Magnetic Nanoparticles for Biomedical Heating Applications

Abstract

Summary: In the past, magnetic nanoparticles have found increasing interest in different biomedical applications, e.g. the magnetic hyperthermia of tumor cells or the remote controlled drug delivery to the gut. These applications are based on a magnetically induced heating effect caused by different magnetic loss mechanisms in the nanoparticles. To advance the present state of the art of these methods, it is important to use particles with a higher specific heating power (SHP) at lower magnetic field amplitudes. To this aim, several iron oxide nanoparticle powders, consisting of particles in the diameter range from 10 nm up to 100 nm, were prepared by two different chemical methods and magnetically as well as morphologically characterized. The magnetic characterization was done by using a vibrating sample magnetometer and the calorimetrical determination of SHP. The dependence of the magnetic losses on the morphological properties was investigated. Magnetic characterization showed that several suitable iron oxide absorbers can be utilized. With decreasing particle size, hysteresis loss underestimates SHP at higher frequencies as measured calorimetrically. The effect of measurement frequency on the hysteresis losses is shown experimentally. Experimental results are discussed in the frame of known theoretical models of nanoparticle magnetism.