Ln(III) complexes display sensitized Ln(III) emissions by energy transfer from excited ligands. The long-lived Ln(III) emissions, rangings from visible to NIR region, hold great application potential in biomedical fields. This mini–review highlights recent advances in developing Ln(III) complexes for bioimaging, biosensing, and biodiagnosis. The mentioned Ln(III) emission colors include Sm(III) pink–purple, Eu(III) red, Tb(III) green, Dy(III) yellow/gray, and Yb(III) near–IR.

Abstract

Luminescent molecule–based bioimaging system is widely used for precise localization and distinction of cancer/tumor cells. Luminescent lanthanide (Ln(III)) complexes offer long–lived (sub–millisecond time scale) and sharp (FWHM <10 nm) emission, arising from the forbidden 4f–4f electronic transitions. Luminescent Ln(III) complex–based bioimaging has emerged as a promising option for both in vitro and in vivo visualizations. In this mini–review, the historical development and recent significant progress of luminescent Ln(III) probes for bioapplications are introduced. The recent studies are mainly focused on three points: (i) the structural modifications of Ln(III) complexes in both macrocyclic and small ligands, (ii) the acquirement of high resolution luminescence images of cancer/tumor cells and (iii) the constructions of ratiometric biosensors. Furthermore, our recent study is explained as a new Cancer GPS (cancer grade probing for determining tumor grade through photophysical property analyses of intracellular Eu(III) complex.