Metal Catalyzed Click Chemistry for Molecular Imaging Probes

Cu-catalyzed azide-alkyne cycloaddition has been developed as a new, simple, efficient, and generally applicable synthetic strategy, known as ‘Click Chemistry’. The reaction utilizes two bioorthogonal functional groups, azide and alkyne, which can be readily incorporated into biological molecules with straightforward chemical modification. The reaction can be performed in low substrate concentration under a wide range of conditions including aqueous physiological conditions, which finds a span of application ranging from material science, chemical biology/bio-conjugation, and pharmaceutical research and development. In this review, we focused on the new progress in developing the metal catalyzed, bioorthogonal azide-alkyne cycloaddition reaction (‘Click chemistry’) about catalyst species, the ligands and substrates and its application in the bio-imaging field from four aspects: (a) labeling of live cell surface; (b) imaging small molecules inside of living cells; (c) modifying cells with nanomaterials; and (d) vivo imaging. Keywords: Click chemistry, Cu(I)-catalyzed azide-alkyne 1, 3-dipolar cycloaddition (CuAAC), CuI catalyst, Molecular imaging probe, Bioorthgonal reaction