Magnetic nanomaterials for biomedical applications

F. H. SÁNCHEZ; M.B. FERNÁNDEZ VAN RAAP; P. MENDOZA ZÉLIS; G.A. PASQUEVICH; S. STEWART; S. JACOBO; J. APHESTEGUY; A.G. LEYVA; C.A. ALBORNOZ

Manizales

Workshop; IX Latin American Workshop on Magnetism, Magnetic Materials and Their Applications; 2010

Universidad Nacional de Colombia in Manizales

The diversity of biomedical magnetic nanomaterials (MNM) increases continuously and sotheir 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 manydiseases.MNM are especially suitable for biomedical applications because their sizes are on thescale of the natural, biologic nanomachines. On the other hand, due to their largesurface/volume ratio and small confinement volume they may present enhanced reactivityand quantum effects which posse new challenges to their understanding, design andfabrication. There are several promising applications of MNM in diagnosis and on sitetherapy. While currently artificial materials are far less sophisticated than their naturalcounterparts they may perform functions not existing in nature. Among these, theimprovement of magnetic resonance imaging, magnetic separation, targeting delivery ofdrugs and localized hyperthermia therapy can be mentioned. Magnetic nanoparticles canhelp 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 enoughas to prevent their agglomeration, they have a sufficiently strong response to moderatemagnetic fields which easies their external manipulation, they can be functionalized forbiocompatibility, to evade the immunological system and to deliver specific drugs, and theycan be externally activated by RF fields to kill malignant cells by hyperthermia and/or byreleasing chemicals. For several of these applications the materials must be designed tohave preselected 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 eachfabrication stage, in order to correlate their biomedical performance with their physicalproperties. On the other hand DC applicators must be capable of inducing localizedmagnetic forces larger than the average hydrodynamic drag forces, thus retaining theparticles in the treatment area, and RF applicators must provide fields with optimumamplitudes and frequencies.During this talk, examples of structural and magnetic studies of MNM in the form of cubicdoped magnetite particles, spherical manganese perovskite particles with tailored Curietemperature, and magnetic aerogels, will be discussed. Accounts of the power dissipationability under RF fields of ferrofluids made out of these nanoparticles, will be alsopresented.