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A new fluorescence probe L was rationally designed and synthesized for the recognition of Cu2+ ions by the combination of coumarin hydrazide and 2-acetylpyrazine. The photochemical properties and selectivity of L for Cu2+ ions in a CH3CN/HEPES (3 : 2, v/v) buffer were investigated by UV-vis absorption and fluorescence emission spectra. A highly selective and sensitive response of L for Cu2+ ions over other competing metal ions was observed with limit of detection in 3 μM. The coordination stoichiometry of L to Cu2+ ions was determined to be 1 : 1 by the UV-vis absorption spectrum, the fluorescence titrations, and density functional theory (DFT) calculations. Moreover, L was applied successfully for recognition of intracellular Cu2+ ions in living cells. [ABSTRACT FROM AUTHOR]

Effective discrimination of cysteine (Cys) from biothiols and other amino acids has gained increasing attention due to the essential roles of this molecule in biological systems. In this work, we report a new strategy for the detection of Cys in aqueous media and live cells using a simple Cu2+ ensemble (L–Cu2+). A coumarin–salicylaldehyde hydrazone fluorescent ligand (L) was initially synthesized and well characterized. L features high affinity towards Cu2+ (Ka = 1.995 × 106 M−1), accompanied by effective quenching of fluorescence in HEPES buffer. The in situ generated chemosensing ensemble, L–Cu2+, is able to specifically respond to Cys over other biothiols and amino acids through a displacement approach. As a result, a remarkable recovery of fluorescence and UV-vis absorption spectra can be observed. L–Cu2+ showed high selectivity and sensitivity towards Cys. The detection limit is estimated to be 15 nM. Using L–Cu2+ as the fluorescent probe, imaging of Cys in live A549 cells was successfully demonstrated. [ABSTRACT FROM AUTHOR]

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]

Copper, as the third most abundant transition metal ions of human, plays an essential role in the redox reaction, signal transduction, hematopoiesis, and other physiological processes. Abnormal content of copper ions in the body will cause some diseases such as anemia, coronary heart disease, Menkes’ syndrome. In this article, a new fluorescence probe L for Cu2+ was designed and synthetized by using 4-bromo-1,8 naphthalene anhydride and 2-thiophene formaldehyde as raw materials. Fluorescent probe L itself exhibited strong fluorescence, upon the addition of Cu2+ ions, the fluorescence was quenched. The fluorescent detection limit for Cu2+ ions was determined to be 1.8 μM based on a 3δ/S method. UV-vis absorption and fluorescence spectra indicated that probe L showed good selectivity and sensitivity for Cu2+, and this selectivity was not interfered by other metal ions and anions. Further cell fluorescence imaging experiments indicated that the probe L had potential to be used to examine copper ions in vivo. [ABSTRACT FROM AUTHOR]

By the incorporation of coumarin fluorophores within the benzyldihydrazone moiety and by carefully adjusting the redox potential of the fluorophore and its excited state energy, one of the brightest Cu2+-binding sensors in aqueous media was achieved and could be used for the detection of Cu2+in living cells. [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]

A fluorescence "turn-on" probe for Cu (Ⅱ) ions was prepared based on the condensation reaction of coumaraldehyde and 1-hydroxy-2-acetylnaphthalene. A strong fluorescent flavonoid intermediate was formed and verified by the NMR and ESI-MS experiments. The water-soluble and pH dependence experiments were performed to confirm the optimal solvent condition (CH 3 CN: HEPES = 1:1, v/v, pH = 7.2–7.4). The dynamic experiments indicated that the formation process of the intermediate catalyzed by Cu(Ⅱ) ions was probably pseudo-first-order reaction process. The probe showed good selectivity toward copper ions and almost no interference except Ag+ ions by the selectivity and competitive experiments. The HeLa cells were used in the cell fluorescence imaging tests and it was demonstrated that the probe could be used in the phycological condition and showed weak cytotoxicity by the MTT experiments. [Display omitted] • A Cu2+ ions biosensor was constructed by the condensation reaction of coumaraldehyde and 1-hydroxy-2-acetylnaphthalene. • The probe exhibited high selectivity for Cu2+ and could not be disturbed even if high concentration of GSH existed. • The mechanism probably involved the procedure of copper-mediated cyclization to generate the flavonoid intermediate. • The probe can be used to detect Cu2+ ions in physiological environment proven by the cell image experiments. [ABSTRACT FROM AUTHOR]