A novel polymer-based probe for fluorescently ratiometric sensing of hydrogen sulfide with multiple applications

Hydrogen sulfide (H₂S) as an endogenous signaling molecule, plays an irreplaceable role in many important physiological activities. It is also closely related to sewage treatment, wine quality evaluation, and food spoilage. Herein, we have successfully synthesized a novel polymer-based probe P1 for fluorescently ratiometric sensing of H₂S with a high selectivity and sensitivity. By virtue of ring-opening metathesis polymerization (ROMP), P1 was prepared with the disulfide bond linked coumarin-norbornene dyad NB-SS-COU as energy donor, the aggregation-induced emission (AIE) fluorophore anchored norbornene NB-TPE as energy receptor, and the polyethylene glycol (PEG) attached norbornene NB-PEG as a hydrophilic chain. At the 400 nm excitation, P1 displays a bright red emission at 615 nm due to the efficient fluorescence resonance energy transfer (FRET) from energy donor COU to energy acceptor TPE. Upon addition of H₂S, it shows strong COU-based blue emission at 473 nm for cleavage of the disulfide bond. We also constructed a smartphone sensing platform to conduct visual quantitative detection of H₂S by calculating the B/R (blue/red) emission ratio values. Moreover, P1 can be successfully employed in evaluating the level fluctuations of endogenous and exogenous H₂S in living cells, testing water samples/wine samples, and monitoring food freshness.