A combined nonequilibrium Green's function/density-functional theory study of electrical conducting properties of artificial DNA duplexes

DNA duplexes have attracted much attention as a primary candidate for nanowires possessing self-organizing capability. To employ DNA duplexes as nanowires, however, a major drawback must be overcome; the guanine bases undergo oxidative degradation in a hole transport through DNA duplexes, which is likely caused by the presence of adjoining adenine bases that do not effectively mediate the charge transport through DNA duplexes. To overcome the drawback, several artificial nucleobases based on adenine have been designed and tested, confirming that the artificial nucleobase-containing DNA duplexes do not suffer from such an oxidative damage and exhibit high efficiency in hole transport through the DNA duplexes. In the present study, we examine the electrical conducting properties of these artificial DNA duplexes by use of nonequilibrium Green's function and density-functional theory methods. The results explicate the origin of the experimentally observed high conductivity through the DNA duplexes containing the artificial DNA bases. We also put forth a computer-aided design of novel artificial DNA bases with low ionization energies, and examine the electrical conductivity of the DNA duplexes containing the designer nucleobases for potential use as highly conductive nanowires. (C) 2011 Elsevier B.V. All rights reserved.