Impact of polyelectrolyte coating in fluorescent response of Eu(III)-containing nanoparticles on small chelating anions including nucleotides

© 2014 Elsevier B.V. The present work introduces a novel route to sense the permeability of the polyelectrolyte layer deposited onto luminescent core. The use of ternary Eu(III) complexes as the luminescent core enables to detect the permeability of the polyelectrolyte layers through the change of the Eu(III)-centered luminescence. The chelating anions, such as adenosine phosphates, glutamic acid and ethylenediaminetetraacetic acid disodium salt were used as substrates. The origin of the fluorescent response is the complex formation of the substrates with the Eu(III) complexes, which is greatly affected by the equilibrium concentration of the substrates at the surface of the core. The latter in turn is influenced by the permeability of the polyelectrolyte layer. The obtained results highlight the impact of the nature of the exterior layer in the penetration of the substrates through the negatively and positively charged polyelectrolyte layers

Extraction of lanthanum and gadolinium(III) at the cloud point using p-sulfonatocalyx[n]arenes as chelating agents

The extraction of gadolinium(III) and lanthanum(III) ions at the cloud point is studied in Triton X100 micellar solutions in a wide range of pH. In the absence of chelating agents, lanthanum(III) and gadolinium(III) ions are unselectively extracted at pH > 6. It is shown that the use of p-sulfonatothiacalyx[6(8)]arenes as chelating agents noticeably enhances the degree of extraction at pH 2-6. The composition and stability of lanthanum-p-sulfonatothiacalyx[n]arene complexes (n = 4, 6, 8) are estimated in a wide range of pH by pH-potentiometry. The degree of Gd3+ and La3+ ions extraction, which is performed at the cloud points employing calyxarene macrocycles of different sizes, is depended on the acidity of a medium. © 2009 Pleiades Publishing, Ltd

Nanoparticles based on gadolinium(iii) and europium(iii) complexes for biovisualization

© 2016, Springer Science+Business Media New York.Complexes Ln(TTA)3 and [Ln(TTA)3·1] (Ln = Eu, Gd; ТТА is thenoyltrifluoroacetyl-acetonate; 1 is 2-(5-chlorophenylene-2-hydroxy)-2-phenylethylene-bis(2-methoxy)phosphine oxide) in individual form, and as a part of a core of the polyelectrolyte stabilized colloids have been studied by Mössbauer spectroscopy and X-ray powder diffraction. The photophysical and colloidal characteristics of the solutions of polyelectrolyte nanoparticles were studied in water, artificial cerebrospinal fluid solution, solution of bovine serum albumin, and human blood serum. A stability of a luminescent response of the nanoparticles in solutions of bovine serum albumin and human blood serum at 37 °С for 2 hours has been revealed. This is a prerequisite for the potential application of studied nanoparticles for biovisualization

Fighting malaria without DDT : better management of the environment a key to disease control

French version available in IDRC Digital Library: Lutter contre le paludisme sans DDT : le contrôle de la maladie passe par une meilleure gestion de l'environnementSpanish version available in IDRC Digital Library: Combatiendo a la malaria sin DDT : mejor manejo ambiental, clave para el control de la enfermedadUnder the terms of the North American Free Trade Agreement, Mexico was committed to eliminating DDT use by 2002. The country’s malaria-control efforts, however, depended on this chemical. Researchers set about to develop alternate strategies by addressing factors that affect malaria’s spread: humans, mosquitoes, and the local environment in which the parasites persist. As a result of this integrated approach, Mexico was able to abandon DDT ahead of schedule

Hydration number: Crucial role in nuclear magnetic relaxivity of Gd(III) chelate-based nanoparticles

© 2017 The Author(s). Today, nanostructure-based contrast agents (CA) are emerging in the field of magnetic resonance imaging (MRI). Their sensitivity is reported as greatly improved in comparison to commercially used chelate-based ones. The present work is aimed at revealing the factors governing the efficiency of longitudinal magnetic relaxivity (r 1 ) in aqueous colloids of core-shell Gd(III)-based nanoparticles. We report for the first time on hyd ration number (q) of gadolinium(III) as a substantial factor in controlling r 1 values of polyelectrolyte-stabilized nanoparticles built from water insoluble complexes of Gd(III). The use of specific complex structure enables to reveal the impact of the inner-sphere hydration number on both r 1 values for the Gd(III)-based nanoparticles and the photophysical properties of their luminescent Tb(III) and Eu(III) counterparts. The low hydration of TTA-based Gd(III) complexes (q ≈ 1) agrees well with the poor relaxivity values (r 1 = 2.82 mM -1 s -1 and r 2 = 3.95 mM -1 s -1 ), while these values tend to increase substantially (r 1 = 12.41 mM -1 s -1 , r 2 = 14.36 mM -1 s -1 ) for aqueous Gd(III)-based colloids, when macrocyclic 1,3-diketonate is applied as the ligand (q ≈ 3). The regularities obtained in this work are fundamental in understanding the efficiency of MRI probes in the fast growing field of nanoparticulate contrast agents

Cloud point extraction of lanthanide(III) ions via use of Triton X-100 without and with water-soluble calixarenes as added chelating agents

