Solubilization and acidic and receptor properties of calix[4]resorcinarenes in aqueous solutions of oxyethylated dodecanol Brij-35

Solubilization of calix [4]resorcinarenes (Cn) with a varied length of hydrophobic substituents (R =Me, Pr, C5H11, C 7H15, C9H19, and C 11H23) in aqueous solutions of oxyethylated dodecanol Brij-35 was studied by the solubility method and 1D and 2D 1H NMR spectroscopy. The solubilization of Cn in micellar solutions of Brij-35 is caused by the formation of mixed Cn-Brij-35 aggregates and is weakened substantially with the elongation of R. It was shown by pH-metry and 1D 1H NMR spectroscopy that the receptor properties of the Cn anions toward the tetramethylammonium cations in the mixed aggregates differ substantially from those for the monomeric molecules in aqueous-organic and aqueous solutions. In particular, the binding of the tetramethylammonium cations does not result in screening of their N-Me fragments with the cyclophane cavity of the receptor. © 2005 Springer Science+Business Media, Inc

Self-assembly of Gd³⁺-bound keplerate polyanions into nanoparticles as a route for the synthesis of positive MRI contrast agents. Impact of the structure on the magnetic relaxivity

© The Royal Society of Chemistry. The present work introduces Gd3+ complexes with giant keplerate polyanions as a promising basis for MRI contrast agents. The impact of Gd3+ binding with different building blocks of keplerates on the magnetic relaxivity of the complexes is revealed by comparative study of the keplerates [{Mo6O21}12{Mo2O4(OAc)}30]42−, [{Mo6O21}12{Mo2O4(HPO4)}30]72−, and [{Mo6O21}12{Mo2O2S2(OAc)}30]42−. Unprecedentedly high longitudinal and transverse relaxivity values (up to 250 and 300 mM−1 s−1 correspondingly) are achieved for the keplerates possessing edl{Mo2O4(OAc)} and {Mo2O4(HPO42−)} moieties under their 1 : 1 complex formation with Gd3+. The transformation of the external pores from Mo9O9 to Mo9O6S3 in the {Mo2O2S2(OAc)}-keplerate and an increase in the Gd3+-to-keplerate ratio are the factors that decrease the relaxivity. The rapid degradation of the free keplerates in aqueous solutions restricts the use of the Gd3+-bound keplerates with 1 : 1 stoichiometry as MRI contrast agents. In this work, the optimized stoichiometry of the complexes, their self-assembly into ultra-small nanoparticles and their hydrophilic coating by a triblock copolymer are highlighted as tools for increasing both the colloid and chemical stability of the keplerate complexes. Optimal keplerate compositions have been identified to achieve a compromise of low cytotoxicity and high stability; these Gd3+-bound keplerates exhibit longitudinal and transverse relaxivity values (95 and 114 mM−1 s−1, respectively), well within the region of interest for MRI techniques

Supramolecular assemblies of triblock copolymers with hexanuclear molybdenum clusters for sensing antibiotics in aqueous solutions via energy transfer

The work introduces the supramolecular assembly of triblock copolymers, namely (PEO)13(PPO)30(PEO)13 (L64), (PPO) 14(PEO)24(PPO)14 (17R4), (PPO) 8(PEO)22(PPO)8 (10R5) and (PEO) 21(PPO)67(PEO)21 (P123) with novel cluster complexes [K(diglyme)(CH3CN)]2[Mo6I 14] (1) and [K2(diglyme)(CH3CN) 5][Mo6I14] (2) as a route to increase their water solubility. Dynamic light scattering and photophysical measurements reveal the decisive influence of the arrangement of PEO and PPO blocks and of their length on both colloidal and photophysical properties of these solutions. ES-MS data reveal [Mo6I14]2- clusters as the predominant form in aqueous solutions of L64 and P123. The steady state and time resolved luminescence data indicate concentration dependent sensitizing of the Mo-centered luminescence through the energy transfer from difloxacin to [Mo 6I14]2- mediated by the ion-pairing. The impact of both arrangement and length of PEO and PPO blocks in the luminescent response of [Mo6I14]2- to difloxacin is discussed. The aqueous solutions of L64 at pH 4 provide the optimal conditions for the sensing of difloxacin through the cluster luminescence. This journal is © the Partner Organisations 2014

Nanoscale hydrophilic colloids with high relaxivity and low cytotoxicity based on Gd(III) complexes with Keplerate polyanions

© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. The work introduces for the first time Mo-132-type Keplerates (Kp) and Gd 3+ ions as a basis for the one-pot synthesis of aqueous colloids with high longitudinal relaxivity (r 1 = 96.4 mM -1 s -1 at 20 MHz). The hydrophilic coating of small (3-5 nm) Gd x (Kp) y -based cores provides their colloid stabilization, protection from degradation and low cytotoxicity

The effect of temperature induced phase transitions in aqueous solutions of triblock copolymers and Triton X-100 on the EPR, magnetic relaxation and luminescent characteristics of Gd(III) and Eu(III) ions

