Synthesis of Fe3O4@Gd2O3:Tb3+@SiOx multifunctional nanoparticles and their luminescent, magnetic and hyperthermia properties.

Multifunctional Fe3O4@Gd2O3:Tb3+@SiOx nanoparticles were successfully synthesized by co-precipitation and polyol methods. The synthesized nanoparticles were composed by cubic phase as core of Fe3O4 and Gd2O3:Tb3+ and the shell of amorphous SiOx. The composites exhibited a spherical shape with a diameter of 10-15 nm and highly uniform dispersion. They showed not only excellent fluorescence under excitation at a wavelength of 278 nm, but also strong magnetic responsiveness (MS = 24.040 emu g-1). The results of magnetic resonance imaging in vitro (r1 = 6.00 mm-1 s-1, r2 = 63.95 mm-1 s-1) showed that the samples could be used as T1-positive and T2-negative contrast agents. In addition, it was found that Fe3O4@Gd2O3:Tb3+@SiOx attains hyperthermia temperature (43 °C) in 90 s under the alternating current magnetic field, and their specific absorption rate (229.9 w g-1) was higher than that of Fe3O4 (183.92 w g-1). Hence, the multifunctional nanoparticle could be used for the diagnosis and therapy of cancer.