Effect Of Cosolvents Research Articles

Effects of Cosolvent on the Intermolecular Interactions between an Analyte and a Gold Nanostar Surface Studied Using SERS.

For surface-enhanced Raman scattering (SERS), reproducible solution-phase results are typically obtained using nanoparticles functionalized with surface-stabilizing molecules that can prevent the adsorption of analyte molecules with surface affinities lower than those of the stabilizing agent. Herein, we investigate the effects of intermolecular interactions between a nonthiolated analyte and cosolvent to facilitate and modulate analyte adsorption to gold nanostars. SERS, extinction spectroscopy, transmission electron microscopy (TEM), and density functional theory (DFT) calculations are employed in this regard. Tetrahydrofuran (THF) is utilized as a cosolvent in water to facilitate the detection of acetylsalicylic acid (aspirin) on anisotropic gold nanoparticles. Intermolecular interactions between the analyte, solvent, and surface are modulated by changing the solution composition to understand how THF facilitates the SERS detection of aspirin in THF-water cosolvents. SERS signals for 5 mM aspirin arise only in the presence of THF at and above 60 mM, while no signal with or without THF below 60 mM is observed. SERS detection of aspirin is hypothesized to depend on THF forming a hydrogen-bonded complex with aspirin that reduces aspirin hydrophobicity, thus stabilizing the acid form of the molecule and allowing it to weakly interact with the gold nanoparticles. The aspirin-THF complex adsorbs to the gold surface through π-orbital overlap between the aromatic ring and gold, where additional THF weakens orbital overlap. Understanding the mechanism by which organic cosolvents facilitate the SERS detection of nonthiolated analytes such as aspirin, in aqueous media, allows other cosolvents, nonthiolated analytes, and other surfaces to obtain a SERS signal in a variety of systems.

Optimization of oil extraction from Melia azedarach fruits using methanol-modified SC-CO2 for highly efficient biodiesel production using a modified LAC catalyst

A highly efficient oil extraction method including modified Supercritical carbon dioxide (SC-CO2) with co-solvents was applied for oil extraction from Melia azedarach fruits and then using a modified LAC (luffa activated carbon) catalyst, the oil was converted to biodiesel for the first time. The effect of pressure (22–30 MPa), temperature (40–80 °C), extraction time (0–240 min) and co-solvent (methanol and n-hexane) were determined on SC-CO2 extraction to obtain the optimum condition. The optimum extraction conditions for Melia azedarach oil corresponded to a pressure of 30 MPa and temperature of 40 °C at 180 min using methanol as of co-solvent. The maximum yield was obtained by addition of methanol as co-solvent in an amount of 10 %, w/w. The methanol- modified SC-CO2 extraction oil yield was 43 % (w/w) and the oil yield by n-hexane-modified SC-CO2 extraction was 38 %, while the oil yield obtained by pure SC-CO2 extraction was 32 %. Then, the effect of catalysts LAC-NH2 and LAC-N(Et)2 as safe, economical, free-metal, and less time-consuming heterogeneous catalysts was investigated on biodiesel production from extracted oil. The results revealed that the optimum yields of 98 % was obtained for biodiesel production using 2 wt% of LAC-NH2 catalyst at the reaction conditions of oil to methanol ratio of 1:6, reaction temperature of 60 °C, and reaction time of 3 h.

Aqueous co-solvent synthesis of Zeolitic Imidazolate Frameworks: The impact of co-solvents in the crystal growth kinetics

Zeolitic Imidazolate Frameworks (ZIFs) have been widely studied in recent decades in a variety of applications. However, a fundamental understanding of crystal growth kinetics as well as their formation mechanisms has been very limited. Underpinning such mechanisms might be of key importance for the predictable synthesis of ZIFs to rationally tune the structural and morphological properties for respective applications. Herein, the crystal growth kinetics and structural evolution of ZIF-8 crystals in various aqueous co-solvent reaction environments were studied with respect to synthesis time. By tracking the nucleation, crystal growth, stabilization and ripening, three potential kinetic formation mechanisms were proposed. More specifically, with methanol, isopropanol and acetone, a fast nucleation rate and crystal growth occurred within 60 minutes (min) at room temperature. However, ethanol and n-propanol showed prolonged nucleation which resulted in the slow formation of ZIF-L/ZIF-8 mixed phases at the early stage. Phase transformation to pure ZIF-8 was observed in longer syntheses. Nitrogen-containing solvent, N, N–dimethyl formaldehyde (DMF), was found to induce both nucleation and growth, resulting in large crystals in less than 60 min of fabrication. In each case, the crystal formation follows Avrami's classical model. Hence, by understanding the effects of co-solvents in ZIF nucleation, crystallization and phase selection, one can rationally design the crystals with predictable crystallinity, size, morphology, purity and surface properties for targeted applications such as adsorption of small molecules from aqueous mixtures.

