Electronic structure of DNA revealed

Using a technique that combines low temperature measurements and theoretical calculations, Hebrew University of Jerusalem scientists and others have revealed the electronic structure of single DNA molecules.

Knowledge of the electronic properties of DNA is an important issue in many scientific areas from biochemistry to nanotechnology, for example in the study of DNA damage by ultraviolet radiation that may cause the generation of 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 it has been suggested that DNA, or its derivatives, may become used as possible conducting molecular wires in molecular computing networks that are smaller and more efficient than those produced with silicon.

The researchers decoded the electronic structure of DNA leading to an understanding of how the electrons are distributed into the various parts of the double helix, a quest that has been pursued by scientists for many years, but was previously hindered by technical problems.

The project succeeded thanks to collaboration between experimental and theoretical scientists who worked with long and homogeneous DNA molecules at minus 195°C, using a scanning tunnelling microscope to measure the current that passes across a molecule deposited on a gold substrate.

Then, using theoretical calculations based on the solution of quantum equations, the electronic structure of DNA corresponding to the measured current was revealed.

These results suggest an identification of the parts of the double helix that contribute to the charge flow along the molecule.

The research was conducted by Errez Shapir and coordinated by Dr Danny Porath at the Department of Physical Chemistry and Center for Nanoscience and Nanotechnology at the Hebrew University and by Dr Rosa Di Felice at the S3 Center of INFM-CNR in Modena, Italy.

Also collaborating in the project were Prof Alexander Kotlyar at Tel Aviv University, who synthesised the molecules, the CINECA supercomputing centre in Italy and Prof Gianaurelio Cuniberti at the University of Regensburg, Germany.