Search results for "Sulfonate"
showing 10 items of 447 documents
CCDC 960138: Experimental Crystal Structure Determination
2013
Related Article: Mainak Mitra, Julio Lloret-Fillol, Matti Haukka, Miquel Costas, Ebbe Nordlander|2014|Chem.Commun.|50|1408|doi:10.1039/C3CC47830K
Development of an ion-pair to improve the colon permeability of a low permeability drug: Atenolol.
2016
Abstract To ensure the optimal performance of oral controlled release formulations, drug colon permeability is one of the critical parameters. Consequently developing this kind of formulations for low permeability molecules requires strategies to increase their ability to cross the colonic membrane. The objective of this work is to show if an ion-pair formation can improve the colon permeability of atenolol as a low permeability drug model. Two counter ions have been tested: brilliant blue and bromophenol blue. The Distribution coefficients at pH 7.00 (DpH7) of atenolol, atenolol + brilliant blue and atenolol + bromophenol blue were experimentally determined in n-octanol. Moreover, the colo…
Ion-pair approach coupled with nanoparticle formation to increase bioavailability of a low permeability charged drug.
2018
Abstract Atenolol is a drug widely used for the treatment of hypertension. However, the great drawback it presents is a low bioavailability after oral administration. To obtain formulations that allow to improve the bioavailability of this drug is a challenge for the pharmaceutical technology. The objective of this work was to increase the rate and extent of intestinal absorption of atenolol as model of a low permeability drug, developing a double technology strategy. To increase atenolol permeability an ion pair with brilliant blue was designed and the sustained release achieved through encapsulation in polymeric nanoparticles (NPs). The in vitro release studies showed a pH-dependent relea…
Azo-Dyes Photocatalytic Degradation in Aqueous Suspension of TiO2 Under Solar Irradiation
2002
Abstract The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C14H14N3SO3Na) and orange II (C16H11N2SO4Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO2 irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almeria” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediate…
Involvement of carboxyl groups in chloride transport and reversible DIDS binding to band 3 protein in human erythrocytes
2011
AbstractNoncovalent DIDS binding to Band 3 (AE1) protein in human erythrocyte membranes, modified by non-penetrating, water soluble 1-ethyl-3-(4-azonia-4,4-dimethylpentyl)-carbodiimide iodide (EAC), was studied at 0°C in the presence of 165 mM KCl. Under experimental conditions applied up to (48 ± 5) % of irreversible chloride self-exchange inhibition was observed. The apparent dissociation constant, KD, for “DIDS-Band 3” complex, determined from the chloride transport experiments, was (34 ± 3) nM and (80 ± 12) nM for control and EAC-treated resealed ghosts, respectively. The inhibition constant, Ki, for DIDS was (35 ± 6) nM and (60 ± 8) nM in control and EAC-treated ghosts, respectively. T…
Refractive Indices and Deviations in Refractive Indices for Binary Mixtures of 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate with Methanol, E…
2009
Refractive indices of the binary mixtures of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]) with methanol, ethanol, 1-propanol, and 2-propanol were experimentally measured over the whole range of compositions at T = (288.15 to 338.15) K and atmospheric pressure. From the experimental data, deviations in refractive indices have been calculated and fitted to an extended version of the Redlich−Kister equation, which takes into account the dependence on composition and temperature simultaneously. This dependence has been discussed. The deviations are always positive, and their extent follows the sequence methanol > ethanol > 2-propanol > 1-propanol, increasing when tem…
Isobaric Vapor−Liquid Equilibria for Ethyl Acetate + Ethanol + 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate at 100 kPa
2007
Isobaric vapor−liquid equilibria for the binary systems ethyl acetate + ethanol, ethyl acetate + 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]), and ethanol + [emim][triflate] as well as the vapor−liquid equilibria for the ethyl acetate + ethanol + [emim][triflate] ternary system have been obtained at 100 kPa using a recirculating still. NRTL fitting parameters for the ethyl acetate + ethanol and ethanol + [emim][triflate] systems were calculated. The measured ternary data were correlated using the Mock electrolyte NRTL model, which reproduces reasonably well the experimental values. The results suggest that the addition of [emim][triflate] to the ethyl acetate + e…
A multicommuted stop-flow system employing LEDs-based photometer for the sequential determination of anionic and cationic surfactants in water
2006
It has been developed an automatic stop-flow procedure for sequential photometric determination of anionic and cationic surfactants in a same sample of water. The flow system was based on multicommutation process that was designed employing two solenoid micro-pumps and six solenoid pinch valves, which under microcomputer control carry out fluid propelling and reagent solutions handling. A homemade photometer using a photodiode as detector and two light emitting diodes (LEDs) with emission at 470 nm (blue) and 650 nm (red) as radiation sources, which was tailored to allow the determination of anionic and cationic surfactants in waters. The procedure for anionic surfactant determination was b…
A fluorescent molecular sensor for pH windows in traditional and polymeric biocompatible micelles: comicellization of anionic species to shift and re…
2011
A new approach is presented to obtain fluorescent sensors for pH windows that work in water and under biomimetic conditions. A single molecule that features all-covalently linked components is used, thus making it capable of working as a fluorescent sensor with an OFF/ON/OFF response to pH value. The components are a tertiary amine, a pyridine, and a fluorophore (pyrene). The forms with both protonated bases or both neutral bases quench the pyrene fluorescence, whereas the form with the neutral pyridine and protonated amine groups is fluorescent. The molecular sensor is also equipped with a long alkyl chain to make it highly hydrophobic in all its protonated and unprotonated forms, that is,…
[The in vitro effect of the addition of ion exchange resins on the bioavailability of electrolytes in artificial enteral feeding formulas].
2008
Objective: To determine in vitro free ion concentration in 3 standard artificial enteral feeding formulas following the addition of ion exchange resins. Method: Three standard types of AEF were chosen: Osmolite HN®, Nutrison Standard®, and Isosource Standard®. The ion exchange resins used were: sodium polystyrene sulfonate and calcium polystyrene sulfonate. In a beaker were mixed 100 mL of AEF with 1.5 g or 3 g of ion exchange resins for 48 hours at 37oC. Subsequently, the samples were precipitated and the supernatant obtained was used for determining the concentrations of calcium, magnesium, sodium, and potassium ions. Results: The addition of sodium polystyrene sulfonate to different type…