The physics behind magnetic hyperthermia

M.B. FERNÁNDEZ VAN RAAP; F.H. SÁNCHEZ; G. PASQUEVICH; P. MENDOZA ZELIS; S. STEWART; E. DE SOUSA ; I. BRUVERA; P. GIRARDIN

La Plata

Conferencia; HK2010; 2011

The physics behind magnetic hyperthermia Fernández van Raap M. B.1, Sánchez F.H.1, Pasquevich G. A.1, Mendoza Zélis P.1, Stewart S.1, de Sousa E. L.1, Bruvera I.1, Laborde C.1, Girardin P1 1IFLP-CONICET, CCT-La Plata and Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C. C. 67, 1900 La Plata, Argentina Magnetic nanoparticles (MNP) are multifunctional objects which show growing interest in biomedical applications for both diagnosis and therapy. Due to their nanometric size they can interact with living cells and can be internalized. The MNPs locate in intracellular membrane bound vesicles known as endosomes. Localization at the nanoscale is clearly seen by electron microscopy. Once internalized, the functionality of these magnetic agents is exported into the cells. The MNP magnetic moment acts as a mediator and allows non invasive long distance manipulation. In fact, they are used as agents for various strategies like: enhancement in magnetic resonant imaging, selective cell separation, drug delivery and local heat dissipation. In the latter, named magnetic hyperthermia, temperature increase is achieved when the MNP is subjected to an alternating magnetic field in the radio frequency range. The heating power is governed by the mechanisms of magnetic energy dissipation for single-domain particles (Brown and Néel relaxations) and is highly sensitive to MNP properties like size, magnetic anisotropy, and saturation magnetization; to solvent viscosity, and to the magnetic field frequency f and amplitude H0. The MNP power lost can be improved increasing both f and H0, but this rise is limited by physiological issues i.e there is a maximum value of the product f H0 to which human bodies can be exposed without discomfort. MNP are subjected to other restrictions aside to biocompatibility and toxicity. Even local hyperthermia offers numerous advantages as a novel cancer therapy; however, it requires for small tumours a remarkably high heating power of more than 1 kWg−1 for heat agents. In the present talk the current state of knowledge in nanoparticle properties, their internalization and magnetic intracellular hyperthermia in discussed. Keywords: magnetic hyperthermia, magnetic nanoparticles, cellular magnetic labelling. Email: raap@fisica.unlp.edu.ar