Magnetic nanoparticles present some attractive applications in biomedicine. First, they can be prepared from a size ranging from a few nanometers up to hundreds of nanometers, which places the particles at dimensions that are smaller than or comparable to those of cells (10–100 μm), virus (20–450 nm), proteins (5–50 nm) and genes (2 nm wide and 10–100 nm long). As a consequence they can “get close” to these biological entities. Furthermore, when coated with appropriate molecules magnetic nanoparticles can interact or bind to biological entities, which provides a mean of actuating on these entities by noncontact magnetic forces. This ‘action at a distance’, combined with the intrinsic penetrability of magnetic fields into biological tissues, possibilities a number of biomedical applications of magnetic nanoparticles.In this seminar, a revision of the state of the art in the fields of synthesis, properties and biomedical applications of magnetic nanoparticles is presented. This seminar is organized as it follows:1. Chemistry of iron oxides and oxo-hydroxides: Diversity of methods to prepare colloidal nanoparticles, either in non aqueous solvents: hydrothermal synthesis, polyol synthesis, thermal decomposition… or in water: co-precipitation of iron salts2. Magnetic behavior: ferro- /ferri- /antiferro- /superpara– magnetism, magnetophoresis (magnetic guiding)3. Optical properties: UV-vis absorption, circular dichroism (Faraday rotation), magnetic birefringence4. Relaxivity properties (T1/T2 of H spins): Contrast agents in MRI5. Magnetic relaxations in radiofrequency (kHz-MHz) fields: Magnetic hyperthermia and RF-induced drug release< Leer menos