The use of water-soluble calixarenes: p-sulfonato thiacalixarene (ST), tetra-sulfonatomethylated calix[4]resorcinarene (SR), calix[4]resorcinarene phosphonic acid (PhR) as chelating agents in cloud point extraction (CPE) of La(III), Gd(III) and Yb(III) ions using Triton X-100 as non-ionic surfactant is introduced. The data obtained indicate that both complexation ability and structure of calixarenes govern the extraction efficiency of lanthanides. In particular ST and SR, forming 1:1 lanthanide complexes with similar stability in aqueous media, exhibit different extractability when used as chelating agents in CPE. First synthesized PhR was found to be the most efficient chelating agent exhibiting pH-dependent selectivity within La(III), Gd(III) and Yb(III) in CPE. © 2005 Elsevier B.V. All rights reserved

Interfacial interactions of hard polyelectrolyte-stabilized luminescent colloids with substrates

© 2015 Elsevier B.V.. The present work introduces an origin of sensing function of polyelectrolyte-coated colloids based on Tb(III) complexes with calix[4]resorcinarene cavitand bearing four 1,3-diketone groups at the upper rim. The Tb(III)-centered luminescence of the colloids remains unchanged at pH 3-9, although the Tb(III) complexes are highly pH-dependent in DMF solutions. Both colloidal and luminescent properties of the colloids are stable within one month at least, which reveals stability of complex-based hard nanotemplates and soft polyelectrolyte deposition. The chelating substrates (catechol, tetracycline and fluoroquinolone derivatives) induce quick and reproducible luminescent response of the complex-based colloids without any detectable changes of their colloidal properties. The ternary complex formation at the interface of the colloids is the reason for their luminescent response on the substrates in aqueous solutions. Both the insolubility of the Tb(III)-containing cores and the shielding and/or buffer effect of the polyelectrolyte coating affect the interfacial complex formation, which results in more selective luminescent response of the colloids on the tetracycline and fluoroquinolone antibiotics in comparison with the complexes in solutions

The outer-sphere association of p-sulfonatothiacalix[4]arene with some Co(III) complexes: The effect on their redox activity in aqueous solutions

The effect of the ion-pairing of Co(III) complexes with p-sulfonatothiacalix[4]arene (STCA) on Fe(II)-Co(III) electron transfer rate was evaluated from the analysis and comparison of kinetic data in double Co(III)-Fe(II) and triple Co(III)-Fe(II)-STCA systems at various concentration conditions. Complexes [Co(en)3]3+(1), [Co(en) 2ox]+(2), [Co(dipy)3]3+ (3), [Co(His)2]+(4) and [Fe(CN)6]4- were chosen as Co(III) and Fe(II) compounds. The effect of STCA was found to correlate with the association mode. The outer-sphere association with STCA was found to exhibit the insignificant effect on Fe(II)-Co(III) electron transfer k et constants for complexes 3 and 4 with bulky and rigid chelate rings, while more sufficient inclusion of flexible ethylendiaminate rings of 1 and 2 into the cavity of STCA results in the unusual increase of k et. © 2007 Springer Science+Business Media, Inc

Spectral-luminescence and magnetic relaxation properties of lanthanide-p-sulfonatothiacalix[4]arenes in aqueous solution of surfactants

The influence of nonionogenic, anionic and cationic surfactants on the magnetic relaxation and luminescence properties of gadolinium(III), terbium(III), and dysprosium(III) complexes with p-sulfonatothiacalix[4]arene (TCAS) was studied. It was shown that the presence of both neutral and anionic surfactant does not influence the magnetic relaxation properties of GdTCAS as well as on the luminescence intensity of the TbTCAS and DyTCAS complexes. The presence of cationic surfactant at the concentration less than critical micellar concentration led to the formation of associates with stoichiometric composition with the Tb (Dy, Gd) TCAS complexes. These associates are characterized by more intensive luminescence, as compared to the initial TbTCAS and DyTCAS complexes. © 2008 Springer Science+Business Media, Inc

Phosphineoxide-Chelated Europium(III) Nanoparticles for Ceftriaxone Detection

The present work demonstrates the optimization of the ligand structure in the series of bis(phosphine oxide) and β-ketophosphine oxide representatives for efficient coordination of Tb3+ and Eu3+ ions with the formation of the complexes exhibiting high Tb3+- and Eu3+-centered luminescence. The analysis of the stoichiometry and structure of the lanthanide complexes obtained using the XRD method reveals the great impact of the bridging group nature between two phosphine oxide moieties on the coordination mode of the ligands with Tb3+ and Eu3+ ions. The bridging imido-group facilitates the deprotonation of the imido- bis(phosphine oxide) ligand followed by the formation of tris-complexes. The spectral and PXRD analysis of the separated colloids indicates that the high stability of the tris-complexes provides their safe conversion into polystyrenesulfonate-stabilized colloids using the solvent exchange method. The red Eu3+-centered luminescence of the tris-complex exhibits the same specificity in the solutions and the colloids. The pronounced luminescent response on the antibiotic ceftriaxone allows for sensing the latter in aqueous solutions with an LOD value equal to 0.974 μM