Non-polymer coated Fe3O4 aqueous dispersion with NH3+-surface modification as new magnetite nanoparticles and their biomedical applications

Well-dispersed Fe₃O₄ nanoparticles were synthesized using chemical coprecipitation and the addition of organic acid as adherent in an aqueous solution. The resulting iron oxide particles were manipulated as small as 6 nm diameter in size. The nanoparticles exhibit cationic surface mostly decorated with terminal -NH₃⁺. The in vitro cytotoxicity test revealed excellent biocompatibility to further explore for their potential in vivo applications. NMR measurements showed significantly reduced water proton relaxation times T₁ and T₂. The MR images of the nanoparticles in water and serum were then investigated using 1.5 T clinical MR imager.