AVS 51st International Symposium
    Organic Films and Devices Thursday Sessions
       Session OF+NS-ThM

Paper OF+NS-ThM11
Electrical Properties of DNA Characterized by Conducting-Atomic Force Microscopy

Thursday, November 18, 2004, 11:40 am, Room 304C

Session: Molecular Electronics
Presenter: S.R. Cohen, Weizmann Institute of Science, Israel
Authors: C. Nogues, Weizmann Institute of Science, Israel
S.R. Cohen, Weizmann Institute of Science, Israel
S. Daube, Weizmann Institute of Science, Israel
R. Naaman, Weizmann Institute of Science, Israel
Correspondent: Click to Email
DNA has been widely promoted as the key component of future molecular devices, due to its unique assembly and recognition properties. Specifically, the strong interaction between complementary base-pair sequences on interacting DNA strands can be utilized to self-assemble a desired structure in a molecular circuit. The most basic building blocks of such circuits can be formed through the hybridization of two single strands into a double one, and the specific binding of functionalized DNA strands to gold electrodes using the chemical thiol-gold linkage. Such manipulations can exploit the ease in which DNA strands can be synthesized, and modified chemically. Despite these advantages, the electrical properties of individual strands of DNA have yet to be reproducibly characterized, due to the inherent difficulties in reliably accessing and measuring single molecules. We have attacked this problem by developing protocols for reproducible formation and characterization of DNA monolayers, and then probing their electrical functioning using conducting atomic force microscopy (cAFM). The electrical contact to the DNA was made by chemical binding to a gold electrode on one end, and to a gold nanoparticle on the other. Thus, repeatable measurements of the conductivity of individual DNA strands have been performed. Meaningful differences could be detected between conductivity in single- and double-strand DNA. The single strand DNA was found to be insulating over the range of -2 to +2 V, while the double strand DNA passes significant current outside a 3 eV gap.