Fig. 4. Quantitative analysis of enzymatic activity in HCT-116 cells (MTT-test) with nanoparticles in 100 μg ml^–1concentration (A); HCT-116 cell growth assessed by measurement of cell impedance; the arrow indicates the moment in which nanomaterials were added (B); flow cytometry data demonstrating the viability of RDF cells: intact RDF (C), RDF treated with kaolin (100 μg ml^–1) (D), RDF treated with GO (100 μg ml^–1) (E), and RDF treated with GO-KNPs (100 μg ml^–1) (F). The data demonstrated that addition of kaolin + graphene oxide mixture to the cells reduces the toxicity of graphene.