Dual-emissive nanohybrid for ratiometric luminescence and lifetime imaging of intracellular hydrogen sulfide

We design a nanohybrid for the detection of hydrogen sulfide (H₂S) based on mesoporous silica nanoparticles (MSNs). A phosphorescent iridium(III) complex and a specific H₂S-sensitive merocyanine derivative are embedded into the nanohybrid. It exhibits a unique dual emission that is ascribed to the iridium(III) complex and the merocyanine derivative, respectively. Upon addition of sodium hydrogen sulfide (NaHS), the emission from the merocyanine derivative is quenched, while the emission from the iridium(III) complex is almost unchanged, which enables the ratiometric detection of H₂S. Additionally, the nanohybrid has a long luminescence lifetime and displays a significant change in luminescence lifetime in response to H₂S. Intracellular detection of H₂S is performed via ratiometric imaging and photoluminescence lifetime imaging microscopy. Compared with the intensity-based method, the lifetime-based detection is independent of the probe concentration and can efficiently distinguish the signals of the probe from the autofluorescence in complex biological samples.