Coumarin-based turn-on fluorescence probes for highly selective detection of Pi in cell culture and Caenorhabditis elegans

Abstract Two coumarin-based fluorescence probes, 1 and 2 , containing a methoxy oxalyl group as a reaction site were developed. These two novel probes displayed an instant turn-on fluorescence response specific towards Pi without interference from ATP and PPi. A selective 23-fold increase in fluorescence for 1 (in DMSO–HEPES) and a 20-fold increase for 2 (in DMSO) were observed. The proposed sensing mechanism for these compounds is Pi-triggered acetamide bond cleavage leading to release of the blue fluorophore coumarin, which was supported by 1 H NMR and mass spectrometry data. Probe 1 was successfully used to image endogenous and exogenous Pi in living cells and to trace Pi released from ATP by apyrase in Caenorhabditis elegans .