Sequential detection of H2S and HOBr with a novel lysosome-targetable fluorescent probe and its application in biological imaging.

Understanding the complex relationship between active small molecules is of great significance in various physiological processes. Herein, we present the design and synthesis of a sequential responsive Lysosome-Naphthalene imide-Azido (lyso-NP-N3) reporter for probing the H2S and HOBr within organelle (lysosome) in living cells. Probe lyso-NP-N3 exhibited high selectivity and sensitivity towards H2S (LOD = 23.5 nM) and HOBr (LOD = 254 nM). Additionally, lyso-NP-N3 possessed an excellent lysosome targeting ability and was utilized to visualize the exogenous/endogenous H2S and HOBr in RAW 264.7, Hela and HepG2 cells. Facilitated by this sequentially activated mechanism, the probe was successfully applied to confirm that the reported scavenger of HOBr, N-acetyl-L-cysteine (NAC) mainly relied on its metabolite H2S to eliminate excess HOBr, thereby playing the role of cell regulation and protection. These results establish the crosstalk between H2S and HOBr in lysosome and provide a promising tool to study metabolite interactions.