Table 2.

Oxidative stress caused by NPs in different cells and tissues.

type of NPs	size	experimental target	effects	ref.
Fe2O3	50 nm	human hepatoma Hep G2 cells	concentration-dependent increase of intracellular ROS generation after 12 and 24 h of exposure	[98]
SO-Fe3O	44 nm	human lung adenocarcinoma epithelial cell	significant ROS level in cells for the 24 h treatment interval	[99]
ZnO (rod-shape)	15.38 ± 1.47 nm (width); 82.34 ± 14.23 nm (length)	mouse skin epidermal normal cells	time-dependent ROS generation after treatment for 24, 48 and 72 h	[100]
CdS QDs	5–10 nm	mussel hemocytes, mussel gill cells	in hemocytes: increased ROS production with 5 mg Cd/L; in gill cells ROS production was induced with 1.25 mg Cd/L showing time-dependent behavior	[101]
Si/SiO2 QDs	3–4 nm	human fetal lung fibroblast cell line	increase of ROS due to the exposure of Si/SiO2 QDs	[102]