Solutes In Aqueous Media Research Articles

Effects of calcium and barium chloride salts on the solubility and dissolution thermodynamics of glycine and DL-alanine from 288.15 K to 328.15 K

This investigation primarily examines the solubility at equilibrium and the dissolution thermodynamics of two crucial amino acids, glycine and DL-alanine, in aqueous solutions containing calcium and barium chloride salts. The solubilities were measured from 288.15 K to 328.15 K using the analytical gravimetric method. The resulting solubilities were then used to deduce the thermodynamics of the solutions. Subsequently, the free energies associated with solvation through transfer were examined.Furthermore, the research delved into various thermophysical characteristics within electrolyte solutions in aqueous media, establishing correlations. In addition, this study elucidated various non-covalent processes, including the solubility and stability of amino acids, by considering short-range interactions such as solute–solvent, solvent–solvent, and acid–base interactions. This analysis primarily provides insights into the involved molecular interactions and energetics that govern the solubility and behavior of amino acids in various solution environments.

Analyzing the modulations induced in the mixed micellar behavior of 1-alkyl-3-butylimidazolium based surface-active ionic liquids with an antibiotic drug in aqueous media

Abstract The study aims to scrutinize the mixed micellization and interfacial behavior of two 1-alkyl-3-butylimidazolium based surface-active ionic liquids (SAILs) i.e., 1-decyl-3-butylimidazolium bromide [C10bim][Br] and 1-tetradecyl-3-butylimidazolium bromide [C14bim][Br] under the influence of streptomycin sulphate (SS) drug in 5 mM concentration in aqueous media. Imidazolium-based SAILs have unique physicochemical properties and greater surface activity than conventional surfactants, which allows them to increase drug permeability, making them better drug carriers than currently available formulations. To fully utilize [C14bim][Br] and [C10bim][Br] in drug delivery applications, deep insight into the interactions occurring in the mixed micellar [C10bim][Br]/[C14bim][Br] systems in the drug’s presence are necessary to be examined. Thus, the study is conducted using conductivity and surface tension measurement techniques to fully exploit the self-assembly, micellization behavior and interactions occurring in the pure and mixed micellar system of [C10bim][Br]/[C14bim][Br] in water and 5 mM of SS solution in aqueous media. For this, various thermodynamic, surface-active and mixed micellar parameters of micellization have been calculated and analyzed with respect to change in mole fraction, temperature and addition of SS in solution.

Eu3+-ion doped LnF3 NPs: Comparative study of the crystallographic, and photophysical properties

The thermal co-precipitation approach was employed for the synthesis of the Eu3+-ion doped YF3, LaF3, and GdF3 nanoparticles (NPs) and compared their photophysical properties. Ammonium fluorite was used as a fluorine source for the synthesis of metal fluorides at lower temperatures. Luminescent lanthanide fluoride (LnF3) NPs were characterized by different techniques containing X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), FT-Raman, UV/Visible absorption spectra, and photoluminescence spectroscopic procedures to investigate the crystal structural, thermal, Raman effect, surface, optical, and luminescent properties. XRD study shows two types of crystal phase orthorhombic in YF3:Eu & GdF3:Eu and hexagonal in LaF3:Eu NPs. TGA, FTIR, and absorption spectra studies show the exterior adsorbed –OH molecules, which assist in the development of colloidal solution in aqueous media. Raman vibrations were strongly affected which were correlated with the XRD reflection planes. In comparative photo-physical properties, the excitation and emission spectra exhibited remarkable intensities of the Eu3+-ion transitions. Similarly, the emission spectra of all three samples exhibited the highest emission efficiency of the magnetically-dipole(5D0→7F2) transition in comparison to the electric-dipole 5D0→7F1 transition, which reflected the transformation of the crystal symmetry. Comparative analysis was presented to investigate the role of the host lattice on crystallinity, thermal stability, and luminescent properties. These findings are highly fruitful in designing photonic-based applications including optical biosensors, fingermark detection, security systems, etc.

