Fig. 3

a Effect of MSN, MWCNT, and ZnO NPs on the CHO-K1 cell line: Cytotoxicity was measured by MTT (a), WST-8 (b), LDH release assay (c), and Trypan blue uptake (d) after treatment with ZnO, MSN, and MWCNT. CHO-K1 cells were cultured in Ham's-F12 culture medium for 24 h and then treated with different concentrations of NPs for 24 h. Cell viability was found to decrease with increasing concentration. The results were represented from three independent experiments as % of cell viability (mean ± SD) versus control cells (100%). Statistical analysis was calculated by one-way ANOVA with Tukey’s posthoc test (*p < 0.05, **p < 0.01, ***p < 0.001). e Nanoparticles induced colony formation inhibition of CHO-K1 cells: CHO-K1 cells were seeded in 6-well culture plates for 3 days and exposed with MWCNT5 (5 μg/mL), MSN15 (15 μg/mL), ZnO1 (1 μg/mL) and ZnO5 (5 μg/mL) for 24 h. The medium was replaced at every 24 h time intervals. After three days of nanoparticle treatment, colony formation of CHO-K1 cells were detected by crystal violet staining. Images were captured by a phase-contrast light microscope. 20X magnification