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[Display omitted] • An "off–on" long-wavelength fluorescent probe is synthesized for Cys detection. • The probe has a large Stokes shift (211 nm) and reacted with Cys specifically. • The probe can monitor Cys fluctuations caused by redox imbalance in HepG2 cells. • The probe can be used for fluorescence imaging in cells and mice. In this research, an "off–on" long-wavelength fluorescent probe (DCMN-Cl) based on (E)-2-(3-(2-(6-hydroxynaphthalen-2-yl)vinyl)-5,5-dimethylcyclohex-2-en-1-ylidene) malononitrile (DCMN) is designed and synthesized for cysteine (Cys) detection. DCMN-Cl exhibits a large Stokes shift (211 nm) and shows rapid response and high specificity to Cys. The fluorescence initensity at 635 nm reveals a good linear relationship with Cys concentration in the 0 to 50 μM range, and the detection limit is as low as 159 nM. The probe is also used for fluorescence imaging of Cys in cells and mice. Moreover, the probe provided visual evidence of Cu2+ and curcumin-induced intracellular Cys fluctuations. [ABSTRACT FROM AUTHOR]

Abstract In this work, we have designed and synthesized a dinitrobenzene-sulfonate tetrahydro[5]helicene (H-DNP) as an effective fluorescent probe for detection of hydrogen sulfide (H 2 S). Upon the addition of H 2 S, a significant fluorescence enhancement (75-fold) at 495 nm can be observed with a distinct color change from colorless to yellow. Additionally, H-DNP shows low background spectroscopic signal, large Stokes Shift up to ~140 nm, good sensitivity, rapid response time less than 2 min, low detection limit (48 nM) and high selectivity toward common bio-thiols (Cysteine, Homocysteine and Glutathione). Compared with the previous dinitrophenoxy tetrahydro[5]helicene, this probe has shorter response time and lower detection limit. Most importantly, this probe H-DNP has low toxicity to cells and excellent cell permeability, which can be applied to visualize H 2 S in living cells. Graphical abstract Unlabelled Image Highlights • A tetrahydro[5]helicene based fluorescence probe displayed a rapid, sensitive and selective in response to H 2 S. • The probe has very low detection limit and fast response time. • The response mechanism is confirmed to be thiolysis reaction induced by H 2 S. • The detection of intracellular H 2 S was successfully demonstrated in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • An easily prepared and novel flavone-based fluorescent probe LFA was synthesized for detecting Cys in lysosome. • Experimental results indicated that LFA exhibited rapid response, high sensitivity and selectivity toward Cys. • Living cell imaging of LFA toward Cys was successfully performed for lysosomal imaging in CHL cells with low cytotoxicity. Cysteine (Cys) is one of the most important biothiols that plays a crucial role in many physiological and pathological processes, and therefore it is of great importance to detect and analyze Cys in subcellular environments, such as in lysosomes. However, only a few fluorescent probes were reported to be capable of detecting Cys in lysosomes selectively. In this wok, we designed and developed a simple, accessible flavone-based fluorescent probe LFA for detecting Cys in lysosomes. Morpholine was employed as the targeting unit for lysosome, and acrylate group was chosen as the Cys-response unit. The probe was easily prepared by a two-step procedure and displayed large Stokes shift, high sensitivity, turn-on response toward Cys over homocysteine (Hcy), glutathione (GSH), and other amino acids. With low cytotoxicity and good cell permeability, the probe could be successfully applied for fluorescence imaging of Cys in living cells. Furthermore, colocalization experiment revealed that lysosomal-targetable ability of LFA was significant. These results indicated that such simple fluorescent probe could provide a promising tool for detection of lysosomal Cys in living biological systems. [ABSTRACT FROM AUTHOR]

