Chalcone dye-based fluorescent probe for selective and specific detection of cysteine in lysosomes of living cells

Cysteine is an organic small molecule that plays an important role in human physiological processes. It is meaningful to detect it easily with high selectivity and sensitivity. In this work, a fluorescent probe Lyso-CDC based on chalcone fluorescent dyes for the effective detection of Cys in lysosomes was designed and synthesized. After adding Cys, the fluorescence of the probe Lyso-CDC at 568 nm was significantly enhanced, displaying a large Stokes shift (168 nm) and a color change from light yellow to bright yellow that was visible to naked eyes. The selectivity and sensitivity of the probe Lyso-CDC for Cys were much higher than other amino acids, and the detection limit for Cys was calculated to be 1.44 × 10−8 M. Furthermore, the probe Lyso-CDC possessed low cytotoxicity, excellent biocompatibility and outstanding lysosome targeting ability. The probe was successfully applied to detect Cys in lysosomes of living cells.