Efficient up-conversion in Yb:Er:NaT(XO4)2 thermal nanoprobes. Imaging of their distribution in a perfused mouse

PLoS One. 2017 May 18;12(5):e0177596. doi: 10.1371/journal.pone.0177596. eCollection 2017.

Abstract

Yb and Er codoped NaT(XO4)2 (T = Y, La, Gd, Lu and X = Mo, W) disordered oxides show a green (Er3+ related) up-conversion (UC) efficiency comparable to that of Yb:Er:β-NaYF4 compound and unless 3 times larger UC ratiometric thermal sensitivity. The similar UC efficiency of Yb:Er doped NaT(XO4)2 and β-NaYF4 compounds allowed testing equal subcutaneous depths of ex-vivo chicken tissue in both cases. This extraordinary behavior for NaT(XO4)2 oxides with large cutoff phonon energy (ħω≈ 920 cm-1) is ascribed to 4F9/2 electron population recycling to higher energy 4G11/2 level by a phonon assisted transition. Crystalline nanoparticles of Yb:Er:NaLu(MoO4)2 have been synthesized by sol-gel with sizes most commonly in the 50-80 nm range, showing a relatively small reduction of the UC efficiency with regards to bulk materials. Fluorescence lifetime and multiphoton imaging microscopies show that these nanoparticles can be efficiently distributed to all body organs of a perfused mouse.

MeSH terms

  • Animals
  • Erbium / chemistry*
  • Fluorescence*
  • Fluorescent Dyes / chemistry
  • Fluorescent Dyes / metabolism
  • Mice
  • Nanoparticles / chemistry*
  • Optical Imaging*
  • Oxides / chemistry*
  • Oxides / metabolism
  • Particle Size
  • Perfusion
  • Temperature*
  • Ytterbium / chemistry*

Substances

  • Fluorescent Dyes
  • Oxides
  • Erbium
  • Ytterbium

Grants and funding

The authors thankfully acknowledge the financial support by Ministry of Economy and Competitiveness and the European Regional Development Fund grant number MAT2014-56607-R, the Spanish Ministry of Economy and Competitiveness support as a Severo Ochoa Center of Excellence, grant nunber SEV-2015-0505, and by the Pro CNIC Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.