Smart Applications of Lanthanide Chelates-based Luminescent Probes in Bio-Imaging

Luminescent Lanthanide (III) (Ln(III)) bioprobes (LLBs) have been extensively used in the last two decades as intracellular molecular probes in bio-imaging for the efficient revelation of analytes, to signal intracellular events (enzymes/protein activity, antigen-antibody interaction), target specific organelles, and determine parameters of particular biophysical interest, to gain important insights on pathologies or diseases. The choice of using a luminescent Ln(III) coordination compound with respect to a common organic fluorophore is intimately connected to how their photophysical sensitization (antenna effect) can be finely tuned and especially triggered to respond (even quantitatively) to a certain biophysical event, condition or analyte. While there are other reviews focused on how to design chromophoric ligands for an efficient sensitization of Ln(III) ions, both in the visible and NIR region, this review is application-driven: it is a small collection of particularly interesting examples where the LLB's emissive information is acquired by imaging the emission intensity and/or the fluorescence lifetime (fluorescence lifetime imaging microscopy, FLIM).