High-efficient fabrication of core-shell-shell structured SiO2@GdPO4:Tb@SiO2 nanoparticles with improved luminescence.

He Bai,Jinrong Bao,Xueyuan Guo,Mingyuan Wang,Ying Liu,Wenxian Li,Yan Qiao,Xiaowei Zhu,Yunjiang Yang,Anping Wu

doi:10.1098/rsos.192235

Abstract

SiO2@GdPO4:Tb@SiO2 nanoparticles with core-shell-shell structure were successfully synthesized by a cheap silane coupling agent grafting method at room temperature. This method not only homogeneously coated rare-earth phosphate nanoparticles on the surface of silica spheres but also saved the use of rare-earth resources. The obtained nanoparticles consisted of SiO2 core with a diameter of approximately 210 nm, GdPO4:Tb intermediate shell with thickness of approximately 7 nm, and SiO2 outer shell with thickness of approximately 20 nm. This unique core-shell-shell structured nanoparticles exhibited strong luminescence properties compared with GdPO4:Tb nanoparticles. The core-shell-shell structured nanoparticles can effectively quench the intrinsic fluorescence of bovine serum albumin through a static quenching mode. The as-synthesized nanoparticles show great potential in biological cell imaging and cancer treatment.

Highlights

Because of the unique 4f shell of the ions, lanthanide compounds often show good electronic, optical and magnetic characteristics
We report a room-temperature silane coupling agent grafting method to simultaneously graft 3-(aminopropyl) triethoxysilane (APTES) on the surface of the silicon spheres and bond with carboxyl of maleic anhydride (MAH)
Several new weak diffraction peaks appeared in SiO2@GdPO4:Tb@SiO2, which were matched with monoclinic phase of GdPO4 (JCPDS No 32–386)

Summary

Introduction

Because of the unique 4f shell of the ions, lanthanide compounds often show good electronic, optical and magnetic characteristics. The lanthanide compounds have attracted considerable interest with major applications in optics, plasma display, drug delivery, magnets and biological labelling [1,2,3,4]. Among the rare-earth phosphates, gadolinium phosphate (GdPO4) is an important host matrix for luminescent lanthanide ion-doped nanophosphors [8]. GdPO4 matrix nanoparticles have been proved to be a potential multifunctional nano-platform for magnetic resonance imaging (MR) and effective optical imaging materials [9]. GdPO4:Eu3+ nanoparticles have been synthesized by co-precipitation, and the nanoparticles can emit intense orange-red fluorescence [11]. GdPO4:Eu3+/Tb3+ was synthesized via typical hydrothermal method; the nanoparticles can obtain a bright colour-tunable photoluminescence from red, orange, yellow to green region when the GdPO4 nanoparticles are co-doped with Eu3+ and Tb3+ ions [12]. Most conventional synthesis methods required high temperature, pressure and expensive precursors

Methods

Results

Conclusion