Abstract:Magnetic nanoparticles are important tools in tumor imaging and therapy. However, low therapeutic concentration of the nanoparticles at the tumor sites has limited their clinical applications. Active targeting employs magnetic nanoparticles conjugated to specific ligands that selectively bind to biomarkers on target cells. Several receptor systems are overexpressed in cancerous diseases and have been investigated as targets for ligand-directed magnetic nanoparticles. The target receptors undergo repeated recycling between the cell surface and internalization, and bind to magnetic nanoparticles, thereby amplifying the magnetic signal for more precise diagnosis and treatment. This paper summarizes the recent advances in the development of active targeted magnetic iron oxide nanoparticles for tumor imaging and therapy. Magnetic nanoparticles with an alternating magnetic field can convert electromagnetic energy into heat and confine the heat to the tumor tissue. Magnetic fluid hyperthermia is a promising approach to cancer therapy because it not only directly kills cancer cells, but also indirectly activates anticancer immunity. Modifying the surface of magnetic nanoparticles to target specific molecules could improve their intracellular accumulation and their ability to target on tumor cells, and thus enhance their hyperthermia effects.