The electronic structure of individual DNA molecules in cells has been revealed for the first time by Hebrew University and Tel Aviv University researchers along with collaborators in Italy and Germany. The discovery, made possible by a technique that combines low-temperature measurements and theoretical calculations, has important applications to medicine and industry. Knowing the electronic properties of the genetic code of DNA molecules is an important issue in many scientific areas from biochemistry to nanotechnology, including study of the damage caused to DNA by ultraviolet radiation from the sun that may cause the production of oxygen free radicals and genetic mutations. In those cases, DNA repair occurs spontaneously via an electronic charge transfer along the DNA helix that restores the damaged molecular bonds. In nano-bioelectronics, which is the study of biological molecules (to produce electrical nanocircuits, for example), it has been suggested that DNA or its derivatives might be used for conducting molecular wires. This could lead to molecular computing networks smaller and more efficient than those produced today with silicon technology. The knowledge that has been acquired in this project, say the researchers, may also be relevant for attempts to develop sophisticated, reliable, faster and cheaper ways to decode the sequence of human DNA. The research was published in the prestigious journal Nature Materials and headed by Errez Shapir; coordinated by Dr. Danny Porath at HU's department of physical chemistry and center for nanoscience and nanotechnology; and joined by Dr. Rosa Di Felice at the S3 Center of INFM-CNR in Modena; TAU Prof. Alexander Kotlyar, who synthesized the molecules; the CINECA supercomputing center in Italy; and Prof. Gianaurelio Cuniberti at the University of Regensburg. The researchers were able to decode the electronic structure of DNA and understand how the electrons distribute into the various parts of the double helix, a result that has been pursued by scientists for many years but was previously hindered by technical problems. The success of this project was finally achieved by the collaboration of experimental and theoretical scientists who worked with long and homogeneous DNA molecules at minus 195 degrees Celsius, using a scanning tunneling microscope to measure the current that passes across a molecule deposited on a gold substrate. Then, by means of theoretical calculations based on quantum equations, the electronic structure of DNA corresponding to the measured current has been obtained.