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On base of the good optical properties of coumarin and fluorescein, we designed and synthesized two coumarin/fluorescein-fused fluorescent dyes ( CF dyes), which enlarged the emission wavelength and increased the Stokes shift of fluorescein moiety. The corresponding optical properties of CF dyes were investigated in detail. CF dyes could easily introduce other groups to design different functional molecules. CF dyes also exhibited rapid and sensitive responses to pH values in the range of 4.0–7.4 through the characterization of absorption and fluorescence spectra in buffer solution. More importantly, CF ethyl ester dye ( CFE dye) not only showed good cell membrane permeability and low cytotoxicity, but also had the ability to rapidly monitor mitochondrial pH changes in living cells. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe O-hNRSel based on tetralin-xanthene fused dye O-hNR was designed and synthesized by introducing 2,4-dinitrobenzenesulfonate functionality. This probe is able to detect selenocysteine (Sec) with rapid response time (2 min) and a large fluorescence enhancement at 624 nm (124-fold). O-hNRSel exhibited selective response to Sec over many other analy and high sensitivity with the detection limit as low as 17 nM. Furthermore, O-hNRSel has been used for fluorescent imaging of Sec in living cells with good biocompatibility. [ABSTRACT FROM AUTHOR]

The development of a fluorescent probe to distinguish between cysteine (Cys) and homocysteine (Hcy) is always a challenge owing to their structural similarity, and the simultaneous detection of Cys and Hcy by utilizing different emission channels is especially difficult. In this work, we designed and synthesized a new fluorescent probe to differentiate between Cys and Hcy on the basis of a coumarin derivative with a chlorine atom and an α,β-unsaturated aldehyde. Cys and Hcy induced different cascade reactions with the probe, which led to different products with distinct photophysical properties. The nonfluorescent probe responded to Cys and emitted strong blue fluorescence, whereas it reacted with Hcy and generated yellow fluorescence without interference from glutathione. In addition, the probe was successfully applied to distinguish between Cys and Hcy in living cells. [ABSTRACT FROM AUTHOR]

A fluorescent probe ( 1 ) for distinguishing amongst biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), is developed based on different cascade reactions. The key design feature of fluorescent probe 1 is the integration of two potential reaction groups for the thiol and amino groups of biothiols in one molecule. By reacting with the halogen atom and α, β-unsaturated malonitrile in probe 1 , Cys, Hcy and GSH can generate a total of three main products with distinct photophysical properties. Probe 1 shows a strong fluorescence turn-on response to Cys with blue–green emission by using an excitation wavelength of 390 nm. At an excitation wavelength of 500 nm, probe 1 responds to GSH over Cys and Hcy and emits strong orange fluorescence. The discrimination of biothiols can be demonstrated by cell imaging experiments, indicating that probe 1 can be a useful tool for the selective imaging of Cys and GSH in living cells. [ABSTRACT FROM AUTHOR]

More and more attention has been paid to the design of new fluorescent imaging agents with good photostability and water solubility, especially those with emissions in the deep-red and near-infrared regions. In this work, we designed and synthesized four novel fluorescent dyes with deep-red or NIR fluorescence by hybridizing coumarin and pyronin moieties based on our previous work. Introduction of carboxylic acid in the dyes not only imparted the dyes with water solubility but also provided a versatile sensing platform for designing the fluorescent probes and sensors of biomolecules. The photophysical properties of these new dyes were investigated through absorption and fluorescence spectroscopy. Cell imaging experiments showed that esterification products could selectively stain lysosomes with good photostability, thereby indicating that they could be useful in the development of fluorescent probes for bioimaging. [ABSTRACT FROM AUTHOR]