Solubility In Aqueous Solutions Research Articles

Co3O4/NiCo2O4 heterojunction as oxygen evolution reaction catalyst for efficient luminol anode electrochemiluminescence

Luminol has garnered significant attention from analysts as one of the most effective and commonly used electrochemiluminescence (ECL) reagents. However, the efficient luminescence of luminol anode is limited by the excitation of various reactive oxygen species (ROS). Typically, ROS are generated through co-reactive reagents and dissolved oxygen. Unfortunately, the former suffers from two drawbacks, namely biotoxicity and instability, while the latter cannot offer sufficient oxygen due to its limited solubility in aqueous solutions. Consequently, a low decomposition rate is usually obtained, leading to insufficient ROS. Therefore, there is an urgent need to develop efficient luminol anode systems. This study focuses on the use of zeolitic imidazolate framework-67 (ZIF-67) as a template, employing a controlled chemical etching method to create a ZIF-67/Ni-Co-layered double hydroxide (LDH). The intermediate composite is then annealed in air, resulting in the formation of a Co3O4/NiCo2O4 double-shelled nanobox (DSNB) heterostructure. Due to its structural advantages, the DSNB exhibits excellent electrocatalytic performance in the oxygen evolution reaction (OER). Furthermore, it was found that both the intermediates and products of OER can directly participate in the luminol chemiluminescence process, ultimately resulting in a 700-fold increase in the electrochemiluminescence (ECL) signal compared to an equal molar concentration of luminol solution. This work not only establishes the OER-mediated ECL system but also deepens the understanding of the relationship between ROS and luminol, providing a new pathway to study the luminol anodic ECL luminescence system.

Quantification of crystallinity during indomethacin crystalline transformation from α- to γ-polymorphic forms and of the thermodynamic contribution to dissolution in aqueous buffer and solutions of solubilizer.

The thermodynamic properties and dissolution of indomethacin (INM) were analyzed as models for poorly water-soluble drugs. Physical mixtures of the most stable γ-form and metastable α-form of INM at various proportions were prepared, and their individual signal intensities proportional to their mole fractions were observed using X-ray powder diffraction and Fourier transform infrared spectrometry at standard temperature. The endothermic signals of the α-form, with a melting point of 426 K, and that of the γ-form, with a melting point of 433 K, were obtained by differential scanning calorimetry (DSC). Furthermore, an exothermic DSC peak of the α/γ-phase transition at approximately 428 K was obtained. As we computed the melting entropy of the α-form and that of its transformation, the frequency of the transition was quantitatively determined, which indicated the maximum of the α/γ-phase transition at an α-form proportion of 68%. Subsequently, the thermodynamic contributions of the α- and γ-forms were analyzed using a Van't Hoff plot for solubility in aqueous solutions at pH 6.8. The dissolution enthalpies for α- and γ-forms were 28.2 and 31.2 kJ mol-1, respectively, which are in agreement with the quantitative contribution predicted by the product of the temperature and melting entropy. The contribution of melting entropy was conserved in different dissolution processes with aqueous solvents containing lidocaine, diltiazem, l-carnosine, and aspartame as solubilizers; their γ-form Setschenow coefficients were -39.6, +82.9, -17.3, and +23.2, whereas those of the α-form were -39.7, +80.4, -16.7, and +22.7, respectively. We conclude that the dissolution ability of the solid state and solubilizers indicate their additivity independently.

Uniform trehalose nanogels for glucagon stabilization.

