Properties Of Aqueous Solutions Research Articles

Review of the Low-Temperature Acoustic Properties of Water, Aqueous Solutions, Lipids, and Soft Biological Tissues.

Existing data on the acoustic properties of low-temperature biological materials is limited and widely dispersed across fields. This makes it difficult to employ this information in the development of ultrasound applications in the medical field, such as cryosurgery and rewarming of cryopreserved tissues. In this review, the low-temperature acoustic properties of biological materials, and the measurement methods used to acquire them were collected from a range of scientific fields. The measurements were reviewed from the acoustic setup to thermal methodologies for samples preparation, temperature monitoring, and system insulation. The collected data contain the longitudinal and shear velocity, and attenuation coefficient of biological soft tissues and biologically relevant substances-water, aqueous solutions, and lipids-in the temperature range down to -50 °C and in the frequency range from 108 kHz to 25 MHz. The multiple reflection method (MRM) was found to be the preferred method for low-temperature samples, with a buffer rod inserted between the transducer and sample to avoid direct contact. Longitudinal velocity changes are observed through the phase transition zone, which is sharp in pure water, and occurs more slowly and at lower temperatures with added solutes. Lipids show longer transition zones with smaller sound velocity changes; with the longitudinal velocity changes observed during phase transition in tissues lying between these two extremes. More general conclusions on the shear velocity and attenuation coefficient at low-temperatures are restricted by the limited data. This review enhance knowledge guiding for further development of ultrasound applications in low-temperature biomedical fields, and may help to increase the precision and standardization of low-temperature acoustic property measurements.

Albumin-mediated molecular competition of supramolecular photosensitizers for NIR-II imaging-guided phototherapy

Heptamethine cyanines (Cy7) typically exhibit strong near-infrared (NIR) fluorescence signals when in monodisperse states, but their distinctive π-conjugated structure leads to limited solubility in aqueous solutions, ultimately resulting in inherent fluorescence self-quenching. Enhancing the fluorescence quantum yield of these agents within aqueous environments, in order to achieve high-resolution biological imaging, presents a significant challenge. Herein, a benzothiazole-based Cy7-derivative (Cy7-BTH) is developed, exhibiting unique H-aggregation properties in aqueous solutions. Bovine serum albumin (BSA) binds to Cy7-BTH (BSA@Cy7-BTH) to modulate its molecular stacking and energy transfer, boosting its fluorescence accompanied by bright NIR-II tail emission. The competitive binding alters the planarity of Cy7-BTH, restricting its intramolecular rotation, and simutaneously changes the conformation of BSA, leading to BSA@Cy7-BTH aggregation to form hierarchical-structured nanoparticles. Notably, the BSA@Cy7-BTH nanoparticles significantly enhanced photothermal response of Cy7-BTH while maintaining its controlled reactive oxygen species (ROS) generation, offering NIR-II imaging-guided surgical removal of primary tumors, and simultaneously inhibiting cancer cell metastasis by synergistic PDT/PTT dissection of metastatic tumor cells in sentinel lymph nodes (SLNs). This study provides an innovative but facile strategy for their potential clinical applications by precisely regulating the intermolecular competitive interactions of NIR theranostic agents.

Quasi-intrinsic thiobase derivatives as potential targeted photosensitizers in two-photon photodynamic therapy

In this study, a set of potential quasi-intrinsic photosensitizers for two-photon photodynamic therapy (PDT) are proposed based on the unnatural 2-amino-8-(1′-β-ᴅ-2′-deoxyribofuranosyl)-imidazo[1,2-ɑ]-1,3,5-triazin-4(8H)-one (P), which is paired with the 6-amino-5-nitro-3-(1′-β-ᴅ-2′-deoxyribofuranosyl)-2(1H)-pyridone (Z) and can specifically recognize breast and liver cancer cells. Herein, the effects of sulfur substitution and electron-donating/electron-withdrawing groups on the photophysical properties in aqueous solution are systematically investigated. The one- and two-photon absorption spectra evidence that the modifications could result in red-shifted absorption wavelength and large two-photon absorption cross-section, which contributes to selective excitation and provides effective PDT for deep-seated tissues. To ensure the efficient triplet state population, the singlet–triplet energy gaps and spin–orbit coupling constants were examined, which is responsible for a rapid intersystem crossing rate. Furthermore, these thiobase derivatives are characterized by the long-lived T1 state and the large energy gap for radiationless transition to ensure the generation of cytotoxic singlet oxygen.

