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ACS Nano. 2012 Sep 25;6(9):8280-7. Epub 2012 Sep 4.

(α-NaYbF4:Tm(3+))/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared upconversion for high-contrast deep tissue bioimaging.

Author information

1
School of Chemical Engineering and Technology, Harbin Institute of Technology, 150001 Harbin, People's Republic of China.

Abstract

We describe the development of novel and biocompatible core/shell (α-NaYbF(4):Tm(3+))/CaF(2) nanoparticles that exhibit highly efficient NIR(in)-NIR(out) upconversion (UC) for high contrast and deep bioimaging. When excited at ~980 nm, these nanoparticles emit photoluminescence (PL) peaked at ~800 nm. The quantum yield of this UC PL under low power density excitation (~0.3 W/cm(2)) is 0.6 ± 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF(2) shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).

PMID:
22928629
PMCID:
PMC3523358
DOI:
10.1021/nn302972r
[Indexed for MEDLINE]
Free PMC Article

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