Glucagon is a peptide hormone that acts via receptor-mediated signaling predominantly in the liver to raise glucose levels by hepatic glycogen breakdown or conversion of noncarbohydrate, 3 carbon precursors to glucose by gluconeogenesis. Glucagon is administered to reverse severe hypoglycemia, a clinical complication associated with type 1 diabetes. However, due to low stability and solubility at neutral pH, there are limitations in the current formulations of glucagon. Trehalose methacrylate-based nanoparticles were utilized as the stabilizing and solubilizing moiety in the system reported herein. Glucagon was site-selectively modified to contain a cysteine at amino acid number 24 to covalently attach to the methacrylate-based polymer containing pyridyl disulfide side chains. PEG2000 dithiol was employed as the crosslinker to form uniform nanoparticles. Glucagon nanogels were monitored in Dulbecco's phosphate-buffered saline (DPBS) pH 7.4 at various temperatures to determine its long-term stability in solution. Glucagon nanogels were stable up to at least 5 months by size uniformity when stored at -20 °C and 4 °C, up to 5 days at 25 °C, and less than 12 hours at 37 °C. When glucagon stability was studied by either HPLC or thioflavin T assays, the glucagon was intact for at least 5 months at -20 °C and 4 °C within the nanoparticles at -20 °C and 4 °C and up to 2 days at 25 °C. Additionally, the glucagon nanogels were studied for toxicity and efficacy using various assays in vitro. The findings indicate that the nanogels were nontoxic to fibroblast cells and nonhemolytic to red blood cells. The glucagon in the nanogels was as active as glucagon alone. These results demonstrate the utility of trehalose nanogels towards a glucagon formulation with improved stability and solubility in aqueous solutions, particularly useful for storage at cold temperatures.

Exploring novel Cd(II) complexes with 5-methyl-4-imidazolecarboxaldehyde: synthesis, structure, computational insights, and affinity to DNA through switchSense methodology.

A series of four Cd(II) complexes with 5-methyl-4-imidazolecarboxaldehyde (L) with different inorganic anions within or outside the coordination sphere of general formula: [CdCl2L2] (1), [CdBr2L2] (2), [CdI2L2] (3), and [CdL4](PF6)2·3H2O (4) was synthesized through one-step and two-step reactions, respectively. All complexes were obtained as colorless crystals without the need for recrystallization and exhibited solubility in aqueous solutions. Structural analysis revealed different coordination environments for each complex, with variations in bond lengths and angles. The crystal packing of the complexes was stabilized by hydrogen bonding and π-π stacking interactions. FT-IR analysis indicated coordination of the ligand to the metal ion, and UV-Vis studies confirmed the stability of the complexes in solution. Computational analysis has revealed the polar nature of the complexes and their favorable stability constants. Affinity studies with DNA using the switchSense technique demonstrated rapid association and dissociation processes for all complexes, with temperature-dependent binding constants. Thermodynamic analysis suggested spontaneous with positive entropy change and endothermic formation processes for the complexes. Overall, the study underscores the synthesis, examination, and interaction with DNA of Cd(II) complexes, demonstrating their promise within medicinal chemistry.

Hyperbranched TEMPO-based polymers as catholytes for redox flow battery applications.

Application of redox-active polymers (RAPs) in redox flow batteries (RFBs) can potentially reduce the stack cost through substitution of costly ion-exchange membranes by cheap size-exclusion membranes. However, intermolecular interactions of polymer molecules, i.e., entanglements, particularly in concentrated solutions, result in relatively high electrolyte viscosities. Furthermore, the large size and limited mobility of polymers lead to slow diffusion and more sluggish heterogeneous electron transfer rates compared to quickly diffusing small molecules. Although a number of RAPs with varying electrolyte viscosities have been reported in the literature, the relation between the RAP structure and the hydrodynamic properties has not been thoroughly investigated. Herein, hyperbranched 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO)-based polymers intended for application as low-viscosity catholytes for RFBs are presented and the influence of the structure and the molar mass distribution on the hydrodynamic properties is investigated. A new synthesis approach for TEMPO-based polymers is established based on step-growth polymerization of a TEMPO-containing monomer using an aza-Michael addition followed by a postpolymerization modification to improve solubility in aqueous solutions. The compact structure of hyperbranched polymers was demonstrated using size-exclusion chromatography (SEC) with viscometric detection and the optimum molar mass was found based on the results of viscometric and crossover investigations. The resulting RAP revealed a viscosity of around 21 mPas at a concentration corresponding to around 1 M TEMPO-containing units, according to the calculated mass of the repeating unit, showing potential for high capacity polymer-based catholytes for RFBs. Nevertheless, possible partial deactivation of TEMPO units lowered the active TEMPO concentration of the hyperbranched RAPs. A faster diffusion and higher charge transfer rate were observed for the hyperbranched polymer compared to the previously reported linear polymers. However, in RFB tests, a poor performance was observed, which is attributed to the side reactions of the oxidized TEMPO moieties. Finally, pathways for overcoming the main remaining challenges, i.e., high loss of material during dialysis as an indication of being prone to crossover, the partial deactivation of TEMPO moieties, and the subsequent side reactions under battery conditions, are suggested.