Improvement of suspension-assisted total reflection X-ray fluorescence analysis of ores using wet grinding and empirical calibrations

In this study, the suspension-assisted total-reflection X-ray fluorescence analysis of ores was improved using the wet grinding procedure to produce ultra-fine suspended powder mixed with internal standard solution in aqueous media. The advantages of the proposed technique were demonstrated by the example of the determination of S, Fe, Ni, and Cu in sulfide copper‑nickel ores containing various ratios of sulfide and silicate minerals. We showed that the powerful mixing of 100 mg of ore powder and 4 mL of ultra-pure water as a dispersing medium with 20 g of grinding balls of 1 mm in diameter leads to the preparation of homogeneous suspension with monomodal particle size distribution having 90% of the particle size <6 μm. The suspension after wet grinding was diluted up to 50 mL with ultra-pure water to obtain a final concentration of the suspended powder of 2 mg/mL. Relative precision of the described sample preparation technique calculated from duplicate pairs of suspensions was 16% for S, 9% for Fe, 15% for Ni and 10% for Cu. Three spectral data processing techniques were further compared with respect to the quantification accuracy of target elements: internal standard, univariate and multivariate regressions. It was shown that the two latter methods can be used to improve the trueness of the internal standard method, especially for Cu and Fe.

Influence of an antibiotic drug neomycin sulphate on mixed micellization behavior of imidazolium based surface-active ionic liquids in aqueous media

Imidazolium-based surface-active ionic liquids (SAILs) have unique physicochemical features that make them ideal for biomedical applications. Because SAILs have a higher surface activity than conventional surfactants, they can improve drug permeability across biomembranes, making them superior drug carriers than existing solutions. In-depth studies of interactions prevailing in mixed micellar system of SAILs in the presence of drug are required to fully exploit the promise of these materials in drug delivery applications. Thus, various thermodynamic, mixed micellar and surface-active properties of two imidazolium-based SAILs with different cationic structures i.e.1-dodecyl-3-ethylimidazolium bromide [C12eim][Br] and 1-dodecyl-3-butylimidazolium bromide [C12bim][Br] have been determined in water and 5 mM neomycin sulphate solution in aqueous media. The study has been conducted for different mole fractions of mixed micellar system of SAILs using conductivity and surface tension measurement techniques. Various theoretical models such as Clint, Rubingh, Motomura and Rodenas models have been applied to understand the interactions prevailing in the mixed [C12eim][Br] /[C12bim][Br] system in water and neomycin sulphate solution in aqueous media.

Kinetics of Silver Accumulation in Tissues of Laboratory Mice after Long-Term Oral Administration of Silver Nanoparticles.

Since ancient times, silver has been known for its pronounced bactericidal, antiviral and fungicidal properties. Currently, nanoparticles of this metal are widely used in the food, light and pharmaceutical industries, as well as in medicine. Silver in any form can have a toxic effect not only on pathogens, but also on healthy cells. The biological activity and bioavailability of silver preparations depend on the degree of their solubility in water. In addition, the maximum permissible concentration of soluble forms of silver is an order of magnitude lower than that of insoluble forms. This makes nanoparticles of silver with a hydrophilic coating that form stable colloidal solutions in aqueous media potentially unsafe objects. In this work, we studied the kinetics of the accumulation of silver nanoparticles with an average size of 34 ± 5 nm stabilized with polyvinylpyrrolidone in the organs of laboratory C57Bl/6 mice. The administration of nanoparticles was carried out orally for 30, 60, 120 and 180 days at the dose of 50 µg/day/animal. All the mice developed and gained weight normally during the experiment. No adverse effects were observed. Determination of the silver content in biological tissues of mammals was accomplished by neutron activation analysis. The masses and concentrations of silver in the brain and its different sections (hippocampus, cerebellum, cortex and remnants), as well as in the lungs, testes, liver, blood, kidneys, spleen and heart, were determined. The injection times at which the accumulation curves reached saturation were established. An extremely high accumulation of silver in the testes was shown at 120 days of administration, and a significant accumulation of silver in the lungs and brain was observed. The accumulation of silver in all parts of the brain except the cortex was significant, and its trend was similar to that in the whole brain.

