Sequence Dependence of Charge Transport Properties of DNA

• Published in: The journal of physical chemistry. B Vol. 110; no. 18; pp. 8910 - 8913
• Main Authors: Nogues, C, Cohen, S. R, Daube, S, Apter, N, Naaman, R
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.05.2006
• Subjects: Base Composition; Base Sequence; Cytosine - chemistry; DNA - chemistry; DNA, Single-Stranded - chemistry; Electric Conductivity; Gold - chemistry; Guanine - chemistry; Metal Nanoparticles - chemistry; Microscopy, Atomic Force; Molecular Sequence Data
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp060870o

The electrical conduction through three short oligomers (26 base pairs, 8 nm long) with differing numbers of GC base pairs was measured. One strand is poly(A)−poly(T), which is entirely devoid of GC base pairs. Of the two additional strands, one contains 8 and the other 14 GC base pairs. The oligomers were adsorbed on a gold substrate on one side and to a gold nanoparticle on the other side. Conducting atomic force microscope was used for obtaining the current versus voltage curves. We found that in all cases the DNA behaves as a wide band-gap semiconductor, with width depending on the number of GC base pairs. As this number increases, the band-gap narrows. For applied voltages exceeding the band-gap, the current density rises dramatically. The rise becomes sharper with increasing number of GC base pairs, reaching more than 1 nA/nm2 for the oligomer containing 14 GC pairs.