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

Abstract

Novel magnetic-upconversion fluorescent bifunctional core–shell nanofibers have been successfully fabricated by coaxial electrospinning technology. NaYF₄:Yb³⁺,Er³⁺ and Fe₃O₄ nanoparticles (Nps) were incorporated into polyvinylpyrrolidone (PVP) and electrospun into core–shell nanofibers with Fe₃O₄/PVP as core and NaYF₄:Yb³⁺,Er³⁺/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 NaYF₄:Yb³⁺, Er³⁺ Nps was ca. 80 nm in thickness. Fluorescence emission peaks of Er³⁺ in the [Fe₃O₄/PVP]@[NaYF₄:Yb³⁺,Er³⁺/PVP] core–shell nanofibers were observed. Compared with Fe₃O₄/NaYF₄:Yb³⁺,Er³⁺/PVP composite nanofibers, the luminescent intensity of the [Fe₃O₄/PVP]@[NaYF₄:Yb³⁺,Er³⁺/PVP] core–shell nanofibers was much higher, because the Fe₃O₄ 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 [Fe₃O₄/PVP]@[NaYF₄:Yb³⁺,Er³⁺/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.

Graphical Abstract

A novel magnetic-upconversion fluorescent bifunctional core-shell nanofibers are fabricated by coaxial electrospinning technique. Because the Fe₃O₄ nanoparticles are only distributed in the core of the core-shell nanofibers, they barely decrease the fluorescent emission intensity of the core-shell nanofibers, and strong upconversion fluorescent of the magnetic-upconversion coaxial nanofibers can be achieved.