11. Magnetic Nanoparticle-Based Hyperthermia for Cancer Treatment: Factors Affecting Heat Generation Efficiency

Hyperthermic treatment of cancer by magnetic nanoparticles has shown promising results in recent years. Magnetic nanoparticles in the form of stable fluids can be transported to the effected cells noninvasively through a variety of drug delivery routes. Upon stimulation by a radio frequency magnetic field, these nanoparticles induce local heat remotely, which causes the temperature in organs and tissues containing tumoral cells to rise and causes the death of infected cells. The heat generation mainly results from three independent physical mechanisms, Néel relaxation, Brownian relaxation, and hysteresis loss. The involvement of each mechanism firmly depends on the crystal size, crystal structure, morphology, and degree of aggregation of the nanoparticles. Nanostructures based on iron oxide and its relevant ferrites, such as cobalt ferrite and nickel ferrite, in a range of a few nanometers, showing superparamagnetic properties have been investigated extensively for magnetic hyperthermia. This chapter will cover different aspects of magnetic hyperthermia from a material science point of view, including mechanisms, materials, crystal size, shape, the effect of architecture on heat generation efficiency, and practical procedures to measure the therapeutic properties of fluidic nanoparticles preinjection.