Synthesis of iron oxide nanocubes and their incorporation with luminescent lanthanide (Ln = Tb/ Eu)-Terephthalate complex in silica nanospheres using a reverse microemulsion method

Luminescent magnetic nanocomposites are of interest because of their promising applications in the biomedical field. This article reports the preparation of silica-coated lanthanide terephthalate complexes, Ln-TA (Ln = Tb and Eu) containing luminescent magnetic nanocomposites. Cubic-shaped iron oxide nanoparticles were synthesized through the thermal decomposition of the iron-oleate complex. Then, polymerization of tetraethyl ortho silicate in a water-in-oil reverse microemulsion in the presence of previously prepared iron oxide nanocubes and a terbium (Tb3+)/europium (Eu3+)-terephthalate (TA) complex was performed to obtain luminescent magnetic Fe3O4@Ln-TA (Ln = Tb, Eu)/SiO2 nanocomposites. The size (8.9 nm) and cubic shape of magnetic core were determined via transmission electron microscopy and the superparamagnetic behavior using a vibrating sample magnetometer. Energy dispersive X-ray analysis and inductively coupled plasma optical emission spectroscopy found that the luminescent Tb-TA and Eu-TA complexes were incorporated in the magnetic silica nanocomposites. The nanocomposites, Fe3O4@Ln-TA/SiO2, exhibited distinct luminescent green and red emission peaks and showed promise as a T1 contrast agent for magnetic resonance imaging.