Assessing metal extraction from metalliferous waste: A study using deep eutectic solvents and chelating agents vs. ethylenediaminetetraacetic acid.

Conventional methods of metal recovery involving solvents have raised environmental concerns. To address these concerns and promote sustainable resource recovery, we explored the use of deep eutectic solvents (DES) and chelating agents (CA) as more environmentally friendly alternatives. Goethite and blast oxide slag dust (BOS-D) from heap piles at their respective sites and characterised via ICP-MS. The greatest extraction of critical metals was from goethite, removing 38% of all metals compared to 21% from the blast oxide slag. Among the tested CA, nitrilotriacetic acid (NTA) was the most effective, while for DES, choline chloride ethylene glycol (ChCl-EG) demonstrated superior performance in extracting metals from both blast oxide slag dust and goethite. The study further highlighted the selectivity for transition metals and metalloids was influenced by the carboxyl groups of DES. Alkaline metals and rare earth lanthanides extractions were favoured with DES due to improved mass transfer and increased denticity, respectively. In comparison to ethylenediaminetetraacetic acid (EDTA), typically used for metal extraction, CA and DES showed comparable extraction efficiency for Fe, Cu, Pb, Li, Al, Mn, and Ni. Using these greener chelators and solvents for metal extraction show significant promise in enhancing the sustainability of solvometallurgy. Additional conditions e.g., temperature and agitation combined with a cascading leaching process could further enhance metal extraction potential.

Investigation of antifungal and antibacterial potential of green extracts of propolis.

Propolis extracts have been used in traditional medicines since ages due to its advantageous complex chemical composition. However, the antibacterial and antifungal activity of poplar propolis extracts prepared in Natural Deep Eutectic Solvent (NADES) are seldom studied. This study investigates suitable alternate for ethanol as a solvent for extraction for Polish poplar propolis. It also attempts to identify suitable extraction condition for the efficient transfer of compounds from propolis to the solvents. The extraction efficiency of NADES extracts was assessed in terms of total phenolic content, antioxidant activity and antimicrobial activity. The chemical composition of the extracts was analysed using UHPLC-DAD-QqTOF-MS. Four extracts, prepared in Propylene Glycol, Choline Chloride:Propylene Glycol (1:3), Choline Chloride:Propylene Glycol (1:4) and Choline Chloride:Glycerol (1:2), demonstrated activity and properties similar to ethanolic extract and extraction at 50 °C was found the most suitable for propolis. HPLC analysis confirmed that the chemical cocktail extracted by these solvents from propolis were identical with minor variations in their concentration as compared to its ethanolic extract. Thus, extracts of propolis at 50 °C in Propylene Glycol, Choline Chloride:Propylene Glycol (1:3) and Choline Chloride:Propylene Glycol (1:4) can be alternates for ethanolic extracts.

Green Extraction of Polyphenols from Elaeagnus angustifolia L. Using Natural Deep Eutectic Solvents and Evaluation of Bioactivity.

In the study, natural deep eutectic solvents (NADESs) were used as alternatives to traditional chemical solvents for the extraction of polyphenols from Elaeagnus angustifolia L. Nine NADESs were tested for the first time and compared with ethanol and water (traditional solvents) regarding the extraction of phenolic compounds from E. angustifolia L. These solvents were particularly effective at extracting polyphenols, whose low water solubility usually requires high amounts of organic solvents. The solvent based on choline chloride and malonic acid provided optimal results and was selected for further optimization. The effects of material-to-liquid ratio, ultrasound time, and ultrasound temperature on the extraction efficiency were studied through single-factor experiments. These parameters were optimized by Box-Behnken design using response surface methodology. The optimal conditions identified were 49.86 g/mL of material-to-liquid ratio, 31.10 min of ultrasound time, and 62.35 °C of ultrasound temperature, resulting in a high yield of 140.30 ± 0.19 mg/g. The results indicated that the NADES extraction technique provided a higher yield than the conventional extraction process. The antioxidant activity of the extract of polyphenols from E. angustifolia L. was determined, and UPLC-IMS-QTOF-MS was used to analyze the phenolic compounds in it. The results revealed that the scavenging ability of 1,1-diphenyl-2-picryl-hydrazil and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) extracted by NADES was higher than that of polyphenols extracted by water and ethanol. Furthermore, a total of 24 phenolic compounds were identified in the extract. To the best of our knowledge, this is the first study in which a green and efficient NADES extraction method has been used to extract bioactive polyphenols from E. angustifolia L., which could provide potential value in pharmaceuticals, cosmetics, and food additives.

