Robust Denaturation of Villin Headpiece by MoS2 Nanosheet: Potential Molecular Origin of the Nanotoxicity

MoS 2 nanosheet, a new two-dimensional transition metal dichalcogenides nanomaterial, has attracted significant attentions lately due to many potential promising biomedical applications. Meanwhile, there is also a growing concern on its biocompatibility, with little known on its interactions with various biomolecules such as proteins. In this study, we use all-atom molecular dynamics simulations to investigate the interaction of a MoS 2 nanosheet with Villin Headpiece (HP35), a model protein widely used in protein folding studies. We find that MoS 2 exhibits robust denaturing capability to HP35, with its secondary structures severely destroyed within hundreds of nanosecond simulations. Both aromatic and basic residues are critical for the protein anchoring onto MoS 2 surface, which then triggers the successive protein unfolding process. The main driving force behind the adsorption process is the dispersion interaction between protein and MoS 2 monolayer. Moreover, water molecules at the interface between some key hydrophobic residues (e.g. Trp-64) and MoS 2 surface also help to accelerate the process driven by nanoscale drying, which provides a strong hydrophobic force. These findings might have shed new light on the potential nanotoxicity of MoS 2 to proteins with atomic details, which should be helpful in guiding future biomedical applications of MoS 2 with its nanotoxicity mitigated.