Optimization of peptide synthesis time and sustainability using novel eco-friendly binary solvent systems with induction heating on an automated peptide synthesizer

On December 12th, 2023, the European Commission took regulatory action to amend Annex XVII of REACH, imposing restrictions on the use of N,N-dimethylformamide (DMF) within the EU market owing to its high toxicity. Historically, DMF has been widely considered the gold standard for solid-phase peptide synthesis (SPPS). Being urgent to propose alternative solvents, we tested the suitability of non-hazardous neat and mixed solvents. Notably, binary solvent mixtures containing dimethyl sulfoxide as one of the solvent partners demonstrated high efficacy in solubilizing reagents while maintaining the desired swelling characteristics of common resins. A series of binary solvent mixtures were tested in automated SPPS, both at room temperature and high temperature, employing the PurePep® Chorus synthesizer, which enabled controlled induction heating between 25 and 90°C with oscillation mixing. The performances were assessed in challenging peptide sequences, i.e., ACP (65-74), and in longer and aggregating sequences like SARS-CoV-2 RBM (436-507) and β-amyloid (1-42). Furthermore, as part of the proposed sustainable approach to minimize the utilization of hazardous solvents, we coupled the novel PurePep EasyClean catch-and-release purification technology. This work, addressing regulatory compliance, emphasizes the crucial role of green chemistry in advancing safer and more environmentally friendly practices in SPPS.

Tuning Local Order in Starch Nanoparticles Exploiting Nonsolvency with "Green" Solvents

Starch is a renewable biopolymer that can be sourced from agricultural waste and used to produce nanoparticles (SNPs). In particular, amorphous SNPs have potential application in numerous fields, including the consolidation of weakened paintings in the cultural heritage preservation. Starch dissolution followed by nanoprecipitation in nonsolvents is an advantageous synthetic route, but new methodologies are needed to feasibly control the physicochemical properties of the SNPs. Here, we explored nanoprecipitation by nonsolvency using a set of "green" solvents to obtain amorphous SNPs, rather than starch nanocrystals already reported in the literature. The effect of the nonsolvent on the ordering of polymer chains in the obtained SNPs was studied. The recovery of local order (e.g., isolated V-type helices) after dissolution was shown to depend on the type of solvents used in the dissolution and precipitation steps, while long-range order (extended arrays of helices) is lost. Aqueous dispersions of the SNPs provided effective consolidation of powdery painted layers, showing that the selection of particle synthetic routes can be dictated by sustainability and scalability criteria. These "green" formulations are candidates as new consolidants in art preservation, and the possibility of tuning local order in amorphous starch assemblies might also impact fields like food chemistry, pharmaceutics, and nanocomposites, where SNPs with tunable amorphousness are more advantageous than nanocrystals.

Experimental and Theoretical Insights into the Intermolecular Interactions in Saturated Systems of Dapsone in Conventional and Deep Eutectic Solvents

Solubility is not only a crucial physicochemical property for laboratory practice but also provides valuable insight into the mechanism of saturated system organization, as a measure of the interplay between various intermolecular interactions. The importance of these data cannot be overstated, particularly when dealing with active pharmaceutical ingredients (APIs), such as dapsone. It is a commonly used anti-inflammatory and antimicrobial agent. However, its low solubility hampers its efficient applications. In this project, deep eutectic solvents (DESs) were used as solubilizing agents for dapsone as an alternative to traditional solvents. DESs were composed of choline chloride and one of six polyols. Additionally, water-DES mixtures were studied as a type of ternary solvents. The solubility of dapsone in these systems was determined spectrophotometrically. This study also analyzed the intermolecular interactions, not only in the studied eutectic systems, but also in a wide range of systems found in the literature, determined using the COSMO-RS framework. The intermolecular interactions were quantified as affinity values, which correspond to the Gibbs free energy of pair formation of dapsone molecules with constituents of regular solvents and choline chloride-based deep eutectic solvents. The patterns of solute-solute, solute-solvent, and solvent-solvent interactions that affect solubility were recognized using Orange data mining software (version 3.36.2). Finally, the computed affinity values were used to provide useful descriptors for machine learning purposes. The impact of intermolecular interactions on dapsone solubility in neat solvents, binary organic solvent mixtures, and deep eutectic solvents was analyzed and highlighted, underscoring the crucial role of dapsone self-association and providing valuable insights into complex solubility phenomena. Also the importance of solvent-solvent diversity was highlighted as a factor determining dapsone solubility. The Non-Linear Support Vector Regression (NuSVR) model, in conjunction with unique molecular descriptors, revealed exceptional predictive accuracy. Overall, this study underscores the potency of computed molecular characteristics and machine learning models in unraveling complex molecular interactions, thereby advancing our understanding of solubility phenomena within the scientific community.

High-Performance Wearable Organic Photodetectors by Molecular Design and Green Solvent Processing for Pulse Oximetry and Photoplethysmography

White-light detection from the visible to the near-infrared region is central to many applications such as high-speed cameras, autonomous vehicles, and wearable electronics. While organic photodetectors (OPDs) are being developed for such applications, several challenges must be overcome to produce scalable high-detectivity OPDs. This includes issues associated with low responsivity, narrow absorption range, and environmentally friendly device fabrication. Here, an OPD system processed from 2-methyltetrahydrofuran (2-MeTHF) sets a record in light detectivity, which is also comparable with commercially available silicon-based photodiodes is reported. The newly designed OPD is employed in wearable devices to monitor heart rate and blood oxygen saturation using a flexible OPD-based finger pulse oximeter. In achieving this, a framework for a detailed understanding of the structure-processing-property relationship in these OPDs is also developed. The bulk heterojunction (BHJ) thin films processed from 2-MeTHF are characterized at different length scales with advanced techniques. The BHJ morphology exhibits optimal intermixing and phase separation of donor and acceptor moieties, which facilitates the charge generation and collection process. Benefitting from high charge carrier mobilities and a low shunt leakage current, the newly developed OPD exhibits a specific detectivity of above 1012  Jones over 400-900 nm, which is higher than those of reference devices processed from chlorobenzene and ortho-xylene.

