Engineering a mitochondria-targeted ratiometric fluorescent probe with a large Stokes shift for H2S-specific assaying in foodstuffs and living cells

Hydrogen sulfide (H2S) is a toxic gas found in foods. On-site monitoring hydrogen sulfide level in foodstuffs is desired. Hence, a mitochondria-targeted ratiometric fluorescent sensor (NBP-HS) with a large Stokes shift for H2S detection was constructed based on assembling 2-thiophenecarbonyl group and merocyanine (T-B). The fluorescence ratio (I590/I520) of NBP-HS displayed a good linear relationship related to H2S concentration (0−60 μM) with the detection limit of 5.4 × 10−8 M in HEPES buffer. The sensing mechanism was determined by HRMS analysis and DFT calculation. Interestingly, the H2S-response ratiometric probe was successfully used to on-site measure the freshness of meat by recording the color change. The analysis results of test strips were completely consistent with the analysis results of the colonies count. The probe shows an excellent response to H2S in ratiometric fluorescence in living cells, illustrating the broad applicability of NBP-HS for imaging in biosystems.