Europium(III) complex-functionalized magnetic nanoparticle as a chemosensor for ultrasensitive detection and removal of copper(II) from aqueous solution

Ultrasensitive, accurate detection and separation of heavy metal ions is very important in environmental monitoring and biological detection. In this paper, a highly sensitive and specific detection method for Cu(2+) based on the fluorescence quenching of a europium(III) hybrid magnetic nanoprobe is presented. This nanoprobe can detect Cu(2+) over a wide pH range (5.0-10.0) with a detection limit as low as 0.1 nM and it can be used for detecting Cu(2+) in living cells. After the magnetic separation, the Cu(2+) concentration decreased to 1.18 ppm, which is less than the US EPA drinking water standard (1.3 ppm), and more than 70% Cu(2+) could be removed when the amount of nanocomposite 1 reached 1 mg.

A ratiometric fluorescent probe based on a coumarin-hemicyanine scaffold for sensitive and selective detection of endogenous peroxynitrite

In the study described herein, the red emitting probe CHCN, which possesses a linked coumarin-hemicyanine scaffold, was developed for detection of peroxynitrite (ONOO(-)) under physiological conditions. The studies show that CHCN displays a dual ratiometric and colorimetric response to ONOO(-) that is caused by an oxidation process. A possible mechanism of this oxidation process was proposed and confirmed by ESI-MS spectra for the first time. CHCN shown highly selective and sensitive towards ONOO(-) with a low limit of detection LOD (49.7 nM). Moreover, CHCN has appreciable cell permeability and, as a result, it is applicable to ratiometric detection of exogenous and endogenous ONOO(-) in living cells during phagocytic immune response. We anticipate that, owing to their ideal properties, probes of this type will find great use in explorations of the role played by ONOO(-) in biology.

Near-infrared fluorescent probe for detection of thiophenols in water samples and living cells

The development of probes for rapid, selective, and sensitive detection of the highly toxic thiophenols is of great importance in both environmental and biological science. Despite the appealing advantages of near-infrared (NIR) fluorescent detection, no NIR fluorescent probes have been reported for thiophenols to date. Using the chemical properties of thiophenols that are able to cleave sulfonamide selectively and efficiently under mild conditions, we herein report a dicyanomethylene-benzopyran (DCMB)-based NIR fluorescent probe for thiophenols. This probe features remarkable large Stokes shift and shows a rapid, highly selective, and sensitive detection process for thiophenols with significant NIR fluorescent turn-on responses. The potential applications of this new NIR fluorescent probe were demonstrated by the quantitative detection of thiophenol in real water samples and by fluorescent imaging of thiophenol in living cells.

Tunable heptamethine-azo dye conjugate as an NIR fluorescent probe for the selective detection of mitochondrial glutathione over cysteine and homocysteine

Although a lot of mitochondria-targeting biothiol probes have been developed and applied to cellular imaging through thiol-induced disulfide cleavage or Michael addition reactions, relatively few probes assess mitochondrial GSH with high selectivity over Cys and Hcy and with NIR fluorescence capable of noninvasive imaging in biological samples. In order to monitor mitochondrial GSH with low background autofluorescence, we designed a heptamethine-azo conjugate as an NIR fluorescent probe by introducing a tunable lipophilic cation unit as the biomarker for mitochondria and a nitroazo group as the GSH-selective reaction site as well as the fluorescence quencher. The probe exhibited a dramatic off-on NIR fluorescence response toward GSH with high selectivity over other amino acids including Cys and Hcy. Further application to cellular imaging indicated that the probe was highly responsive to the changes of mitochondrial GSH in cells.

Cyanine-based fluorescent probe for highly selective detection of glutathione in cell cultures and live mouse tissues

Glutathione (GSH) plays a crucial role in human pathologies. Near-infrared fluorescence-based sensors capable of detecting intracellular GSH in vivo would be useful tools to understand the mechanisms of diseases. In this work, two cyanine-based fluorescent probes, 1 and 2, containing sulfonamide groups were prepared. Evaluation of the fluorescence changes displayed by probe 1, which contains a 2,4-dinitrobenzenesulfonamide group, shows that it is cell-membrane-permeable and can selectively detect thiols such as GSH, cysteine (Cys), and homocysteine (Hcy) in living cells. The response of 1 to thiols can be reversed by treatment with N-methylmaleimide (NMM). Probe 2, which possesses a 5-(dimethylamino)naphthalenesulfonamide group, displays high selectivity for GSH over Cys and Hcy, and its response can be reversed using NMM. The potential biological utility of 2 was shown by its use in fluorescence imaging of GSH in living cells. Furthermore, probe 2 can determine changes in the intracellular levels of GSH modualated by H2O2. The properties of 2 enable its use in monitoring GSH in vivo in a mouse model. The results showed that intravenous injection of 2 into a mouse generates a dramatic image in which strong fluorescence is emitted from various tissues, including the liver, kidney, lung, and spleen. Importantly, 2 can be utilized to monitor the depletion of GSH in mouse tissue cells promoted by excessive administration of the painkiller acetaminophen. The combined results coming from this effort suggest that the new probe will serve as an efficient tool for detecting cellular GSH in animals.