Designing low toxic deep eutectic solvents for the green recycle of lithium-ion batteries cathodes

The Lithium-ion battery (LIB) is one of the main energy storage equipment. Its cathode material contains Li, Co, and other valuable metals. Therefore, recycling spent LIBs can reduce environmental pollution and resource waste, which is significant for sustainable development. However, traditional metallurgical methods are not environmentally friendly, with high cost and environmental toxicity. Recently, the concept of green chemistry gives rise to environmental and efficient recycling technology, which promotes the transition of recycling solvents from organic solvents to green solvents represented by deep eutectic solvents (DESs). DESs are considered as ideal alternative solvents in extraction processes, attracting great attention due to their low cost, low toxicity, good biodegradability, and high extraction capacity. It is very important to develop the DESs system for LIBs recycling for sustainable development of energy and green economic development of recycling technology. In this work, the applications and research progress of DESs in LIBs recovery are reviewed, and the physicochemical properties such as viscosity, toxicity and regulatory properties are summarized and discussed. In particular, the toxicity data of DESs are collected and analyzed. Finally, the guidance and prospects for future research are put forward, aiming to explore more suitable DESs for recycling valuable metals in batteries.

Green Solvents for Extraction of Natural Food Colorants from Plants: Selectivity and Stability Issues

Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

Magnetically Recyclable Nanoscale Zero-Valent Iron-Mediated PhotoRDRP in Ionic Liquid toward Smart, Functional Polymers

A facile method based on recyclable nanoscale zero-valent iron (nZVI)-mediated photoinduced reversible deactivation radical polymerization in ionic liquid (IL) leads to the synthesis of narrow disperse poly(tert-butyl methacrylate) (PTBMA), amphiphilic PTBMA-block-poly(poly(ethylene glycol)methacrylate) diblock copolymer and double hydrophilic poly(methacrylic acid)-block-poly(poly(ethylene glycol)methacrylate) (PMAA-b-PPEGMA) diblock copolymers thereof. Stimuli response of the synthesized PMAA-b-PPEGMA diblock copolymer against variation in pH and temperature is assessed. Recyclability of the nZVI (catalyst) and IL (solvent) is established. Polymerization may be switched ON or OFF, simply by turning the UVA light irradiation ON or OFF, offering temporal control. The diblock copolymer self-aggregates into spherical nanoaggregates which are employed for encapsulation of coumarin 102 (C102, a typical hydrophobic dye), describing their potential application in drug delivery applications. The facile synthesis strategy may open up new avenues for the preparation of intelligent functional polymers for engineering and biomedical applications.

Green Solvent Ethanol-Based Inks for Industrially Applicable Deposition of High-Quality Perovskite Films for Optoelectronic Device Applications

Incontrovertibly there is an increasing demand for the development of benign inks suitable for fabrication of high-performing perovskite-based thin film functional layers. Nevertheless, most reported perovskite precursors rely on the use of highly toxic solvents such as acetonitrile, 2-methoxyethanol, dimethylformamide, and many others. Hence, there is a strong imperative for the development of novel and greener inks, which will facilitate smoother commercialization of technologies based on functional perovskite films. Therefore, four perovskite precursors are studied, some of which consist of up to 90% ethanol. All inks are developed to fulfill the requirements of a high-throughput deposition compatible with roll-to-roll techniques at room temperature, assisted by an air knife for instant solvent removal. Two of the inks are particularly suitable for the fabrication of high-quality and densely packed multi-crystalline (CH3 NH3 )PbI3 layers, as confirmed by numerous nanoscale spectroscopic and material characterization techniques. Additionally, large-area photoluminescence (PL) imaging is demonstrated to improve the quality of the deposited perovskite films, with a route to enhance deposition uniformity when upscaling for manufacture. The genuine potential of the developed greener perovskite inks is demonstrated with the fabrication of solar cells with power conversion efficiencies above 19.5%.

Sustainable In Silico-Supported Ultrasonic-Assisted Extraction of Oligomeric Stilbenoids from Grapevine Roots Using Natural Deep Eutectic Solvents (NADES) and Stability Study of Potential Ready-to-Use Extracts

Grapevine roots, as a side-stream of a vineyard, are a sustainable resource for the recovery of oligomeric stilbenoids, such as the bioactive r-viniferin. The aim of this study is to evaluate an in silico-supported method, based on the Conductor-like Screening Model for Real Solvents (COSMO-RS), for selection of environmentally friendly natural deep eutectic solvents (NADES) with regard to the extraction of grapevine roots. The most suitable NADES system for ultrasonic-assisted extraction of r-viniferin was choline chloride/1,2-propanediol. The optimal extraction parameters for r-viniferin were determined using single-factor experiments as follows: choline chloride/1,2-propanediol 1/2 mol/mol, 10 wt% H2O, biomass/NADES ratio 1/10 g/g, and 10 min extraction time. Under optimized conditions, the extraction yield of r-viniferin from grapevine roots reached 76% of the total r-viniferin content. Regarding stability, stilbenoids in choline chloride/1,2-propanediol remained stable during 128 days of storage at ambient temperature. However, fructose/lactic acid-based NADES were observed to degrade stilbenoids; therefore, the removal of the NADES will be of interest, with a suitable method implemented using Amberlite® XAD-16N resin. As green solvents, the NADES have been used as effective and environmentally friendly extractants of stilbenoid-containing extracts from grapevine roots for potential applications in the cosmetic and pharmaceutical industry or as nutraceuticals in the food industry.

Green Synthesis of Cation Exchange Membranes: A Review

Cation exchange membranes (CEMs) play a significant role in the transition to a more sustainable/green society. They are important components for applications such as water electrolysis, artificial photosynthesis, electrodialysis and fuel cells. Their synthesis, however, is far from being sustainable, affecting safety, health and the environment. This review discusses and evaluates the possibilities of synthesizing CEMs that are more sustainable and green. First, the concepts of green and sustainable chemistry are discussed. Subsequently, this review discusses the fabrication of conventional perfluorinated CEMs and how they violate the green/sustainability principles, eventually leading to environmental and health incidents. Furthermore, the synthesis of green CEMs is presented by dividing the synthesis into three parts: sulfonation, material selection and solvent selection. Innovations in using gaseous SO3 or gas-liquid interfacial plasma technology can make the sulfonation process more sustainable. Regarding the selection of polymers, chitosan, cellulose, polylactic acid, alginate, carrageenan and cellulose are promising alternatives to fossil fuel-based polymers. Finally, water is the most sustainable solvent and many biopolymers are soluble in it. For other polymers, there are a limited number of studies using green solvents. Promising solvents are found back in other membrane, such as dimethyl sulfoxide, Cyrene™, Rhodiasolv® PolarClean, TamiSolve NxG and γ-valerolactone.

