Table 1.

Green synthesis methods of CeO₂-NPs

Method of green synthesis	Applied material/organism	Particle size (nm)	Morphology of NPs	Critical point of view	Reference
Plant-mediated synthesis	Gloriosa superba	5	Spherical	Different kinds of alkaloids acted as stabilizing agents	33
Plant-mediated synthesis	Acalypha indica	36	Spherical	Agglomeration of particles were observed due to covalent bonding of the individual particles	34
Plant-mediated synthesis	Aloe vera	63.6	Spherical		35
Fungus-mediated synthesis	Curvularia lunata	5–20	Spherical	Enzymes, proteins and heterocyclic derivatives could act as reducing and capping agent	37
Nutrient-mediated synthesis	EW protein	8.2, 11.7 and 17.3	Spherical	Being soluble and foam-like in water, EW has several proteins acting as stabilizing agents	47
Nutrient-mediated synthesis	Honey	23	Spherical	Follow-up the sol–gel method	48
Biopolymer-mediated synthesis	Agarose	10.5	Spherical	Follow-up the sol–gel method	51
Biopolymer-mediated synthesis	Starch	6	Spherical	Providing ultrafine product	27
Biopolymer-mediated synthesis	Gum	10	Spherical		27
Biopolymer-mediated synthesis	Dextran	5	Spherical	pH-dependent response	57
Biopolymer-mediated synthesis	Polyethylene glycol	~2	Spherical	Providing a framework for designing a hybrid metal oxide sol	58
Biopolymer-mediated synthesis	Chitosan	~10	Spherical	Applicable in food borne mycoplasma detection	61

Abbreviations: EW, egg white; NPs, nanoparticles.