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Hydrogen sulfide (H 2 S) plays an important role as a signaling compound (gasotransmitter) in living systems. However, the development of an efficient imaging chemosensor of H 2 S in live animals is a challenging field for chemists. Herein, a novel peptide-based fluorescence chemosensor L -Cu was designed and synthesized on the basis of the copper chelating with the peptide ligand (FITC–Ahx–Ser–Pro–Gly–His–NH 2 , L ), and its H 2 S sensing ability has been evaluated both in living cells and zebrafish. The peptide backbone and Cu 2+ -removal sensing mechanism are used to deliver rapid response time, high sensitivity, and good biocompatibility. After a fast fluorescence quench by Cu 2+ coordinated with L , the fluorescence of L is recovered by adding S 2− to form insoluble copper sulfide in aqueous solution with a detection limit for hydrogen sulfide measured to be 31 nM. Furthermore, the fluorescence chemosensor L -Cu showed excellent cell permeation and low biotoxicity to realize the intracellular biosensing, L -Cu has also been applied to image hydrogen sulfide in live zebrafish larvae. We expect that this peptide-based fluorescence chemosensor L -Cu can be used to study H 2 S-related chemical biology in physiological and pathological events. [ABSTRACT FROM AUTHOR]

A new biocompatible fluorescent receptor 1 was synthesized by conjugating diaminomaleonitrile (DMN) with benzothiazole unit, and characterized by single X-ray. In DMF/water (1:1, v/v ), the receptor 1 showed a selectivity turn-on fluorescence at 517 nm in the presence of CN − . Receptor 1 showed a detection limit down to 0.16 µM without any interference from other tested anions. The reversibility and reusability of 1 for the detection of CN − ion was also tested for five cycles indicating the probe 1 could be used in a reversible manner. Importantly, the receptor 1 showed excellent cells viability and was successfully applied for the detection of CN − in live mouse fibroblast cells L929 cells. [ABSTRACT FROM AUTHOR]

A new complex between coumarin-based ligand ( CL ) and copper ion has been prepared and applied to be an ON–OFF–ON reversible fluorescence chemosensor for the detection of Cys with high sensitivity and specificity. In HEPES buffer, CL displayed high affinity towards Cu 2+ ion over other physiological and environmental metal ions, accompanied with a 98.4% of fluorescence quenching. In the presence of Cys, the detachment of Cu 2+ ion of CL –Cu 2+ ensemble led to the liberation of the fluorophore, CL , and thus fluorescence was recovered. The results of absorption and emission spectroscopy analyses confirmed that the fluorescence turn ON response of CL –Cu 2+ ensemble was selective towards Cys only with high sensitivity (detection of limit, 7.2×10 −7 M). Confocal microscopy studies indicated that the lipophilic CL targets the endoplasmic reticulum (ER) of live cells, where it could be functioned as a fluorescent chemosensor for visualization of Cys in this organelle. Quantitative fluorescence detection of Cys in ER was successfully realized by flow cytometry analysis. The developed chemosensor was further applied to detect Cys in real urine samples with great recoveries ranges from 95.41% to 107.40%. [ABSTRACT FROM AUTHOR]

A novel multifunctional peptide fluorescent chemosensor ( DP-3 ) with a lysine backbone and double sides conjugated with histidine and dansyl groups has been designed and synthesized by solid phase synthesis. This chemosensor is a promising analytical tool for detecting Zn 2+ , Cu 2+ , and S 2− based on different mechanisms in 100% aqueous solutions, and intracellular biosensing has been successfully actualized. The peptide beacon structure of DP-3 makes it more stable and capable of achieving multianalyte detection, especially for sulfide ions. Until now, there have been few examples of using a peptide fluorescent chemosensor to detect anions with a continuous method. As designed, DP-3 exhibits excellent cell permeation and low biotoxicity and displays high selectivity and sensitivity, with Zn 2+ and Cu 2+ detection limits of 82 nM and 78 nM, respectively. This study raises the new possibility of a highly selective peptide fluorescent chemosensor for multifunctional detection, including cation and anions, by different mechanisms in environmental and biological systems. We expect that this work will inspire the development of a multifunctional beacon peptide-based fluorescent chemosensor library using modifiable lateral and terminal groups for a variety of practical applications in physiological and pathological events. [ABSTRACT FROM AUTHOR]

An electronically active and spectral sensitive fluorescent "turn-on" chemosensor (BTP-1) based on the benzo-thiazolo-pyrimidine unit was designed and synthesized for the highly selective and sensitive detection of Fe3+ from aqueous medium. With Fe3+, the sensor BTP-1 showed a remarkable fluorescence enhancement at 554nm (λex=314nm) due to the inhibition of photo-induced electron transfer. The sensor formed a host-guest complex in 1:1 stoichiometry with the detection limit down to 0.74nM. Further, the sensor was successfully utilized for the qualitative and quantitative intracellular detection of Fe3+ in two liver cell lines i.e., HepG2 cells (human hepatocellular liver carcinoma cell line) and HL-7701 cells (human normal liver cell line) by a confocal imaging technique. [ABSTRACT FROM AUTHOR]

A new Zn2+ selective chemosensor (3) was synthesized by condensation of commercially available substituted salicylaldehyde and isonicotinohydrazide, and characterized by single crystal X-ray crystallography. Receptor 3 with Zn2+ exhibited a highly selective and pronounced enhancement in the fluorescence emission among different cations by forming a 2:1 complex. The receptor can detect Zn2+ up to nanomolar level (6.75nM) with good tolerance of other metal ions and can be used for in vitro cellular imaging. [ABSTRACT FROM AUTHOR]

Abstract: Time-resolved luminescence detection technique using lanthanide chelates as luminescent probes or sensors is a highly sensitive and widely used tool for the luminescence detections of various biological and bioactive molecules. The essential of this technique is the developments of various functional luminescent probes or sensors that can selectively recognize the biological targets. In this work, a dual-chelating ligand N,N,N1,N1-{2,6-bis(3′-aminomethyl-1′-pyrazolyl)-4-[N,N-bis(2-picolyl)amino-methylenepyridine]} tetrakis(acetic acid) (BBATA) has been designed and synthesized. The luminescence of its Tb3+ chelate is very weak, but can be selectively and strongly enhanced upon reaction with Zn2+ ions. Thus a Tb3+ chelate-based luminescent chemosensor, BBATA-Tb3+, for highly selective and sensitive time-resolved luminescence detection of Zn2+ ions was developed. To confirm the utility of new chemosensor for the detection of intracellular Zn2+ ions, the performance of BBATA-Tb3+ as a chemosensor for time-resolved luminescent imaging detection of Zn2+ ions in living cells was investigated. The results demonstrated the efficacy and advantage of the new luminescent chemosensor for time-resolved luminescence detection of intracellular Zn2+ ions. [Copyright &y& Elsevier]