Actin reorganization through dynamic interactions with single-wall carbon nanotubes.

Single-wall carbon nanotubes (SWCNTs) have been widely used for biological applications in recent years, and thus, it is critical to understand how these inert nanomaterials influence cell behavior. Recently, it has been observed that cellular phenotypes such as proliferation, force generation and growth change upon SWCNT treatment, and SWCNTs directly affect the organization and redistribution of the actin cytoskeleton. However, the interactions between SWCNTs and actin at the molecular level or how this interaction changes actin structure remain largely unknown. Here, we investigated direct interaction of actin with SWCNT using all-atom molecular dynamics simulations and NIR spectroscopy of actin-dispersed SWCNTs. Actin can stably bind to the SWCNT surfaces via hydrophobic interactions but still allows nanotubes to slide and rotate on the actin surface. Our results establish several nanoscale conformational changes for the actin-SWCNT complexes, and we suggest these changes likely induce reorganization of actin filaments observed at larger scales.