LDH enzyme release from MCF-7 and Panc-1 cells treated with Gn and SWCNT. Cells were treated with increasing concentrations of nanomaterials (1–50 μg ml−1) and concentration-dependent toxicity of these materials after 24, 48, and 72 h of exposure was determined based on the release of LDH from the cells. Data were collected from three independent experiments performed in duplicate (n = 6) and presented as mean ± SEM. Gn, graphene; LDH, lactate dehydrogenase; SWCNT, single-walled carbon nanotube.