Efficiently mitochondrial targeting fluorescent imaging of H2S invivo based on a conjugate-lengthened cyanine NIR fluorescent probe

•A conjugate-lengthened cyanine NIR fluorescent probe was firstly obtained.•The probe displayed good selectivity and high sensitivity towards H2S with a detection limit 20 nM.•The probe can efficiently realize mitochondria-targeted H2S in vivo. As an important biological messenger and effector molecule, hydrogen sulfide (H2S) not only is involved in maintaining the physiological function in cardiovascular, immune and nervous systems but also controls the activity of mitochondrial atpase and antioxidant stress in living cells. Herein, a new PET-based mitochondria-targeted NIR probe Mito-N3 with good selectivity and high sensitivity for H2S was presented in this work. The free probe has no fluorescence, however, once reacts with H2S, Mito-N3 goes through an analyte-prompted immolation, resulting in the releasing of the fluorophore (Mito−OH) and the concomitant restoring of remarkable fluorescence in the NIR emission at 736 nm. The detection limit was calculated as low as 20 nM. Most importantly, fluorescence imaging experiments showed that the probe can monitor the intracellular H2S level in mitochondria of MCF-7 cells, the probe Mito-N3 also had the potential application in sensing and tracking H2S in living nude mice.