Possibilities for improving the technology of roasting zinc concentrates

The paper presents an investigation into the oxidation process of zinc sulfide concentrate. A common challenge encountered during the fluidized calcination process is the high concentration of sulfide sulfur in the condensed products, such as the mixture collected at the furnace threshold and in the dust. This scientific work reports the results of laboratory studies aimed at improving the technology of roasting zinc concentrates. The study's objective was to obtain zinc cinders with increased solubility in aqueous solutions by roasting sulfide zinc concentrates. The results show that the optimal composition of the charge for roasting was determined using limestone and wastewater from the processing plant, which contains alkaline earth metal oxides. This composition helped reduce the formation of ferrites and silicates by 1.5-1.7 times.

TECHNOLOGIES FOR WASTEWATER TREATMENT FROM ARSENIC

The current recycling water supply of metallurgical enterprises does not completely eliminate the discharge of wastewater into environmental water bodies, where the maximum permissible concentration (MPC) of arsenic is 0.05 mg/dm3. Arsenic accumulates in large quantities in washing solutions for cleaning exhaust gases sent to produce sulfuric acid. In this case, a closed gas washing system is used, aimed at concentrating the washing water with arsenic to 10 g/dm3 and sulfuric acid to 40 g/dm3 in order to reduce the volume of wastewater discharge. Another source of arsenic contamination of the hydrosphere is the waters of tailings from enrichment plants, due to the possible oxidation of arsenopyrite and the formation of a soluble form of arsenic compounds.
 A number of methods for arsenic precipitation have been developed: pyrolusite, lime in the form of calcium arsenate; ions of ferric iron and other metals; adsorption by iron (III) hydroxide, aluminum hydroxide, carbon, etc.; sludge flotation; metal sulfides, sorption and extraction. The main criterion for the operation of purifying a solution from arsenic is the possibility of recycling the resulting sediment or the formation of its compounds with minimal solubility in aqueous solutions, allowing its burial in burial grounds.

Effect of Selenium on Dissolution of Manganese Sulfide Inclusions in Stainless Steel

The pit initiation sites for commercial stainless steels have been attributed to sulfide inclusions such as MnS. The chemical composition of the inclusions affects the pitting corrosion resistance of stainless steels.1,2 It is known that the inclusion solubility in aqueous solutions affects pitting corrosion resistance. The dissolution of sulfide inclusions produces S species and exposes the bare surface of the steel matrix, resulting in high pitting susceptibility near the inclusions. Selenium is known to improve the machinability of stainless steels. However, the effect of selenium on the dissolution and pit initiation of MnS inclusions in stainless steels remains unclear. In this study, a microelectrochemical technique was applied to analyze the effect of Se on the dissolution and pit initiation of MnS inclusions in stainless steels.Two re-sulfurized stainless steels were prepared by vacuum induction melting: one was Se-free, and the other was Se-added. The specimens were heat-treated at 1373 K for 30 min and quenched in water. After heat treatment, the specimens were polished with 1 µm diamond paste. Polarization curves were measured in 0.1 M NaCl and 0.1 M Na2SO4. An optical microscope and a scanning electron microscope equipped with an energy dispersive X-ray spectroscopy system were used to capture images of the specimen surfaces.

