Direct conductance measurement of individual metallo-DNA duplexes within single-molecule break junctions.

DNA, as the product of million years of evolution, possesses the maximal density of functionalities embedded in its framework and superior sequence-specific self-assembly properties that make it a useful scaffold for the organization of molecules into higher-order nanostructures for the development of functional nanoscale devices and materials. In this context, one major effort is to transform DNA into a conductive material that would make a significant contribution to the development of the vibrant field of DNA-based molecular electronics. It turns out that unmodified DNA lacks sufficient electrical conductance, thus making it unsuitable for application in nanoelectronics. To address this issue, a fascinating alternative solution of recent years is to exchange some or all of the Watson–Crick base pairs in DNA by metal complexes in a programmable fashion pioneered by Shionoya, Schultz, Carell, M ller, and others. The combination of DNA and functional metal complexes can introduce significant advantages for both the metals and the DNA structures, thus representing an important step for their potential application as nanomagnets, as self-assembling molecular wires, or as catalysts in chemical reactions. With a focus on DNA-based molecular electronics, it is currently urgent to unambiguously characterize the electrical conductance of these metal-containing DNA strands. Herein we demonstrate the first direct charge transport (CT) measurement of individual metallo-DNA duplexes using singlemolecule break junctions (Figure 1). These findings provide a foundation for DNA-based hybrid materials as conductive biocompatible bridges that may interface electronic circuits with biological systems.