Exploring Phenolic Compounds Extraction from Saffron (C. sativus) Floral By-Products Using Ultrasound-Assisted Extraction, Deep Eutectic Solvent Extraction, and Subcritical Water Extraction.

Saffron (Crocus sativus) floral by-products are a source of phenolic compounds that can be recovered and used in the nutraceutical, pharmaceutical, or cosmetic industries. This study aimed to evaluate the phenolic compounds' extraction using green extraction techniques (GETs) in saffron floral by-products and to explore the influence of selected extraction techniques on the phytochemical composition of the extracts. Specifically, ultrasound-assisted extraction (UAE), subcritical water extraction (SWE), and deep eutectic solvents extraction (DESE) were used. Phenolic compounds were identified with (HR) LC-ESI-QTOF MS/MS analysis, and the quantitative analysis was performed with HPLC-PDA. Concerning the extraction techniques, UAE showed the highest amount for both anthocyanins and flavonoids with 50:50% v/v ethanol/water as solvent (93.43 ± 4.67 mg/g of dry plant, dp). Among SWE, extraction with 96% ethanol and t = 125 °C gave the best quantitative results. The 16 different solvent mixtures used for the DESE showed the highest amount of flavonoids (110.95 ± 5.55-73.25 ± 3.66 mg/g dp), while anthocyanins were better extracted with choline chloride:butane-1,4-diol (16.0 ± 0.80 mg/g dp). Consequently, GETs can be employed to extract the bioactive compounds from saffron floral by-products, implementing recycling and reduction of waste and fitting into the broader circular economy discussion.

A Comprehensive Analysis of Diversity, Structure, Biosynthesis and Extraction of Biologically Active Tannins from Various Plant-Based Materials Using Deep Eutectic Solvents.

This paper explores the emerging subject of extracting tannins from various plant sources using deep eutectic solvents (DESs). Tannins are widely used in the food and feed industries as they have outstanding antioxidant qualities and greatly enhance the flavor and nutritional content of a wide range of food products. Organic solvents are frequently used in traditional extraction techniques, which raises questions about their safety for human health and the environment. DESs present a prospective substitute because of their low toxicity, adaptability, and environmental friendliness. The fundamental ideas supporting the application of DESs in the extraction of tannins from a range of plant-based materials frequently used in daily life are all well covered in this paper. Furthermore, this paper covers the impact of extraction parameters on the yield of extracted tannins, as well as possible obstacles and directions for future research in this emerging subject. This includes challenges such as high viscosity, intricated recovery of compounds, thermal degradation, and the occurrence of esterification. An extensive summary of the diversity, structure, biosynthesis, distribution, and roles of tannins in plants is given in this paper. Additionally, this paper thoroughly examines various bioactivities of tannins and their metabolites.

Deep eutectic solvent-assisted synthesis of La-Ce hybrid nanorods for the colorimetric determination of tetracycline in foods.

