Intercalation of DNA nucleobases inside bilayer graphene and bilayer MoS₂: a comparative DFT study

The detection and discrimination of DNA bases (adenine, guanine, cytosine, and thymine) are foundational to genomics, diagnostics, and biotechnology. Two-dimensional (2D) layered materials, particularly bilayer graphene (BLG) and bilayer molybdenum disulfide (BLMoS₂), offer unique advantages for label-free DNA sensing due to their high surface sensitivity, tunable electronic properties, and ability to interact with biomolecules via non-covalent forces. In this study, we present a systematic density functional theory (DFT) investigation of the interaction between DNA bases and BLG/BLMoS₂, leveraging intercalation energy calculations, electronic band structure analysis, and topological bonding characterization. The results reveal that BLMoS₂ exhibits stronger intercalation energies with DNA bases (-1.00 to -1.02 eV) compared to BLG (-0.82 to -1.10 eV), driven by sulfur-mediated interactions alongside π-π stacking. Electronic band structure analysis shows significant band gap modulation in BLMoS₂ upon base intercalation, with shifts up to 0.5 eV, whereas BLG displays more subtle changes due to its semi-metallic nature. Topological analysis confirms non-covalent bonding in both systems, with BLMoS₂ showing higher electron density at bond critical points, indicating stronger intermolecular coupling. These findings highlight BLMoS₂ as a superior candidate for high-sensitivity DNA base detection, with implications for next-generation biosensors and DNA sequencing technologies. This focus on bilayer intercalation fills a critical gap in the literature, as no prior study has compared BLG and BLMoS₂ for nucleobase detection in the interlayer region.