Aromas: Lovely to Smell and Nice Solvents for Polyphenols? Curcumin Solubilisation Power of Fragrances and Flavours

Natural aromas like cinnamaldehyde are suitable solvents to extract curcuminoids, the active ingredients found in the rhizomes of Curcuma longa L. In a pursuit to find other nature-based solvents, capable of solving curcumin, forty fragrances and flavours were investigated in terms of their solubilisation power. Aroma compounds were selected according to their molecular structure and functional groups. Their capabilities of solving curcumin were examined by UV-Vis spectroscopy and COSMO-RS calculations. The trends of these calculations were in accordance with the experimental solubilisation trend of the solubility screening and a list with the respective curcumin concentrations is given; σ-profiles and Gibbs free energy were considered to further investigate the solubilisation process of curcumin, which was found to be based on hydrogen bonding. High curcumin solubility was achieved in the presence of solvent (mixtures) with high hydrogen-bond-acceptor and low hydrogen-bond-donor abilities, like γ- and δ-lactones. The special case of DMSO was also examined, as the highest curcumin solubility was observed with it. Possible specific interactions of selected aroma compounds (citral and δ-hexalactone) with curcumin were investigated via 1H NMR and NOESY experiments. The tested flavours and fragrances were evaluated regarding their potential as green alternative solvents.

Recovery and separation of glycyrrhizic acid from Natural Deep Eutectic Solvent (NADES) extract by macroporous resin: adsorption kinetics and isotherm studies

Natural Deep Eutectic Solvents (NADESs) have emerged as a green and sustainable alternative to conventional organic solvents to extract bioactive compounds. However, the recovery of bioactive compounds from the NADES extracts is challenging, restricting their large-scale applications. The present work investigated the recovery of glycyrrhizic acid (GA) from choline-chloride/lactic acid NADES extract using macroporous resins. GA possesses a wide spectrum of biological activities, and it is extracted from the well-known herb Glycyrrhiza glabra. During resin screening, DIAIONTM SP700 showed high adsorption and desorption capacities. The adsorption kinetics study demonstrated that the adsorption of GA on SP700 followed Pseudo First-order kinetic model. Moreover, the adsorption behaviors were elucidated by the Freundlich isotherm using a correlation coefficient based on a static adsorption study at different temperatures and pH. Furthermore, the thermodynamic parameters, for instance, the change of Gibbs free energy (ΔG*), entropy (ΔS*), and enthalpy (ΔH*), showed that the adsorption process was spontaneous, favorable and exothermic. In addition, the sample after macroporous resin treatment, which is enriched with GA exhibited good anticancer potential analyzed by SRB assay. The regenerated NADES solvent was recycled twice, keeping more than 90% extraction efficiency, indicating good reusability of NADES in the GA extraction process by using macroporous resin.

Development of sustainable downstream processing for nutritional oil production

Nutritional oils (mainly omega-3 fatty acids) are receiving increased attention as critical supplementary compounds for the improvement and maintenance of human health and wellbeing. However, the predominant sources of these oils have historically shown numerous limitations relating to desirability and sustainability; hence the crucial focus is now on developing smarter, greener, and more environmentally favourable alternatives. This study was undertaken to consider and assess the numerous prevailing and emerging techniques implicated across the stages of fatty acid downstream processing. A structured and critical comparison of the major classes of disruption methodology (physical, chemical, thermal, and biological) is presented, with discussion and consideration of the viability of new extraction techniques. Owing to a greater desire for sustainable industrial practices, and a desperate need to make nutritional oils more available; great emphasis has been placed on the discovery and adoption of highly sought-after 'green' alternatives, which demonstrate improved efficiency and reduced toxicity compared to conventional practices. Based on these findings, this review also advocates new forays into application of novel nanomaterials in fatty acid separation to improve the sustainability of nutritional oil downstream processing. In summary, this review provides a detailed overview of the current and developing landscape of nutritional oil; and concludes that adoption and refinement of these sustainable alternatives could promptly allow for development of a more complete 'green' process for nutritional oil extraction; allowing us to better meet worldwide needs without costing the environment.

Development of Greener and Stable Inkjet-Printable Perovskite Precursor Inks for All-Printed Annealing-Free Perovskite Solar Mini-Modules Manufacturing

Inkjet-printing is considered an emerging manufacturing process for developing perovskite solar cells (PSCs) with low material wastes and high production throughput. Up-to-now, all case studies on inkjet-printed PSCs are based on the exploitation of toxic solvents and/or high-molarity perovskite precursor inks that are known to enable the development of high-efficiency photovoltaics (PVs). The present study provides a new insight for developing lower-toxicity, high performance and stable (for more than 2 months) inkjet-printable perovskite precursor inks for fully ambient air processed PSCs. Using an ink composed of a green low vapor pressure noncoordinating solvent and only 0.8 m of perovskite precursors, the feasibility of fabricating high-quality and with minimum coffee-ring defects, annealing-free perovskite absorbent layers under ambient atmosphere is demonstrated. Noteworthily, the PSCs fabricated using the industry-compatible carbon-based hole transport material free architecture and the proposed ink present an efficiency >13% that is considered on the performance records for the under-consideration PV architecture employing an inkjet-printed active layer. Outstanding is also found the stability of the devices under the conditions determined by the ISOS-D-1 protocol (T95  = 1000 h). Finally, the perspective of upscaling PSCs to the mini-module level (100 cm2 aperture area) is demonstrated, with the upscaling losses to be as low as 8.3%rel dec-1 per upscaled active area.

Exploring the Solubility Limits of Edaravone in Neat Solvents and Binary Mixtures: Experimental and Machine Learning Study

This study explores the edaravone solubility space encompassing both neat and binary dissolution media. Efforts were made to reveal the inherent concentration limits of common pure and mixed solvents. For this purpose, the published solubility data of the title drug were scrupulously inspected and cured, which made the dataset consistent and coherent. However, the lack of some important types of solvents in the collection called for an extension of the available pool of edaravone solubility data. Hence, new measurements were performed to collect edaravone solubility values in polar non-protic and diprotic media. Such an extended set of data was used in the machine learning process for tuning the parameters of regressor models and formulating the ensemble for predicting new data. In both phases, namely the model training and ensemble formulation, close attention was paid not only to minimizing the deviation of computed values from the experimental ones but also to ensuring high predictive power and accurate solubility computations for new systems. Furthermore, the environmental friendliness characteristics determined based on the common green solvent selection criteria, were included in the analysis. Our applied protocol led to the conclusion that the solubility space defined by ordinary solvents is limited, and it is unlikely to find solvents that are better suited for edaravone dissolution than those described in this manuscript. The theoretical framework presented in this study provides a precise guideline for conducting experiments, as well as saving time and resources in the pursuit of new findings.

