Magnetic nanomaterials for biomedical applications

F. H. SÁNCHEZ; M. B. FERNÁNDEZ VAN RAAP; P. MENDOZA ZÉLIS; G. A. PASQUEVICH; S. STEWART; I. J. BRUVERA; M. E. DE SOUSA; C. LABORDE

La Plata

Conferencia; HK 2010 - Humboldt Kolleg; 2011

Physics Department - Faculty of Exact Sciences National University of La Plata

The diversity of biomedical magnetic nanomaterials (MNM) increases continuously and so their many applications do. MNM in the form of particles, rods, tubes, films, aerogels, etc., continuously find potential new uses in diagnosis, prevention, and therapy of many diseases.MNM are especially suitable for biomedical applications because their sizes are on the scale of the natural, biologic nanomachines. On the other hand, due to their large surface/volume ratio and small confinement volume they may present enhanced reactivity and quantum effects which posse new challenges to their understanding, design and fabrication. There are several promising applications of MNM in diagnosis and on site therapy. While currently artificial materials are far less sophisticated than their natural counterparts they may perform functions not existing in nature. Among these, the improvement of magnetic resonance imaging, magnetic separation, targeting delivery of drugs and genes, and localized hyperthermia therapy can be mentioned.Magnetic nanoparticles can help cell level detection of diseases and cell level therapies due to the following features: their relaxation time at body temperature in the absence of an external field is short enough as to prevent their agglomeration, they have a sufficiently strong response to moderate magnetic fields which easies their external manipulation, they can be functionalized for biocompatibility, to evade the immunological system and to deliver specific drugs, and they can be externally activated by RF fields to kill malignant cells by hyperthermia and/or by releasing chemicals. For several of these applications the materials must be designed to have preselected values of particle size and size dispersion, shape, saturation magnetization, supermoment relaxation time at body temperature, and magnetic ordering temperature.They must also be structurally and magnetically characterized in detail after each fabrication stage, in order to correlate their biomedical performance with their physical properties and determine research paths to further improve their efficiency for a given application. On the other hand DC applicators must be capable of inducing localized magnetic forces larger than the average hydrodynamic drag forces, thus retaining the particles in the treatment area, and RF applicators must provide fields with optimum amplitudes and frequencies.During this talk, besides introducing the above mentioned topics, a discussion will be presented on the expected behavior of MNM in a biological system, based on the estimation of the order of magnitude of interaction energies, forces and torques to which they are submitted due to external (applied) as well as inner fields.