Binding of blood proteins to carbon nanotubes reduces cytotoxicity

TLDR

With the growing use of nanoparticles in biomedical applications, the potential nanotoxicity of carbon nanotubes underscores the importance of studying nanoparticle‑protein interactions. The study aims to investigate how single‑wall carbon nanotubes bind human serum proteins and how such binding influences cytotoxicity. The authors employed atomic force microscopy, fluorescence spectroscopy, circular dichroism, SDS‑PAGE, and molecular dynamics simulations to characterize protein adsorption on SWCNTs. π‑π stacking with aromatic residues determines adsorption capacity, and protein‑coated SWCNTs exhibit markedly reduced cytotoxicity in monocytic leukemia and endothelial cells, informing safer nanotube design.

Abstract

With the potential wide uses of nanoparticles such as carbon nanotubes in biomedical applications, and the growing concerns of nanotoxicity of these engineered nanoparticles, the importance of nanoparticle-protein interactions cannot be stressed enough. In this study, we use both experimental and theoretical approaches, including atomic force microscope images, fluorescence spectroscopy, CD, SDS-PAGE, and molecular dynamics simulations, to investigate the interactions of single-wall carbon nanotubes (SWCNTs) with human serum proteins, and find a competitive binding of these proteins with different adsorption capacity and packing modes. The π-π stacking interactions between SWCNTs and aromatic residues (Trp, Phe, Tyr) are found to play a critical role in determining their adsorption capacity. Additional cellular cytotoxicity assays, with human acute monocytic leukemia cell line and human umbilical vein endothelial cells, reveal that the competitive bindings of blood proteins on the SWCNT surface can greatly alter their cellular interaction pathways and result in much reduced cytotoxicity for these protein-coated SWCNTs, according to their respective adsorption capacity. These findings have shed light toward the design of safe carbon nanotube nanomaterials by comprehensive preconsideration of their interactions with human serum proteins.