Tetracycline (TC) as a broad-spectrum antibiotic, is widely used in the prevention and treatment of various bacterial diseases. However, its abuse in the livestock industry may lead to interference in human microecology, thereby causing various side effects. In this study, deep eutectic solvents (DESs) were synthesized using L-(-)-threonine (L-(-)-Thr) and cerium nitrate hexahydrate (Ce(NO3)3·6H2O), and later lanthanum nitrate hexahydrate (La(NO3)3·6H2O) was doped to synthesize La-Ce hybrid nanorods. These nanorods can be used for the determination of TC with high sensitivity and selectivity by the colorimetric method. This approach has a linear response to TC between 0.05 µM and 10 µM, with a detection limit of 0.016 µM. In this system, good dispersion provides the substance with a distinct peroxidase activity, which is used to create a colorimetric sensor for detecting TC. Mechanism studies show that the superoxide radical generated by the La-Ce nanomembrane plays a key role in peroxidase catalysis. Finally, the practicality of the method was verified by the determination of TC in food products (milk, pork and honey), which demonstrated that a good recovery rate can be obtained (91.4-102%).

Green Extraction of Depsidones and Depsides from Hypogymnia physodes (L.) Nyl. Using Natural Deep Eutectic Solvents.

Various studies have shown that Hypogymnia physodes are a source of many biologically active compounds, including lichen acids. These lichen-specific compounds are characterized by antioxidant, antiproliferative, and antimicrobial properties, and they can be used in the cosmetic and pharmaceutical industries. The main aim of this study was to optimize the composition of natural deep eutectic solvents based on proline or betaine and lactic acid for the extraction of metabolites from H. physodes. The design of the experimental method and the response surface approach allowed the optimization of the extraction process of specific lichen metabolites. Based on preliminary research, a multivariate model of the experiment was developed. For optimization, the following parameters were employed in the experiment to confirm the model: a proline/lactic acid/water molar ratio of 1:2:2. Such a mixture allowed the efficient extraction of three depsidones (i.e., physodic acid, physodalic acid, 3-hydroyphysodic acid) and one depside (i.e., atranorin). The developed composition of the solvent mixtures ensured good efficiency when extracting the metabolites from the thallus of H. physodes with high antioxidant properties.

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.

Separation and Detection of Catechins and Epicatechins in Shanxi Aged Vinegar Using Solid-Phase Extraction and Hydrophobic Deep Eutectic Solvents Combined with HPLC.

This research presents a new, eco-friendly, and swift method combining solid-phase extraction and hydrophobic deep eutectic solvents (DES) with high-performance liquid chromatography (SPE-DES-HPLC) for extracting and quantifying catechin and epicatechin in Shanxi aged vinegar (SAV). The parameters, such as the elution solvent type, the XAD-2 macroporous resin dosage, the DES ratio, the DES volume, the adsorption time, and the desorption time, were optimized via a one-way experiment. A central composite design using the Box-Behnken methodology was employed to investigate the effects of various factors, including 17 experimental runs and the construction of three-dimensional response surface plots to identify the optimal conditions. The results show that the optimal conditions were an HDES (tetraethylammonium chloride and octanoic acid) ratio of 1:3, an XAD-2 macroporous resin dosage of 188 mg, and an adsorption time of 11 min. Under these optimal conditions, the coefficients of determination of the method were greater than or equal to 0.9917, the precision was less than 5%, and the recoveries ranged from 98.8% to 118.8%. The environmentally friendly nature of the analytical process and sample preparation was assessed via the Analytical Eco-Scale and AGREE, demonstrating that this method is a practical and eco-friendly alternative to conventional determination techniques. In summary, this innovative approach offers a solid foundation for the assessment of flavanol compounds present in SAV samples.

Extraction and Biological Activity of Lignanoids from Magnolia officinalis Rehder & E.H.Wilson Residual Waste Biomass Using Deep Eutectic Solvents.

