Responsive Fluorophore Aggregation Provides Spectral Contrast for Fluorescence Lifetime Imaging

Fluorophores experience altered emission lifetimes when incorporated into and liberated from macromolecules or molecular aggregates; this trend suggests the potential for a fluorescent, responsive probe capable of undergoing self‐assembly and aggregation and consequently altering the lifetime of its fluorescent moiety to provide contrast between the active and inactive probes. We developed a cyanobenzothioazole‐fluorescein conjugate ( 1 ), and spectroscopically examined the lifetime changes caused by its reduction‐induced aggregation in vitro . A decrease in lifetime was observed for compound 1 in a buffered system activated by the biological reducing agent glutathione, thus suggesting a possible approach for designing responsive self‐aggregating lifetime imaging probes.