Chemigenetic fluorescent biosensors in biological imaging - New trends and advances

Chemigenetic fluorescent biosensors combine genetically encoded and synthetic approaches, showing superior photophysical properties compared with fluorescent protein-based tools and enabling subcellular and tissue specific targeting as well as selective analyte detection. Here, we review how two of the most widely used chemigenetic systems, HaloTag and fluorescence-activating and absorption-shifting tag (FAST), have been incorporated into biosensors and used to expand the functionality of biosensors. We highlight how bright, photostable, and far-red fluorophores improve in vivo and multiplexed imaging. We discuss how chemigenetic biosensors with fluorescence lifetime readouts are advancing quantitative imaging through fluorescence lifetime imaging microscopy (FLIM) and we showcase chemigenetic integrators that can record physiological events for post hoc analysis. Finally, we offer an outlook on where chemigenetic biosensors are headed and their anticipated impact on biological imaging in the coming years.