Weak Magnetic Fields Regulate the Ability of High Dilutions of Water to Enhance ROS Production by Neutrophils

The influence of magnetic fields on the physico–chemical properties of water and aqueous solutions is well known. We have previously shown that weak combined magnetic fields with a 60 µT static component and a 100 nT (at 12.6 Hz) variable component are able to activate neutrophils, both directly and indirectly, through water pre-incubated in these fields. The ability to influence the activity of neutrophils was retained in serial dilutions of water, but only when a mechanical effect (shaking) was applied at each dilution step. Here, we confirm that combined magnetic fields are required for the formation of the stimulatory activity of water on ROS production by neutrophils. For the first time, we determined the threshold values of a constant magnetic field (at least 350–550 nT) necessary to maintain this activity in a series of successive dilutions. Additionally, the biophysical properties of various dilutions appeared to be not identical. This confirms that the number of technological steps (successive dilutions with physical influence) is a key factor that determines the activity of highly diluted samples.

Micellization, aggregation, interaction, and solubilization behaviors of mixed solutions of cationic gemini and nonionic surfactants

AbstractThe micellization properties of mixed aqueous solutions of a cationic gemini surfactant (CGS) and Triton X‐100, a conventional non‐ionic surfactant, with various mole fractions, were determined by measuring the surface tension at different temperatures. Various theoretical models were used to analyze the behavior of this mixed system. The interactions between CGS and Triton X‐100 were determined to be non‐ideal and synergistic. The calculated interaction parameters (βM) have negative values at all temperatures and for all mole fractions, showing attractive interactions. It was found that increasing the mole fraction of Triton X‐100 significantly increased the synergistic effect (more negative values). Micellar aggregation number (Nagg) values of pure surfactants and their mixtures in different ratios were obtained with the steady‐state fluorescence quenching method. Furthermore, the molar solubilization ratio of Sudan III organic dye in all surfactants aqueous systems was obtained using UV–Visible spectrophotometry. At concentrations above critical micelle concentration, the solubility of Sudan III in water was substantially increased linearly for all systems and it was observed that the enhancement was even more significant for mixed surfactant systems.

Protective action of water-soluble fullerene adducts on the example of an adduct with l-arginine

We present radioprotective, antiglycating, and photoprotective properties of a water-soluble C60 fullerene derivative with l-arginine (C60-Arg) and composite films based on collagen containing C60-Arg. The synthesis of these materials is described. The identification of the synthesised materials was carried out using modern physicochemical methods of analysis. The physicochemical properties of aqueous solutions of C60-Arg, such as, particle size distribution, zeta potentials, distribution coefficient in the octan-1-ol–water system were measured. The computer simulation of the process of C60-Arg association in aqueous and isotonic solutions was carried out using Molecular Dynamics. Composite films based on collagen containing C60-Arg demonstrate significant improvement in mechanical properties, cell adhesion, and cell proliferation when the nano-modifier is added. This shows high potential for the use of the C60-Arg adduct in biomedicine.

Competition between indigo carmine and water in the formation of dynamics behavior at different temperatures

We apply molecular dynamics methods to determine the impact of temperature on the structural and dynamic properties of aqueous solution of indigo carmine at temperatures between 300 and 323 К. We report that indigo carmine motion changes from the sub-diffuse to the diffuse regime at t = 100 ps, while water molecules continue to move in the slowed sub-diffuse regime. We demonstrate that the determining factor in the change of the structural and dynamic properties of the aqueous solution of indigo carmine at temperatures between 300 and 323 K is the change in the local structure of water and that the presence of indigo carmine leads to the decrease in temperatures at which a slowed motion of solution components is observed.

