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Chemical sensing for the sensitive and reliable detection of mercury(II) ions (Hg2+) is of great importance in environmental protection, food safety, and biomedical applications. Due to the bio-enrichment property of Hg2+ in organisms, it is particularly meaningful to develop an effective tool that can in situ and rapidly monitor the level of Hg2+ in living organisms. In this work, we report ligand functionalized gold-silver bimetallic nanoclusters with bright red fluorescence as intracellular probes for imaging Hg2+ in living cells and zebrafish. The bimetallic nanoclusters of DTT-GSH@Au/AgNCs (DG-Au/AgNCs) with strong fluorescence that benefited from the synergistic effect of Au and Ag atoms were obtained through a one-pot synthesis method, incorporating glutathione (GSH) and dithiothreitol (DTT) as the reducers and functionalized ligands. Attractively, the bright red fluorescence of DG-Au/AgNCs could be rapidly and selectively quenched by Hg2+ within 1 min with a very low detection limit of 1.01 nM. Additionally, DG-Au/AgNCs had a great advantage in the detection of Hg2+ in living cells and zebrafish owing to its notably strong red fluorescence at 665 nm, which could avoid effectively auto-fluorescence interference from the organism. Such easily prepared bimetallic fluorescent nanoclusters would be expected to provide a noninvasive and sensitive approach in the detection of heavy metals in situ for environmental protection. [ABSTRACT FROM AUTHOR]

A novel Ru-based phosphorescent probe was designed for the detection of thiophenol using 2,4-dinitrobenzenesulfonate as a sensing unit. The probe exhibited a remarkable off–on type of phosphorescent response towards thiophenol over other commonly encountered metal ions, anions, and aliphatic thiols. The probe was able to work in pure water medium and instantaneously responded to thiophenol with a 36-fold enhancement in 30 seconds. This probe displayed a large Stokes shift (216 nm) and long luminescence lifetime, and the detection limit reached as low as 30 nM. Moreover, detection of thiophenol is based on the thiol-induced cleavage of a sulfonamide linkage to generate a strongly phosphorescent species, Ru-NH2, which showed obvious AIEE activity. Furthermore, the potential for practical applications of this probe has been successfully demonstrated in monitoring thiophenol in real water samples and on test paper. [ABSTRACT FROM AUTHOR]

