Development of a semiacenaphthenofluorescein-based optical and fluorescent sensor for imaging cysteine in cells.

• An "off-on" fluorescein-based chemodosimeter probe 1 for the recognition of Cys was designed and developed. • Probe 1 exhibited rapid, highly selective and sensitive for determination Cys over Hcy and GSH. • The recognition mechanism was studied by spectroscopy titrations, mass spectra determination and DFT calculations. • Fluorescence cell imaging demonstrated that probe 1 could detect Cys in HeLa cells. A novel chromogenic and fluorescent sensor based on semiacenaphthenofluorescein (Probe 1) was designed and synthesized. This probe exhibited superior selectivity and sensitivity for cysteine (Cys) over other analogues, such as homocysteine and glutathione, and the corresponding detection limit was 0.086 μM, which was much lower than intracellular concentration. The tandem conjugate addition/cyclization sequence mechanism was revealed by mass spectrometry, 1H NMR examination and density functional theory (DFT) calculations. Finally, the results of photostability, cell imaging and viability assays showed that the probe possessed excellent membrane permeability, hypotoxicity and fluorescent imaging of cysteine, which indicated its potential applications in living cells. [ABSTRACT FROM AUTHOR]