▎ 摘　　要

Graphene quantum dots (GQDs) have been of high interest due to their size and optical characteristics, which improves when functional groups are added to their borders and defects. In this work, the in vitro toxicity of aqueous dispersion of GQDs (w/wo amino-functionalization) was investigated in two different cellular models (S. cerevisiae and H9c2 cell line). Results in yeast suggest that when at up to 25 % volume concentration, the effect of all tested GQDs was only inhibitory, and, in both cellular models, the toxic effect is rigorously dose-dependent. The comparison of IC50 values of all the tested GQDs reveals no significant variations among them, pointing to non-carbonized citric acid as the more toxic precursor. The obtained data suggest that functionalization makes GQDs less toxic, being the one functionalized with thioacetamide slightly more toxic, followed by the ones functionalized with thiourea and glutathione, respectively. Results confirm that their toxicity is characteristics as a whole, and not as the sum of the toxicity of the precursors. In both models, concentrations up to 2 % showed no significant toxicity. Finally, fluorescence microscopy images suggest that GQDs interact with the cellular membrane and enter in the cell, manifesting fluorescent properties.