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A highly selective copper ions fluorescent probe based on the coumarin-type Schiff base derivative 1 (probe) was produced by condensation reaction between coumarin carbohydrazide and 1H-indazole-3-carbaldehyde. The UV–vis spectroscopy showed that the maximum absorption peak of compound 1 appeared at 439 nm. In the presence of Cu 2 + ions, the maximum peak decreased remarkably compared with other physiological important metal ions and a new absorption peak at 500 nm appeared. The job's plot experiments showed that complexes of 1:2 binding mode were formed in CH 3 CN:HEPES (3:2, v/v) solution. Compound 1 exhibited a strong blue fluorescence. Upon addition of copper ions, the fluorescence gradually decreased and reached a plateau with the fluorescence quenching rate up to 98.73%. The detection limit for Cu 2 + ions was estimated to 0.384 ppm. Fluorescent microscopy experiments demonstrated that probe 1 had potential to be used to investigate biological processes involving Cu 2 + ions within living cells. [ABSTRACT FROM AUTHOR]

Glutathione is the most abundant non-protein thiols compound in cells and plays important metabolic roles. Changes in the amount of glutathione or its metabolic dysregulation can lead to a series of diseases. The determination of glutathione levels is very helpful to the diagnosis and treatment of the related diseases. A coumarin schiff base (compound 1 ) was synthesized from coumarin hydrazide and 2,6-pyridine dicarboxaldehyde and the fluorogenic probe for thiols (compound 1-Cu 2+ ) was prepared by coordinating compound 1 with copper ions. Compound 1 showed strong fluorescence, while compound 1-Cu 2+ hardly had fluorescence due to the paramagnetism and/or photoinduced electron transfer of Cu 2+ . However, after the addition of thiols-containing compounds, the fluorescence of compound 1 was restored. The UV–vis absorption and fluorescence spectra indicated that the fluorogenic probe had good thiols selectivity and sensitivity, particularly for glutathione in CH 3 CN:HEPES (3:2, v/v) buffer. It was successfully applied to the fluorescence imaging detection of glutathione in human cervical squamous cancer cells (SiHa cells). [ABSTRACT FROM AUTHOR]

Small-molecule thiols, such as cysteine (CYS) and glutathione (GSH), are essential for maintaining the cellular redox environment and play important roles in regulating various cellular physiological functions. A fluorescence probe (compound 1-Cu2+) for thiols based on coumarin carbohydrazide dinuclear copper complex was developed. Compound 1 was synthesized from the reaction of 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide with 4-tert-butyl-2,6- diformylphenol. Accordingly, the copper complex (compound 1-Cu2+) was prepared by mixing compound 1 with 2 equivalents copper ions. Compound 1 had strong fluorescence while compound 1-Cu2+ hardly possessed fluorescence owing to the quenching nature of paramagnetism Cu2+ to the fluorescence molecule excited state. However, the fluorescence intensity of compound 1-Cu2+ was increased dramatically after the addition of thiol-containing amino acids, but not the other non-sulfhydryl amino acids. UV-vis absorption and fluorescence spectra indicated that compound 1-Cu2+ had good selectivity and sensitivity for thiols such as glutathione in CH3CN:H2O (3:2, v/v) PBS solution. The fluorescence imaging experiments implied that compound 1-Cu2+ has potential application in thiol-containing amino acids detection in living cells. [ABSTRACT FROM AUTHOR]

Abstract: A system based on FRET mechanism, comprising a coumarin donor and a rhodamine acceptor, was developed for the selective and quantitative detection of metal ions. Fluorescent chemosensors RCs, linked by 1,2-diethylamine, exhibit significant fluorescence enhancement and excellent selectivity toward Cu2+. Fluorescent probes CRB and CR6G, linked by hydrazide, function as ratiometric receptors for Cu2+ chromogentically and fluorogentically in organic-aqueous media. Furthermore, the characteristic rhodamine-based fluorescence response of CRB (excitation at 550 nm) exhibits high selectivity for Hg(II). The construction of this kind of universal FRET system opens a broader prospect for future design of ratiometric fluorescent probes. [ABSTRACT FROM AUTHOR]

• A novel probe for endogenous GSH was produced based on the coumarin derivative. • The probe exhibited high selectivity for GSH with the detection limit of 0.12 μM. • The fluorescence "turn on" of the probe is depended on de-metallization process. • The probe could be used to detect GSH in the HepG2 cells by fluorescence image. Discrimination and quantification of intracellular biothiols, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH) under physiological conditions is significant for academic research and disease diagnosis. A new fluorescent probe (complex 1 -Cu2+) for discriminate detection of GSH was prepared by copper ions coordinate with coumarin carbohydrazide Schiff base derivative 1. In suitable buffer solution (CH 3 CN: HEPES = 3:2, v/v) and under appropriate pH condition (pH = 7.2–7.4), the UV–vis spectroscopy experiments showed that compound 1 and copper ion exhibited a 1:1 ratio binding mode and moderate binding ability. Fluorescence quenching of compound 1 was observed when it complexed with Cu2+ ions. An obviously fluorescence restoration appeared after addition of GSH to the solution of probe, which also exhibited a highly selectivity relative to cysteine (Cys) and homocysteine (Hcy) in the amino acid competitive experiments. The minimum detection limit was calculated to 0.12 μM by fluorescent method, which was distinctly below the physiological concentration of GSH in live cells. Its biological application to detect the endogenous GSH was further proved by the HepG2 cell fluorescence image test. [ABSTRACT FROM AUTHOR]