Fig. 6.

Synthesis of trimeric TRAP bioconjugates. The preferred route B for elaboration of trimeric integrin ligands by means of 'click chemistry' (CuAAC) is indicated by red arrows [91]. Of note, the CuAAC coupling was occasionally conducted with azide-decorated integrin ligands and alkyne-functionalized TRAP (obtained by amide coupling of propargyl amine, H₂N–CH₂–C≡CH, in step 1), e.g., for synthesis of ⁶⁸ Ga-Aquibeprin (see Fig. 7)