Thermophysical properties of amino acids L-serine and L-leucine in aqueous diammonium hydrogen phosphate solutions: Volumetric and acoustic studies

Densities and speeds of sound measurements have been done for the amino acids (AAs) L-serine and L-leucine in aqueous diammonium hydrogen phosphate (DAP) solution at different temperatures with a specific interval of temperature. Thermophysical parameters including apparent molar volume (Vϕ), partial molar volume (Vϕ0), apparent molar isentropic compression (Kϕ,s), partial molar isentropic compression (Kϕ,s0) and transfer volumes like partial molar volumes of transfer (ΔVϕ0) and partial molar isentropic compression of transfer (ΔKϕ,so) were determined using the measured experimental data. The co-sphere overlap model was used to interpret the sort of interactions dominating in the system. The obtained transfer quantities are positive which indicates the dominance of ion-hydrophilic and hydrophilic–hydrophilic interactions existing among the amino acids and diammonium hydrogen phosphate salt solution in aqueous medium. Pair and triple interaction coefficients calculated for the system of amino acids and phosphate salt in aqueous medium. Overall results have been elaborated in terms of the solute-solvent or solute-solute interactions prevailing in the system.

Assessment of strategies for the formation of stable suspensions of titanium dioxide nanoparticles in aqueous media suitable for the analysis of biological fluids.

Due to their omnipresence in consumer products, there is a growing concern about the potential effects of nanoparticles on human health. Toxicological assessment and NP end-product studies require proper quantification of these materials in biological fluids. However, their quantifications in these media require stable predispersed NP solutions in aqueous media to enable the fortification in the matrices of interest or the preparation of calibration standards. In this study, a sample preparation scheme was developed by studying various dispersion media (polyvinylpyrrolidone and polyethylene glycol) and sonication strategies (bath and ultrasonic probe) to ensure homogeneous dispersion of titanium dioxide nanoparticles. Optimization of the various parameters was performed using SRM NIST 1898 NP reference material, composed of rutile and anatase phases. Number-based size distribution for titanium dioxide NPs was determined by dynamic light scattering and single-particle inductively coupled plasma mass spectrometry to evaluate the procedure efficiency. Changes in mean size and most frequent size distribution were also studied to determine if the agglomeration of nanoparticles occurs at the various dispersion conditions tested. Among the different dispersion parameters tested herein, the use of polyvinylpyrrolidone combined with a sonication process generated by a probe leads to a significant improvement in terms of suspension efficiency and stability over 72h. The dispersion efficiency of the proposed methodology was assessed by single-particle inductively coupled plasma mass spectrometry with spiked biological fluids such as urine and blood. Graphical abstract.

Self-Assemblable Polymer Smart-Blocks for Temperature-Induced Injectable Hydrogel in Biomedical Applications.

Self-assembled temperature-induced injectable hydrogels fabricated via self-assembly of polymer smart-blocks have been widely investigated as drug delivery systems and platforms for tissue regeneration. Polymer smart-blocks that can be self-assembly play an important role in fabrication of hydrogels because they can self-assemble to induce the gelation of their copolymer in aqueous solution. The self-assembly occurs in response to an external stimulus change, such as temperature, pH, glucose, ionic strength, light, magnetic field, electric field, or their combination, which results in property transformations like hydrophobicity, ionization, and conformational change. The self-assembly smart-block based copolymers exist as a solution in aqueous media at certain conditions that are suitable for mixing with bioactive molecules and/or cells. However, this solution turns into a hydrogel due to the self-assembly of the smart-blocks under exposure to an external stimulus change in vitro or injection into the living body for a controllable release of loaded bioactive molecules or serving as a biomaterial scaffold for tissue regeneration. This work reports current scenery in the development of these self-assembly smart-blocks for fabrication of temperature-induced injectable physically cross-linked hydrogels and their potential application as drug delivery systems and platforms for tissue engineering.

3D printing of polylactic-co-glycolic acid fiber scaffolds using an antisolvent phase separation process

We present the results of experimental studies into the computer-controlled fabrication of polylactic-co-glycolic acid (PLGA) scaffolds under conditions of diffusion and antisolvent phase separation of PLGA/tetraglycol (TG) solutions in aqueous media. The effect of the initial concentrations of the polymer solutions and the 3D printing process parameters on the type of the fiber structures formed was studied. The resultant scaffolds were found to be produced in the form of either fractal-like or spongy polymeric microstructures. The specific type of the structures formed was shown to depend on the intensity of the diffusion processes in the ternary system PLGA–TG–antisolvent. This approach can be used for highly efficient 3D printing of both microporous and hollow fiber biocompatible scaffolds of various architectonics.

