Superparamagnetic iron oxide nanoparticles have received great attention owing to their potential applications as contest agents for magnetic resonance imaging (MRI).Through the thermal decomposition approach high quality magnetic iron oxide nanocrystals can facilely be obtained.Nevertheless, acids, alcohols, and amines bearing long hydrophobic chain are commonly adopted as stabilizing agents.Consequently the direct products of the thermal decomposition syntheses are typically hydrophobic.Only through further surface engineering, they become usable as MRI contrast agents.