Coordination Chemistry as a Universal Strategy for a Controlled Perovskite Crystallization

The most efficient and stable perovskite solar cells (PSCs) are made from a complex mixture of precursors. Typically, to then form a thin film, an extreme oversaturation of the perovskite precursor is initiated to trigger nucleation sites, e.g., by vacuum, an airstream, or a so-called antisolvent. Unfortunately, most oversaturation triggers do not expel the lingering (and highly coordinating) dimethyl sulfoxide (DMSO), which is used as a precursor solvent, from the thin films; this detrimentally affects long-term stability. In this work, (the green) dimethyl sulfide (DMS) is introduced as a novel nucleation trigger for perovskite films combining, uniquely, high coordination and high vapor pressure. This gives DMS a universal scope: DMS replaces other solvents by coordinating more strongly and removes itself once the film formation is finished. To demonstrate this novel coordination chemistry approach, MAPbI3 PSCs are processed, typically dissolved in hard-to-remove (and green) DMSO achieving 21.6% efficiency, among the highest reported efficiencies for this system. To confirm the universality of the strategy, DMS is tested for FAPbI3 as another composition, which shows higher efficiency of 23.5% compared to 20.9% for a device fabricated with chlorobenzene. This work provides a universal strategy to control perovskite crystallization using coordination chemistry, heralding the revival of perovskite compositions with pure DMSO.

Lipase-Catalyzed Strategies for the Preparation of Enantiomeric THIQ and THβC Derivatives: Green Aspects

This report reviews the most important lipase-catalyzed strategies for the preparation of pharmaceutically and chemically important tetrahydroisoquinoline and tetrahydro-β-carboline enantiomers through O-acylation of the primary hydroxy group, N-acylation of the secondary amino group, and COOEt hydrolysis of the corresponding racemic compounds with simple molecular structure, which have been reported during the last decade. A brief introduction describes the importance and synthesis of tetrahydroisoquinoline and tetrahydro-β-carboline derivatives, and it formulates the objectives of this compilation. The strategies are presented in chronological order, classified according to function of the reaction type, as kinetic and dynamic kinetic resolutions, in the main text. These reactions result in the desired products with excellent ee values. The pharmacological importance of the products together with their synthesis is given in the main text. The enzymatic hydrolysis of the hydrochloride salts as racemates of the starting amino carboxylic esters furnished the desired enantiomeric amino carboxylic acids quantitatively. The enzymatic reactions, performed in tBuOMe or H2O as usable solvents, and the transformations carried out in a continuous-flow system, indicate clear advantages, including atom economy, reproducibility, safer solvents, short reaction time, rapid heating and compression vs. shaker reactions. These features are highlighted in the main text.

Critical Investigation of Betaine Hydrochloride-Based Deep Eutectic Solvent for Ionometallurgical Metal Production

The applicability of a deep eutectic solvent (DES) consisting of betainium hydrochloride, urea and glycerol is examined with respect to ionometallurgical metal extraction and compared with the ionic liquid (IL) betainium bis(trifluoromethylsulfonyl)imide ([Hbet][NTf2 ]). The DES dissolves numerous metal oxides, where not only betaine and chloride act as stabilizing ligands, but also nascent ammonia seems to be essential. From such solutions, cobalt, copper, zinc, tin, lead, and even vanadium can be electrodeposited, demonstrating the feasibility of ionometallurgy. However, repeated recycling of the DES is not conceivable. NMR spectroscopy and mass spectrometry identify numerous decomposition reactions taking place at 60 °C already. The by-products that are formed not only make recycling more difficult, but also pose a toxicity problem. The opportunities and obstacles of DESs and ILs for their application in ionometallurgy are critically discussed. It is shown that a thorough understanding of the underlying chemical processes is critical.

The Most Potent Natural Pharmaceuticals, Cosmetics, and Food Ingredients Isolated from Plants with Deep Eutectic Solvents

There is growing interest in reducing the number of synthetic products or additives and replacing them with natural ones. The pharmaceutical, cosmetic, and food industries are especially focused on natural and bioactive chemicals isolated from plants or microorganisms. The main challenge here is to develop efficient and ecological methods for their isolation. According to the strategies and rules of sustainable development and green chemistry, green solvents and environmentally friendly technologies must be used. The application of deep eutectic solvents as efficient and biodegradable solvents seems to be a promising alternative to traditional methods. They are classified as being green and ecological but, most importantly, very efficient extraction media compared to organic solvents. The aim of this review is to present the recent findings on green extraction, as well as the biological activities and the possible applications of natural plant ingredients, namely, phenolics, flavonoids, terpenes, saponins, and some others. This paper thoroughly reviews modern, ecological, and efficient extraction methods with the use of deep eutectic solvents (DESs). The newest findings, as well as the factors influencing the efficiency of extraction, such as water content, and hydrogen bond donor and acceptor types, as well as the extraction systems, are also discussed. New solutions to the major problem of separating DESs from the extract and for solvent recycling are also presented.

Subcritical and Supercritical Fluids to Valorize Industrial Fruit and Vegetable Waste

The valorization of industrial fruit and vegetable waste has gained significant attention due to the environmental concerns and economic opportunities associated with its effective utilization. This review article comprehensively discusses the application of subcritical and supercritical fluid technologies in the valorization process, highlighting the potential benefits of these advanced extraction techniques for the recovery of bioactive compounds and unconventional oils from waste materials. Novel pressurized fluid extraction techniques offer significant advantages over conventional methods, enabling effective and sustainable processes that contribute to greener production in the global manufacturing sector. Recovered bio-extract compounds can be used to uplift the nutritional profile of other food products and determine their application in the food, pharmaceutical, and nutraceutical industries. Valorization processes also play an important role in coping with the increasing demand for bioactive compounds and natural substitutes. Moreover, the integration of spent material in biorefinery and biorefining processes is also explored in terms of energy generation, such as biofuels or electricity, thus showcasing the potential for a circular economy approach in the management of waste streams. An economic evaluation is presented, detailing the cost analysis and potential barriers in the implementation of these valorization strategies. The article emphasizes the importance of fostering collaboration between academia, industry, and policymakers to enable the widespread adoption of these promising technologies. This, in turn, will contribute to a more sustainable and circular economy, maximizing the potential of fruit and vegetable waste as a source of valuable products.