The Synthesis Conditions Influence on Silver Nanostructures Formation Under the Effect of Electromagnetic Radiation

In the present work the influence of the synthesis conditions, particularly the effect of used surrounding media on the silver nanostructures formation with various spatial configuration under the effect of the visible electromagnetic radiation has been studied. Silver nanoparticles were synthesized by photostimulated reduction of silver ions from the silver nitrate water solution in aqueous medium and in water yeast extract. The modification of the configuration of resulting nanoobjects was carried out by irradiating the testing samples with red, green, and blue photon flows under the similar conditions. For this task the unique devise with three isolated cells for irradiating silver colloids under the room temperature was developed. The parameters of obtained silver nanostructures were characterized by spectrophotometry and their optical properties have been researched. For the obtained silver colloids the polydispersity indexes were also determined. Besides, the changes in morphology were confirmed by transmission electron microscopy. The shift of the absorption spectra of the testing colloids to the long-wavelength spectral region and their splitting in some cases after irradiation by different wavelength has been showed. For nanoparticles synthesized in the distilled water after irradiating by red, green, and blue photon flows the additional absorption peaks appeared in the longer-wavelength spectral region. Moreover, the colloidal solutions changed the colors after the electromagnetic radiation effect. This indicates the change in nanostructures shapes. The formation of triangular nanoprisms under the influence of red and green photon flows and formation of decahedral nanostructures under the influence of blue light was found. It has been shown that this method can be successfully used to obtain the large silver nanostructures in aqueous solution of the known spatial and optical parameters. The absorption spectrum of the silver nanostructures obtained in water yeast extract shows one clearly expressed peak. But, after irradiation of this colloid with red and green light, the absorption curves are very close in shape to the initial one. Only under the blue light irradiation an additional weak absorption peak can be observed at the wavelength of 523 nm, which might indicates a partial change in the nanostructures shapes. It has been shown that the use of water yeast extract as a surrounding medium for the synthesis of nanoparticles with different spatial morphology minimizes the photoinduced effect of the shape transformation, which was observed in pure aqueous colloids. The effectiveness and the ability to use of different surrounding media for the silver nanoparticles synthesis by photostimulated reduction for obtaining nanostructures with the predetermined spatial parameters and to shift their absorption peaks to the visible and near infrared spectral region has been shown.Ref. 17, fig. 7, tabl. 1.

Gas Fermentation Enhancement for Chemolithotrophic Growth of Cupriavidus necator on Carbon Dioxide

Cupriavidus necator, a facultative hydrogen-oxidizing bacterium, was grown on carbon dioxide, hydrogen, and oxygen for value-added products. High cell density and productivity were the goal of gas fermentation, but limited by gas substrates because of their low solubility in the aqueous medium solution. Enhancement of gas fermentation was investigated by (i) adding n-hexadecane as a gas vector to increase the volumetric mass transfer coefficient (kLa) and gas solubility, (ii) growing C. necator under a raised gas pressure, and (iii) using cell mass hydrolysates as the nutrients of chemolithotrophic growth. In contrast to previous studies, little positive but negative effects of the gas vector were observed on gas mass transfer and cell growth. The gas fermentation could be significantly enhanced under a raised pressure, resulting in a higher growth rate (0.12 h−1), cell density (18 g L−1), and gas uptake rate (200 mmole L−1 h−1) than a fermentation under atmospheric pressure. The gain, however, was not proportional to the pressure increase as predicted by Henry’s law. The hydrolysates of cell mass were found a good source of nutrients and the organic nitrogen was equivalent to or better than ammonium nitrogen for chemolithotrophic growth of C. necator on carbon dioxide.

