Investigation of Charge Transport Along the DNA Double Helix

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This experimental condensed matter physics program will investigate the temperature and frequency dependent transport properties and charge excitation spectra of the various modifications of the DNA double helix. The method employed - the measurement of the electric loss at micro and millimeter wave frequencies - allows the determination of the conductivity and dielectric constant without applying electrical contacts, and will be used in combination of optical studies. The DNA modifications to be investigated include synthetic DNA oligomers with tailor-made base pair sequences, together with native DNA duplexes; the influence of various counter ions, buffer environment and denaturing will also be studied. The experiments will shed light on the electronic and ionic charge transport process along the double helix, will lead to information concerning the role of disorder, molecular fluctuations and interactions between the electrons and will thus distinguish between the different models which have been proposed. These studies will also lay the groundwork for the investigation of electronic effects associated with biological processes, such as radiation induced defects and repair.%%%DNA is an important biological molecule whose function and properties in connection with genetic phenomena are well known. Less studied are its fundamental physical properties, for example electronic processes such as charge migration, which may be related to oxidation processes and radiation-caused damage and repair mechanisms. This experimental condensed matter physics program will study the motion of electronic and ionic charges on the DNA double helix by conducting experiments at radio frequency, microwave and optical frequencies. Such experiments should determine whether DNA is a nanoscale conductor or semiconductor and help clarify electronic mechanisms of possible biological significance. In the long term the techniques to be developed to study charge migration may also be useful as diagnostic tools for the detection of molecular properties related to genetic events.