Fig. 7. Effect of the protein corona on nanodiamond cytotoxicity. (a) Metabolic activity of cells exposed to nanodiamonds in the complete medium. (b, d and e) Bright field images of cells before and after exposure to aminated (ANDs) and pristine nanodiamonds (PNDs) with and without coronas (BSA and FN) under serum-free conditions (scale bar 200 μm). (c) Metabolic activity of cells exposed to nanodiamonds with BSA and FN9-10 coronas under serum-free conditions. (f) Metabolic activity of cells exposed to BSA and FN9-10; (*p < 0.05, ****p < 0.001, two-way ANOVA test). (g) Bright field images of cells exposed to BSA and FN.