Efficient removal of Co(II), Ni(II), and Zn(II) metal ions from binary and ternary solutions using a pH responsive bifunctional graft copolymer

A novel, pH responsive graft copolymer hydroxyethyl cellulose-graft-poly(N-vinyl imidazole-co-acrylic acid) containing both acidic and basic functionalities was prepared in water medium by using potassium peroxydisulfate as an initiator. Several techniques like FTIR, XRD, NMR, SEM and TGA/DTGA studies were used to characterize the synthesized copolymer. The polymer was used for the adsorption of toxic heavy metal ions namely Co(II), Ni(II) and Zn(II) from the ternary mixture of three metal ion’s solution in aqueous medium. The graft copolymer showed an excellent pH dependence for the adsorption of aforementioned three metal ions. Ni(II) and Co(II) showed maximum adsorption efficiency at pH 5.5, whereas for Zn(II), it was at 6.5. Metal complexation studies by the synthesized graft copolymer were carried out experimentally by using conductometric titration and theoretically by Density Functional Theory (DFT) using Gaussian 09 software. Metal complexation studies showed that at low pH (≤ 5.5), it is the carboxylic acid group, and at pH > 5.5, it is only the carboxylic acid and imidazole functionalities that both are responsible for the adsorption. Adsorption dynamics, isotherms, kinetics and thermodynamics were studied for all the three metal ions’ adsorption onto the polymer surface. The adsorption follows Langmuir isotherm model and pseudo-second-order kinetics for all the metal ions. Maximum adsorption capacity was found to be 165, 122 and 68 mg/g for Ni(II), Co(II) and Zn(II) metal ion, respectively. Thermodynamic study showed that the adsorption process was endothermic and spontaneous in nature. The preferential metal adsorption by the graft copolymer was followed in the order Ni(II) > Co(II) > Zn(II).

Organic-inorganic hybrid carbon dots for cell imaging

In this paper, nitrogen-doped carbon dots (CDs) had been synthesized directly by one-step ultrasonic treatment under mild conditions. During the functionalization process, Octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt (OA-POSS) was used as stabilizing and passivation agent, which lead to self-assembling of CDs in aqueous medium solution. OA-POSS was obtained via hydrolytic condensation of γ-aminopropyl triethoxy silane (APTES). The average size of CDs prepared was approximately 3.3 nm with distribution between 2.5 nm and 4.5 nm. The prepared organic-inorganic hybrid carbon dots have several characteristics such as photoluminescence emission wavelength, efficient cellular uptake, and good biocompatibility. The results indicate that OA-POSS can maintain the fluorescence properties of the carbon dots effectively, and reduced cytotoxicity provides the possibility for biomedical applications. More than 89% of the Hela cells were viable when incubated with 2 mg ml−1 or lesser organic-inorganic hybrid carbon dots. Thus, it provides a potential for multicolor imaging with HeLa cells.

Synthesis and Characterization of ZnO Microfiber By Electrospinning Technique

Ultrathin 1D assembly of pure crystalline ZnO microfibers were fabricated using facile, low-cost electrospinning technique. Nanofibrous membrane preforms were synthesized by electrospinning a ZnO precursor containing PVA solution in aqueous medium. The crystalline ZnO microfibers were obtained by calcining PVA/Zinc Acetate precursor fibers at 500°C. The structure and morphologies of ZnO microfibers were studied by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FE-SEM).

Low temperature synthesis of Co3O4 and (Co1−xMnx)3O4 spinels nanoparticles

The (Co1−xMnx)3O4 solid solution have been synthesized in water at 60°C by soda addition to a cationic solution. XRD patterns show that spinel oxide has been obtained except for pure cobalt composition which exhibits also the presence of hydroxide and oxy-hydroxide. Therefore, to reach this composition, a different synthesis route has been developed: the cationic solution is added to the soda and for the first time Co3O4 nanoparticles have been synthesized by a direct precipitation in aqueous solution at low temperature. For each composition, the particles are well crystallized and exhibit a size close to 50nm. Each particle is composed by several crystallographic domains of about 10nm. The cubic to tetragonal transition reported in the literature for x=0.46 is observed in between x=0.33 and x=0.50. Raman spectra show that substitution of Co by Mn, in the cubic phase, introduces a random high disorder. In the tetragonal phase, occupation of the octahedral site remains a random occupation, while the tetrahedral site seems to be preferentially occupied by Co ions. All these results show that the precipitation is a simple, fast and safe process to synthesize pure phase of (Co1−xMnx)3O4 spinel solid solution in aqueous media at low temperature.

