Graphene: Insights on Biological, Radiochemical and Ecotoxicological Aspects

Graphene, including graphene quantum dots, its oxide and unoxidized forms (pure graphene) have several properties, like fluorescence, electrical conductivity, theoretical surface area, low toxicity, and high biocompatibility. In this study, we evaluated genotoxicity (in silico analysis using the functional density theory-FDT), cytotoxicity (human glioblastoma cell line), in vivo pharmacokinetics, in vivo impact on microcirculation and cell internalization assay. It was also radiolabeled with lutetium 177 (177Lu), a beta emitter radioisotope to explore its therapeutic use as nanodrug. Finally, the impact of its disposal in the environment was analyzed using ecotoxicological evaluation. FDT analysis demonstrated that graphene can construct covalent and non-covalent bonds with different nucleobases, and graphene oxide is responsible for generation of reactive oxygen species (ROS), corroborating its genotoxicity. On the other hand, non-cytotoxic effect on glioblastoma cells could be demonstrated. The pharmacokinetics analysis showed high plasmatic concentration and clearance. Topical application of 0.1 and 1 mg/kg of graphene nanoparticles on the hamster skinfold preparation did not show inflammatory effect. The cell internalization assay showed that 1-hour post contact with cells, graphene can cross the plasmatic membrane and accumulate in the cytoplasm. Radio labeling with 177Lu is possible and its use as therapeutic nanosystem is viable. Finally, the ecotoxicity analysis showed that A. silina exposed to graphene showed pronounced uptake and absorption in the nauplii gut and formation of ROS. The data obtained showed that although being formed exclusively of carbon and carbon-oxygen, graphene and graphene oxide respectively generate somewhat contradictory results and more studies should be performed to certify the safety use of this nanoplatform.