(Invited) Selective and Efficient Electrochemical CO2 Reduction Reaction from Cu and Cu-M Binary Alloys

Electrochemical CO2 reduction reaction (CO2RR) has attracted a great deal of attention due to its potential to convert CO2 into valuable chemical fuels and feedstocks. The production of C2+ chemicals, such as ethylene and ethanol, from CO2RR is particularly important because of their large market demand. However, several challenges must be addressed before CO2RR can be commercially scaled up, including high overpotential, low selectivity, and poor CO2 solubility in aqueous solutions. In this presentation, I will discuss our recent efforts to overcome these challenges in CO2RR by using a gas diffusion electrode (GDE) to achieve a CO2RR current density of over 100 mA/cm2 in a flow reactor. First, I will highlight the crucial role of the local CO2RR environment in promoting C-C coupling on Cu surfaces, and I will present strategies for controlling this environment based on steady-state modeling and monodisperse Cu2O nanoparticles as a model catalyst system. Using this approach, we have been able to produce C2+ products, such as ethylene and ethanol, with a Faraday efficiency of over 70% at a current density of over 300 mA/cm2 in near-neutral electrolytes. Additionally, I will discuss the impact of alloying Cu with Ni and Zn on tailoring product selectivity. By introducing elements with different CO binding strengths, we can significantly alter the selectivity for hydrocarbons and alcohols. I will provide further details on these findings during the presentation.

Data-driven machine learning models for the prediction of hydrogen solubility in aqueous systems of varying salinity: Implications for underground hydrogen storage

Hydrogen is a clean and sustainable renewable energy source with significant potential for use in energy storage applications because of its high energy density. In particular, underground hydrogen storage via the dissolution of hydrogen gas in an aqueous solution has been identified as a promising strategy to address the difficulties associated with large-scale energy storage. However, this process requires the accurate prediction of the solubility of hydrogen in aqueous solutions, which is affected by a range of factors, including temperature, pressure, and the presence of solutes. The present study thus aimed to effectively predict the solubility of hydrogen in aqueous solutions that vary in their salinity by employing a machine learning approach. Four machine learning models were developed and tested: adaptive gradient boosting (Adaboost), gradient boosting, random forest, and extreme gradient boosting. The performance of each model was quantified in terms of their coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE). The Adaboost algorithm exhibited superior performance across all metrics, with an R2 of 0.994, MAE of 0.006, and RMSE of 0.018. A Williams plot detected only 18 outliers in the Adaboost predictions from a total of 255 data points. These results indicate that machine learning techniques have the potential to serve as a valuable tool in the prediction of hydrogen solubility in aqueous solutions for underground hydrogen storage, facilitating the development of smart, cost-effective, and safe hydrogen storage technologies.

N-Methyl- and N-Phenylpiperazine Functionalized Styryl Dyes Inside Cucurbiturils: Theoretical Assessment of the Factors Governing the Host-Guest Recognition.

The family of cucurbiturils (CBs), the unique pumpkin-shaped macrocycles, has received great attention over the past four decades owing to their remarkable recognition properties. They have found diverse applications including biosensing and drug delivery technologies. The cucurbituril complexation of guest molecules can modulate their pKas, improve their solubility in aqueous solution, and reduce the adverse effects of the drugs, as well as enhance the stability and/or enable targeted delivery of the drug molecule. Employing twelve cationic styryl dyes with N-methyl- and N-phenylpiperazine functionality as probes, we attempted to understand the factors that govern the host-guest complexation of such molecules within CB[7] and CB[8] host systems. Various key factors determining the process were recognized, such as the pH and dielectric constant of the medium, the cavity size of the host, the chemical characteristics of the substituents in the guest entity, and the presence/absence of metal cations. The presented results add to our understanding (at the molecular level) of the mechanism of encapsulation of styryl dyes by cucurbiturils, thus shedding new light on various aspects of the intriguing complexation chemistry and the underlying recognition processes.

Levofloxacin-Fatty Acid Systems: Dual Enhancement Through Deep Eutectic Formation and Solubilization for Pharmaceutical Potential and Antibacterial Activity.