Lignanoids are an active ingredient exerting powerful antioxidant and anti-inflammatory effects in the treatment of many diseases. In order to improve the efficiency of the resource utilization of traditional Chinese medicine waste, Magnolia officinalis Rehder & E.H.Wilson residue (MOR) waste biomass was used as raw material in this study, and a series of deep eutectic solvents (ChUre, ChAce, ChPro, ChCit, ChOxa, ChMal, ChLac, ChLev, ChGly and ChEG) were selected to evaluate the extraction efficiency of lignanoids from MORs. The results showed that the best conditions for lignanoid extraction were a liquid-solid ratio of 40.50 mL/g, an HBD-HBA ratio of 2.06, a water percentage of 29.3%, an extract temperature of 337.65 K, and a time of 107 min. Under these conditions, the maximum lignanoid amount was 39.18 mg/g. In addition, the kinetics of the extraction process were investigated by mathematic modeling. In our antioxidant activity study, high antioxidant activity of the lignanoid extract was shown in scavenging four different types of free radicals (DPPH, ·OH, ABTS, and superoxide anions). At a concentration of 3 mg/mL, the total antioxidant capacity of the lignanoid extract was 1.795 U/mL, which was equal to 0.12 mg/mL of Vc solution. Furthermore, the antibacterial activity study found that the lignanoid extract exhibited good antibacterial effects against six tested pathogens. Among them, Staphylococcus aureus exerted the strongest antibacterial activity. Eventually, the correlation of the lignanoid extract with the biological activity and physicochemical properties of DESs is described using a heatmap, along with the evaluation of the in vitro hypoglycemic, in vitro hypolipidemic, immunomodulatory, and anti-inflammatory activity of the lignanoid extract. These findings can provide a theoretical foundation for the extraction of high-value components from waste biomass by deep eutectic solvents, as well as highlighting its specific significance in natural product development and utilization.

Ultrasound-Assisted Extraction of Phenolic Compounds from Celtuce (Lactuca sativa var. augustana) Leaves Using Natural Deep Eutectic Solvents (NADES): Process Optimization and Extraction Mechanism Research.

Natural deep eutectic solvents (NADESs), as emerging green solvents, can efficiently extract natural products from natural resources. However, studies on the extraction of phenolic compounds from celtuce (Lactuca sativa var. augustana) leaves (CLs) by NADESs are still lacking. This study screened the NADES L-proline-lactic acid (Pr-LA), combined it with ultrasound-assisted extraction (UAE) to extract phenolic compounds from CLs, and conducted a comparative study on the extraction effect with traditional extraction solvents. Both SEM and FT-IR confirmed that Pr-LA can enhance the degree of fragmentation of cell structures and improve the extraction rate of phenolic compounds. Molecular dynamics simulation results show that Pr-LA can improve the solubility of phenolic compounds and has stronger hydrogen bonds and van der Waals interactions with phenolic compounds. Single-factor and Box-Behnken experiments optimized the process parameters for the extraction of phenolic compounds from CLs. The second-order kinetic model describes the extraction process of phenolic compounds from CLs under optimal process parameters and provides theoretical guidance for actual industrial production. This study not only provides an efficient and green method for extracting phenolic compounds from CLs but also clarifies the mechanism of improved extraction efficiency, which provides a basis for research on the NADES extraction mechanism.

Molecular dynamics simulations of choline chloride and ascorbic acid deep eutectic solvents: Investigation of structural and dynamics properties.

Deep eutectic solvents (DESs) composed of choline chloride (ChCl) and ascorbic acid (AA) were investigated using the molecular dynamics (MD) simulations. The analyses of the configuration, radial distribution function (RDFs), coordination number, spatial distribution function (SDFs), interaction energies, hydrogen bond number, and self-diffusion coefficient of the ChCl/AA binary systems of different concentrations showed that the stability of the hydrogen bond network and the mutual attraction between systems were the strongest at the experimental eutectic concentration (molar ratio of 2:1). In our simulated temperature range from 303.15 to 353.15 K, the hydrogen bonding network of ChCl/AA DES does not undergo considerable alterations, indicating that its stability was insensitive to temperature. In addition, the influence of the water content on the ChCl/AA DES system was further investigated. The simulated results revealed that the water molecules could disrupt the formation of the hydrogen bonding network by occupyin positions that are essential for the formation of hydrogen bonds within the DES system.

