Immobilization of the Gas Signaling Molecule H ₂ S by Radioisotopes: Detection, Quantification, and In Vivo Imaging

Hydrogen sulfide (H 2 S) has multifunctional roles as a gas signaling molecule in living systems. However, the efficient detection and imaging of H 2 S in live animals is very challenging. Herein, we report the first radioisotope‐based immobilization technique for the detection, quantification, and in vivo imaging of endogenous H 2 S. Macrocyclic 64 Cu complexes that instantly reacted with gaseous H 2 S to form insoluble 64 CuS in a highly sensitive and selective manner were prepared. The H 2 S concentration in biological samples was measured by a thin‐layer radiochromatography method. When 64 Cu–cyclen was injected into mice, an elevated H 2 S concentration in the inflamed paw was clearly visualized and quantified by Cerenkov luminescence and positron emission tomography (PET) imaging. PET imaging was also able to pinpoint increased H 2 S levels in a millimeter‐sized infarcted lesion of the rat heart.