Fig. 5

Cytotoxicity of PEI-GO in MDA-MB-231 cells. Human breast carcinoma cells MDA-MB-231 were treated with 0–20 μg/ml of PEI-GO for 48 h. Cell viability was determined by WST-1 assay and quantitated spectrophotometrically by measuring the optical density at 450 nm, with a reference wavelength of 650 nm. Error bars represent standard deviations (n ≥ 3). *p < 0.05 and **p < 0.01 compared to the control