The present report is inspired by the idea to develop novel spectroscopy based techniques to detect the phase transitions in solutions of triblock copolymers with the use of Gd(III) and Eu(III) ions as probes. The choice of (PEO)13(PPO)30(PEO)13 (L64), (PPO)14(PEO)24(PPO)14 (17R4), (PPO)8(PEO)22(PPO)8 (10R5) and Triton X-100 is conditioned by their phase transitions occurring in mild conditions. The cloud point extraction (CPE) data reveal the conditions (pH and chelating agent) where the binding of lanthanides with surfactant rich phase of triblock copolymers and Triton X-100 occurs. The effect of phase transitions in solutions of triblock copolymers on the temperature resolved line widths in EPR spectra of Gd(III) aqua ions and transverse relaxation rates of Gd(III) inner-sphere water protons depends on the architecture of triblock copolymers and pH conditions. The steady state luminescence of Eu(III) complexes with phosphine oxide in aqueous solutions of triblock copolymers and TX-100 is influenced by the temperature induced aggregation and phase separation in solutions of reverse triblock copolymers 17R4 and 10R5, while the effect of the aggregation is insignificant for L64. © 2012 Elsevier B.V

Sensing activity of cholinesterases through a luminescence response of the hexarhenium cluster complex [{Re<inf>6</inf>S<inf>8</inf>}(OH)<inf>6</inf>]^4-

© 2016 The Royal Society of Chemistry.The present work describes a new method to sense cholinesterase-catalyzed hydrolysis of acetylcholine (ACh) through a luminescence response of the hexarhenium cluster complex [{Re6S8}(OH)6]4-. A proton released from acetylcholinesterase (AChE)- or butyrylcholinesterase (BuChE)-catalyzed hydrolysis of ACh results in time-resolved sensitization of cluster-centered luminescence. The sensitization results from protonation of apical hydroxo-groups of the cluster complex. The protonation is affected by a counter ion effect. Thus, optimal conditions for adequate sensing of acetic acid produced by ACh hydrolysis are highlighted. Time-resolved luminescence and pH measurements under conditions of AChE-catalyzed hydrolysis of ACh show a good correlation between the cluster-centered luminescence and pH-induced inhibition of AChE. The inhibition is not significant within the first two minutes of ACh hydrolysis. Thus, the luminescence response measured within two minutes is dependent on both substrate and enzyme concentrations, which fits with AChE and BuChE kinetics. The usability of cluster-centered luminescence for monitoring the concentration-dependent inhibition of AChE with irreversible inhibitors is demonstrated, using a carbamylating agent, pyridostigmine bromide, as a model

Water transverse relaxation rates in aqueous dispersions of superparamagnetic iron oxide nanoclusters with diverse hydrophilic coating

The article introduces transverse relaxation rates of water protons in the aqueous hydrophilic colloids synthesized on the basis of the oleate-coated iron oxide nanoparticles (17. nm) with non-ionic and cationic surfactants, triblock copolymers, polyethyleneimine (PEI) and 4,5-dihydroxybenzene-1,3-disulfoacid disodium salt (Tiron) as hydrophilic components. The IR spectroscopy, atomic force and transmission electron microscopy, along with dynamic light scattering data were obtained to evaluate the content of the hydrophilic coating, the clustering of iron oxide nanoparticles within the hydrophilic covering and the aggregation of hydrophilic nanoclusters. The analysis of the obtained results together with transverse relaxation rates under various concentration, counter-ion and temperature conditions reveals the particular importance of the water molecules diffusion in the outer hydrophilic layer versus the nearest to the iron oxide core layer. The obtained results reveal the counter ion binding with the charged hydrophilic iron oxide colloids as a route to affect the water transverse relaxation rates by biorelevant anionic substrates such as adenosine triphosphates. © 2013 Elsevier B.V

COMPLICATED DIAGNOSIS: RETROPERITONEAL ALVEOCOCCOSIS IN THE GUISE OF ORMOND’S DISEASE

Diagnosis of parasitic diseases, in a type of their rarity and diversity, always presents considerable difficulties. Clinical observation of an alveococcosis with invasion in the retroperitoneal space with distribution on mediastinal fat proceeding with progressing retroperitoneal fibrosis with ureteral obstruction and hydronephrosis development, with an aorta lumen stenosis, with formation of SVC syndrome in the absence of changes in other parts of the body, first of all in the liver, in the absence of eosinophilia in the peripheral blood throughout all disease and lack of antibodies to echinococci in the blood serum, twice during observation determined by an immunofermental method is presented in this article

Solubilization and acidic and receptor properties of calix[4]resorcinarenes in aqueous solutions of oxyethylated dodecanol Brij-35

Solubilization of calix [4]resorcinarenes (Cn) with a varied length of hydrophobic substituents (R =Me, Pr, C5H11, C 7H15, C9H19, and C 11H23) in aqueous solutions of oxyethylated dodecanol Brij-35 was studied by the solubility method and 1D and 2D 1H NMR spectroscopy. The solubilization of Cn in micellar solutions of Brij-35 is caused by the formation of mixed Cn-Brij-35 aggregates and is weakened substantially with the elongation of R. It was shown by pH-metry and 1D 1H NMR spectroscopy that the receptor properties of the Cn anions toward the tetramethylammonium cations in the mixed aggregates differ substantially from those for the monomeric molecules in aqueous-organic and aqueous solutions. In particular, the binding of the tetramethylammonium cations does not result in screening of their N-Me fragments with the cyclophane cavity of the receptor. © 2005 Springer Science+Business Media, Inc