Absolute Mag™ Amine Iron Oxide Nanoparticles, lipid surface, which have a lipid coating and amine groups on their surface, are water soluble iron oxide nanoparticles. Their organic layers have about 1-2 nm thickness and near neutral zeta potential. Their hydrodynamic size using a Zeta Trac (DLS) is about 3-8 nm larger than the inorganic core size measured with TEM. The amine groups on the surface can be used in conjugations with different molecules. And the coating physiological lipid makes excellent compatibility for in vivo studies. Absolute Mag™ Amine Iron Oxide Nanoparticles(lipid surface) are stable and resistant in general biocompatible buffers like borate, Tris, HEPES, PBS and MES buffers, as well as in cell culture medium. Also, these iron oxide nanoparticles are autoclavable.