Patent ID: 8828357

Claim:
Hydrophilic FeO nanoparticles which are intermediates for preparing iron oxide nano contrast agents, comprising: hydrophobic FeO nanoparticles; and a coating material which is coated on the surface of the hydrophobic FeO nanoparticles, and selected from the group consisting of polyethylene glycol-phospholipid conjugate, dextran, chitosan, dimercaptosuccinic acid and mixtures thereof, wherein the amount of the coating material is 30 to 200 weight parts with respect to 100 weight parts of the hydrophobic FeO nanoparticles, and the diameter of the hydrophilic FeO nanoparticles is 20 to 100 nm, and the iron oxide nano contrast agents comprise iron oxide (Fe 3 O 4 ) nanoparticles having 5 to 50% of interior space with respect to the total volume of the nanoparticles.