Electrical characterization of self-assembled single- and double-stranded DNA monolayers using conductive AFM

Hezy Cohen, Claude Nogues, Daniela Ullien, Shirley Daube, Ron Naaman, Danny Porath*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

We recently reported electrical transport measurements through double-stranded (ds)DNA molecules that are embedded in a self-assembled monolayer of single-stranded (ss)DNA and attached to a metal substrate and to a gold nanoparticle (GNP) on opposite ends. The measured current flowing through the dsDNA amounts to 220 nA at 2 V. In the present report we compare electrical transport through an ssDNA monolayer and dsDNA monolayers with and without upper thiol end-groups. The measurements are done with a conductive atomic force microscope (AFM) using various techniques. We find that the ssDNA monolayer is unable to transport current. The dsDNA monolayer without thiols in the upper end can transport low current on rare occasions and the dsDNA monolayer with thiols on both ends can transport significant current but with a much lower reliability and reproducibility than the GNP-connected dsDNA. These results reconfirm the ability of dsDNA to transport electrical current under the appropriate conditions, demonstrate the efficiency of an ssDNA monolayer as an insulating layer, and emphasize the crucial role of an efficient charge injection through covalent bonding for electrical transport in single dsDNA molecules.

Original languageAmerican English
Pages (from-to)367-376
Number of pages10
JournalFaraday Discussions
Volume131
DOIs
StatePublished - 2006

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