Hopes that DNA might be useful as a molecular wire are ill-founded, according to research by Northwestern University and Argonne National Laboratory scientists, published today in Science magazine.
Some researchers, most notably at Columbia University and the California Institute of Technology, had offered the theory that duplex DNA might transport electrons over long distanced, functioning as molecular wire. If true, the approach would not only be useful in microelectronic devices, but would also have ramifications for biological electron transfer.
However, the Northwestern-Argonne research shows that DNA does carry electrons, but doesn't carry them very far, and certainly not far enough to make it useful for microelectronic devices.
"What we've learned is that DNA is a molecular material with no special conductive properties," said Frederick D. Lewis, chemistry professor at Northwestern and leader of the research team. The researchers prepared synthetic strands of DNA, the genetic material of all cells, and excited the strands with a laser to initiate the electron transfer. "We learned that the DNA would accept the electron, but that the rate of electron transfer falls off very quickly with distance," Lewis said.
Lewis and his colleagues joined with Michael R. Wasielewski and his colleagues at Argonne for the research project. Wasielewski, who also is a member of the Northwestern chemistry faculty, has been studying electron transfer in living materials for several years.
Northwestern, a major private university, is located in Evanston, Ill. Argonne is operated by the University of Chicago as a part of the U.S. Department of Energy's National Laboratory System.