Prototypes of Lanthanide(III) Agents Responsive to Enzymatic Activities in Three Complementary Imaging Modalities: Visible/Near-Infrared Luminescence, PARACEST‑, and T₁‑MRI

We report first prototypes of responsive lanthanide­(III) complexes that can be monitored independently in three complementary imaging modalities. Through the appropriate choice of lanthanide­(III) cations, the same reactive ligand can be used to form complexes providing detection by (i) visible (Tb3+) and near-infrared (Yb3+) luminescence, (ii) PARACEST- (Tb3+, Yb3+), or (iii) T1-weighted (Gd3+) MRI. The use of lanthanide­(III) ions of different natures for these imaging modalities induces only a minor change in the structure of complexes that are therefore expected to have a single biodistribution and cytotoxicity.