Computational Study on the Interaction of Modified Nucleobases with Graphene and Doped Graphenes

The interaction between graphene-based nanomaterials and modified nucleobases (MBs) is important in the development and design of new biosensors. The adsorption of MBs on the surface of graphene (G), boron-doped graphene (BG), nitrogen-doped graphene (NG), and silicon-doped graphene (SiG) has been investigated using electronic structure calculations and associated analysis methods. It is found from the calculations that the MBs stack with the surface of G, BG, NG, and SiG models and that the pi-pi stacking interaction plays a dominant role in the stabilization of the intermolecular complexes. The stability of MBs on the surface of SiG is the highest when compared to that of G, BG, and NG models. The highest interaction energies of MBs with SiG is due to the presence of Si center dot center dot center dot O(N) and pi-pi stacking interactions. The theory of atoms in molecules (AIM) analysis indicates that Si center dot center dot center dot O(N) interaction has both electrostatic and covalent characters. The calculation of charge transfer by employing the natural bond orbital method showed the donor nature of MBs. It is also found that the variations in the density of states and highest occupied molecular orbital-lowest unoccupied molecular orbital gap of SiG occur upon adsorption of MBs. These results illustrate that SiG can act as a sensor for the detection of MBs.