Table 2 Comparison of important synthetic methods used of MIONPs

Co-precipitation

3–100 nm with broad distribution

Spherical

Affordable, rapid and can be easily scaled up to larger scale

High polydispersity index

and controlling shape and size of NPs is challenging

20–50

Microemulsion and reverse microemulsions

4–15 nm with narrow distribution

Spherical or cubic

Desired size of the nanoparticles can be obtained by adjusting the aqueous core droplet size

Difficult to remove surfactants and only small amounts can be synthesized

> 30

Sonochemical

20–80 nm with broad distribution

Spherical

Use of fewer reagents and minimal purification steps

Highly specific experimental device required

20–85

Polyol

10–50 nm with narrow distribution

Cubic

Easy to control the size and shape of the

nanoparticles

High-temperature required

50–80

Thermal decomposition

6–80 nm with broad distribution

Spherical

Ability to synthesize highly crystalline MIONPs in the presence of surfactants

High temperature is required for producing nanoparticles

65

Hydrothermal

2–40 nm with narrow distribution

Spherical or cubic

The particle size can be controlled easily by regulating the rate of nucleation and grain growth

High temperature and pressure are required

56–72