Highly sensitive fluorescent sensor based on coumarin organic dye for pyrophosphate ion turn-on biosensing in synovial fluid.

Highly sensitive fluorescence detection of pyrophosphate ion (PPi) is in urgent demand but remains a great obstacle, ascribing to scarcity of high-performance materials with promising optical property and high affinity. Herein, we report the design and fabrication of a coumarin-based organic dye (DCCH-TPD) containing both hydrazide group and terpyridine moiety for PPi biosensing through Cu-induced photo-electron transfer (PET) effect and target analyte-switched competitive coordination reaction. Individual DCCH-TPD was found to be highly emissive, and displayed a turn-off response toward Cu due to formation of Cu@DCCH-TPD and PET effect. The recognition of Cu@DCCH-TPD by PPi leads to generation of Cu@PPi complex, which greatly reduces the amount of Cu coordinated with DCCH-TPD, subsequently decreasing PET effect. Significantly enhanced fluorescence is recorded and the fluorescence intensity is closely relied on PPi concentration. Thus, highly sensitive detection of PPi is achieved, and the detection limit was calculated to be 0.075 μM. Furthermore, the proposed sensor presented good selectivity, and excellent practical ability for application in arthritic fluid.