Superparamagnetic iron oxide (Fe3O4, magnetite) nanoparticles are one of the most widely studied nanomaterials today. They are colloidally stable as there is no net magnetic moment and magnetic coupling between particles. However, the intrinsic ferromagnetic character of the materials leads to the high magnetic moment of these nanoparticles.

Applications include medical diagnostics, catalysis, probing agents to indirectly study the structure of mixed SAMs, solid phase extraction, anode materials for Li-ion batteries, and electromagnetic interference (EMI) shielding materials.

Nanodiagnostics iron oxide nanocrystals are available in both water soluble and non-polar solvent soluble formats and with 5 nm, 10 nm, and 20 nm diameters.