Table 2.

Different coating and doping materials for iron oxide nanoparticles

S no	Coating and doping materials	Advantages	Disadvantages	References
Polymer coatings over iron oxide
1	Poly (D,L-lactide)	Enhanced biocompatibility	Usually very unstable (affected with varying pH and temperature); agglomeration and adherence property (causing toxic and immunogenic effects); inside body system, hydrodynamic flow retards its movement (mostly dissolved in body fluids and degradation due to enzyme activity)	13, 14
2	Polyacrylic acid	Improves bioadhesion		15, 16
3	Phosphorylcholine	Initiates coagulation		17
4	Polyvinyl pyrrolidone	Improves functionalization		18
5	Polyvinyl alcohol	Increases monodisperse particle formation		19–22
6	Polyethylene glycol	Improves biocompatibility		23, 24
7	Dextran	Biocompatible, controlling particle size and shapes		25, 26
8	Polystyrene	Uniform cluster formation, controlling particle size and shapes		27
9	Starch	Biocompatible, coating material		28, 29
10	Ethyl cellulose	Enhances drug uptake, good functional property		30, 31
11	Gelatin	Natural, biocompatible		32–34
12	Chitosan	Natural, biocompatible		35
13	Fatty acids	Terminal group functionalization, biocatalyst		36, 37
14	Bovine serum albumin	Biocompatible		38
15	Folic acid	Targets cancer cells, less immunogenic		39
16	Insulin	Improves gene therapy		40
17	Liposome	Long circulatory time in body system		41
Metal and metal oxide coatings over iron oxide
1	Gold	Enhances optical properties and stabilization	Toxic effects, fabrication difficulties, and cost associated with its synthesis	42, 43
2	Silver	Enhances optical properties and antimicrobial activity		44
3	Platinum	Enhances optical and electrochemical properties		45
4	Zinc	Enhances magnetic property		46
5	SiO2	Increases surface area and binding affinity	Increases oxidative stress and agglomerates	47, 48
6	TiO2	Photocatalytic activity	Nonbiological application only	49
7	Calcium phosphate coating	Biocompatible, osteoconductive	Difficult to control coating layer thickness	50
8	Hydroxyapatite	Biocompatible, stable, osteoconductive	Difficult to control coating layer thickness	65–107