Probing DNA nucleobases with diamond (111) surfaces

Abstract

DNA units, the nucleobases, are probed with diamond (111) surfaces. The nucleobases are placed on top of a diamond surface interacting in a very specific way with the surface atoms. Different elements, such as hydrogen, nitrogen, and fluorine are chosen for the termination of the diamond. The energetic features and electronic properties of the combined system 'nucleobase/diamond surface' are thoroughly studied using quantum-mechanical calculations. These point to nucleobase-and termination-specific characteristics linking to the potential of using diamond surfaces for identifying the DNA nucleobases. Focus is further given on mixed surfaces with a varying nitrogen and hydrogen coverage. For these, we provide pathways for tuning the electronic band gap of the surface/nucleobase complex with the nitrogen content of the surface. The results could unravel a clear crossover in the surface electron affinity and its relation to a reversal in the positions of the electronic band extremes from the material to the molecule and vice versa. These features link to a further selective modulation of the electronic transport and the excitation properties of the complexes with a strong biosensing potential.