Enhancement of Luminescence, Multiple-Sensing, and Differentiated Live-Cell-Imaging Properties of High-Nuclear Lanthanide Nanoclusters via the Zn(II)-Chelate-Controlled Dual Antenna Effect

Enhancing
the “antenna effect” of ligands
and promoting
energy transfer to a lanthanide metal center is one of the most effective
ways to construct lanthanide complex-based emitters with bright emissions.
Herein, highly stable lanthanide nanoclusters (Ln9Zn8; Ln
= Dy, Tb, Eu, or Gd) were constructed using a Zn(II) metalloligand
protection strategy, and a “dual antenna effect” was
selectively turned on to enhance the luminescence of Eu9Zn8. The Zn(II) metalloligand enabled the dual antenna effect for Eu9Zn8, resulting in its solid state luminescence being significantly
stronger than that of Tb9Zn8. Eu9Zn8 has excellent optical
sensing properties for Al3+, Fe3+, and Cr2O72–. Notably, ultrasmall Eu9Zn8 nanocluster showed excellent cellular uptake and labeling
capabilities after incubation with HeLa, MDA–MB–231,
HepG2, H9c2, 4T1, SK–OV–3, and MCF–7 cells. This
work opens up new horizons for the application of lanthanide nanoclusters
in biological imaging.