Synergism of jet milling and deep eutectic solvent pretreatment on grapevine lignin fractionation and enhancing enzymatic hydrolysis.

Herein, we investigated the synergistic effects of jet milling (JM) and deep eutectic solvent (DES) pretreatment on the fractionation of grapevine lignin and the consequent enhancement of enzymatic hydrolysis. Grapevine, a substantial byproduct of the wine industry, was subjected to JM pretreatment to produce finely powdered particles (median diameter D50 = 98.90), which were then further treated with acidic ChCl-LA and alkaline K2CO3-EG DESs. The results revealed that the combined JM + ChCl-LA pretreatment significantly increased the cellulose preservation under optimal conditions (110 °C, 4 h, and 20 % water content), achieving removal rates of 74.18 % xylan and 66.05 % lignin, respectively. The pretreatment temperature and inhibitor production were reduced, resulting in a remarkable threefold increase in glucose yield compared to untreated samples. Moreover, the structural analysis of the pretreated lignin indicated an enrichment of phenolic units, leading to enhanced antioxidant and antibacterial activities, particularly in the JM pretreated samples. These findings underscore the promising potential of the synergistic JM and DES pretreatment in facilitating the efficient utilization of grapevine lignocellulosic biomass for sustainable biorefinery technologies.

Deep-eutectic-solvent modulation of self-assembled multi-responsive films based on polyvinyl alcohol/cellulose nanocrystal and grape skin red for highly sensitive food monitoring.

To enhance the mechanics performance, sensitivity and response range of multi-responsive photonic films, herein, a facile method for fabricating multi-responsive films is demonstrated using the evaporative self-assembly of a mixture of grape skin red (GSR), cellulose nanocrystal (CNC), polyvinyl alcohol (PVA) and deep eutectic solvent (DES). The prepared materials exhibited excellent thermal stability, strain properties, solvent resistance, ultraviolet (UV) resistance and antioxidant activity. Compared to a pure PVA film, the presence of GSR strengthened the antioxidant property of the film by 240.1 % and provided excellent UV barrier capability. The additional cross-linking of DES and CNC promoted more efficient phase fusion, yielding a film strain of 41.5 %. The addition of hydrophilic compound GSR, wetting and swelling due to the DES and the surface inhomogeneity of the films rendered the multi-responsive films high sensitivity, wide response range and multi-cyclic stability in environments with varying pH and humidity. A sample application showed that a PVA/CNC/DES film has the potential to differentiate between fresh, sub-fresh and fully spoiled shrimps. The above results help in designing intelligent thin film materials that integrate antioxidant properties, which help in monitoring the changes in food freshness and food packaging.

Green and efficient extraction of flavonoids from Perilla frutescens (L.) Britt. leaves based on natural deep eutectic solvents: Process optimization, component identification, and biological activity.

In this study, an ultrasonic-assisted natural deep eutectic solvent (NaDES) was used to extract flavonoids from Perilla frutescens (L.) Britt. leaves. Of 10 tested NaDESs, that comprising D-(+)-glucose and glycerol exhibited the best total flavonoid extraction rate. Response surface methodology (RSM) was used for extraction modeling and optimization, and the total flavonoid content reached 87.48 ± 1.61 mg RE/g DW, which was a significant increase of 5.36% compared with that of 80% ethanol extraction. Morphological changes in P. frutescens leaves before and after extraction were analyzed by scanning electron microscopy (SEM), and the mechanism of NaDES formation was studied by Fourier transform infrared (FT-IR) spectroscopy. Furthermore, 10 flavonoids were identified by UPLC-Q-TOF-MS. In addition, the NaDES extract had better biological activity according to five kinds of antioxidant capacity measurements, cyclooxygenase-2 (COX-2) and hyaluronidase (Hyal) inhibition experiments. Moreover, the stability test revealed that the total flavonoid loss rate of the NaDES extract after four weeks was 37.75% lower than that of the ethanol extract. These results indicate that the NaDES can effectively extract flavonoids from P. frutescens leaves and provide a reference for further applications in the food, medicine, health product and cosmetic industries.

