Fig. 6.

Effects of 100- or 10-nm SiO₂ NPs on intracellular GSH (micrograms GSH per milligrams protein) levels of human PBMCs (n = 4). Cells were treated with 100-nm SiO₂ NPs (2,000, 1,000, or 500 ppm) or 10-nm SiO₂ NPs (1,000, 500, or 250 ppm) for 24 h. The negative control was cells cultured in the absence of NPs; positive control was cells cultured with concanavalin A (stimulated control) and absence of NEM (no GS-NEM adduct for 8.1GSH antibody). Values reported are the mean ± SD from four separate PBMC donors and experiments. *ρ < 0.05, significant differences from the control values