Flake size-dependent cyto and genotoxic evaluation of graphene oxide on in vitro A549, CaCo2 and vero cell lines

This study was carried out by varying both graphene oxide (GO) concentration (10 μg/mL, 50 μg/mL, 100 μg/mL) and flakes sizes of 1320 nm and 130 nm. Characterization by scanning electron microscopy and Raman spectroscopy demonstrate that the area of GO flakes varies of one order of magnitude but their chemical structure remains unmodified. A 24-h cytotoxicity test showed, for A549, a loss in the viability, while the test exhibits overall a positive increase in the viability for CaCo2 and Vero. A 24-h comet assay shows a marked GO genotoxicity: for micrometer-sized GO flakes the genotoxicity is in positive correlation with the concentration, while for nanometer-sized GO flakes there was a high degree of genotoxicity at the lowest concentration tested.