Liquid-Liquid Equilibrium of Sesame Fatty Acid (Ethyl and Methyl) Ester + Glycerol + Ethanol/Methanol Mixtures at Different Temperatures.

This study aimed to investigate the liquid-liquid equilibrium (LLE) behavior of sesame fatty acid ethyl ester (FAEE) and methyl ester (FAME) in combination with glycerol and the co-solvents ethanol and methanol. FAEE and FAME were produced through the transesterification of mechanically extracted and purified sesame oil, using potassium hydroxide (KOH) as a homogeneous base catalyst. The reactions were conducted in ethanol and methanol to produce FAEE and FAME, respectively. Post-reaction, the products were separated and purified, followed by an analysis of the LLE behavior at 313.15 K and 323.15 K under atmospheric pressure (101.3 kPa). The experimental process for the miscibility analysis utilized a jacketed glass cell adapted for this study. Miscibility limits or binodal curves were determined using the turbidity-point method. Tie lines were constructed by preparing mixtures of known concentrations within the two-phase region, which allowed the phases to separate after agitation. Samples from both phases were analyzed to determine their composition. This study revealed that higher temperatures promoted greater phase separation and enhanced the biodiesel purification process. The NRTL model effectively correlated the activity coefficients with the experimental data, showing good agreement, with a root-mean-square deviation of 3.5%. Additionally, the data quality was validated using Marcilla's method, which yielded an R2 value close to 1. Attraction factors and distribution coefficients were also calculated to evaluate the efficiency of the co-solvents as extraction agents. The findings indicated higher selectivity for methanol than for ethanol, with varying degrees of distribution among the co-solvents. These results offer significant insights into enhancing biodiesel production processes by considering the effects of co-solvents on the LLE properties of mixtures, ultimately contributing to more efficient and cost-effective biodiesel production.

Molecular Mechanism of the Cosolvency Effect in Organic Solutes with Similar Structures

Molecular Mechanism of the Cosolvency Effect in Organic Solutes with Similar Structures

Co-Solvent effect and Kinetics of Alkaline Hydrolysis of Butyle Salicylate

The base catalised hydrolysis of buyl salicylate has been carred out in water-DMF binary solvent mixture covering range of 30 to 70% (v/v) of solvent composition at different Temperature (20 to 400 C). The reaction followed second order rate constant which decreases with increase of solvent composition. The salvation and desolvation concept are used to explain the solvent influence on rate and mechanism is the reaction. The relation between changes in dielectric constant due to variation of reaction mixture and change in specific rate constant has been explained on the basis of electrostatic and non-electrostatic contribution of solvent mixture. Calculated value of Iso-composition activation energy is found to be increases with increase of solvent composition. The thermodynamic parameters (ΔG*, ΔH* & ΔS*) has been determined with help of Wynne Jone and Eyring equation which show the great dependency on solvent composition.

Effects of Macromolecular Cosolutes on the Kinetics of Huntingtin Aggregation Monitored by NMR Spectroscopy.

The effects of two macromolecular cosolutes, specifically the polysaccharide dextran-20 and the protein lysozyme, on the aggregation kinetics of a pathogenic huntingtin exon-1 protein (hhtex1) with a 35 polyglutamine repeat, httex1Q35, are described. A unified kinetic model that establishes a direct connection between reversible tetramerization occurring on the microsecond time scale and irreversible fibril formation on a time scale of hours/days forms the basis for quantitative analysis of httex1Q35 aggregation, monitored by measuring cross-peak intensities in a series of 2D 1H-15N NMR correlation spectra acquired during the course of aggregation. The primary effects of the two cosolutes are associated with shifts in the prenucleation tetramerization equilibrium resulting in substantial changes in concentration of "preformed" httex1Q35 tetramers. Similar effects of the two cosolutes on the tetramerization equilibrium observed for a shorter, nonaggregating huntingtin variant with a 7-glutamine repeat, httex1Q7, lend confidence to the conclusions drawn from the fits to the httex1Q35 aggregation kinetics.

