Abstract: The present invention relates to a method for producing a radioactive zirconium-labeled complex that can realize a high labeling index in a reaction between a radioactive zirconium ion and a ligand compound. The production method of the present invention includes a step of reacting a radioactive zirconium ion with a ligand compound in a reaction solution containing water to coordinate the radioactive zirconium ion. This step is performed in a state where the pH of the reaction solution is in an acidic region. The reaction solution does not contain an organic solvent but contains a water-soluble organic compound having one or two sulfo groups or carboxy groups in its structure, separately from the ligand compound.

Abstract: A conjugate of an anti-HER2 antibody site-specifically modified with a peptide and a chelating agent. The chelating agent is chelated with a metal radionuclide, the peptide and the chelating agent are linked by a linker (L), and the linker (L) does not contain a thiourea bond. A radiopharmaceutical including the conjugate as an active ingredient.

Abstract: The production method of a radioactive metal-labeled antibody of the present invention includes a step of conducting a click reaction of a radioactive metal complex and an antibody site-specifically modified with a peptide to produce a radioactive metal-labeled antibody. The click reaction is performed between a first atomic group of the radioactive metal complex and a second atomic group directly or indirectly linked to the peptide. The second atomic group is an atomic group containing an azide group, or an atomic group containing trans-cyclooctene.

Abstract: A fluorescent probe can be used to detect and visualize carboxypeptidase activity with high sensitivity. The fluorescent probe has, as a base nucleus, a fluorescent skeleton that functions in the visible light region, and makes carboxypeptidase activity detectable and visible, for example, within a cell or clinical specimen, with high sensitivity.