Probing the adsorption behavior and free energy landscape of single-stranded DNA oligonucleotides on single-layer MoS2with molecular dynamics.

Interfacing single-stranded DNA (ssDNA) with 2D transition metal dichalcogenides are important for numerous technological advancements. However, the molecular mechanism of this process, including the nature of intermolecular association and conformational details of the self-assembled hybrids is still not well understood. Here, atomistic Molecular Dynamics (MD) simulation is employed to study the distinct adsorption behavior of ssDNA on a single-layer MoS2 in aqueous environment. The ssDNA sequences [T10, G10, A10, C10, U10, (GT)5, and (AC)5] are chosen on the basis that short ssDNA segments can undergo a spontaneous conformational change upon adsorption and allow efficient sampling of the conformational landscape. Differences in hybridization is attributed to the inherent molecular recognition ability of the bases. While the binding appears to be primarily driven by energetically favorable van der Waals π-stacking interactions, equilibrium structures are modulated by the ssDNA conformational changes. The poly-purines demonstrate two concurrently competing π-stacking interactions: nucleobase-nucleobase (intramolecular) and nucleobase-MoS2 (intermolecular). The poly-pyrimidines, on the other hand, reveal enhanced π-stacking interactions, thereby maximizing the number of contacts. The results provide new molecular-level understanding of ssDNA adsorption on the MoS2 surface and facilitate future studies in design of functional DNA/MoS2 structure-based platforms for DNA sequencing, biosensing (optical, electrochemical, and electronic), and drug delivery.