Fabrication of a multifunctional magnetic-fluorescent material for medical applications

Abstract

Multifunctional biocompatible materials have evoked considerable interest in the field of medical applications. Here we report the thermal decomposition preparation of homogeneous fluorescent-magnetic particles with a composite structure containing CoFe₂O₄ nanoparticles as nucleation seeds for fluorescent Gd_2−xO₃:Eu_x. The composite exhibited a wide range of fluorescence transitions in the whole visible spectrum, displaying 18 different emission peaks when excited at a 250 nm wavelength. Moreover, at low temperature the peaks of the composite were wider than the peaks of the fluorescent material, which may be attributed to a set of new energy levels due to a combination of Stark splitting with the magnetic field of CoFe₂O₄. Because this material is intended to be used for biomedical applications, the potential toxicity of the composite was tested using an invertebrate hemocyte cell model. The cells showed slight morphological and biochemical changes upon exposure to the composite; however, there was no increase in cell death at concentrations of up to 40 ppm. In addition, the material could be tracked by its fluorescence inside the cells, when excited at a more bio-friendly and less energetic wavelength of 405 nm. Furthermore, MRI showed T₁ and T₂ dual contrast with relaxivity values in the range of most reported materials.