Advances of responsive deep eutectic solvents and application in extraction and separation of bioactive compounds

In recent years, it has been found that changing ambient conditions (CO₂ /N₂ , temperature, pH) can trigger a switchable phase transition of deep eutectic solvents, and such solvents are known as responsive deep eutectic solvents. In this work, we present the development history, properties, and preparation of responsive deep eutectic solvents, followed by the application of responsive deep eutectic solvents in the extraction and separation of bioactive compounds are presented. Importantly, the mechanism of responsive deep eutectic solvents in the extraction of bioactive compounds is discussed. Finally, the challenges and prospects of responsive deep eutectic solvents in the extraction and separation of bioactive compounds are proposed. Responsive deep eutectic solvents are considered green and efficient solvents. Some methods for extraction and separation of bioactive compounds by responsive deep eutectic solvents can increase the possibility of recycling the deep eutectic solvents, and provide higher efficiency in the extraction and separation field. It is hoped that this will provide a reference for the green and sustainable extraction and separation of various bioactive compounds.

Spark Discharge Doping-Achieving Unprecedented Control over Aggregate Fraction and Backbone Ordering in Poly(3-hexylthiophene) Solutions

The properties of semiconducting polymers are strongly influenced by their aggregation behavior, that is, their aggregate fraction and backbone planarity. However, tuning these properties, particularly the backbone planarity, is challenging. This work introduces a novel solution treatment to precisely control the aggregation of semiconducting polymers, namely current-induced doping (CID). It utilizes spark discharges between two electrodes immersed in a polymer solution to create strong electrical currents resulting in temporary doping of the polymer. Rapid doping-induced aggregation occurs upon every treatment step for the semiconducting model-polymer poly(3-hexylthiophene). Therefore, the aggregate fraction in solution can be precisely tuned up to a maximum value determined by the solubility of the doped state. A qualitative model for the dependences of the achievable aggregate fraction on the CID treatment strength and various solution parameters is presented. Moreover, the CID treatment can yield an extraordinarily high quality of backbone order and planarization, expressed in UV-vis absorption spectroscopy and differential scanning calorimetry measurements. Depending on the selected parameters, an arbitrarily lower backbone order can be chosen using the CID treatment, allowing for maximum control of aggregation. This method may become an elegant pathway to finely tune aggregation and solid-state morphology for thin-films of semiconducting polymers.

A Green and Effective Polyethylene Glycols-Based Microwave-Assisted Extraction of Carnosic and Rosmarinic Acids from Rosmarinus officinalis Leaves

Rosmarinus officinalis leaves (ROLs) are widely used as a popular culinary spice for flavoring food, in which carnosic acid (CA) and rosmarinic acid (RA) are the main active components. The extraction of CA and RA is limited by lowextraction efficiency and extraction rate. In this work, a microwave-assisted extraction (MAE) method using biodegradable, low-toxic and nonflammable solvents polyethylene glycols (PEGs) as extraction solvents was developed for theextraction of CA and RA from ROLs. Experimental results suggest that PEG-400 was a better choice compared with PEG-200, and the optimal extraction conditions were as follows: 45% of PEG-400, 4.3% of phosphoric acid, 20 s of microwave irradiation time at 280 W of microwave irradiation power, and a 10 mg mL^-1 solid-liquid ratio, respectively. The tissue structures of ROLs could be effectively disrupted by PEG-based MAE, leading to high CA and RA extraction efficiencies. The PEG-400 extract exhibited stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability compared with butylated hydroxytoluene (BHT). Finally, compared with heating reflux extraction, ultrasound-assisted extraction, maceration, and MAE using ionic liquid and ethanol as extraction solvents, the developed PEG-400 based MAE exhibited the highest extraction ability and fastest extraction rate for CA and RA. These findings suggest that MAE using PEGs as extraction solvents is a promising method for the separation of bioactive compounds from natural plants.

Application of Recently used Green Solvents in Sample Preparation Techniques: A Comprehensive Review of Existing Trends, Challenges, and Future Opportunities

Green solvents (GSs) has gained significant attention in recent years due to their potential as safer and more sustainable alternatives to traditional organic solvents. Solvents are used in a wide range of applications, from industrial processes to everyday products. Solvent emissions and losses can have a significant impact on the environment and human health, which is why many initiatives are being undertaken to get rid of or switch to eco-friendly alternatives. A key area of green chemistry that led to the concept of "green" solvents is the development of alternative solvents that are less toxic and more environmentally friendly than traditional organic solvents. The advantages of using green solvents over conventional ones are their environmental friendliness, biocompatibility, biodegradability, and simplicity of preparation. Different sample preparation techniques have successfully utilized green solvents to offer a sustainable separation media for the extraction of a variety of inorganic and organic compounds which are crucial for research in environmental samples. Recent developments in green analytical chemistry (GAC) have focused on how to prepare and use samples using environmentally sustainable solvents. The current study covers the advance and currently used green solvents with an emphasis on environmentally friendly sample preparation methods. This review aims to briefly summarize the current state of knowledge about the use of green solvents particularly ionic liquids, deep eutectic solvents and switchable solvents (SSs) with the perspective of GAC in sample preparation methods.

