Methylation Detection and DNA Sequencing Based on Adsorption of Nucleobases on Silicene Nanoribbon

Nanodevices based on two-dimensional materials hold great promise for DNA sequencing. Owing to some unique properties, silicene has become a potential alternative to the well-known graphene as a sequencing material. Recently, the recognition of DNA methylation has garnered great attention, since methylated nucleobases are indicated as biomarkers of various forms of cancers. In this work, we investigated the interactions of eight nucleobases (adenine, guanine, thymine, cytosine, 5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine) with a zigzag silicene nanoribbon. The stabilities of adsorption geometries and electronic properties of nucleobases attached on a silicene nanoribbon surface were examined using density functional theory (DFT) with a van der Waals dispersion correction. The results reveal that adenine is physisorbed on the surface of the silicene nanoribbon, while the other seven nucleobases are weakly chemisorbed. Moreover, the charge transport properties of nucleobase-silicene complexes were analyzed by DFT combined with the nonequilibrium Green's function. The adsorption effects of the different nucleobases on the charge transport properties of silicene nanoribbon were clarified by the transmission spectra and density of states. According to the obtained current-voltage characteristics, one electrical detection strategy for methylation and DNA sequencing was proposed. We deduced that it is possible to differentiate between all eight nucleobases using electrical signals at distinct applied bias voltages of 0.5 and 1.0 V. Our results indicate that silicene can serve as a potential candidate for exploring methylation discrimination in addition to DNA sequencing.