Protein from tiger nut meal extracted by deep eutectic solvent and alkali-soluble acid precipitation: A comparative study on structure, function, and nutrition.

Protein from tiger nut meal (TNP) performance high nutritional value. This study optimized the extraction parameters for TNP (DES-TNP) using deep eutectic solvent, with HBD: HBA = 5:1, Liquid: Solid = 11:1, and the moisture content was 15 %. A comprehensive comparison was conducted with the protein extracted using alkali-soluble acid precipitation (ASAE-TNP). DES-TNP demonstrated significantly higher purity (76.21 ± 2.59 %) than ASAE-TNP (67.48 ± 1.11 %). Density functional theory confirmed the successful synthesis of DES and its strong interaction with TNP. Moreover, DES-TNP and ASAE-TNP were different in structure (microscopic, secondary, and tertiary) and molecular weight distribution. The discrepancy contributed to the different functional properties, DES-TNP exhibiting better solubility, emulsification and foaming properties at pH13 compared to ASAE-TNP. For nutritional properties, DES-TNP and ASAE-TNP exhibited similar amino acid composition and digestibility, but the total amino acid content of DES-TNP was higher. This study presented a novel method for the extraction and comprehensive utilization of TNP.

Determination of pesticide residues in soybeans using QuEChERS followed by deep eutectic solvent-based DLLME preconcentration prior to gas chromatography-mass spectrometry analysis.

A reliable and greener alternative to the usual extraction methods is reported for the determination of pesticide residues in soybeans. This novel approach combines the classical QuEChERS extraction method with a DLLME (dispersive liquid-liquid microextraction) step, utilizing a deep eutectic solvent (DES) - camphor: hexanoic acid (1:1 molar ratio) - as the microextraction solvent. This DES has never been employed in pesticide analysis by gas chromatography-mass spectrometry of complex matrices like soybeans. A Plackett-Burman screening design was employed to optimize sample preparation variables of QuEChERS (amount of sodium chloride and magnesium sulfate, and amount of PSA and C18 sorbents) and DLLME (pH of medium, amount of sodium chloride, and volume of microextraction solvent). This design allowed for a systematic evaluation of the impact of each parameter on the method's performance. The optimized method was evaluated using a certified reference material and commercial samples of soybeans. The method exhibited high accuracy and precision for most of the analytes under study, demonstrating its applicability for pesticide residue analysis in soybeans. To assess the greenness and practicality of the developed method, the Analytical Greenness (AGREE) and Blue Applicability Grade Index (BAGI) metric systems were employed, respectively. Overall, the proposed QuEChERS-DLLME method using a DES solvent is a reliable and greener alternative to conventional extraction methods for the determination of pesticide residues in soybeans. Its high performance, coupled with its environmental friendliness, makes it a promising tool for food safety analysis.

Anhydrous volatile fatty acid extraction through omniphobic membranes by hydrophobic deep eutectic solvents: Mechanistic understanding and future perspective.

Volatile fatty acids (VFAs) derived from arrested anaerobic digestion (AD) can be recovered as a valuable commodity for value-added synthesis. However, separating VFAs from digestate with complex constituents and a high-water content is an energy-prohibitive process. This study developed an innovative technology to overcome this barrier by integrating deep eutectic solvents (DESs) with an omniphobic membrane into a membrane contactor for efficient extraction of anhydrous VFAs with low energy consumption. A kinetic model was developed to elucidate the mechanistic differences between this novel omniphobic membrane-enabled DES extraction and the previous hydrophobic membrane-enabled NaOH extraction. Experimental results and mechanistic modeling suggested that VFA extraction by the DES is a reversible adsorption process facilitating subsequent VFA separation via anhydrous distillation. High vapor pressure of shorter-chain VFAs and low Nernst distribution coefficients of longer-chain VFAs contributed to DES-driven extraction, which could enable continuous and in-situ recovery and conversion of VFAs from AD streams.

