Evolution of Magnetic Nanoparticles: From Imaging to Therapy
As was described earlier, iron oxide nanoparticles are one of the few nanomaterials that have been utilized clinically. is is due to the numerous advantageous properties possessed by this class of nanoparticles, including superparamagnetism, the ability to alter the relaxation rates of adjacent water molecules, and, depending on the surface properties and sizes of the particles, extended blood half-lives. For the most part, they are also biocompatible. Biodegradation of the iron oxide core is assumed to occur within the macrophages of the RES, where the elemental iron is incorporated into the iron pool of the body. is was demonstrated in rats, where 20% of the iron from particles synthesized utilizing iron-59 was found within hemoglobin within 14 days of intravenous administration (Weissleder et al. 1989), which is similar to the biodegradation of radiolabeled ferritin (Hershko et al. 1973). Of course,
overall biocompatibility is based on a number of factors, each of which may alter the toxicity of the nanoagents.