Interaction of modified nucleic bases with graphene and doped graphenes: a DFT study

In order to design biosensors, it is quite necessary to have an insight upon the nature of interaction between the modified nucleic bases (MNBs) and carbonaceous materials. This study is focussed upon the interaction of the various doped graphene models like graphene (GR), aluminium doped graphene (AlG), sulphur doped graphene (SG), nickel doped graphene (NiG), chromium doped graphene (CrG) and germanium doped graphene (GeG) with MNBs (caffeine, hypoxanthine, uric acid and xanthine) by employing the electronic structure calculations and the associated methodology. All the geometries considered in this study (MNBs and graphene models) were initially optimized at M06-2X/6-31+G** basis set without any constraints followed by the single point energy calculation at three different and well established methods using the Gaussian 09 software package. A detailed comparison of the interaction energy is accomplished in this study. The interaction energy values were further corrected for the basis set superposition error. The theory of atoms in molecules analysis is also performed in detail, which showcases the bond critical points, Laplacian and various other parameters of interest. The variation of frontier molecular orbitals, i.e., highest occupied molecular orbital–lowest unoccupied molecular orbital gap for different models of graphene have been discussed in detail upon the adsorption of MNBs. Among the doped graphene models, the graphene model doped with Cr seems to be more suitable for the application of sensors, also it is found that the MNBs interact primarily via $$\pi $$ – $$\pi $$ interaction. The results highlight that the CrG can act as a sensor for the detection of MNBs.