Table 6.

Ligands used in the surface coating of cerium oxide nanoparticles

S. No	Ligand for surface coating	Nature of ligand	Type of interaction	Changes after surface coating	Reference
1	Dextran	Polymer	Physical adsorption	Improvement in the oxidase-like activity of CeNPs	Asati et al. (2009b)
2	Polyacrylic acid and polyethylene glycol	Polymer	Electrostatic interaction and Covalent binding	No impact on the SOD-, increase in peroxidase- and decrease in catalase and oxidase-like activity	Baldim et al. (2020)
3	Dextran	Polymer	Physical adsorption	Improvement in stability and antibacterial property of CeNPs	Shah et al. (2012)
4	Citric acid	Carboxylic acid	Electrostatic interaction	Improvement in the dissolution of CeNPs in an acidic environment	Yokel et al. (2019)
5	Triethyl phosphine and 2,4,6 trimethoxyphenyl) phosphine	Organophosphorus	Electrostatic interaction	Reversal of enzymatic activities	Patel et al. (2018)
6	Phosphotungstic acid and phosphomolybdic acid	Polyoxometalates	Electrostatic interaction	Improvement in the catalase, SOD, and peroxidase-like in presence of PTA, whereas SOD-like activity got compromised after interaction with PMA	Yadav and Singh (2021b)
7	Gold	Inorganic material	Electrostatic deposition	Improved antibacterial and anticancer properties of CeNPs	Babu et al. (2014)
8	6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy} bi-hexyl)triethoxysilane	Silanes	Hydrogen bonding (siloxane binding)	Improved angiogenic properties of CeNPs	Nethi et al. (2017)
9	Brevinin-2R	Peptide	Covalent binding (peptide bond)	Improved anticancer activities of CeNPs	Homayouni-Tabrizi et al. (2016)
10	Anti HER-2	Antibody	Covalent binding	Improved anticancer activities of CeNPs	Hartati et al. (2020)

The nature of ligand, type of interaction among CeNPs and ligands, and the changes induced after surface coating are summarized in the table