[en] In this work, the preparation, characterization and implications of magnetic nanocomposites for possible biomedical applications were studied. The investigated materials were magnetite nanoparticles (Fe₃O₄), common (I₂) and ¹³¹I) iodine. Two different types of nanocomposites were synthesized: one radioactive, composed of pure magnetite nanoparticles and radioactive iodine (Fe₃O₄+ ¹³¹I); and another nonradioactive, composed of pure magnetite nanoparticles and common iodine (Fe₃O₄+I₂). The samples were analyzed by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, Raman Confocal spectroscopy, ultraviolet/visible light spectroscopy, X-ray dispersive energy spectroscopy, Fourier transform infrared spectroscopy and MTT cell viability test [bromide of 3- [4,5-dimethyl-thiazol-2il] - 2,5 diphenyltetrazolium]. Scanning electron microscopy studies have been identified the presence of iodine together the magnetite nanoparticles, indicating the need for more washes to minimize residual iodine. The results of the X-ray diffraction showed that the found peaks correspond to magnetite (Fe₃O₄). The vibration sample magnetometry measurements indicated that magnetization curves vs magnetic field, in the (Fe₃O₄+I₂) nanocomposite, obey a superparamagnetic behavior. In parallel, among the spectroscopies used in this work, only the X-ray dispersive energy identified the presence of iodine on the surface of magnetite nanoparticles (Fe₃O₄). In addition, the MTT cell viability test showed higher cytotoxicity to the common iodine applied alone and non-observance of high toxicity in the other nanocomposites, due to low concentrations, however among the nanocomposites, that with the radioactive iodine showed lower absorbance in 72 h. Considering the obtained results during the investigation, it can be affirmed that the analyzed materials, alone or forming nanocomposites, have excellent properties for technological applications, mainly in the obtaining of multifunctional devices applied to the biological field. (author)