Alkali hydroxide (LiOH, NaOH, KOH) in water: Structural and vibrational properties, including neutron scattering results.

Structural and vibrational properties of aqueous solutions of alkali hydroxides (LiOH, NaOH, and KOH) are computed using quantum molecular dynamics simulations for solute concentrations ranging between 1 and 10M. Element-resolved partial radial distribution functions, neutron and x-ray structure factors, and angular distribution functions are computed for the three hydroxide solutions as a function of concentration. The vibrational spectra and frequency-dependent conductivity are computed from the Fourier transforms of velocity autocorrelation and current autocorrelation functions. Our results for the structure are validated with the available neutron data for 17M concentration of NaOH in water [Semrouni et al., Phys. Chem. Chem. Phys. 21, 6828 (2019)]. We found that the larger ionic radius [rLi+<rNa+<rK+] and higher concentration disturb the hydrogen-bond network of water, resulting in more disordered cationic hydration shell. Our abinitio simulation data for solute concentrations ranging between 1 and 10M can be used to guide future elastic and inelastic neutron-scattering experiments.

Donor-Acceptor Assembly of Amphiphilic Molecules Based on 9,10-Distyrylanthracene Derivatives with Terminal Naphthalene Groups.

Amphiphilic rod-coil compounds have excellent photophysical properties and can be assembled into supramolecular nanostructures of different sizes in water or polar solvents. Herein, we synthesized the amphiphilic compounds 2N-DSA, 4N-DSA, and 6N-DSA with 9,10-distyrylanthracene (DSA) as the core and a naphthalene unit as the terminal group that connected DSA through a tetraethylene glycol chain. These compounds have excellent aggregation-induced emission (AIE) properties in aqueous solution and are assembled into worm-like fragments or different sizes of spherical assemblies, defending the volume ratio of the rod to coil segments. Notably, the donor-acceptor interaction between DSA and electron- deficient compounds 2,4,6-trinitrophenol (TNP), 2,4,5,7-tetranitrofluorenone (TNF), and tetraethylene glycol dinitrobenzoate (TGDNB) forms a charge transfer complex, which can be used as a nanoreactor to improve the yield of the Suzuki coupling reaction about 8-10 times. The experimental results reveal that the synergy effect of the donor-acceptor, intermolecular π-π stacking, and hydrophobic-hydrophilic interactions significantly influences the morphology of aggregates and the efficiency of the nanoreactor.

Self-assembling and foaming properties of nonionic, cardanol-based surfactants in aqueous solutions

Surfactants from renewable sources have gained attention due to their potential as substituents for petroleum-based chemicals. In this sense, surfactants based on cardanol, a compound abundant in the cashew nutshell liquid, have been proposed as suitable candidates for this purpose. However, their application is hindered by the lack of quantitative and reliable information about their bulk and surface properties in aqueous solutions. In this work, for the first time, three nonionic, cardanol-derived surfactants (7EO, 9EO, and 12EO), with different number of ethylene oxide (EO) units in the polar headgroup, had their foaming performances analyzed and correlated with their respective surface (equilibrium and dynamic surface tension and surface viscoelasticity) and bulk (cloud points, critical micelle concentration, micelle diameter, and viscosity) properties. Depending on the EO number, different scenarios were seen. Solutions containing the 7EO surfactant were below the cloud point at room temperature and presented antifoaming properties. Aqueous solutions of 9EO and 12EO displayed foamability comparable to solutions prepared with a traditionally employed anionic surfactant (sodium dodecyl sulfate, SDS) at the same concentrations. The surfactant 12EO presented a rapid surface adsorption, thus favoring the formation of large amounts of foam during aeration. Furthermore, solutions of 9EO resulted in foams that were considerably more stable than the ones formed by SDS. Such an enhanced stability was attributed to the presence of elongated micelles, formed at the vicinity of the cloud point, that increased solution viscosity and delayed the liquid drainage in the foams. This surfactant also promoted the formation of highly viscoelastic surface films that contributed to foam stabilization. The obtained results suggest that these surfactants can be used in the formulation of new products with a more sustainable character and with improved properties. Moreover, they indicate the important interchange among bulk aggregates, surface properties and foam stability in aqueous surfactant systems.

