Activating Surface Dark Emitters in Lanthanide-Doped Ultrasmall Nanoparticles for Biological Applications Based on Interparticle Energy Transfer

Abstract

Lanthanide-doped ultrasmall nanoparticles (NPs) are attractive for diverse applications because of their unique optical properties compared with their bulk materials; their practical use, however, is greatly limited by extremely weak photoluminescence (PL) associated with severe surface quenching. Herein, we demonstrate an effective strategy to activate surface dark emitters of Eu 3+ in ultrasmall Sc 2 O 3 ∶Eu NPs based on NP size-dependent energy transfer from a loaded sensitizer of 2-naphthoyltrifluoroacetone (β-NTA) to surface Eu 3+ . Using this strategy, 2.6-nm ultrasmall Sc 2 O 3 : Eu NPs exhibit an amplification factor of approximately 100 of red PL emission over their pristine counterparts. More importantly, efficient interparticle energy transfer (IPET) can be achieved across individual Sc 2 O 3 :Eu NPs, thereby enabling us to construct an ultrasensitive 2.6-nm IPET sensor for quantitative homogeneous bioassay of avidin. Aside from the significantly enhanced PL emission, these ultrasmall Sc 2 O 3 ∶Eu NPs can be excreted from the body of mice without evident toxicity, which makes them highly suitable as contrast agents for bioapplications in vivo.

Thermal Enhancement of Upconversion in Sub‐10 nm Yb3+/Er3+/Na+ Tridoped Cs2ZrF6 Nanocrystals for Ratiometric Temperature Sensing

“…Various inorganic materials like oxides, fluorides, oxyfluorides, molybdates, and silicates are currently used as hosts for fabricating Ln 3+ -doped UCNCs, wherein fluorides are considered excellent hosts due to their high refractive index and low phonon energy. [12][13][14][15][16][17] Nevertheless, most of previous studies are focused on UCNCs based on rare-earth fluorides, such as NaYF 4 , NaYbF 4 , NaErF 4 , LiYF 4 , LiLuF 4 , KYb 2 F 7 , and YF 3 . [18][19][20][21][22][23][24] Recently, a new class of alkaline zirconium fluorides (A x Zr y F x+4y , A = Li, Na, and K) has been explored as hosts for the preparation of UCNCs with distinct features in terms of morphological appearance, physicochemical properties, and UCL performance.…”