Hard corona composition and cellular toxicities of the graphene sheets.

Graphene nanomaterials are recognized as one of the most promising nanomaterials because of their unique and highly attractive physicochemical properties (e.g., thermal conductivity, superlative mechanical strength, and ultrahigh surface-to-volume ratios). It is well established that when nanomaterials interact with biological medium, biomolecules and in particular proteins attach to their surfaces, which form a complex between surface of nanoparticles and proteins called corona. Thus, the interaction of the biological system with the nanomaterials depends on the composition of the protein layer, rather than the surface characteristics of the nanomaterials itself. Although there is a significant increase of interest in the application of graphene in medical science, there has been a little attention to the nanotoxicological aspects of these newly developed materials. For this reason, we aimed to investigate whether the effect of the interactions between graphene-sheets with various human plasma concentrations (i.e. both in vitro (cells/tissues) and in vivo simulating states) is toxic. The results showed that by increasing the human plasma concentration, the affinity of proteins with low molecular weights to graphene-sheets surface is significantly increased. Fluorescence microscopy of Hela and Panc-1 cell lines showed a reduction of nuclei number and an increase of reactive oxygen species (ROS) production respectively after a longer incubation of graphene-sheets with plasma proteins. ROS production was higher in Panc-1 cell line, when used as protein source for graphene-sheets than HeLa cell line.