The Ti2CO2 MXene as a nucleobase 2D sensor: A first-principles study

Abstract MXenes are a recently discovered class of two-dimensional materials, which have been attracting much interest by virtue of their promising biomedical and electronic applications. Here, we report on the results of first-principles calculations, based on density functional theory (DFT) including dispersion, of the adsorption energies and configurations of the five nucleobases, molecules conforming nucleotides in nucleic acids, such as DNA and RNA, on the oxygen-terminated titanium carbide MXene surface (Ti2CO2), chosen as a prototype MXene due to titanium being the most biocompatible transition metal. We find that physisorption is the most likely mechanism of adsorption on the Ti2CO2 (0001) basal surface, with the molecules sitting parallel to the MXene, about 2.5 A away. The calculated adsorption energies and Bader charge transfer values are moderate, as desired for sensing applications. We find a fair correlation between the adsorption energies and the van der Waals volumes of the nucleobases, hinting towards an adsorption dominated by van der Waals interactions. No structural deformation is observed on the molecules or on the surface. Thus, all of our conclusions support the potential applicability of the Ti2CO2 MXene as a suitable nucleobase sensor.