Figure 9
Cytotoxicity of PEI-NH-SWNTs and PEI-NH-MWNTs compared to PEI. Human cervical cancer cells HeLa-S3 were treated with 0 to 100 μg/ml of PEI-NH-SWNTs, PEI-NH-MWNTs, or pure PEI for 48 h. Cell viability was determined by MTT assay and expressed as the percentage of the optical density at 570 nm of treated cells relative to control cells. Error bars represent standard deviations (n ≥ 3). Statistical significance was observed at all concentrations of PEI-NH-SWNTs, PEI-NH-MWNTs, or pure PEI compared to the control (0 μg/ml).