Moderate binding of villin headpiece protein to CN nanosheet reveals the suitable biocompatibility of this nanomaterial.

Since its recent successful synthesis and due to its promising physical and chemical properties, the carbon nitrite nanomaterial, CN, has attracted considerable attention in various scientific areas. However, thus far, little effort has been devoted to investigating the structural influence of the direct interaction of this 2D nanomaterial and biomolecules, including proteins and biomembranes so as to understand the physical origin of its bio-effect, particularly from the molecular landscape. Such information is fundamental to correlate to the potential nanotoxicology of the CN nanomaterial. In this work, we explored the potential structural influence of a CN nanosheet on the prototypical globular protein, villin headpiece (HP35) using all-atom molecular dynamics (MD) simulations. We found that HP35 could maintain its native conformations upon adsorption onto the CN nanosheet regardless of the diversity in the binding sites, implying the potential advantage of CN in protecting the biomolecular structure. The adsorption was mediated primarily by vdW interactions. Moreover, once adsorbed on the CN surface, HP35 remains relatively fixed on the nanostructure without a distinct lateral translation, which may aid in keeping the structural integrity of the protein. In addition, the porous topological structure of CN and the special water layer present on the CN holes conjointly contributed to the restricted motion of HP35 via the formation of a high free energy barrier and a steric hindrance to prevent the surface displacement. This work revealed for the first time the potential influence of the 2D CN nanomaterial in the protein structure and provided the corresponding in-depth molecular-level mechanism, which is valuable for future applications of CN in bionanomedicine.