Natural Deep Eutectic Solvent Extraction of Bioactive Pigments from Spirulina platensis and Electrospinning Ability Assessment

The first ever nanofibers produced by the electrospinning of polyvinyl alcohol (PVA) and Spirulina platensis extracts are presented in this article. Spirulina platensis extracts were obtained by ultrasound-assisted extraction (UAE) using two different solvents: a glucose/glycerol-based natural deep eutectic solvent (NADES) and water. Through spectrophotometry analysis, it was possible to determine the pigment yield of the extractions for both extracts: phycocyanin = 3.79 ± 0.05 mg/g of dry biomass (DB); chlorophylls = 0.24 ± 0.05 mg/g DB; carotenoids = 0.13 ± 0.03 mg/g DB for the NADES/Spirulina extracts, and phycocyanin = 0.001 ± 0.0005 mg/g DB; chlorophylls = 0.10 ± 0.05 mg/g DB; carotenoids = 0.20 ± 0.05 mg/g DB for water/Spirulina extracts. Emulsions were formed by mixing the microalgae extracts in PVA (9%, w/v) at different concentrations: 5, 20, 40, and 50% (v/v). Electrospinning was carried out at the following conditions: 13 cm of distance to collector; 80 kV of applied voltage; and 85 rpm of electrode rotation. After the nanofibers were collected, they were checked under a scanning electron microscope (SEM). ImageJ was also used to determine fiber diameter and frequency. SEM results showed the formation of nanofibers for 5 and 20% (v/v) of NADES/Spirulina extract content in the electrospinning emulsions, presenting diameters of 423.52 ± 142.61 nm and 680.54 ± 271.92 nm, respectively. FTIR confirmed the presence of the NADES extracts in the nanofibers produced. Overall, the nanofibers produced showed promising antioxidant activities, with the NADES/Spirulina- and PVA-based nanofibers displaying the highest antioxidant activity (47%). The highest antimicrobial activity (89.26%) was also obtained by the NADES/Spirulina and PVA nanofibers (20%, v/v). Principal Component Analysis (PCA) revealed positive correlations between both the antioxidant and antimicrobial activities of the electrospun nanofibers, and extract content in the emulsions. Moreover, PCA also indicated positive correlations between the viscosity and conductivity of the emulsions and the diameter of the nanofibers produced.

Advances in green solvents for production of polysaccharide-based packaging films: Insights of ionic liquids and deep eutectic solvents

The problems with plastic materials and the good film-forming properties of polysaccharides motivated research in the development of polysaccharide-based films. In the last 5 years, there has been an explosion of publications on using green solvents, including ionic liquids (ILs), and deep eutectic solvents (DESs) as candidates to substitute the conventional solvents/plasticizers for preparations of desired polysaccharide-based films. This review summarizes related properties and recovery of ILs and DESs, a series of green preparation strategies (including pretreatment solvents/reaction media, ILs/DESs as components, extraction solvents of bioactive compounds added into films), and inherent properties of polysaccharide-based films with/without ILs and DESs. Major reported advantages of these new solvents are high dissolving capacity of certain ILs/DESs for polysaccharides (i.e., up to 30 wt% for cellulose) and better plasticizing ability than traditional plasticizers. In addition, they frequently display intrinsic antioxidant and antibacterial activities that facilitate ILs/DESs applications in the processing of polysaccharide-based films (especially active food packaging films). ILs/DESs in the film could also be further recycled by water or ethanol/methanol treatment followed by drying/evaporation. One particularly promising approach is to use bioactive cholinium-based ILs and DESs with good safety and plasticizing ability to improve the functional properties of prepared films. Whole extracts by ILs/DESs from various byproducts can also be directly used in films without separation/polishing of compounds from the extracting agents. Scaling-up, including costs and environmental footprint, as well as the safety and applications in real foods of polysaccharide-based film with ILs/DESs (extracts) deserves more studies.

Green Solvents: Emerging Alternatives for Carotenoid Extraction from Fruit and Vegetable By-Products

Carotenoids have important implications for human health and the food industry due to their antioxidant and functional properties. Their extraction is a crucial step for being able to concentrate them and potentially include them in food products. Traditionally, the extraction of carotenoids is performed using organic solvents that have toxicological effects. Developing greener solvents and techniques for extracting high-value compounds is one of the principles of green chemistry and a challenge for the food industry. This review will analyze the use of green solvents, namely, vegetable oils, supercritical fluids, deep eutectic solvents, ionic liquids, and limonene, combined with nonconventional techniques (ultrasound-assisted extraction and microwave), for carotenoid extraction from fruit and vegetable by-products as upcoming alternatives to organic solvents. Recent developments in the isolation of carotenoids from green solvents and their inclusion in food products will also be discussed. The use of green solvents offers significant advantages in extracting carotenoids, both by decreasing the downstream process of solvent elimination, and the fact that the carotenoids can be included directly in food products without posing a risk to human health.

Recent Advances in Supercritical CO2 Extraction of Pigments, Lipids and Bioactive Compounds from Microalgae

Supercritical CO₂ extraction is a green method that combines economic and environmental benefits. Microalgae, on the other hand, is a biomass in abundance, capable of providing a vast variety of valuable compounds, finding applications in the food industry, cosmetics, pharmaceuticals and biofuels. An extensive study on the existing literature concerning supercritical fluid extraction (SFE) of microalgae has been carried out focusing on carotenoids, chlorophylls, lipids and fatty acids recovery, as well as the bioactivity of the extracts. Moreover, kinetic models used to describe SFE process and experimental design are included. Finally, biomass pretreatment processes applied prior to SFE are mentioned, and other extraction methods used as benchmarks are also presented.

Direct Evidence of the Exfoliation Efficiency and Graphene Dispersibility of Green Solvents toward Sustainable Graphene Production

Achieving a sustainable production of pristine high-quality graphene and other layered materials at a low cost is one of the bottlenecks that needs to be overcome for reaching 2D material applications at a large scale. Liquid phase exfoliation in conjunction with N-methyl-2-pyrrolidone (NMP) is recognized as the most efficient method for both the exfoliation and dispersion of graphene. Unfortunately, NMP is neither sustainable nor suitable for up-scaling production due to its adverse impact on the environment. Here, we show the real potential of green solvents by revealing the independent contributions of their exfoliation efficiency and graphene dispersibility to the graphene yield. By experimentally separating these two factors, we demonstrate that the exfoliation efficiency of a given solvent is independent of its dispersibility. Our studies revealed that isopropanol can be used to exfoliate graphite as efficiently as NMP. Our finding is corroborated by the matching ratio between the polar and dispersive energies of graphite and that of the solvent surface tension. This direct evidence of exfoliation efficiency and dispersibility of solvents paves the way to developing a deeper understanding of the real potential of sustainable graphene manufacturing at a large scale.

