Ratiometric Two-Photon Fluorescent Probes for Mitochondria! Hydrogen Sulfide in Living Cells

Hydrogen sulfide (H2S) is an important signaling molecule with diverse biological roles. Various fluorescent probes for H2S with biological application have been developed. However, two-photon ratiometric imaging of mitochondrial H2S is scarce. In this paper, we report two ratiometric two-photon probes, AcHS-1 and AcHS-2, which employ 4-amino-1,8-naphthalimide as the fluorophore and 4azidobenzyl carbamate as the H2S response site. These probes exhibit high selectivity toward H2S over biothiols and other reactive species, low detection limits of 50-85 nM, low cytotoxicity, and high stability under physiological conditions. Furthermore, through cell imaging with one-photon and two-photon microscopy, MCF-7 cells incubated with two probes show a from marked change in emission color blue to green in response to I-Ie. Cell images es costraining with a mitochondria] dye reveal that AcHS-2 is a mitochondria-specific two-photon probe for H2S. These results show that AcHS-2 may find useful applications in biological research such as tracking mitochondria] H2S in living biological specimens.