Electronic Properties of DNA Nucleosides Adsorbed on a Au(100) Surface

Abstract

The geometrical properties and electronic structure of single DNA nucleosides (deoxyadenosine, deoxythymidine, deoxyguanosine, deoxycytidine) adsorbed on a metallic surface of Au(100) are determined using density functional theory computations. We investigate multiple adsorption geometries and the resulting molecule–surface interaction mechanisms. For adenosine, we found negligible differences between the binding energy in the two configurations investigated by us, while for guanosine this difference reaches the maximum value among the four nucleosides (i.e., 0.38 eV). The projected density of states indicates that the physisorption is the main cause of the binding energy. Nevertheless, for the adsorbed deoxycytosine (dC), we point out the presence of the chemical interaction too. While the absolute values of the molecule–surface charge transfer are small, they are qualitatively dependent on the orientation of the nucleosides to the surface. If the DNA bases are oriented perpendicular to the surface, the electronic population of molecules decreases, while the parallel orientation of the DNA bases with respect to metal surface leads to an increase of electronic population on the molecules.