Fatty acids, including medium-chain saturated and polyunsaturated fatty acids, are known for their broad health benefits, including antimicrobial activity. Through their green properties, deep eutectic systems have been heralded as having the potential to be at the forefront of pharmaceutical applications. In this work, capric acid and geranic acid, two examples of medium-chain saturated and polyunsaturated fatty acids, were employed to enhance the pharmaceutical properties and the antibacterial activity of levofloxacin. To this end, levofloxacin formulations with either capric or geranic acid were prepared and characterized using appropriate techniques. Levofloxacin was utilized to create innovative deep eutectic systems in conjunction with capric acid at three different molar ratios: 1:9, 2:8 and 3:7. This was confirmed through a rigorous analysis involving nuclear magnetic resonance, infrared spectroscopy and differential scanning calorimetry. Furthermore, it is noteworthy that geranic acid demonstrated an impressive threefold improvement in levofloxacin's solubility compared to its solubility in aqueous solutions. The antibacterial activity of the novel combinations of levofloxacin with either fatty acid was evaluated using a checkerboard titration assay. Gratifyingly, both formulations exhibited synergistic effects against a panel of levofloxacin-sensitive and resistant Gram-negative bacteria. In conclusion, the observed superior antibacterial activity of levofloxacin illuminates the potential use of fatty acid-based formulations and deep eutectic systems as green and innovative strategies to combat the global antimicrobial resistance problem.

Study the Anticancer Properties of Thymol-Loaded PEGylated Bovine Serum Albumin Nanoparticles Conjugated with Folic Acid.

Phenolic compounds such as Thymol have an effective role in suppressing cancer, however, their low solubility in aqueous solution has limited their use. This study aimed to prepare Thymol (TY)-loaded bovine serum albumin (BSA) nanoparticles surface-modified with polyethylene glycol (PEG) conjugated with folic acid (FA) and evaluate their inhibitory activity on cancer cells. The TY-BSA-PEG-FA was characterized using DLS, FESEM, and FTIR. The encapsulation efficiency (EE) was evaluated indirectly by using UV absorption. The antioxidant property of nanoparticles was evaluated by 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing ability of plasm (FRAP) methods. The effects of nanoparticles against cancer cells were investigated by MTT, AO/PI, flow cytometry, and real-time qPCR methods. The results showed the spherical morphology of TY-BSA-PEG-FA with an average size of 70.0 nm, a PDI of 0.32, a zeta potential of -11.3 mV, and an EE of 89.0±2.3 %. The cytotoxicity effects of nanoparticles against all cell lines were in a concentration-dependent manner. AGS gastric cancer cells were reported to be the most vulnerable to treatment, while pancreatic cancer cells (PANC-1) and normal skin cells (HFF) would be the most resistant. The SubG1 phase arrest of about 66 % occurred at 85 μg/mL. An increase in apoptotic cells in fluorescent staining, along with decreased expression of Bcl-2 and increased expression of the BAX gene demonstrated the induction of apoptosis in treated cells. The powerful inhibitory effect of nanoparticles in inhibiting ABTS free radicals (IC50 =82 μg/mL) and DPPH free radicals (IC50 =844 μg/mL) and the ability to reduce iron ions indicated the antioxidant effects of TY-BSA-PEG-FA. Based on these results, the synthesized nanoparticles may be suitable for further investigation in the treatment of cancer, notably gastric cancer.

Estimation of CO2 solubility in aqueous solutions of commonly used blended amines: Application to optimised greenhouse gas capture

One of the key concerns in the 21st century, alongside the growing population, is the increase in energy consumption and the resulting global warming. The impact of CO2, a prominent greenhouse gas, has garnered significant attention in the realm of CO2 capture and gas purification. CO2 absorption can be enhanced by introducing some additives into the aqueous solution. In this study, the accuracies of some of the most up-to-date computational approaches are investigated. The employed machine learning methods are hybrid-adaptive neuro-fuzzy inference system (Hybrid-ANFIS), particle swarm optimization-adaptive neuro-fuzzy inference system (PSO-ANFIS), least-squares support vector machines (LSSVM) and genetic algorithm-radial basis function (GA-RBF). The developed models were used in estimating the solubility of CO2 in binary and ternary amines aqueous solutions. i.e. blends of monoethanolamine (MEA), triethanolamine (TEA), aminomethyl propanol (AMP), and methyldiethanolamine (MDEA). This modeling study was undertaken over relatively significant ranges of CO2 loading (mole of CO2/mole of solution) as a function of input parameters, which are 0.4–2908 kPa for pressure, 303–393.15 K for temperature, 36.22–68.89 g/mol for apparent molecular weight, and 30–55 wt % for total concentration. In this work, the validity of approaches based on different statistical graphs was investigated, and it was observed that the developed methods, especially the GA-RBF model, are highly accurate in estimating the data of interest. The obtained AARD% values for the developed models are 18.63, 8.25, 12.22, and 7.54 for Hybrid-ANFIS, PSO-ANFIS, LSSVM, and GA-RBF, respectively.

