Intermolecular driving forces on the adsorption of DNA/RNA nucleobases to graphene and phosphorene: An atomistic perspective from DFT calculations

Abstract

Graphene and phosphorene show a strong affinity towards DNA/RNA nucleobases, serving as promising materials to be integrated as part of bioinorganic interfaces for either self-assembly, sensing, or sequencing of DNA/RNA constituents. Here, the intermolecular driving forces determining the adsorption of DNA/RNA nucleobases and base-pairs onto graphene and phosphorene are studied with density functional theory (DFT) calculations in the gas phase and solution with a polarizable continuum model (PCM). The formed complexes are studied through binding analyses (adsorption energy, AIM, IGM), charge transfer, and energy decomposition analyses based on absolutely localized molecular orbitals (ALMO-EDA). It is found that nucleobases are adsorbed with similar stability onto graphene and phosphorene in stacked patterns. Electrostatics and dispersion effects are the primary stabilizing intermolecular forces, standing for ~85% of the stabilizing energy. Dispersion is higher than electrostatic effects for nucleobase-Graphene complexes; conversely, nucleobase-Phosphorene complexes show a greater contribution from electrostatics to the stability. Moreover, solvent effects lead to energy destabilization of complexes with respect to the gas phase due to the relative difference in the solute-solvent polarity of the components, which are higher for those complexes stabilized by electrostatic forces. Consequently, the adsorption on phosphorene is more destabilized than graphene in aqueous solution; while, dispersion/electrostatic effects turn almost balanced for nucleobase-Phosphorene complexes in solution as a result of the decrease in the magnitude of electrostatic interactions. Otherwise, an extra energy lowering is reached by adsorption with phosphorene due to the high adsorbent polarizability and its response upon nucleobase adsorption; nevertheless, Pauli repulsion compensates all the stabilizing effects due to the larger electron density of the phosphorene surface compared to graphene. Finally, physical effects along the dissociation path reveal the dominant factors on the stabilization of the nucleobase-Graphene(Phosphorene) complexes during the entire adsorption process.