Highly Bright and Photostable Li(Gd,Y)F4:Yb,Er/LiGdF4 Core/Shell Upconversion Nanophosphors for Bioimaging Applications

Jeehae Shin, Youngsun Kim, Jiyeon Lee, Sehoon Kim, Ho Seong Jang

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Intense green-emitting Li(Gd,Y)F4:Yb,Er/LiGdF4 core/shell (C/S) upconversion nanophosphors (UCNPs) with a tetragonal bipyramidal morphology are synthesized. The morphology and UC luminescence of the Li(Gd,Y)F4:Yb,Er UCNPs are significantly affected by the Li precursors, and bright UC green-emitting Li(Gd,Y)F4:Yb,Er UCNPs with a tetragonal bipyramidal shape, i.e., UC tetragonal bipyramids (UCTBs), are synthesized using LiOH·H2O as a Li precursor. A LiGdF4 shell is grown on the Li(Gd,Y)F4:Yb,Er UCTBs, and the C/S UCNPs exhibit 4.7 times higher luminescence intensity than core UCTBs. The C/S UCNPs show a high absolute UC quantum yield of 4.6% under excitation with 980 nm near infrared (NIR) light, and the UC luminescence from the C/S UCNPs is stable under continuous irradiation with the 980 nm NIR laser for 1 h. The hydrophobic surfaces of the as-synthesized C/S UCNPs are modified to hydrophilic surfaces by using poly(acrylic acid) (PAA) for bioimaging applications. They are applied to human cervical adenocarcinoma (HeLa) cell imaging and SK-MEL-2 melanoma cell imaging and in vivo imaging, including subcutaneous and intramuscular imaging, and UC luminescence images with high signal-to-noise ratio are obtained. Furthermore, sentinel-lymph-node imaging is successfully conducted with the PAA-capped Li(Gd,Y)F4:Yb,Er/LiGdF4 C/S UCNPs under illumination with NIR light.

Original languageEnglish
Article number1600183
JournalParticle and Particle Systems Characterization
Volume34
Issue number1
DOIs
Publication statusPublished - 2017 Jan 1
Externally publishedYes

Keywords

  • lanthanide doping
  • luminescence
  • lymph-node imaging
  • nanophosphors
  • upconversion

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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