Efficient lignin biodegradation triggered by alkali-tolerant ligninolytic bacteria through improving lignin solubility in alkaline solution

Low lignin solubility in aqueous solution is one of the major bottlenecks for lignin biodegradation and bioconversion. Alkaline solution contributes to improving lignin solubility, whereas most microbes can not survive in alkaline conditions. Herein, lignin dissolution behaviors in different pH solutions were systematically investigated, which indicated that solution pH above 10.5 contributed to high solubility of alkali lignin. To match with alkaline lignin aqueous system, several alkali-tolerant ligninolytic bacteria were isolated, most of which are distinct to previously reported ones. Then, the ligninolytic capabilities of these isolates were assessed in different pH conditions by determining their assimilation on alkali lignin, lignin-derived monomers and dimers, their decolorization capabilities, and their lignin peroxidase activities. Thereafter, the underlying ligninolytic and alkali-tolerant mechanisms of Sutcliffiella sp. NC1, an alkalophilic bacterium, was analyzed on the basis of its genome information. The results not only provide valuable information for lignin biodegradation and lignin valorization, but also expand knowledge on alkali-tolerant bacteria.

Antioxidant activity and release profile of electrospun cellulose acetate/gelatine nanofiber containing mangosteen hull extract

The extract of mangosteen fruit hull has been found to have strong antioxidant activity. However, it has low solubility in aqueous solution. Thus, we incorporated the extract of mangosteen hull (EMH) into a nano-sized carrier, particularly nanofibers. The objective of this research was to fabricate cellulose acetate (CA)/gelatine nanofibers embedded with EMH using the electrospinning technique. CA/gelatine/EMH precursor solution was spun at various flow rates of 0.1, 0.2, and 0.3 mL/h yielding nanofibers with average diameters of 525 (CGE1), 640 (CGE2), and 698 (CGE3) nm, respectively. An antioxidative assay using the DPPH method indicated that all samples (EMH, CGE1, CGE2, and CGE3 nanofibers) exhibited strong antioxidant activity, whereas the smallest nanofibers had the lowest antioxidant activity. Moreover, the XRD pattern of composite fiber (CGE2) implied that the electrospinning process altered the structure of EMH. Furthermore, in vitro release study of CGE1, CGE2, and CGE3 nanofibers indicated a rapid release pattern of EMH from the nanofibers. The rate of EMH released from the fiber was related to the fiber diameter, with smaller fiber facilitating a faster release rate of the EMH. Therefore, the results provide a promising approach to enhancing the solubility and bioavailability of mangosteen fruit hull extract, potentially expanding its therapeutic applications.

Equilibrium absorption of CO2 in aqueous solution of N-dimethylamino ethanol and 2-(ethylamino)ethanol, measuring and thermodynamic modeling

The equilibrium carbon dioxide solubility in aqueous solutions of N-dimethylaminoethanol (DMAE) 40 wt% + 2-(ethylamino) ethanol (EAE) 5 wt% and DMAE 30 wt% + EAE 5 wt% was measured at various temperatures (313.15, 328.15, 343.15, 358.15 K) in the range of pressures from 6.5 to 236 kPa. The enthalpy of absorption of carbon dioxide was measured for the mixture of DMAE (40 wt%) + EAE (5 wt%), at 328.15 K. The Deshmukh-Mather model was used to correlate the equilibrium solubility of carbon dioxide data, and the model parameters were optimized. The optimized model could correlate the vapor-liquid equilibrium with the 9.4 average absolute percentage deviation (AAD%), and the obtained AAD% for enthalpy of absorption in aqueous solution of DMAE (40 wt%) + EAE (5 wt%) was 24.0.

