Present status and prospects of magnetite nanoparticles-based hyperthermia

Magnetic fluid hyperthermia is a cancer treatment technique that utilizes the heat dissipated by magnetic nanoparticles exposed to an alternating current magnetic field. The heat dissipated is consequence of the conversion of the magnetic energy through different relaxation mechanisms, which depends on the physical properties of the magnetic particles. Particularly, in the case of magnetic nanoparticles, the magnetic energy is converted to heat energy either by the resistive response of the rotation of the magnetic particles (Brownian relaxation) or the rotation of the magnetic moment within the particles (Neel relaxation) to the alternating magnetic field. In this article, the main focus has been on the progress of theoretical and experimental investigations towards the realization of magnetic fluid hyperthermia (MFH) through heat dissipation by Neel relaxation of magnetite particles. We discuss about the present status and prospects of magnetite nanoparticles-based hyperthermia focusing mainly on the dissipation of heat through Neel relaxation mechanism. In doing so, an attempt has been made to review and deepen the understanding on specific topics such as (a) specific heat absorption characteristics of magnetite, especially the physical properties of particles that generate heat through Neel relaxation, (b) the preparation techniques available to synthesize particles with required properties, (c) experimental investigations carried out to determine the relative contribution of Neel relaxation to dissipate heat and their potential for in vivo application, and (d) the theoretical estimation of and experimental verification of heat diffusion characteristics of magnetite. The theoretical and experimental studies have suggested that the development of case specific treatment technologies based on an integrated approach considering both the physical constraints of the magnetic particles to be used as thermal seeds and practically feasible alternating magnetic field generators is a must for the establishment of MFH therapy in the foreseeable future. (C) 2010 The Ceramic Society of Japan All rights reserved