An asymmetrical flavylium based probe with large Stokes shift and near infrared emission for highly sensitive...

Hydrogen sulfide (H₂S) has been recognized as an important gaseous signaling molecule in living systems, and is of great significance in many pathological and physiological processes. Misregulation of endogenous H₂S is implicated in various diseases in the neuronal, gastrointestinal, circulatory, and endocrine systems. Fluorescent probe with large Stokes shift and near infrared emission, is ideal candidate for imaging applications to prevent excitation scattering, autofluorescence interference, matrix absorption caused signal loss, and sample destruction. In this study, a dual-side expansion approach was performed to develop spectra tunable hydroxyl functional flavylium derivative named HN8 with enlarged Stokes shift of 81 nm, lengthened emission of 671 nm, satisfied quantum yield of 0.23, and good fluorescence enhancement factor of 14.3-fold. Moreover, based on HN8, the screened probe HN8DNP displayed 225-fold fluorescence enhancement containing linear correlations to H₂S from 0 to 50 μM with good limit of detection (LOD) of 0.31 μM. Therefore, HN8DNP was then applied for imaging exogenous H₂S and drug induced enzymatic H₂S generation in living cells with satisfied results, revealing the relationship between intracellular H₂S levels and related enzyme activities. In a word, the present work provided a potential fluorescence probe for highly selective and sensitive detecting H₂S in vitro and in living cells. And the promising dual-side expansion strategy for regulation optical feature of traditional fluorophore may meet the increasing requirements of sensing and imaging applications.