In this paper, we studied the guanine, adenine, thymine, and cytosine as based DNA nucleotides adsorption over Zinc oxide decorated on graphene sheet (ZnO-GS). The stability, the adsorption mechanism, density of states (DOS) and the change of electrical conductivity properties are investigated. All calculations were performed on the basis of Density Functional Theory using Quantum espresso package and BoltzTrap code. The results of the studies showed that ZnO-GS nanostructure as compared with GS has high potential for DNA detection. The energy for adsorption of G, A, T and C on ZnO-GS was 1.70, 1.58, 1.46 and 1.43 eV, respectively (G>A>T>C). The energy of DNA adsorption on ZnO-GS was calculated to be 50 % higher than the graphene. The results of the electrical conductivity change also indicate that the change in electrical conductivity for ZnO-GS occurs in the range from −0.1 eV to +0.1 eV, which is more than twice the conductivity change due to the adsorption of DNA on GS. As a result, the ZnO-GS nanostructure can be used as an electrical biosensor to detect DNA by changing electrical conductivity property. On this basis, it can be concluded that the electrical conductivity is created in ZnO due to the adsorption of DNA by ZnO-GS and strengthens electron transfer by GS, which is also the result of the energy adsorption calculations. Therefore, the ZnO-GS nanostructure, as compared with GS, transmits more current in less time between DNA and electrode surface. This change in behavior is consistent with the results reported by experimental studies.