In vivo and in situ tracking cancer chemotherapy by highly photostable NIR fluorescent theranostic prodrug

In vivo monitoring of the biodistribution and activation of prodrugs is urgently required. Near infrared (NIR) fluorescence-active fluorophores with excellent photostability are preferable for tracking drug release in vivo. Herein, we describe a NIR prodrug DCM-S-CPT and its polyethylene glycol-polylactic acid (PEG-PLA) loaded nanoparticles as a potent cancer therapy. We have conjugated a dicyanomethylene-4H-pyran derivative as the NIR fluorophore with camptothecin (CPT) as the anticancer drug using a disulfide linker. In vitro experiments verify that the high intracellular glutathione (GSH) concentrations in tumor cells cause cleavage of the disulfide linker, resulting in concomitantly the active drug CPT release and significant NIR fluorescence turn-on with large Stokes shift (200 nm). The NIR fluorescence of DCM-S-CPT at 665 nm with fast response to GSH can act as a direct off-on signal reporter for the GSH-activatable prodrug. Particularly, DCM-S-CPT possesses much better photostability than ICG, which is highly desirable for in situ fluorescence-tracking of cancer chemotherapy. DCM-S-CPT has been successfully utilized for in vivo and in situ tracking of drug release and cancer therapeutic efficacy in living animals by NIR fluorescence. DCM-S-CPT exhibits excellent tumor-activatable performance when intravenously injected into tumor-bearing nude mice, as well as specific cancer therapy with few side effects. DCM-S-CPT loaded in PEG-PLA nanoparticles shows even higher antitumor activity than free CPT, and is also retained longer in the plasma. The tumor-targeting ability and the specific drug release in tumors make DCM-S-CPT as a promising prodrug, providing significant advances toward deeper understanding and exploration of theranostic drug-delivery systems.

A fluorescent probe for site I binding and sensitive discrimination of HSA from BSA

A fluorescent HSA probe is designed and successfully utilized to detect trace HSA in healthy human urine.

s-Tetrazines functionalized with phenols: synthesis and physico-chemical properties

s-Tetrazines functionalized with phenols substituted by electron withdrawing or electron donating groups have been synthesized.

A highly selective long-wavelength fluorescent probe for the detection of human carboxylesterase 2 and its biomedical applications

A highly selective long-wavelength fluorescent probe for the detection of human carboxylesterase 2 (hCE2) has been developed and well characterized. The probe can be used for measuring the real activities of hCE2 in complex biological systems.

A novel fluorescent pH probe with valuable pKabased on a twisted intramolecular charge transfer mechanism, and its applications in cell imaging

A novel TICT-mechanism based pH probe with valuable pK_aof 5.32 has been developed. It is a promising visualizing agent for lysosomes in intracellular application.

A BODIPY-based reactive probe for the detection of Au(iii) species and its application to cell imaging

A BODIPY-based chemodosimeter for turn-on detection of gold ions which relies on a novel CN bond hydrolysis mechanism.

Zn(II)-coordination modulated ligand photophysical processes - the development of fluorescent indicators for imaging biological Zn(II) ions

Molecular photophysics and metal coordination chemistry are the two fundamental pillars that support the development of fluorescent cation indicators. In this article, we describe how Zn(II)-coordination alters various ligand-centered photophysical processes that are pertinent to developing Zn(II) indicators. The main aim is to show how small organic Zn(II) indicators work under the constraints of specific requirements, including Zn(II) detection range, photophysical requirements such as excitation energy and emission color, temporal and spatial resolutions in a heterogeneous intracellular environment, and fluorescence response selectivity between similar cations such as Zn(II) and Cd(II). In the last section, the biological questions that fluorescent Zn(II) indicators help to answer are described, which have been motivating and challenging this field of research.

Colorimetric and near infrared fluorescent detection of cyanide by a new phenanthroimidazole–indolium conjugated probe

A new dual colorimetric and fluorescent probe was developed for rapid detection of cyanide anions with high selectivity and sensitivity.

Bio-imaging with neutral luminescent Pt(ii) complexes showing metal⋯metal interactions

Self-assembled platinum compounds resulting in stable, highly emissive and long-lived species are reported for cell imaging.

A colorimetric and near-infrared fluorescent probe for biothiols and its application in living cells

A new highly selective and sensitive colorimetric and NIR fluorescent probe for detection and bioimaging of biothiols was reported.

Ion responsive near-IR BODIPY dyes: two isomers, two different signals

Different responses of two isomeric tetrastyryl-BODIPY's were studied, shedding light on the path to near IR sensors for metal ions.

Photophysical properties of an unusual bichromophoric species constructed from a cyclometalated Pt(ii) chromophore and a blue Bodipy-acetylacetonate species

Complex 1 exhibits a formally forbidden energy transfer from the metal-based triplet to the fluorescent Bodipy singlet state.