Figure 2.

Effects of graphene, SWCNTs, and MWCNTs on mitochondrial toxicity of PC-12 cells. Cells were treated with different concentrations of CNMs for 24 hours. At the end of the incubation period, the WST-8 assay was performed to evaluate the cytotoxicity as described in Section 2. Data were expressed as mean ± standard deviation (SD) based on at least duplicate observations from three independent experiments. The letter “a” indicates statistically significant difference from the untreated control; the letter “b” indicates statistically significant difference from cells treated with graphene at the same concentration (P < 0.05).