Electrospinning fabrication and characterization of magnetic-upconversion fluorescent bifunctional core-shell nanofibers

摘要

Novel magnetic-upconversion fluorescent bifunctional core-shell nanofibers have been successfully fabricated by coaxial electrospinning technology. NaYF_4:Yb~(3+),Er~(3+) and Fe_3O_4 nanoparticles (Nps) were incorporated into polyvinylpyrrolidone (PVP) and electrospun into core-shell nanofibers with Fe_3O_4/ PVP as core and NaYF_4:Yb~(3+),Er~(3+)/PVP as the shell. The morphology and properties of the final products were investigated in detail by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, and fluorescence spectroscopy. The core contained magnetic Nps was ca. 100 nm in diameter, and the shell scattered with NaYF_4:Yb~(3+), Er~(3+) Nps was ca. 80 nm in thickness. Fluorescence emission peaks of Er~(3+) in the [Fe_3O_4/PVP]@[NaYF_4:Yb~(3+),Er~(3+)/PVP] core-shell nanofibers were observed. Compared with Fe_3O_4/ NaYF_4:Yb~(3+),Er~(3+)/PVP composite nanofibers, the luminescent intensity of the [Fe_3O_4/PVP]@[NaYF_4:Yb~(3+),Er~(3+)/PVP] core-shell nanofibers was much higher, because the Fe_3O_4 Nps were only distributed in the core of the core-shell nanofibers, thus the manufactured core-shell nanofibers possessed excellent magnetic properties. The new type magnetic-upconversion fluorescent bifunctional [Fe_3O_4/PVP]@[NaYF_4:Yb~(3+),Er~(3+)/PVP] core-shell nanofibers have many potential applications in display device, nanorobots, protein determination, and target delivery of drug owing to their excellent magnetism and fluorescence.