Understanding the interactions of human follicle stimulating hormone with single-walled carbon nanotubes by molecular dynamics simulation and free energy analysis

Interactions of carbon nanotubes (CNTs) and blood proteins are of interest for nanotoxicology and nanomedicine. It is believed that the interactions of blood proteins and glycoproteins with CNTs may have important biological effects. In spite of many experimental studies of single-walled carbon nanotubes (SWCNT) and glycoproteins with different methods, little is known about the atomistic details of their association process or of structural alterations occurring in adsorbed glycoproteins. In this study, we have applied molecular dynamics simulation to investigate the interaction of follicle stimulating hormone (hFSH) with SWCNT. The aim of this work is to investigate possible mechanisms of nanotoxicity at a molecular level. We present details of the molecular dynamics, structure, and free energy of binding of hFSH on the surface of SWCNT. We find that hFSH in aqueous solution strongly adsorbs onto SWCNT via their concave surface as evidenced by high binding free energies for residues in both protein subunits. It was found that hydrophobic, π-cation, and π-π stacking interactions are the main driving forces for the adsorption of the protein at the nanotube surface.