Concentration Dependence of Elastic and Viscoelastic Properties of Aqueous Solutions of Ficoll and Bovine Serum Albumin by Brillouin Light Scattering Spectroscopy.

The cellular environment is crowded with macromolecules of different shapes and sizes. The effect of this macromolecular crowding has been studied in a variety of synthetic crowding environments: two popular examples are the compact colloid-like Ficoll macromolecule and the globular protein bovine serum albumin (BSA). Recent studies have indicated that a significant component of bound or surface-associated water in these crowders reduces the available free volume. In this work, Brillouin light scattering experiments were performed on aqueous solutions of Ficoll 70 and Ficoll 400 with concentrations ranging from 1 to 35 wt % and BSA with concentrations of 1 to 27 wt %. From the dependence of spectral peak parameters on polymer concentration, we determined fundamental solution properties: hypersound velocity, adiabatic bulk modulus and compressibility, apparent viscosity, and hypersound attenuation. The existing theory that ignores intermolecular interactions can capture only the observed linear trends in the frequency shift up to a threshold concentration, beyond which a quadratic term accounting for intermolecular interactions is necessary. This likely indicates a transition from the dilute to semidilute regime. In the Ficoll solutions (but not BSA), we see evidence for a central mode, which is indicative of relaxation in the hydration shell of Ficoll.

Protein Preferential Solvation in (Sucralose + Water) Mixtures.

Addition of sugars such as sucrose to aqueous protein solutions generally stabilizes proteins against thermal denaturation by preferential exclusion of sugars from proteins (preferential hydration of proteins). In this study, we investigated the effect of sucralose, a chlorinated sucrose derivative, on protein stability and preferential solvation. Circular dichroism and small-angle X-ray scattering measurements showed that sucrose increased the denaturation temperature of myoglobin and was preferentially excluded from the protein, whereas sucralose decreased the denaturation temperature of myoglobin and was preferentially adsorbed to the protein. No clear evidence was obtained for the indirect effects of sucralose on protein destabilization via the structure and properties of solvent water from the physicochemical properties (mass density, sound velocity, viscosity, and osmolality) of aqueous sucralose solutions; therefore, we concluded that a direct protein-sucralose interaction induced protein destabilization.

Stability of Viscoelastic Solutions: BrijL4 and Sodium Cholate Mixtures with Metal Ions Across a Broad pH and Temperature Range.

The impact of pH, temperature, and metal ions on the rheological and interfacial properties of aqueous mixed surfactant solutions composed of anionic NaC (sodium cholate) and nonionic BrijL4 [polyoxyethylene (4) lauryl ether] surfactants has been investigated. The various compound systems were analyzed, considering variations in each selected factor. The results highlight the unique characteristics of the BrijL4/NaC mixture, suggesting its potential as a viable alternative to other existing surfactants. The synergistic effect between BrijL4 and NaC significantly reduces the critical micelle concentration (CMC) and improves the wetting properties on hydrophobic surfaces, surpassing those of single-component solutions. Additionally, sodium, calcium, and magnesium ions enhance surface wetting and decrease the CMC. Besides, the BrijL4/NaC solutions exhibit viscoelastic fluid behavior at higher surfactant concentrations. These viscoelastic BrijL4/NaC solutions demonstrate stability over various pH and temperature variations, exhibiting lower flow activation and scission energy values than those of other viscoelastic surfactant solutions. Notably, the BrijL4/NaC mixture has potential applications in gel-based foliar fertilizers and drug delivery systems. Furthermore, the rheological studies examine the impact of humic acid on the rheological properties of BrijL4/NaC mixture solutions, revealing that incorporating additional humic acids can achieve stable rheological properties.

A Novel Approach for Quantifying Magnetic Susceptibility of Aqueous and Organic Solutions.