Recent Advances of Solvent Effects in Biomass Liquefaction Conversion

Liquefaction conversion technology has become one of the hottest biomass conversion methods due to its flexible material selection and extensive product applications. Exploring biomass liquefaction conversion focuses on catalysts, biomass/water ratio, and reaction temperature. However, it is found that solvents are crucial in the biomass liquefaction process and significantly impact the type of liquefied products and bio-oil yield. Given the current rapid development trend, timely sorting and summary of the solvent effect in the biomass liquefaction process can promote the subsequent development and industrialization of more efficient and cleaner biomass liquefaction technology. Therefore, this review first introduces the characteristics of water as the liquefaction solvent, then summarizes the effects of organic solvents on liquefaction, and finally elaborates on the synergistic effect of co-solvents, which provides a more systematic overview of solvent effects in the liquefaction process. Meanwhile, prospects are put forward for the future development of biomass liquefaction conversion.

Influence of Surfactant on the Skin Permeation of Methylisothiazolinone and Methylchloroisothiazolinone.

Patch tests are often used in safety evaluations to identify the substance causing skin irritation, but the same substance can sometimes give positive or negative results depending on the test conditions. Here, we investigated differences in the skin penetration of two test compounds under different application conditions. We studied the effects of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant polysorbate 80 (PS) on skin penetration of the preservatives methylisothiazolinone (MT) and methylchloroisothiazolinone (MCT), which are used in cosmetics such as shampoos. The skin permeation of MT was enhanced by SDS but was unchanged by PS. Skin impedance decreased in the presence of SDS whereas PS had the same effect as the control aqueous solution, suggesting that SDS reduction of the barrier function of skin affects the permeation of MT, a hydrophilic drug. Application of a mixture of MCT and MT in the presence of SDS did not affect the skin permeation of MCT whereas the permeation of MT was enhanced by SDS, indicating that the skin permeation of MCT is less affected by SDS than is MT. Thus, attention should be paid to the possible effect of co-solutes, especially hydrophilic drugs.

Bioinspired Colorimetric Double Inverse Opal Photonic Crystal Indicators for Ethanol Concentration Sensing in Fermentation Engineering.

Photonic crystal-based ethanol concentration indicators with rapid response and brilliant structural color output definitely take a place in colorimetric sensors. Here, based on the H-bond-regulated swelling of acrylate shape memory polymers (SMPs) and the solvent-induced structural color change of the double inverse opal photonic crystals (DIOPCs), new-type photonic crystals (PCs) colorimetric indicators were constructed, exhibiting a span of maximum reflection wavelength (λmax) up to ∼166 nm in response to alcohols with concentrations from 0 to 100 vol %. DIOPC indicators (DIOPCIs) show a rapid response to alcohols (<1.5 s) and output different structural colors (covering from blue to red). The colorimetric sensing mechanism includes the solvent-triggered recovery of the inverse opal skeleton, the cosolvency effect and H-bonds induced swelling/shrinkage of the polymer, the phase separation between polystyrene (PS) microsphere and polymer skeleton, and the light diffraction of DIOPCs. While ensuring a larger λmax span by regulating the H-bond interactions in polymer chains through acrylamide (AAm), AAm-modified DIOPCIs are sensitive to some specific ethanol concentrations. The real-time sensing of ethanol concentration during fermentation verified the practicability of DIOPCIs, thus establishing a visual model between structural color and corresponding fermentation kinetics. We envisage that the DIOPCIs will contribute to the intelligentization of the alcoholic fermentation and distillation industry.

Experimental and Machine-Learning-Assisted Design of Pharmaceutically Acceptable Deep Eutectic Solvents for the Solubility Improvement of Non-Selective COX Inhibitors Ibuprofen and Ketoprofen.

Deep eutectic solvents (DESs) are commonly used in pharmaceutical applications as excellent solubilizers of active substances. This study investigated the tuning of ibuprofen and ketoprofen solubility utilizing DESs containing choline chloride or betaine as hydrogen bond acceptors and various polyols (ethylene glycol, diethylene glycol, triethylene glycol, glycerol, 1,2-propanediol, 1,3-butanediol) as hydrogen bond donors. Experimental solubility data were collected for all DES systems. A machine learning model was developed using COSMO-RS molecular descriptors to predict solubility. All studied DESs exhibited a cosolvency effect, increasing drug solubility at modest concentrations of water. The model accurately predicted solubility for ibuprofen, ketoprofen, and related analogs (flurbiprofen, felbinac, phenylacetic acid, diphenylacetic acid). A machine learning approach utilizing COSMO-RS descriptors enables the rational design and solubility prediction of DES formulations for improved pharmaceutical applications.

Effect of green co-solvents on properties and synthesis of cellulose esters in superbase ionic liquid

Effect of green co-solvents on properties and synthesis of cellulose esters in superbase ionic liquid

Controlling Interfacial Hydrogen Bonding at a Gold Surface: The Effect of Organic Cosolvents.

