Synthesis, surface modification/decoration of luminescent-magnetic core/shell nanomaterials, based on the lanthanide doped fluorides (Fe3O4/SiO2/NH2/PAA/LnF3)

The synthesized magnetite nanoparticles (10-15 nm) were successfully coated with amine modified silica nanoshell, which led to the formation of core/shell type nanostructures (30-50 nm). The as-prepared nanoparticles were surface modified with polyacrylic acid (PAA) via electrostatic interactions of -NH2 and -COOH groups. Afterwards, the surface PAA molecules acted as complexing agents of the introduced lanthanide (Ln3+) ions. Subsequently, the as-prepared nanostructures were surface decorated with luminescent LnF3 nanoparticles, forming Eu3+ or Tb3+ doped Fe3O4/SiO2/NH2/PAA/LnF3 nanomaterials (50-100 nm). The obtained luminescent-magnetic products exhibited simultaneously bright red or green emission under UV lamp irradiation (λex=254 nm), and a response for the applied magnetic field (strong magnet attracts the colloidal particles, dispersed in aqueous medium). After the synthesis, properties of the nanomaterials were investigated by powder X-ray diffraction (XRD) technique, transmission electron microscopy (TEM), infrared spectroscopy (IR) and spectrofluorometry (analysis of excitation/emission spectra and luminescence decay curves). Such advanced nanomaterials can be potentially used in multimodal imaging, targeted therapies and as multifunctional contrast agents, novel luminescent-magnetic tracers, protection of documents, etc.