Fluorescent Probes for the Detection of Hydrogen Sulfide in Biological Systems

Abstract

Detective work: Three highly sensitive and selective fluorescent probes for the detection of H2S have been developed. Two of the probes detect H2S by the reduction of an azide moiety to an amine group, which changes the probes into their fluorescent forms and generates a fluorescent signal. In the third method, the fluorescent signal is created by using H2S as a nucleophile in a reaction that unmasks fluorescein.

Highly sensitive sulphide mapping in live cells by kinetic spectral analysis of single Au-Ag core-shell nanoparticles

“…Although the PNP probes have performed as well as the fluorescent probes reported previously [23][24][25][26][27][28] , due to the ensemble average effect, bulk measurements are intrinsically not as sensitive as single-particle measurements. The AuNR-Ag PNP with a 2.1-nm thick silver shell, for example, contains B6 Â 10 5 silver atoms, which translates to B30 mM Ag for a B50 pM PNP solution.…”

“…During the past several years, several research groups have developed sulphide-responsive fluorescent organic molecules to detect H 2 S in live cells and have achieved selective intracellular sulphide imaging with limits of detection of 1-10 mM (ref. [23][24][25][26][27][28]. Although most publications suggest that the average endogenous H 2 S level is in the mM range, much lower sulphide concentrations have been reported 29 .…”

“…More importantly, the anabolism and catabolism of cellular sulphide are known to be rapid, which means that the sulphide concentration could fluctuate continuously from as high as submM during its explosive production to as low as a few nM after its rapid consumption 30 . However, almost all existing H 2 Ssensing methods are based on some irreversible stoichiometric reaction between the probe and sulphide species [23][24][25][26][27][28] and cannot be utilized to monitor the dynamics of sulphide generation and elimination inside cells, especially at the single-molecule level. Therefore, more sensitive methods that are capable of following time-dependent changes in H 2 S concentrations over a large dynamic range are needed for in-depth studies of this gaseous transmitter.…”

Cell-trappable fluorescent probes for endogenous hydrogen sulfide signaling and imaging H 2 O 2 -dependent H 2 S production

“…We previously reported two first-generation fluorescent probes for H 2 S, SF1 and SF2, which rely on the chemoselective and biocompatible reduction of an aryl azide to an aniline upon reaction with H 2 S to produce a fluorescent readout that operates in a cellular context (24)(25)(26). Unfortunately, the in vitro detection limit of these probes was in the range of 5-10 μM H 2 S, which may not be sufficiently sensitive to measure endogenous release of H 2 S during cellular signaling cascades (46).…”

“…While chromatographic assays and electrochemical sensors have been used to measure endogenous H 2 S levels in blood, homogenized tissues, and cell lysates (23), these methods are generally incompatible with the detection of H 2 S in live biological specimens. To meet this need, molecular imaging with H 2 S-responsive fluorescent indicators offers an attractive approach, and the development of H 2 S probes has recently seen rapid advances (24,25). Early work in this area from our laboratory (26) as well as from Wang and colleagues (27) exploited the selective H 2 S-mediated reduction of azides and sulfonylazides, respectively, to devise first-generation reagents for fluorescence H 2 S detection.…”