We constructed a novel cysteine fluorescent probe with large stokes shift for imaging in the living cells, zebrafish, and living mice. [Display omitted] • The new probe Ty-Cys1 had a very large Stokes shift. • The robust probe Ty-Cys1 showed a good selectivity, sensitivity to Cysteine. • The novel probe Ty-Cys1 was successfully applied to measure Cys in living cells, zebra fishes, and living mice. The small molecule biological thiols, such as Cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play crucial roles in maintaining various cellular vital activities. In the organism, abnormal levels of small-molecule biological thiols have been associated with a variety of diseases. Therefore, quantitative determination of biological thiols, especially Cys, is significant for understanding their functions in various biological processes. Thus, in this work we designed a new fluorescent probe Ty-Cys1 with a large Stokes shift of 207 nm to monitor Cysteine. The maximum absorption wavelength of Ty-Cys1 was 418 nm, and the maximum emission wavelength was 625 nm. Significantly, the novel probe Ty-Cys1 was effectively in detecting of Cys changes in living cells, zebrafishes, and living mice. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescent probe TNP-SBD-Cl was developed based on naphthimine-sulfonyl benzoxadiazole. • TNP-SBD-Cl can specifically recognize Cys with a large Stokes shift (157 nm). • TNP-SBD-Cl showed good selectivity and sensitivity for the detection of Cys (0.87 μM). • TNP-SBD-Cl has been successfully applied to fluorescence imaging of Cys in living cells. Biothiols play an important role in many physiological and pathological processes, especially in the occurrence of oxidative stress caused by abnormal cysteine (Cys) concentration. Therefore, it is particularly critical to develop a method that can specifically identify Cys to avoid interference from other biological analytes. However, most Cys-specific fluorescent probes are difficult to distinguish between homocysteine (Hcy) and glutathione (GSH). In this work, to avoid the interference of Hcy and GSH, we developed a fluorescent probe triarylimidazole-naphthalimide-piperazine-sulfonyl benzoxadiazole (TNP-SBD-Cl) based on fluorescence resonance energy transfer (FRET) on platform of naphthalimide-sulfonyl benzoxadiazole (SBD), the main SBD 4-chlorine groups have mild reactivity to undergo substitution and rearrangement to distinguish Hcy and GSH. The TNP-SBD-Cl response to Cys would turn on FRET and generate a new yellow fluorescence with a large Stokes shift (157 nm), and with excellent selectivity and low detection limit (0.87 μM). Moreover, TNP-SBD-Cl can be used to monitor Cys in living HeLa cells with low cytotoxicity, suggesting that it has markedly diagnostic significance in physiological and pathological processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel coumarin-based fluorescent probe with large Stokes shift (216 nm) is designed and synthesized. • The probe exhibits fast-response (<4s), high sensitivity and low detection limit (8.82 × 10−8 M) towards Cys. • The probe is successfully applied in living cells. A new fluorescence probe L , which featured with a large Stokes shift (216 nm), was designed for sensitive detection of cysteine (Cys) and a potential sensing mechanism derived from excited state intramolecular proton transfer (ESIPT) was proposed. More importantly, probe L exhibits higher selective to Cys than other amino acid due to its specific cyclization between acrylate group and Cys. Meanwhile, the probe L shows a low detection limit of 8.82 × 10−8 M, which is enough for detecting Cys in organisms. Furthermore, this probe displays high biocompatibility and can image Cys in living cells. [ABSTRACT FROM AUTHOR]

Cysteine has a great effect on the physiological and pathological processes, which could bring out various diseases such as skin lesions, edema, hair depigmentation, Alzheimer's, Parkinson's, and liver damage due to the abnormal concentrations of cysteine. Therefore, it is of great impoatance to develop a method for imaging Cys. Herein, a novel fluorescent probe was developed for imaging Cys in vivo specially. This turn-on probe exhibited favorable advantages including large Stokes shift (90 nm), fast response (10 min), good selectivity, low cytotoxicity and so on. Furthermore, the probe could be applied to monitoring cysteine in living HeLa cells, which indicates that this turn-on probe could penetrate viable cell membranes and image Cys over other analystes especially HCy and GSH. Unlabelled Image • A novel fluorescent probe NBDS was developed for imaging Cys in vivo specially exhibiting favorable advantages including large Stokes shift (90 nm), fast response (10 min), good selectivity, low cytotoxicity. • This turn-on probe exhibited favorable advantages including large Stokes shift (90 nm), fast response (10 min), good selectivity, low cytotoxicity. • In vivo cell imaging indicates that the probe NBDS could be suitable to reveal the vital role of Cys in various physiological processes. [ABSTRACT FROM AUTHOR]