Synthesis and characterization of bifunctional magnetic-optical Fe3O4@SiO2@Y2O3: Yb3+,Er3+ near-infrared-to-visible up-conversion nanoparticles

Bifunctional magnetic-optical Fe3O4@SiO2@Y2O3 : Yb3+, Er3+ near-infrared-to-visible up-conversion nanoparticles (UCNPs) with core-shell structures have been successfully fabricated by a facile layer-by-layer method. The presented materials were characterized by XRD, FTIR, TEM, fluorescence spectrophotometer, NMR Analyzer and SQUID MPMS. The results showed that the Fe3O4 cores were uniformly coated by SiO2 and Y2O3 : Yb3+, Er3+ layers. The amorphous silica used as the transition layer of UCNPs played an essential role in directing the structure of the composites. The inner Fe3O4 cores and the outer Y2O3 : Yb3+, Er3+ layers endow the composites with robust magnetic responsive properties and strong up-conversion fluorescent properties, which endow the nanoparticles with great potential applications in drug targeting, bioseparation and diagnostic analysis.