Tricarbocyanine -triazoles: the scaffold-of-choice for long-term near-infrared imaging of immune cells .

Herein tricarbocyanine -triazoles are first described as a rationally-designed near-infrared (NIR) structure overcoming the brightness and photostability limitations of tricarbocyanines for long-term imaging. The straightforward synthetic approach and the wide availability of alkynes makes this strategy a versatile methodology for the preparation of highly stable -substituted tricarbocyanines. Furthermore, we validated as a non-transferable marker to monitor the fate of therapeutic T cells non-invasively , showing enhanced performance over conventional NIR fluorophores ( , IR800CW and indocyanine green) as well as compatibility with human cells for translational studies. is able to track over time smaller numbers of T cells than current NIR agents, and to visualise antigen-driven accumulation of immune cells at specific sites . This chemical technology will improve longitudinal imaging studies to assess the efficacy of cell-based immunotherapies in preclinical models and in human samples.