impurity energy level is the highest and the band gap is the smallest. At the same time, there is a tendency to form conductive filaments in the direction of charge extension [111], and the resistance change characteristics of vanadium pentoxide are best improved. The research results of this paper can provide certain theoretical guidance for improving the performance of resistive random access memory based on vanadium pentoxide.