Search results for "Dyes"
showing 10 items of 324 documents
Highly Selective Detection of Nerve‐Agent Simulants with BODIPY Dyes
2014
Two chromo-fluorogenic probes, each based on the boron dipyrromethene core, have been developed for the detection of nerve-agent mimics. These chemosensors display both a color change and a significant enhancement of fluorescence in the presence of diethylcyanophosphonate (DCNP) and diisopropylfluorophosphate (DFP). No interference from other organophosphorus compounds or acids has been observed. Two portable chemosensor kits have been developed and tested to demonstrate its practical application in real-time monitoring.
[3.3]Ferrocenophanes with guanidine bridging units as multisignalling receptor molecules for selective recognition of anions, cations, and amino acid…
2007
The synthesis, electrochemical, and optical properties of a new [3.3]ferrocenophane framework in which two ferrocene subunits, with similar electronic environments, are linked through two substituted guanidine moieties, are reported. The receptors 4-7 have been prepared in good yields by the reaction of bis(carbodiimide) 3 with primary amines. This architecture is exceptionally "tunable" because a variety of "legs" may be appended to the basic [3.3]ferrocenophane scaffold to give a wide range of signaling units. These receptors show remarkable ion-sensing properties, due to the presence of a redox active unit (ferrocene), and an amphoteric binding site (guanidine). In this nitrogen-rich str…
Superoxide Flux in Endothelial Cells via the Chloride Channel-3 Mediates Intracellular Signaling
2007
Reactive oxygen species (ROS) have been implicated in both cell signaling and pathology. A major source of ROS in endothelial cells is NADPH oxidase, which generates superoxide (O2.−) on the extracellular side of the plasma membrane but can result in intracellular signaling. To study possible transmembrane flux of O2.−, pulmonary microvascular endothelial cells were preloaded with the O2.−-sensitive fluorophore hydroethidine (HE). Application of an extracellular bolus of O2.−resulted in rapid and concentration-dependent transient HE oxidation that was followed by a progressive and nonreversible increase in nuclear HE fluorescence. These fluorescence changes were inhibited by superoxide dism…
DNA fluorescence induced by polymethine cation pyrvinium binding
1991
Pyrvinium is a polymethine cation which shows interesting fluorescence emission and DNA binding properties. In diluted aqueous solution, pyrvinium pamoate induced a bright yellow fluorescence in kinetoplast DNA from Trypanosoma cruzi epimastigotes as well as in chicken erythrocyte nuclei under a wide range of excitations. No fading was observed after mounting in suitable media. Spectroscopic studies on pyrvinium solutions revealed bathochromic and hypochromic shifts in the absorption spectrum of its complex with DNA. A striking enhancement of pyrvinium fluorescence was found in solvents of high viscosity or after binding to DNA. Experimental results and the chemical structure of pyrvinium a…
Design, Synthesis and Evaluation of Enzyme-Responsive Fluorogenic Probes Based on Pyridine-Flanked Diketopyrrolopyrrole Dyes
2020
The ever-growing demand for fluorogenic dyes usable in the rapid construction of analyte-responsive fluorescent probes, has recently contributed to a revival of interest in the chemistry of diketopyrrolopyrrole (DPP) pigments. In this context, we have explored the potential of symmetrical and unsymmetrical DPP derivatives bearing two or one 4-pyridyl substituents acting as optically tunable group(s). The unique fluorogenic behavior of these molecules, closely linked to N-substitution/charge state of their pyridine unit (i.e., neutral pyridine or cationic pyridinium), has been used to design DPP-based fluorescent probes for detection of hypoxia-related redox enzymes and penicillin G acylase …
Generic Method for Modular Surface Modification of Cellulosic Materials in Aqueous Medium by Sequential Click-Reaction and Adsorption
2012
A generic approach for heterogeneous surface modification of cellulosic materials in aqueous medium, applicable for a wide range of functionalizations, is presented. In the first step, carboxymethyl cellulose (CMC) modified with azide or alkyne functionality, was adsorbed on a cellulosic substrate, thus, providing reactive sites for azide–alkyne cycloaddition click reactions. In the second step, functional units with complementary click units were reacted on the cellulose surface, coated by the click-modified CMC. Selected model functionalizations on diverse cellulosic substrates are shown to demonstrate the generality of the approach. The concept by sequentially combining the robust physic…
Sensory hybrid host materials for the selective chromo-fluorogenic detection of biogenic amines
2006
[EN] Pyrylium-containing mesoporous materials have been used for the chromo-fluorogenic sensing of biogenic amines in an aqueous environment.
Even free radicals should follow some rules: a guide to free radical research terminology and methodology.
2014
Free radicals and oxidants are now implicated in physiological responses and in several diseases. Given the wide range of expertise of free radical researchers, application of the greater understanding of chemistry has not been uniformly applied to biological studies. We suggest that some widely used methodologies and terminologies hamper progress and need to be addressed. We make the case for abandonment and judicious use of several methods and terms and suggest practical and viable alternatives. These changes are suggested in four areas: use of fluorescent dyes to identify and quantify reactive species, methods for measurement of lipid peroxidation in complex biological systems, claims of…
Afferent and efferent projections of the dorsal anterior thalamic nuclei in the lizard Podarcis hispanica (Sauria, Lacertidae).
2002
The aim of this study was to investigate the afferent and efferent connections of the anterior thalamic nuclei in the lizard Podarcis hispanica. To identify potential sources of sensory inputs and to determine the fine organization of the projections of these thalamic nuclei to the telencephalon, we injected the sensitive tracer biotinylated dextran amine (BDA) into different nuclei of the anterior dorsal thalamus. We also injected BDA into several telencephalic areas in order to corroborate the results of thalamic injections. Our results show that the anterior thalamic nuclei receive projections from multiple areas and nuclei distributed throughout most of the brain, from rhombencephalon t…
Flow Cytometric Analysis of Calcium Mobilization in Whole‐Blood Platelets
2003
Flow cytometry provides a convenient method to evaluate platelet activation by following the kinetics of intracellular free Ca2+, using sensitive fluorescent indicators that can be loaded into intact cells. Moreover, in the clinical setting, whole-blood techniques have obvious advantages to avoid artifactual platelet activation and allow the maintenance of near-physiological conditions. This unit describes a fast and sensitive flow cytometric procedure using the Ca2+-sensitive dye fluo-3 AM and the platelet-specific antibody CD41-PE to determine the kinetics of intracellular Ca2+ mobilization in whole-blood platelets with minimal manipulation of the samples. The technique may be applied to …