An eminent approach towards next generation solvents for sustainable packaging and stability of enzymes: a comprehensive study of ionic liquid and deep eutectic solvent mixtures.

Hybrid ionic fluids (HIFs) are newly emerging and fascinating sustainable solvent media, which are attracting a great deal of scientific interest in protecting the native structure of proteins. For a few decades, there has been a demand to consider ionic liquids (ILs) and deep eutectic solvents (DESs) as biocompatible solvent media for enzymes; however, in some cases, these solvent media also show limitations. Therefore, this work focuses on synthesising novel HIFs to intensify the properties of existing ILs and DESs by mixing them. Herein, HIFs have been synthesised by the amalgamation of a deep eutectic solvent (DES) and an ionic liquid (IL) with a common cation or anion. Later on, the stability and activity of hen's egg white lysozyme (Lyz) in the presence of biocompatible solvent media and HIFs were studied by various techniques such as UV-vis, steady-state fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR) and dynamic light scattering (DLS) measurements. This work emphasises the effect of a DES (synthesised using 1 : 2 choline chloride and malonic acid) [Maline], ILs (1-butyl-3-methylimidazolium chloride [BMIM]Cl or choline acetate [Chn][Ac]) and their corresponding HIFs on the structure and functionality of Lyz. Moreover, we also studied the secondary structure, thermal stability, enzymatic activity and thermodynamic profile of Lyz at pH = 7 in the presence of varying concentrations (0.1 to 0.5 M) of [BMIM]Cl and [Chn][Ac] ILs, Maline as a DES, and Maline [BMIM]Cl (HIF1) and Maline [Chn][Ac] (HIF2). Spectroscopic results elucidate that ILs affect the activity and structural stability of Lyz. In contrast, the stability and activity are inhibited by DES and are enhanced by HIFs at all the studied concentrations. Overall, the experimental results studied explicitly elucidate that the structure and stability of Lyz are maintained in the presence of HIF1 while these properties are intensified in HIF2. This study shows various applications in biocompatible green solvents, particularly in the stability and functionality of proteins, due to their unique combination where the properties counteract the negative effect of either DESs or ILs in HIFs.

Deep eutectic solvents as sustainable extraction media for extraction of polysaccharides from natural sources: Status, challenges and prospects.

Deep eutectic solvents (DES) emerge as promising alternatives to conventional solvents, offering outstanding extraction capabilities, low toxicity, eco-friendliness, straightforward synthesis procedures, broad applicability, and impressive recyclability. DES are synthesized by combining two or more components through various synthesis procedures, such as heat-assisted mixing/stirring, grinding, freeze drying, and evaporation. Polysaccharides, as abundant natural materials, are highly valued for their biocompatibility, biodegradability, and sustainability. These versatile biopolymers can be derived from various natural sources such as plants, algae, animals, or microorganisms using diverse extraction techniques. This review explores the synthesis procedures of DES, their physicochemical properties, characterization analysis, and their application in polysaccharide extraction. The extraction optimization strategies, parameters affecting DES-based polysaccharide extraction, and separation mechanisms are comprehensively discussed. Additionally, this review provides insights into recently developed molecular guides for DES screening and the utilization of artificial neural networks for optimizing DES-based extraction processes. DES serve as excellent extraction media for polysaccharides from different sources, preserving their functional features. They are utilized both as extraction solvents and as supporting media to enhance the extraction abilities of other solvents. Continued research aims to improve DES-based extraction methods and achieve selective, energy-efficient processes to meet the demands of this expanding field.