Biodistribution of co-exposure to multi-walled carbon nanotubes and graphene oxide nanoplatelets radiotracers

Technetium-99 (Tc-99m) was used as an isotope tracer to study the biodistribution of oxidized multi-walled carbon nanotubes (oMWCNTs) and/or graphene oxide nanoplatelets (GONP) after intravenous administration (i.v.). The authors also investigated the histological impact of non-radiolabeled oMWCNT or GONP as they passed through systemic circulation and their excretion pathways in comparison to co-exposure groups of both (oMWCNTs and GONP). Results indicated that oMWCNTs were mainly excreted through feces rather than urine. From the blood, oMWCNTs first entered the stomach, then intestines via chyme, and were finally excreted in feces. GONP also followed this pathway, but could also be excreted through urine when co-exposed with oMWCNTs. In summary, the biodistribution patterns and excretion rates of the nanomaterials in vivo depended on their composition and chemical modifications. A new mechanism is proposed to explain how chemical modification groups affect the behavior of nanomaterials in vivo. The behavior and fate of GONP depended strongly on oMWCNTs in mice in vivo, but the GONP did not affect deeply biodistribution and excretion pattern of oMWCNTs in co-exposure.