Reaction-based BODIPY probes for selective bio-imaging

Complex intracellular environment of cells, which involves interaction of a large variety of bio-molecules, is a dynamic medium with full of important information that can be recovered as well as many unanswered questions. It is highly critical to image and track biologically relevant molecules in their native media without interfering with the regular cellular processes in order to gather as much data as possible to illuminate intricacies of the biological mechanisms. To that end, small-molecule fluorescent probes have been extensively developed during the last few decades with the help of current advances in imaging technologies. Although conventional probes utilizing non-covalent supramolecular interactions with the analyte of interest are successful, significant effort has been also put into the design of reaction-based probes (chemodosimeters). Chemodosimeters exploit selective reactions of analytes with fluorophores in attempt to improve the selectivity of the probes, address the limitations of former sensors and broaden the palette of useful probes. Various types of fluorophore scaffolds can be used in the design of chemodosimeters for visualization of different analytes. In this review, we highlight the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) based chemodosimeters which have been used to image bio-thiols, reactive oxygen/nitrogen species, and gaseous molecules in living cells.