A new method for measuring the magnetic properties of aqueous and organic solutions is presented. This approach is based on quantifying the force resulting from the sample's interaction with a magnetic field. The experimental setup utilizes neodymium magnets attached to a stepper motor to adjust the distance between the magnets and the test sample, while an analytical balance serves as a strain gauge. Magnetic susceptibility measurements were performed on selected inorganic and organic solutions. A series of finite element simulations allowed us to convert experimental results to physical quantities describing magnetic susceptibilities of substances. The limit of detection (LoD) and limit of quantification (LoQ) values for the developed method of determining magnetic susceptibility were equal to 6.67·10-3 M and 2.02·10-2 M, respectively.

Convenient syntheses of trans-resveratrol 3-O and 4′-O-β-d-glucuronides and a study of their aqueous stability

The monoglucuronides of resveratrol were prepared from resveratrol triacetate. They showed contrasting properties in aqueous solution: facile E/Z isomerisation for the 3-O-isomer and ready H/D exchange, without isomerisation, for the 4′-O-isomer.

Properties of aqueous electrolyte solutions at carbon electrodes: effects of concentration and surface charge on solution structure, ion clustering and thermodynamics in the electric double layer.

Surfaces are able to control physical-chemical processes in multi-component solution systems and, as such, find application in a wide range of technological devices. Understanding the structure, dynamics and thermodynamics of non-ideal solutions at surfaces, however, is particularly challenging. Here, we use Constant Chemical Potential Molecular Dynamics (CμMD) simulations to gain insight into aqueous NaCl solutions in contact with graphite surfaces at high concentrations and under the effect of applied surface charges: conditions where mean-field theories describing interfaces cannot (typically) be reliably applied. We discover an asymmetric effect of surface charge on the electric double layer structure and resulting thermodynamic properties, which can be explained by considering the affinity of the surface for cations and anions and the cooperative adsorption of ions that occurs at higher concentrations. We characterise how the sign of the surface charge affects ion densities and water structure in the double layer and how the capacitance of the interface-a function of the electric potential drop across the double layer-is largely insensitive to the bulk solution concentration. Notably, we find that negatively charged graphite surfaces induce an increase in the size and concentration of extended liquid-like ion clusters confined to the double layer. Finally, we discuss how concentration and surface charge affect the activity coefficients of ions and water at the interface, demonstrating how electric fields in this region should be explicitly considered when characterising the thermodynamics of both solute and solvent at the solid/liquid interface.

EFFECT OF THE FORM OF ELECTRIC DISCHARGE ON PHYSICOCHEMICAL PROPERTIES OF PLASMA-ACTIVATED DISTILLED AND GROUND WATERS

A comparative study of some physicochemical properties of aqueous solutions resulted from the treatment of distilled and ground waters by pulsed discharges has been performed. Changes in the pH value, the conductivity of the solution, and the content of NO3¯ anions and Ca++, Mg++, K+, and Na+ cations were studied. Water bodies were affected by active particles formed in the air under the action of a pulsed discharge, which is implemented in two options. The first option is conventionally called ‘bubble discharge’ since it assumes the ignition of a discharge in an air bubble in direct contact with a liquid. The second option is the case when active particles, which are formed in an air stream under the action of a barrier discharge, are blown into a liquid. It is shown that the bubble discharge in ground water gives the maximum performance for the NO3¯ anions, while in the case of barrier discharge the best performance in the formation of NO3¯ anions is observed in distilled water. The pH value for ground water increases from 8.1 to 8.6 in the course of a 10-minute treatment using both discharges. However, in the case of distilled water treatment an inverse relationship is observed, so its value decreases from 7.5 to 3.5 pH. A multiple increase in the content of Ca++ and Mg++ cations in the water sample is observed when groundwater treating. Presumably, their increase in solution is associated with the transition of insoluble salts of calcium and magnesium carbonates (constant water hardness) into water-soluble nitrates (temporary hardness). In addition to magnesium and calcium ions, potassium and sodium cations were monitored in water samples. Their concentration in water was insignificantly affected by the treatments with discharges.