Water often serves as both a reactant and solvent in electrocatalytic reactions. Interfacial water networks can affect the transport and kinetics of these reactions, e.g., hydrogen evolution reaction and CO2 reduction reaction. Adding cosolvents that influence the hydrogen-bonding (H-bonding) environment, such as dimethyl sulfoxide (DMSO), has the potential to tune the reactivity of these important electrocatalytic reactions by regulating the interfacial local environment and water network. We investigate interfacial H-bonding networks in water-DMSO cosolvent mixtures on gold surfaces by using surface-enhanced infrared absorption spectroscopy and molecular dynamics simulations. Experiments and simulations show that the gold surface is enriched with dehydrated DMSO molecules and the mixture phase-separates to form water clusters. Simulations show a "buckled" water conformation at the surface, further constraining interfacial H-bonding. The small size of these water clusters and the energetically unfavorable H-bond conformations might inhibit H-bonding with bulk water, suppressing the proton diffusion required for efficient hydrogen evolution reaction processes.

Supercritical cartilage decellularization: Cosolvent effect on mechanical properties

Decellularized animal tissue may serve as scaffolds in tissue engineering. Despite the well-disseminated use of sodium dodecyl sulfate (SDS) for decellularization, SDS-based methods are time-consuming and may cause extracellular matrix (ECM) denaturation. This study explores supercritical CO2 (scCO2) extraction as an alternative to decellularize chicken sternum cartilage. Various scCO2 decellularization methods were tested, including pure scCO2, scCO2 with water, ethanol, or their mixture. SDS outperformed in decellularization but caused the highest extracellular matrix damage. Pure scCO2 treatment for 2 h reduced mechanical resistance due to dehydration. scCO2 with 99 % ethanol led to extensive tissue dehydration, while the addition of 70 % ethanol increased cell removal without significant tissue damage. Further research is recommended to optimize scCO2 decellularization of this tissue with other cosolvents while maintaining adequate hydration.

Binary and ternary approach of solubility of Rivaroxaban for preparation of developed nano drug using supercritical fluid

This study addressed the solubility of Rivaroxaban in supercritical carbon dioxide at a temperature range of 308–338 K and a pressure range of 12–30 MPa with and without a Co-solvent in binary and ternary systems. The impact of ethanol Co-solvent was also examined. Furthermore, the examined systems were modeled using semi-empirical approaches once the tentative solubility data were determined. Rivaroxaban solubility in the binary and ternary systems ranged based on mole fraction from 1.0×10-6 to 2.57×10-5 and 1.9×10-5 to 2.02×10-4, respectively. Based on the results, the use of a Co-solvent can greatly boost the solubility of Rivaroxaban. The highest Co-solvent effect on the Rivaroxaban-Ethanol-CO2 mixture was observed at 18.73 (338 K and 12 MPa). Furthermore, empirical and semi-empirical models can effectively fit the solubility values of the analyzed materials by AARD% and Radj for binary and ternary approaches. The Jouyban et al. (AARD%=7.40 and Radj = 0.993) model for the binary system and the Garlapati-Madras (AARD%=6.16 and Radj = 0.991) and Sodeifian-Sajadian (AARD%=6.13 and Radj = 0.979) and Soltani-Mazloumi (AARD%=6.89 and Radj = 0.987) models for the ternary system are the most accurate models.

Carbohydrate Co-Solutes Stabilize Collagen Triple Helices.

Carbohydrates are common co-solutes for the stabilization of proteins. The effect of carbohydrate solutions on the stability of collagen, the most abundant protein in mammals, is, however, underexplored. In this work, we studied the thermal stability of collagen triple helices derived from a molecularly defined collagen model peptide (CMP), Ac-(Pro-Hyp-Gly)7 -NH2 , in solutions of six common mono- and disaccharides. We show that the carbohydrates stabilize the collagen triple helix in a concentration-dependent manner, with an increase of the melting temperature of up to 17 °C. In addition, we show that the stabilizing effect is similar for all studied sugars, including trehalose, which is otherwise considered a privileged bioprotectant. The results provided insight into the effects of sugar co-solutes on collagen triple helices and can aid the selection of storage environments for collagen-based materials and probes.