Regularities of formation of emboli of liquid polymer solutions in aqueous medium

Work on creating the basis for embolic compositions for the treatment of a wide range of pathologies of various organs was conducted. This basis is a solution of a biocompatible water-insoluble polymer in a biocompatible water-soluble solvent. Formation of the embolus in such an aqueous medium takes place in the transition of the solvent into the aqueous phase and the formation of a solid polymer clot occluding a blood vessel. Criteria for selection of the polymer and the solvent for the basis were formulated, and a number of polymers and solvents that meet these criteria were selected for further research. Research on the solubility of the selected polymers in solvents was carried out, and the rheoviscometric characteristics of polymer solutions, as well as parameters of solid emboli formation of polymer solutions in aqueous media, were found. The solution of cellulose acetate plasticized with OPADRY CA 500F190000 polyethylene glycol in dimethylsulfoxide with concentration of no less than 60 g/L was recognized as optimal for further studies.

Nanostructured Zinc Electrodeposited from Protic Ionic Liquids: Comparison with Zinc Aqueous Electrodeposition Processes

Zinc electrodepositon is one of the more important electrochemical process for surface treatment because of its application in anticorrosion protection and also as electrode material in zinc batteries. The main limitation of the electrodepositon of zinc from acidic or basic solutions in aqueous media, in addition to the very negative potential needed to carry out the electrodeposition, is associated to the simultaneous hydrogen evolucion reaction (HER) limiting the farad¡c efficiency of the electrochemical process. The HER has also a direct effect on the nucleation and on the electrocrystallization of zinc with some negative effects on the physical and structural proporties of zinc electrodeposits obtained from these solution (e.g. (poor adhesion, inhomogeneous deposits, etc). In this work the electrodeposition processes of zinc from protic ionic liquids is studied and compared with results of electrodeposition from aqueous solution in order to determine the avantages of electrodeposition from ionic liquids. Results show that in protic carboxylated ionic liquids, as ethanolammonium propionate, homogeneous electrodeposits of pure metallic zinc are obtained, with a narrow distribution of grain size in the range of 50-70nm, contrariously to electrodeposits obtained from aqueos solutions with grain sizes from 20 to 100nm. In addition, differences in the nucleation-electrocrystallization mechanism and on the electrodeposition rate are observed and they are dependent on the nature of the nature of the solvent. Results allow to conclude that zinc electrodeposits continous, homogeneous and with a well controlled grain sizes can be obtained from protic ionic liquids. These results allow to envisage that these deposits can be more effective for anticorrosion protection since this property is dependent on the homogeneity and contoinuity of an electrodeposit. ACKNOWLEDGEMENTS. The financial support provided by CONACYT (México), project Fondo Sectorial SEP-CONACYT CB 2011 168032 and The Engineering Research Council of Canada (NSERC) are gratefully acknowledged.

The effect of polymer and CaCl2 concentrations on the sulfasalazine release from alginate-N,O-carboxymethyl chitosan beads.

In this study, pH-sensitive blended polymeric beads were prepared by ionic gelation of mixed alginate and N,O-carboxymethyl chitosan (NOCC) solutions in aqueous media containing calcium chloride. To prepare drug-loaded beads, sulfasalazine (SA) as a model drug was added to the initial aqueous polymer solution. These beads were characterized and evaluated in vitro as potential carriers for colon-specific drug delivery. A 32 full factorial experimental design was employed to evaluate the effect of polymer and CaCl2 concentrations on swelling and drug release behavior of the beads in simulated gastrointestinal tract fluid. It was found that the rate of swelling and drug release decreased significantly with increasing polymer and CaCl2 concentrations, but polymer concentration was more effective than CaCl2 concentration. The beads prepared using 4.5% polymer concentration and 4% CaCl2 concentration retained approximately 60% of the loaded drug before approaching the simulated colonic fluid. Based on the results, the alginate-NOCC beads prepared with high polymer concentration could be potentially suitable polymeric carriers for colon-specific delivery of SA.Electronic supplementary materialThe online version of this article (doi:10.1186/2194-0517-2-10) contains supplementary material, which is available to authorized users.

ChemInform Abstract: Miceller Media Accelerated Baylis—Hillman Reaction.

AbstractThe use of micellar solution in aqueous medium accelerates the rate of Baylis—Hillman reaction and enhances the product yield.