Transmission electron microscopy (TEM) of A, maghemite (Fe2O3) nanoparticles coated with anionic DMSA forming ~ 8-nm-thick round-shaped AMNPs. B, magnetite (Fe3O4) of ~8-nm-think core coated with ~2-nm-thick gold (Au), forming core-shell nanoparticles. C, magnification x 50 of B. (D). Silica coated Fe3O4 nanoparticles of ~ 100 nm, synthesized by sol gel method.