CO2 solubility in aqueous solutions of blended amines: Experimental data for mixtures with MDEA, AMP and MPA and modeling with the modified Kent-Eisenberg model

CO2 solubility in aqueous solutions of blended amines: Experimental data for mixtures with MDEA, AMP and MPA and modeling with the modified Kent-Eisenberg model

Thermodynamics of K2HPO4/d-Sucrose/Water System at 298.15 K: Experiment and Modeling

Thermodynamic properties of K2HPO4/d-sucrose/water ternary solutions were investigated at 298.15 K. Water activity, osmotic coefficient, and electrolyte saturation points are determined by measuring relative humidities in the wide range of K2HPO4 molality (ranging from 0.1 to approximately 5 mol·kg–1) and for various d-sucrose contents (0.1, 0.3, 0.5, 1, 2, 3, 4, 5, and 5.5 mol·kg–1) in the ternary K2HPO4/d-sucrose/water system. The solid state was characterized using powder X-ray diffraction (XRD) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) techniques. The obtained data were then analyzed using the Pitzer-Simonson-Clegg (PSC) model to determine several thermodynamic properties. These properties encompass the stoichiometric ionic mean activity coefficient of K2HPO4, excess Gibbs energy, solubility in aqueous solutions, and the Gibbs energy of transfer of K2HPO4 between water (W) and d-sucrose/water (W+S) mixtures. Furthermore, the interactions among water, d-sucrose, and K2HPO4 are also examined and discussed.

Polymer stabilized, phenytoin-loaded nanomicelles as promising nanocarriers: In silico and in vitro evaluations

Many drugs currently used in clinics to treat different diseases show low solubilities in aqueous solutions and must be then administered with the aid of organic solvents within the designed formulations leading to harmful health effects. For such reason, drug delivery using nanocarriers appears as an excellent alternative since it improves the solubilization and controlled release of many different pharmaceuticals, favoring the decrease of the overall administered therapeutic doses and by diminishing the risk of potential associated adverse side effects. Among the different types of nanocarriers, those based on polymeric micelles are an excellent option since the polymer structure and composition may be tuned in order to regulate the characteristics and properties of the resulting nanoassemblies to maximize drug solubilization and release profiles. For this reason, in this paper a drug delivery nanosystem based on oil-in-water polymeric-based microemulsion used to load the anti-epileptic phenytoin drug (PHT) was developed in the oily phase. Two different biocompatible polymers were evaluated to form the nanomicelles and maximize encapsulation efficiencies and colloidal stability: The amphiphilic triblock copolymer Pluronic F127, which poses the ability to cross the blood brain barrier (BBB), and the natural lipophilic lignin, which bears antipathogenic properties. Density functional theory (DFT) calculations were performed with the 6-31G(d) basis set to elucidate the interactions of PHT with F127 and lignin monomers. Simulation data showed that hydrogen bonding (HB) interactions between PHT, F127 and lignin are the predominant force to allow for drug solubilization and stability. Atoms in molecules (AIM) and natural bond orbital (NBO) analyses were performed to evaluate the strength of such HB. and their drug encapsulation efficiency, release profiles, and antibacterial susceptibility were determined. Moreover, the cytotoxicity of the developed nanoformulations together with a morphological examination of PC12 and NIH cells after drug-loaded nanocarrier administration and subsequent uptake were also investigated. In this manner, the obtained nanocarriers were also characterized by dynamic light scattering (DLS) and zeta potential, showing a nanometer size (between ca. 16 and 22 nm) and surface negative charge. PHT loading into F127 and lignin nanomicelles were ca. 96.7 ± 1.5% and 68.2 ± 3.5%, respectively, and the drug release profile kinetics of F127/PHT-loaded nanomicelles was rather slower compared to that of lignin/PHT-loaded ones. On the other hand, in vitro cytotoxicity data confirmed the lack of any significant cytotoxicity of PHT-loaded nanomicelles in both NIH/3T3 and PC12 cell lines, but a slightly higher cell viability and well-preserved cell morphology was observed for PC12 cells compared to NIH/3T3 ones. After culturing in chocolate blood agar medium inoculated with F127/PHT-loaded and lignin/ PHT-loaded nanomicelles, pathogenic bacteria did not grow despite confirming certain antimicrobial character of the encapsulated drug. Hence, thanks to their excellent encapsulation and biocompatibility properties, these nanocarriers appear as an excellent option to configure new drug delivery nanocarriers of hydrophobic drugs.