A water-soluble, low-cytotoxic and sensitive fluorescent probe based on poly(ethylene glycol) for detecting sulfide anion in aqueous media and imaging inside live cells

Sulfide anions are generated not only as a byproduct from industrial processes but also in biosystems. Hence, fluorescent probes for detecting sulfide anion which are water soluble, sensitive, selective and biocompatible are highly sought-after. In this study, we report a water-soluble, low-cytotoxic and sensitive fluorescent sensor for detecting sulfide anion. In this probe, the strong electron-withdrawing dinitrobenzenesulfonate ester group is incorporated onto fluorescein fluorophore, and correspondingly the fluorescence of fluorescein is efficiently quenched; while when the dinitrobenzenesulfonate ester is cleaved by the nucleophilic sulfide anion, the substantial fluorescence enhancement can be observed. Furthermore, poly(ethylene glycol) is coupled onto the fluorophore to impart the probe water-soluble and low cytotoxicity. The probe is capable of permeating the cell membrane and realizing sulfide anion monitoring and imaging in live cells and real sample. This technically-simple modification strategy may be suitable for fabricating some other fluorescent probes with enhanced biocompatibility and water solubility.