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

Abstract

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.