Theoretical study on enhancement of DNA conductivity by copper modification of mismatched base pairs

Abstract

DNA is a potential material for nanodevices. Metallization is a promising way to improve its conductivity. Two copper modified mismatched base pairs were designed by H-by-Cu replacement. The conductivities of these base pairs were studied by density functional theory (DFT) combined with nonequilibrium Green's function (NEGF) method. Energy levels of copper modified mismatched base pairs were firstly compared with those of mismatched base pairs. The results show that HOMO-LUMO gaps are narrowed significantly by copper modification. This change indicates that the modification can enhance electronic properties of the studied systems. Then longitudinal charge transport properties of DNA fragments composed by repeating multilayers of base pairs were investigated with the measurable conductivity indices. The results prove that conductivities of the copper modified mismatched DNA can be significantly improved compared with those of the unmodified. More importantly, the mechanism of the enhancement of H-by-Cu replacement was revealed. This work may provide some theoretical supports for designs of DNA-based nanodevices.