Table 2.

Antioxidant activities of cerium oxide nanoparticles

S No	Size of CeNPs	Type of CeNPs	Type of cell	Type of free radical	Mechanism of Action	Reference
1	40 nm	Levan coated	NIH3T3 (mouse fibroblast cells)	Hydrogen peroxide	Inhibition of H2O2 induced ROS	Kim and Chung (2016)
2	20 nm	Bare	Endothelial cells	Hydrogen peroxide	Inhibition of ROS by mimicking SOD and catalase enzymes	Chen et al. (2013)
3	3–5 nm	Bare	Adult rat spinal cord cells	Hydrogen peroxide	Neuroprotection to rat spinal cord neurons by scavenging ROS during redox switching	Das et al. (2007)
4	3–5 nm	Bare	CRL 1541 (human colon cells)	Superoxide free radical	Protection from cell damage (caused by radiation) by improving the generation of SOD 2	Colon et al. (2010)
5	~1.88 nm	Bare	WRL-68 (human liver cells)	Hydrogen peroxide	Protection from oxidative stress induced by 3-AT	Singh and Singh (2019)
6	48 nm	Bare	WRL-68 (human liver cells)	Hydrogen peroxide	Protection from oxidative stress induced by 3-AT	Yadav and Singh (2021c)
7	< 25 nm	Bare	BEAS-2B (human epithelial lung cells)	Superoxide free radical	Protection from KBrO3 induced oxidative stress by scavenging ROS	Rubio et al. (2016)
8	4 nm	Dextran coated	Cardiomyocytes and human dermal fibroblasts	Hydrogen peroxide	Protection from H2O2 induced oxidative stress	Perez et al. (2008)
9	30 nm	Bare	Brain tissues of rats	Superoxide free radical	Protection against Paraquat induced neuronal oxidative stress and apoptosis	Ranjbar et al. (2018)
10	5–8 nm	Bare	Cardiac progenitor cells	Hydrogen peroxide	Protection against H2O2 induced oxidative stress	Pagliari et al. (2012)
11	5–80 nm	Bare	Neuron-like PC12 cells	Superoxide free radical	Neuroprotection to cells by regulating the genes involved in cellular defense	Ciofani et al. (2014)
12	>5 nm	Gelatin coated	Neuron-like SH-SY5Y cells	Hydrogen peroxide	Protection to cells by neurite development and alignment	Marino et al. (2017)

Types of free radicals scavenged and mechanism of ROS scavenging by CeNPs are summarized in the table