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Abstract Hydrogen polysulfides (H 2 S n , n > 1) influence a variety of important biological functions and activities associated with hydrogen sulfide (H 2 S). The development of probes for rapid, selective, and sensitive detection of H 2 S n still remains a great challenge. Lysosome plays crucial roles in various physiological processes among living cells, which arouse high interest in detecting endogenous lysosome-targetable H 2 S n. To the best of our knowledge, there is no lysosome-targetable probe for H 2 S n has been reported. In this work, a new lysosome-targetable probe NIPY NF , based on the scaffold of imidazo [1,5-]pyridine, with a large Stokes shift (215 nm), low detection limit (84 nM), fast response time (6 min) and low cytotoxicity was designed and synthesized. Furthermore, NIPY NF was successfully applied into the cell imaging for detection of endogenous lysosome-targetable H 2 S n. Graphical abstract Image 1 Highlights • A novel lysosome-targetable probe NIPY NF was reported. • NIPY NF could discriminate H 2 S n over other analytes with high sensitivity, a low detection limit and a large Stokes shift. • NIPY NF could detect the endogenous H 2 S n in lysosome of living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new dye was synthesized and the spectral properties were studied. • The dye showed good spectral properties and was used to detect SO 2 derivatives. • The reactivity of the probe could be regulated by the thiomorpholine group. A new coumarin-hemicyanine dye was synthesized and used as a ratiometric fluorescent probe for SO 2 derivatives (HSO 3 -/SO 3 2-). The probe showed deep-red fluorescence, ratiometric response, good selectivity, low detection limit and well-separated emission bands. Moreover, the probe was mitochondria-targeted, and was applied to image SO 2 derivatives in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new pH sensitive fluorescent probe termed NAP-MDA is developed. • NAP-MDA possesses an excellent linear dependence with neutral to alkaline pH. • NAP-MDA is photostable and solely sensitive to pH. • NAP-MDA is successfully utilized to visualize the intracellular pH. A new pH-sensitive fluorescent probe NAP-MDA was designed and synthesized. NAP-MDA consists of 1,8-naphthalimide as fluorophore, morpholine and N,N-dimethylethylenediamine as pH-responsive groups. Due to the photoinduced electron transfer (PET) mechanism, the fluorescence of 1, 8-naphthalimide was thoroughly quenched under alkaline condition (pH > 10.0), however, NAP-MDA displayed increasing fluorescence as the rise of acidity. Notably, NAP-MDA possessed an excellent linear dependence with neutral to alkaline pH (7.2–9.4), with a pKa of 8.38. NAP-MDA had good photostability and reversibility. Meanwhile, the probe was selective to pH without interference from common reactive species, temperature and viscosity. Fluorescent testing strips were fabricated with NAP-MDA and were successfully utilized to visualize the different pH with a handhold UV lamp. Confocal fluorescence imaging in live cells demonstrated that NAP-MDA mainly fluoresced in lysosomes, and could be applied for quantification of the pH within live cells. [ABSTRACT FROM AUTHOR]