p-Type Sensing of DNA Nucleobases Adsorbed on Graphene Nanoribbon

DNA nucleobases are important in DNA sequencing, disease testing linked to genes, and disease treatment. Here, we report density functional calculations investigating the adsorption of guanine (G), adenine (A), thymine (T), and cytosine (C) on armchair graphene nanoribbons (AGNR). Their mechanical stability, adsorption energies, charge transfer, work function, and electrical properties were calculated. The adsorption strength and charge transfer demonstrate a physisorption mechanism for the nucleobases on AGNR. The adsorption strength between -0.58 and -0.73 eV has a hierarchy of G > A > T > C. Although the energy gap remained unchanged, the variations in the density of states of the nucleobases correspond with the concentration of electronegative atoms present in the nucleobases. The sensitivity of AGNR to the nucleobases is differentiated by the degree of hybridization of the p-orbitals shown in the density of states. The changes in the work function illustrate a p-type sensing mechanism that correlates with the charge transfer mechanism from the substrate to the nucleobases, emphasizing the capability of AGNR in sensing DNA nucleobases.