Supercritical Fluid Extraction of Phenolics from Anisophyllea disticha (Jack) Baill. and Evaluation of their Antioxidant Activities

Background: Anisophyllea disticha (Jack) Baill. (A. disticha) is a species of the Anisophylleaceae family that has undergone the least investigation despite being widely used in folk medicine to cure a wide range of illnesses. Objective: The purpose of this study is to examine the impact of various factors on the supercritical fluid extraction of A. disticha in order to maximise recovery of total phenolic content, antioxidant activity, and polyphenol identification. Method: The total phenolic content (TPC) and antioxidant activities of A. disticha were determined using the supercritical fluid extraction (SFE) method and compared with Soxhlet. Box-Behnken design of response surface methodology was performed to examine the effect of independent variables of SFE such as temperature, pressure, and concentration of ethanol as co-solvent on TPC and antioxidant activities of A. disticha stem extracts. Result: At combined effects of different temperatures, pressure, and co-solvent, the total SFE yield were ranged between 0.65 and 4.14%, which was about half of the Soxhlet extract of 8.75±1.54%. The highest concentration (µg/g) of gallic acid (118.83±1.17), p-coumaric (61.60±0.33), ferulic acid (57.93±1.15), and quercetin (24.16±0.41) were obtained at a temperature of 50 ˚C, the pressure of 25 MPa and co-solvent of 20%, while lowest concentration was found 70 ˚C, 30 MPa, and 20% ethanol. Conclusion: SFE extracts possessed remarkable TPC and concentration of phenolic compounds, indicating superior recovery of compounds. SFE showed more than two-fold higher ferric-reducing antioxidant power compared to Soxhlet with values of 585.32±17.01 mg Fe (II)/g extract and 203.63±16.03 mg Fe (II)/g extract, respectively. SFE demonstrated a potential alternative to the classical solvent extraction methods.

Acetone extraction induced piperazine diffusion reaction for regulating thin film composite nanofiltration membrane

The regulation of monomer diffusion in interfacial polymerization played a vital role in manipulating structure and enhancing separation performance of nanofiltration (NF) membrane. The co-solvent strategy has been recognized to be valid and applicable for improving membrane performance. However, the underlying mechanism for its effect on the diffusion progress of amine monomers was still unclear and contradictory. In this study, we found that the added co-solvent (acetone) induced piperazine diffusion flood through interfacial co-solvent extraction effect due to the interfacial enrichment of acetone and innovatively proposed a concept of “acetone extraction effect”. The mechanism and molecular dynamics simulation (MD) were used to systematically explain the effect of diffusion on the morphology and properties of the membranes. The prepared NF membranes exhibited improved separation performance for Calcium (CaCl2, 71.5 ± 0.6 %) and Magnesium (MgCl2, 83.1 ± 0.8 %) ions, which were better than many of the recorded membranes. This study provided a new idea for the co-solvent effect in interfacial polymerization and promising guidance for the preparation of superior NF membranes.

Effect of cosolvents on the phase separation of polyelectrolyte complexes.

Evidence is shown that cosolvent mixtures control the coacervation of mixtures of oppositely charged polyelectrolytes. Binary and ternary solvent mixtures lead to non-monotonic solubility as a function of the average dielectric constants of the solvent mixtures. These data are rationalized by considering both electrostatic-driven phase separation and solvophobic-driven phase separation using group contribution effects on solubility parameters. These estimates are introduced into an effective Flory-Huggins interaction parameter within the framework of Voorn-Overbeek theory with variable dielectric constants and temperature dependences. Despite its simplicity, the model recovers salient experimental observations not only on their coacervate stabilities, but also on their lower critical solution temperature behaviors. These observations highlight the importance of weak van der Waals interactions in determining the phase behaviors of polyelectrolyte complexes relative to electrostatic correlations.

With or without a co-solvent? highly efficient ultrafast phenanthrenequinone-electron rich alkene (PQ-ERA) photoclick reactions.

The light-induced photocycloaddition of 9,10-phenanthrenequinone (PQ) with electron-rich alkenes (ERA), known as the PQ-ERA reaction, is a highly attractive photoclick reaction characterized by its operational simplicity and high biocompatibility. One essential aspect of photoclick reactions is their high rate, however the limited solubility of PQs often requires the use of a co-solvent. Evaluating the effect of different co-solvents on the PQ-ERA reaction and their influence on the reaction rate, we discovered that sulfur-containing compounds, in particular the frequently used solubilizing co-solvent DMSO, quench the triplet state of the PQ. These experimental results, supported by nanosecond-microsecond and ultrafast transient absorption data, show that even minimal amounts of DMSO result in a decreased lifetime of the reactive triplet state, essential for the photoclick reaction. Without DMSO as co-solvent, exceptionally high photoreaction quantum yields ( Φ P up to 93% with only 1 equivalent ERA) and complete conversion in seconds can be achieved. With these outstanding efficiencies, the PQ-ERA reaction can be used without excess ERA and at low light intensities, facilitating photoclick transformations in various future applications.