Alkyl Levulinates and 2-Methyltetrahydrofuran: Possible Biomass-Based Solvents in Palladium-Catalyzed Aminocarbonylation

In this research, ethyl levulinate, methyl levulinate, and 2-methyltetrahydrofuran as bio-derived hemicellulose-based solvents were applied as green alternatives in palladium-catalyzed aminocarbonylation reactions. Iodobenzene and morpholine were used in optimization reactions under different conditions, such as temperatures, pressures, and ligands. It was shown that the XantPhos ligand had a great influence on conversion (98%) and chemoselectivity (100% carboxamide), compared with the monodentate PPh₃. Following this study, the optimized conditions were used to extend the scope of substrates with nineteen candidates (various para-, ortho-, and meta-substituted iodobenzene derivatives and iodo-heteroarenes), as well as eight different amine nucleophiles.

Ultrasound-Assisted Extraction of Polyphenols from Maritime Pine Residues with Deep Eutectic Solvents

Deep eutectic solvents represent an important alternative in the field of green solvents due to their low volatility, non-toxicity, and low synthesis cost. In the present investigation, we propose the production of enriched polyphenolic extracts from maritime pine forest residues via an ultrasound-assisted approach. A Box-Behnken experimental design with a response surface methodology was used with six variables to be optimized: solid-to-solvent ratio, water percentage, temperature and time of extraction, amplitude, and catalyst concentration. The mixture of levulinic and formic acids achieved the highest extraction yield of polyphenols from pine needle and bark biomass. In addition, the solid-to-solvent ratio was found to be the only influential variable in the extraction (p-value: 0.0000). The optimal conditions were established as: 0.1 g of sample in 10 mL of LA:FA (70:30%, v/v) with 0% water and 0 M H₂SO₄ heated to 30 °C and extracted during 40 min with an ultrasound amplitude of 80% at 37 kHz. The bioactive properties of polyphenol-enriched extracts have been proven with significant antioxidant (45.90 ± 2.10 and 66.96 ± 2.75 mg Trolox equivalents/g dw) and antimicrobial activities. The possibility to recycle and reuse the solvent was also demonstrated; levulinic acid was successfully recovered from the extracts and reused in novel extractions on pine residues. This research shows an important alternative to obtaining polyphenol-enriched extracts from forest residues that are commonly discarded without any clear application, thus opening an important window toward the valorization of such residues.

Double Valorization for a Discard-α-Chitin and Calcium Lactate Production from the Crab Polybius henslowii Using a Deep Eutectic Solvent Approach

Polybius henslowii, an abundant yet unexploited species of swimming crab, was investigated as a potential source of α-chitin and calcium lactate using deep eutectic solvents (DES) as extracting solvents. Choline chloride-malonic acid (CCMA) and choline chloride-lactic acid (CCLA) were used to obtain high purity α-chitin from ball-milled P. henslowii exoskeleton in 2 h at 120 °C, with yields of 12.05 ± 2.54% and 12.8 ± 1.54%, respectively. The physical and chemical characteristics of the obtained chitins were assessed using CHN elemental analysis, attenuated total reflectance-Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Furthermore, the CCLA solvent was reusable three times with little effect on the extract purity, and calcium lactate was produced at the end of the recycling cycles. The ensuing calcium lactate was also characterized in terms of chemical and physical properties. The obtained chitin is a promising raw material for downstream processing and the double valorization pathway with the obtention of calcium salts may increase the viability of a DES-based approach for the processing of mineralized substrates.

Processing of Biomass Prior to Hydrogen Fermentation and Post-Fermentative Broth Management

Using bioconversion and simultaneous value-added product generation requires purification of the gaseous and the liquid streams before, during, and after the bioconversion process. The effect of diversified process parameters on the efficiency of biohydrogen generation via biological processes is a broad object of research. Biomass-based raw materials are often applied in investigations regarding biohydrogen generation using dark fermentation and photo fermentation microorganisms. The literature lacks information regarding model mixtures of lignocellulose and starch-based biomass, while the research is carried out based on a single type of raw material. The utilization of lignocellulosic and starch biomasses as the substrates for bioconversion processes requires the decomposition of lignocellulosic polymers into hexoses and pentoses. Among the components of lignocelluloses, mainly lignin is responsible for biomass recalcitrance. The natural carbohydrate-lignin shields must be disrupted to enable lignin removal before biomass hydrolysis and fermentation. The matrix of chemical compounds resulting from this kind of pretreatment may significantly affect the efficiency of biotransformation processes. Therefore, the actual state of knowledge on the factors affecting the culture of dark fermentation and photo fermentation microorganisms and their adaptation to fermentation of hydrolysates obtained from biomass requires to be monitored and a state of the art regarding this topic shall become a contribution to the field of bioconversion processes and the management of liquid streams after fermentation. The future research direction should be recognized as striving to simplification of the procedure, applying the assumptions of the circular economy and the responsible generation of liquid and gas streams that can be used and purified without large energy expenditure. The optimization of pre-treatment steps is crucial for the latter stages of the procedure.

The Greening of Anthocyanins: Eco-Friendly Techniques for Their Recovery from Agri-Food By-Products

In recent years, several steps forward have been made toward a more sustainable approach for the extraction of bioactive compounds from plant materials based on the application of green extraction principles. It is currently recognized that waste and by-products deriving from agriculture and food industries still contain a wide array of high value-added substances, which can be re-used to obtain new products with various applications in the food, supplement, pharmaceutical, and cosmetic industries. Anthocyanins are a class of these valuable metabolites; they confer the red, violet, and blue color to fruits and vegetables, and scientific evidence has accumulated over the last few decades to support their beneficial effects on human health, in great part deriving from their powerful antioxidant capacity. This review provides a general overview of the most recent green procedures that have been applied for the recovery of anthocyanins from plant-derived wastes and by-products. The most widely used green solvents and the main sustainable techniques utilized for recovering this class of flavonoids from various matrices are discussed, together with the variables that mainly impact the extraction yield.

