A FRET-based ratiometric fluorescent probe for hydrogen polysulfide detection in living cells and zebrafish

Abstract
Hydrogen polysulfide (H2Sn, where n > 1) is a significant active sulfur species (RSS) in biological organisms, known for its involvement in redox signaling and cytoprotective functions. In this study, we focused on developing a quick and accurate method for detecting H2Sn in biological contexts. To achieve this, we utilized 2-fluoro-5-nitrobenzoic ester as the responsive component for H2Sn and employed a Förster Resonance Energy Transfer (FRET) strategy to effectively connect the donor (6-hydroxy-2-naphthoic acid) and acceptor (4-substituted-1,8-naphthalimide). This innovative approach resulted in the creation of a new ratiometric fluorescent probe for H2Sn, termed NPNA-H2Sn.The NPNA-H2Sn probe exhibited an impressive fluorescence ratio enhancement of over ∼ 8.0-fold (I450/I526) in response to H2Sn, demonstrating exceptional sensitivity with a notably low detection limit of 40.3 nM. This sensitivity is crucial for detecting the low concentrations of H2Sn that may play essential roles in cellular processes.Additionally, we applied NPNA-H2Sn for fluorescence imaging of H2Sn in living cells and zebrafish, producing clear ratiometric images that allow for real-time visualization of H2Sn distribution and dynamics. This capability is vital for investigating the biological roles of H2Sn and its involvement in various physiological and pathological processes.Our results suggest that NPNA-H2Sn is a powerful molecular tool for monitoring endogenous H2Sn in living systems. By facilitating the assessment of H2Sn’s physiological roles and its potential implications in disease, this probe offers promising opportunities for advancing our understanding of redox biology and sulfur signaling. Overall, NPNA-H2Sn enhances detection methods for H2Sn and paves the way for further research into its diverse roles in health and AZD-5153 6-hydroxy-2-naphthoic disease.