Biothiols play an important role in cell protein metabolism and signal transduction, especially Hcy was considered as a new risk factor closely related to many diseases. However, there remain some limitations in selectively detecting Hcy due to its structural similarity to Cys. It is urgent for us to develop a novel indicator to study the pathological process of Hcy. Herein, we constructed a new fluorescent probe TCF-SBD composed of tricyanofuran fluorophore and SBD reaction site for detecting Hcy. The probe TCF-SBD exhibited a strong yellow emission response to Hcy in an "off-on" manner, and showed good selectivity for Hcy over Cys and GSH. The sensing mechanism was confirmed by HPLC, NMR titration and DFT studies. The probe was sensitive to the detection of Hcy with LOD low to 0.23 μM. The powerful probe TCF-SBD succeeded in real-time and selectively visualizing Hcy in living cells. [Display omitted] • Fluorescence probe based on substitution-rearrangement process was synthesized for selective detection of Hcy. • The probe displayed high selective and sensitive for Hcy (detection limit is 0.23 μM). • The probe was applied for fluorescence imaging of exogenous Hcy in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple naphthalimide-based chemosensor was synthesized based on ICT process for ratiometric detection of SO 2 derivatives. • The probe displayed high selective and sensitive for derivatives (detection limit is 1.53 μM). • The probe was applied for exogenous and endogenous SO 2 imaging by dual emission channels in living Hela and HepG2 cells. SO 2 is a well-known signal molecule and one of reactive sulfur species, which closely participates in many metabolic processes. While unbalanced metabolism of sulfur dioxide can lead to serious complications of various diseases. Therefore, a rapid and accurate monitoring of SO 2 derivatives with high selectivity and sensitivity would be beneficial for their bio-analytic studies. Herein, a novel ratiometric fluorescent probe (NG-TCF) based on ICT mechanism for monitoring SO 2 was developed. The probe underwent a nucleophilic addition of HSO 3 -/SO 3 2- to give rise to a 120 nm blue-shift dual-emission signal changes in enhanced green channel and subdued red channel under a single wavelength excitation. The probe showed fast response rate (within 7 min), good sensitivity (the detection limit is 1.53 µM), and specific response toward HSO 3 -/SO 3 2- over other bio-species, including H 2 S and ClO-. Moreover, the probe can be applied for visual ratio imaging of exogenous and endogenous SO 2 derivatives in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple flavone-based chemosensor was synthesized based on ESIPT process for ratiometric detection of hydrogen polysulfides. • The probe displayed high selective and sensitive for hydrogen polysulfides (detection limit is 0.63 μM). • The probe was successfully applied to exogenous H 2 S n detection and imaging by dual emission channels in living Hela cells. Hydrogen polysulfides (H 2 S n) as an important member of reactive sulfur species is closely relevant to many physiological functions in redox homeostasis and metabolism. Dual-channel monitor the changes of H 2 S n level in vivo is highly desired. Herein we design a simple ratiometric fluorescent probe based on flavone skeleton for highly selective detection of H 2 S n. The probe HF-NA-MC bearing 2-fluoro-5-nitrobenzoic acid group inhibited the intramolecular ESIPT process, which show the blue fluorescence of adjacent naphthalene unit. In the presence of H 2 S n , the enol form of probe is converted to conjugated keto form, resulted in a 90 nm red-shift of fluorescence emission from 450 nm to 540 nm. The ratiometric intensity (I 540 /I 450) of the probe exhibits a good linear relationship toward H 2 S n in the range of 0–120 μM, and the detection limit is estimated to be 0.63 μM. The ratiometric fluorescent probe shows high specificity and anti-interference ability for H 2 S n over other related reactive sulfur species. The probe HF-NA-MC shows promising outlook and could be applied to the confocal imaging of H 2 S n by dual emission channels in Hela cells. [ABSTRACT FROM AUTHOR]

A novel spiropyran-based colorimetric probe SP-DNP bearing a 2,4-dinitrophenyl group as a PhSH-responsive site was synthesized for the detection of thiophenol based on the ring open/closed isomerization process. Upon the addition of PhSH, the probe SP-DNP displayed a remarkable change in UV–vis spectra with a good linear relationship to concentration of PhSH, and result in apparent color change from purple to colorless that could be easily observed by the naked eye even in the presence of other interfering anions. Probe SP-DNP exhibited specific colorimetric response toward PhSH with very fast response (within 30 s) and high sensitivity (detection limit is 0.55 μM). In addition, the probe showed good selectivity and sensitivity toward PhSH through fluorescence quenching process. The sensing mechanism of the nucleophilic substitution-cyclization process was confirmed by 1H NMR and mass spectroscopic analysis. Moreover, probe SP-DNP could detect PhSH in real water samples. Image 1 • Probe SP-DNP was constructed on basis of thiophenol-induced transform merocyanine to spiropyran isomerization process. • The probe could colorimetric and fluorescent respond toward thiophenol with fast response and high sensitivity. • The probe has been successfully demonstrated in monitoring thiophenol in real water samples. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe 1 was synthesized for the detection of thiophenol on the basis of a unique thiophenol-mediated substitution-cyclization reaction. The probe 1 displayed 420-fold fluorescence intensity enhancement and highly selective and sensitive response for thiophenol over other competing sulfur species. This probe showed an excellent linear relationship in 10–140 μM and the low detection limit of 29 nM. The recognition mechanism of probe 1 toward PhSH was supported by the NMR spectrum and ESI-MS. Furthermore, the probe 1 was successfully applied for detection of thiophenol in living HepG2 cells. Image 1 • A novel fluorescent probe 1 for thiophenol was constructed on the basis of substitution-cyclization reaction. • Probe 1 features significant fluorescence enhancement up to 420-fold in response to thiophenol in aqueous solution. • This probe showed an excellent and wide linear relationship in 10–140 μM and with a low detection limit of 29 nM. • The probe could detect thiophenol in living cells. [ABSTRACT FROM AUTHOR]