Search results for "Aqueous solution"
showing 10 items of 1610 documents
Polyaza and azaoxa macrocyclic receptors functionalised with fluorescent subunits; Hg2+ selective signalling
2000
A polyazacycloalkane containing naphthyl groups, 1,4,8,11-tetrakis(naphthylmethyl)-1,4,8,11-tetraazacyclotetradecane (L1), and the azaoxa cycloalkane receptors containing anthracenyl groups, 7,13-bis(anthracenylmethyl)-1,4,10-trioxa-7,13-diazacyclopentadecane (L2) and 10-anthracenylmethyl-1,4,7-trioxa-10-azacyclododecane (L3), have been synthesized and their activity as fluorescent chemosensors studied towards the metal cations Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ in THF–water (70∶30 v/v, 0.1 mol dm−3 tetrabutylammonium perchlorate, 25 °C) for L1 and 1,4-dioxane–water (70∶30 v/v, 0.1 mol dm−3 potassium nitrate, 25 °C) for L2 and L3. The crystal structure of the complex [Cd(L1)(Cl)][PF6] has been…
Human Hsp60 with Its Mitochondrial Import Signal Occurs in Solution as Heptamers and Tetradecamers Remarkably Stable over a Wide Range of Concentrati…
2014
It has been established that Hsp60 can accumulate in the cytosol in various pathological conditions, including cancer and chronic inflammatory diseases. Part or all of the cytosolic Hsp60 could be naive, namely, bear the mitochondrial import signal (MIS), but neither the structure nor the in solution oligomeric organization of this cytosolic molecule has still been elucidated. Here we present a detailed study of the structure and self-organization of naive cytosolic Hsp60 in solution. Results were obtained by different biophysical methods (light and X ray scattering, single molecule spectroscopy and hydrodynamics) that all together allowed us to assay a wide range of concentrations of Hsp60…
Synergistic behavior of poly(aspartic acid) and Pluronic F127 in aqueous solution as studied by viscometry and dynamic light scattering.
2012
Abstract Pluronic F127/poly(aspartic acid) mixtures were investigated in dilute solutions by viscometry and dynamic light scattering. The two polymers were chosen due to well known applications in biomedical field, taking into account the final purpose (the use of the complex structure as drug delivery systems). The central item was to identify the possibility of complexation between the poly(carboxylic acid) and a non-ionic polymer and to investigate the conditions of the interpolymer complex formation. The ability of Pluronic F127 to form micelle is well known. Poly(aspartic acid), as a polycarboxylic acid with resemblance with polyacrylic acid, can act as dispersant, antiscalant, superab…
An Artificial Neural Network Assisted Dynamic Light Scattering Procedure for Assessing Living Cells Size in Suspension
2020
Dynamic light scattering (DLS) is an essential technique used for assessing the size of the particles in suspension, covering the range from nanometers to microns. Although it has been very well established for quite some time, improvement can still be brought in simplifying the experimental setup and in employing an easier to use data processing procedure for the acquired time-series. A DLS time series processing procedure based on an artificial neural network is presented with details regarding the design, training procedure and error analysis, working over an extended particle size range. The procedure proved to be much faster regarding time-series processing and easier to use than fitti…
Combined Theoretical and Experimental Study of the Photophysics of Asulam
2013
The photophysics of the neutral molecular form of the herbicide asulam has been described in a joint experimental and theoretical, at the CASPT2 level, study. The unique π → π* aromatic electronic transition (f, ca. 0.5) shows a weak red-shift as the polarity of the solvent is increased, whereas the fluorescence band undergoes larger red-shifts. Solvatochromic data point to higher dipole moment in the excited state than in the ground state (μ(g)μ(e)). The observed increase in pKa in the excited state (pKa* - pKa, ca. 3) is consistent with the results of the Kamlet-Abboud-Taft and Catalán et al. multiparametric approaches. Fluorescence quantum yield varies with the solvent, higher in water (…
Effects of Candelilla and Carnauba Wax Incorporation on the Functional Properties of Edible Sodium Caseinate Films
2020
International audience; The aim of this study was to evaluate the effects of candelilla (CAN) or carnauba wax (CAR) incorporation on functional properties of edible sodium caseinate (CAS) films. Glycerol and Tween-80 were used as the plasticizer and the emulsifier, respectively. The results showed that the incorporation of waxes increased film opacity, total color differences (∆E), and mechanical resistance and reduced film lightness, water vapor permeability (WVP), and elongation at break. Scanning electron microscopy showed heterogeneous structure of emulsion films with regular distribution of lipid particles. A different internal arrangement was observed as a function of the film composi…
Influence of temperature and NaCl on the release in aqueous liquid media of aroma compounds encapsulated in edible films
2012
This work analyses the release of n-hexanal and D-limonene from edible films, previously encapsulated in the iota-carrageenan matrix (with and without lipid). Both volatile compounds have different physicochemical properties. The effect of temperature (25 degrees C and 37 degrees C) and dissolution medium (water and 0.9% NaCl) on the release and retention of aroma compounds were studied. Hydrophobicity and wettability properties of active iota-carrageenan films were also studied and they were related with the internal and surface microstructure of films. Results highlight that D-limonene is encapsulated in the lipid phase of the films decreasing the release in the salt medium. D-limonene, t…
Biopolymer coating of soybean lecithin liposomes via layer-by-layer self-assembly as novel delivery system for ellagic acid
2010
Abstract The formulation of a novel delivery system for ellagic acid formulated via layer-by-layer (L-b-L) electrostatic deposition of biopolymers onto soybean lecithin liposomes was achieved. Optimization of parameters affecting the formulation of biopolymer-coated liposomes was carried out by monitoring changes on its size, surface charge and morphology. Ellagic acid was loaded into the liposome core and loading properties were analyzed. Release profiles for ellagic acid from optimized biopolymer-coated liposomes were evaluated as a function of time, temperature and pH of the media. The L-b-L electrostatic deposition of biopolymers succeeded in building nanosized, spherical and stable lip…
Why does vacuum drive to the loading of halloysite nanotubes? The key role of water confinement.
2019
The filling of halloysite nanotubes with active compounds solubilized in aqueous solvent was investigated theoretically and experimentally. Based on Knudsen thermogravimetric data, we demonstrated the water confinement within the cavity of halloysite. This process is crucial to properly describe the driving mechanism of halloysite loading. In addition, Knudsen thermogravimetric experiments were conducted on kaolinite nanoplates as well as on halloysite nanotubes modified with an anionic surfactant (sodium dodecanoate) in order to explore the influence of both the nanoparticle morphology and the hydrophobic/hydrophilic character of the lumen on the confinement phenomenon. The analysis of the…
On the chemiluminescence emission of luminol: protic and aprotic solvents and encapsulation to improve the properties in aqueous solution.
2020
Luminol is a popular molecule that is currently gaining further interest due to its potential role for non-invasive cancer treatments. Design of more efficient derivatives in this context would benefit from a clear knowledge on the origin of the distinct intensity and spectroscopic properties in protic and aprotic solvents observed experimentally, which are still not rationalized. By efficiently combining molecular dynamics, quantum methodologies based on density functional theory and multiconfigurational quantum chemistry and hybrid approaches, and developing herein a computational approach for accurately determining "molar negative extinction (or gain) coefficients of emission", we firstl…