Toxicological evaluation of highly water dispersible few-layer graphene in vivo

In the last decade, graphene-based materials have received increasing attention for both academic research and industrial uses. However, products containing graphene must meet the same standards for quality, safety and efficacy as products not containing nanomaterials. Our aim is to shed light on the toxicological characterization of few-layer graphene (FLG) dispersions. In the present study, graphene was easily dispersed in water using biocompatible riboflavin-5′-phosphate sodium salt (Rib). A highly concentrated FLG dispersion (G-Rib) was stable for months. G-Rib sheets presented an average lateral size of about 840 nm and an average thickness of 5 layers. Our results showed that even at high concentration of G-Rib, cell survival was always above 85%. Then, we investigated the tissue distribution and toxic effects of G-Rib in mice up to 30 days after intravenous injections. Histological analysis of the tissues revealed hepatic accumulation and excretion through the kidneys. The biochemical and hematological parameters remained within the reference range showing no hematotoxicity. Finally, no signs of inflammation were detected in the cells isolated from the lymph nodes and spleen. The results of the study show that highly water dispersed FLG is a material with a very low toxic profile, which is one of the first requirements for the future development of biomedical applications.