Thio-based photosensitizer: a general strategy for preparing visible/NIR light absorbing heavy-atom-free photosensitizers was developed by performing a simple sulfur-for-oxygen atom substitution within existing fluorescent molecules.

Site-specific antibody conjugates with a well-defined structure and superb therapeutic index are of great interest for basic research, disease diagnostics, and therapy. Here, we develop a novel proximity-induced antibody conjugation strategy enabling site-specific covalent bond formation between functional moieties and native antibodies without antibody engineering or additional UV/chemical treatment. A high conjugation efficiency and specificity was achieved with IgGs from different species and subclasses. The utility of this approach was demonstrated by site-specific conjugation of the small-molecule fluorophore to a native antibody and in vitro characterization of its activities.

Tetrazine was demonstrated for the first time as a general phototrigger to design photoactivatable fluorophore probes.