A two photon fluorescent probe for highly selective detection and endogenous imaging of hydrogen sulfide.

Hydrogen sulfide (HS), one of redox-active sulfur species, is known as a signaling molecule and an antioxidant in biological tissues to maintain cellular functions. The development of selective and sensitive HS detection is important to understand the role of HS in vivo. Herein, a new two-photon probe NNE was developed to detect hydrogen sulfide using 6-acetyl-N-methyl-2-naphthylamine with an attachment of 7-nitrobenzo-oxadiazole. The probe NNE exhibits high selectivity towards hydrogen sulfide over other anions. Nucleophilic substitution of HS leads to a turn-on response with 28-fold enhancement in quantum yield (from 0.004 to 0.117). NNE shows a high sensitivity towards hydrogen sulfide with an extremely low detection limit at 6.8 nM. Furthermore, the probe NNE exhibits two-photon excited fluorescence, making it a suitable probe for monitoring HS distribution in live cells and tissues without background fluorescence interference.