A comparative study on the application of single-layer MoS2 and WS2 for probing methylated and mutated nucleobases: a vdW-DFT study†

Abstract Low-cost, swift and reliable DNA sequencing, if achieved, is expected to set the stage for accessible personal medicine and there is an ongoing quest to leverage two-dimensional (2D) materials for the realization of single-molecule-precision DNA sequencing. Towards this, in the present work, we report a comparative van der Waals density functional theory (vdW-DFT) investigation on the adsorption characteristics of one mutated, two methylated, and four canonical DNA nucleobases on single-layer molybdenum disulfide (SL-MoS2) and tungsten disulfide (SL-WS2) substrates. Our findings show that all of the considered nucleobases are physisorbed with negligible electron transfer, in the range of 0.007|e| to 0.041|e| (0.004|e| to 0.032|e|) for SL-MoS2 (SL-WS2), from the adsorbate to the substrate. We demonstrate that, compared to SL-WS2, nucleobase adsorption tends to decrease the work function of SL-MoS2 more drastically which may pave the way for electronic detection of the nucleobases. It is also observed that upon adsorption, the bandgap value of SL-MoS2 (SL-WS2) shrinks by as much as 49% (30%). It is found that nucleobase adsorption gives rise to the emergence of distinct electron energy loss spectra, thereby pointing to the potential offered by the complementary and concurrent application of SL-MoS2 and SL-WS2 to identify both canonical and modified DNA nucleobases.