Study of technological properties of aqueous solutions of polyacrylamide and fcl-1 with different concentrations

The quality and preparation methods of cotton seeds play a crucial role in increasing crop yield. Seed swelling capacity, germination energy, and laboratory germination are essential characteristics for precision sowing. The excessive fibrous covering on cotton seeds necessitates linting and delinting processes to ensure uniform distribution during sowing. However, existing methods have drawbacks, and none can be considered perfect. The results of a study on the structures, compositions, and physicochemical properties of polyacrylamide and other ingredients are presented. The potential utilization of these substances in the development of composite chemical preparations for cotton seed treatment is demonstrated. Based on the research findings, it is evident that the concentration of PAA significantly affects the viscosity, density, and water retention of the solutions. Choosing the right PAA concentration allows for the targeted regulation of the technological parameters of the solutions.

Non-monotonic Soret coefficients of aqueous LiCl solutions with varying concentrations.

We investigate the thermodiffusive properties of aqueous solutions of lithium chloride, using thermal diffusion forced Rayleigh scattering in a concentration range of 0.5-2 mole per kg of solvent and a temperature range of 5 to 45 °C. All solutions exhibit non-monotonic variations of the Soret coefficient ST with a concentration exhibiting a minimum at about one mole per kg of solvent. The depth of the minimum decreases with increasing temperature and shifts slightly towards higher concentrations. We compare the experimental data with published data and apply a recent model based on overlapping hydration shells. Additionally, we calculate the ratio of the phenomenological Onsager coefficients using our experimental results and published data to calculate the thermodynamic factor. Simple linear, quadratic and exponential functions can be used to describe this ratio accurately, and together with the thermodynamic factors, the experimental Soret coefficients can be reproduced. The main conclusion from this analysis is that the minimum of the Soret coefficients results from a maximum in the thermodynamic factor, which appears itself at concentrations far below the experimental concentrations. Only after multiplication by the (negative) monotonous Onsager ratio does the minimum move into the experimental concentration window.

OAT GUM: STRUCTURE, PROPERTIES, PRODUCTION, APPLICATION IN THE FOOD INDUSTRY

Oat gum (β-glucan, glycan) belongs to the group of soluble dietary fibers. Due to their important functional properties, cereal β-glucans are used to reduce the level of cholesterol in the blood, alleviate the symptoms of diabetes, lower blood pressure, and prevent cardiovascular and oncological diseases. Sources of β-glucans are yeast, mushrooms, bacteria, barley, oats. The use of secondary resources of barley and oat processing as a source of β-glucans has both economic and environmental significance. Cereal β-glucans consist of β-D-glucose monomers connected by (1,3)- and (1,4)-glycosidic bonds. β-Glucan dissolves well in cold water and is insoluble in ethyl alcohol. It is able to form very viscous solutions at low concentrations. The viscosity of solutions depends on the concentration and molecular weight of β-glucan. The rheological properties of aqueous gum solutions do not depend on the pH of the medium. The presence of NaCl in concentrations of more than 0.5% leads to a decrease in the viscosity of solutions, and the addition of sucrose in the amount of 20-45% increases the viscosity. The technological features of obtaining β-glucans are related to the method of their extraction from natural sources. Extraction of oat gum from oat bran or rolled oats involves alkaline treatment of flour at 50-70 °C and pH 8.0-10.5, removal of starch and proteins, precipitation of oat gum with alcohol and separation by centrifugation. Solubility, degree of extraction, and yield of β-glucan from oats depend on particle size, pretreatment of grain raw materials, and extraction conditions (temperature, pH, extractants). β-Glucan is isolated from the extract by dialysis, ultrafiltration or alcohol precipitation. When using dialysis, highly viscous β-glucan is obtained, but with a lower yield; ultrafiltration and alcohol precipitation allow a higher yield of β-glucan with lower viscosity. Oat gum can be introduced into a wide range of food products to provide new functional properties and improve nutritional quality, includ ng wheat bread, bakery products, cookies, pasta, soft drinks, as a fat substitute in dairy and meat products. It performs the technological functions of a thickener, gelling agent, stabilizer or coating in food systems.