A Critical Review of Emerging Hydrophobic Deep Eutectic Solvents' Applications in Food Chemistry: Trends and Opportunities

Due to their low cost, biodegradability, and ease of preparation, deep eutectic solvents (DESs) are considered promising green alternatives to conventional solvents, as exploiting green solvents has been a research focus for achieving sustainable development goals. Most DESs in published studies are hydrophilic. On the other hand, the DES's hydrophilicity restricts its practical applicability to just polar molecules, which is a vital disadvantage to this extractant. Hydrophobic DES (HDES) has been developed as a new extractant adept at extracting nonpolar inorganic and organic compounds from aqueous systems. Although there has been little research on HDESs (HDES publications account for <10% of DES), specific intriguing applications have been discovered, requiring investigation and comparisons. As a result, this review covers the applications of emerging HDES in detecting pesticide residues, food additives, contaminants in food packaging, heavy metals, separation and extraction processes in food. According to the available literature, HDESs have the potential to overcome the limitations of hydrophilic DESs and be used in a broader range of applications in food with greater efficiency, which has received little attention. HDES is expected to substitute a lot of harmful organic extractants used for analytical reasons (food chemistry) in the future. Besides, the limitations of HDES were reviewed, and future studies were provided. This will serve as a reference for green chemistry advocates and practitioners in food science who want to minimize pollution and improve efficiency and benefit from the further development of HDESs.

Application of Green Chiral Chromatography in Enantioseparation of Newly Synthesized Racemic Marinoepoxides

Enantioseparation of the newly synthesized series of novel quinoline-2(1H)-one epoxide structures rac-6a-c and rac-8a-c, named marinoepoxides, is described. Marinoepoxide rac-6a, the key intermediate in the total synthesis of natural products marinoaziridines A and B, as well as their structural analogues, was synthesized by addition of the achiral ylide generated in situ from the sulfonium salt 5 or 7, to the carbon-oxygen double bond of the corresponding quinoline-2(1H)-one-4-carbaldehyde 4a-c in good yield. Separation of enantiomers of (±)-2,3,3-trisubstituted marinoepoxides rac-6a-c and (±)-trans-2,3-disubstituted marinoepoxides rac-8a-c was studied using two immobilized polysaccharide type chiral stationary phases (CSPs); tris-(3,5-dichlorophenylcarbamoyl)cellulose stationary phase (CHIRAL ART Cellulose-SC) and tris-(3,5-dimethylphenylcarbamoyl)amylose stationary phase (CHIRAL ART Amylose-SA). Enantioseparation conditions were explored by high-performance liquid chromatography (HPLC) using dimethyl carbonate/alcohol mixtures and n-hexane/ethanol (80/20, v/v) as mobile phase, and by supercritical fluid chromatography (SFC) using CO₂/alcohol mixtures as mobile phase. In all examined racemates, enantioseparation was successfully achieved, but its efficiency largely depended on the structure of chiral selector and type/composition of the mobile phase.

Deep Eutectic Solvents for Extraction and Preconcentration of Organic and Inorganic Species in Water and Food Samples: A Review

Deep eutectic solvents (DESs) have been developed as green solvents and these are capable as alternatives to conventional solvents used for the extraction of organic and inorganic species from food and water samples. The continuous generation of contaminated waste and increasing concern for the human health and environment have compelled the scientific community to investigate more ecological schemes. In this concern, the use of DESs have developed in one of the chief approach in the field of chemistry. These solvents have appeared as a capable substitute to conventional hazardous solvents and ionic liquids. The DESs has distinctive properties, easy preparation and components availability. It is not only used in scienctific fields but also used in quotidian life. There are many advantages of DESs in analytical chemistry, they are largely used for extraction and determination of inorganic and organic compounds from different samples. In previous a few years, several advanced researches have been focused on the separation and preconcentration of low level of pollutants using DESs as the extractants. This review summarizes the use of DESs in the separation and preconcentration of organic and inorganic species from water and food samples using various microextraction processes.

Green bioanalysis: an innovative and eco-friendly approach for analyzing drugs in biological matrices

Green bioanalytical techniques aim to reduce or eliminate the hazardous waste produced by bioanalytical technologies. A well-organized and practical approach towards bioanalytical method development has an enormous contribution to the green analysis. The selection of the appropriate sample extraction process, organic mobile phase components and separation technique makes the bioanalytical method green. UHPLC-MS is the best option, whereas supercritical fluid chromatography is one of the most effective green bioanalytical procedures. Nevertheless, there remains excellent scope for further research on green bioanalytical methods. This review details the various sample preparation techniques that follow green analytical chemistry principles. Furthermore, it presents green solvents as a replacement for conventional organic solvents and highlights the strategies to convert modern analytical techniques to green methods.

Insights into using green and unconventional technologies to recover natural astaxanthin from microbial biomass

Microorganisms such as bacteria, microalgae and fungi, are natural and rich sources of several valuable bioactive antioxidant's compounds, including carotenoids. Among the carotenoids with antioxidant properties, astaxanthin can be highlighted due to its pharmaceutical, feed, food, cosmetic and biotechnological applications. The best-known producers of astaxanthin are yeast and microalgae cells that biosynthesize this pigment intracellularly, requiring efficient and sustainable downstream procedures for its recovery. Conventional multi-step procedures usually involve the consumption of large amounts of volatile organic compounds (VOCs), which are regarded as toxic and hazardous chemicals. Considering these environmental issues, this review is focused on revealing the potential of unconventional extraction procedures [viz., Supercritical Fluid Extraction (SFE), Ultrasound-Assisted Extraction (UAE), Microwave-Assisted Extraction (MAE), High-Pressure Homogenization (HPH)] combined with alternative green solvents (biosolvents, eutectic solvents and ionic liquids) for the recovery of microbial-based astaxanthin from microalgae (such as Haematococcus pluvialis) and yeast (such as Phaffia rhodozyma) cells. The principal advances in the area, process bottlenecks, solvent selection and strategies to improve the recovery of microbial astaxanthin are emphasized. The promising recovery yields using these environmentally friendly procedures in lab-scale are good indications and directions for their effective use in biotechnological processes for the production of commercial feed and food ingredients like astaxanthin.

Greener Solvent-Based Processing of Magnetoelectric Nanocomposites

Polymer-based magnetoelectric (ME) nanocomposites are an enabling material technology for a wide range of applications in the area of digitalization strategies. Due to its highest piezoelectric response among polymers, poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) is the piezoelectric matrix most used in polymer-based ME materials with over 80% of the total reports, with the resulting composites typically processed from solutions with N,N-dimethylformamide (DMF), a toxic solvent. Nevertheless, environmentally friendlier approaches and sustainable technologies are increasingly being required. This work demonstrates that P(VDF-TrFE)/Co₂Fe₂O₄ nanocomposites can be successfully prepared from solution using three different environmentally friendlier solvents: dimethyl sulfoxide (DMSO), N,N'-dimethylpropyleneurea (DMPU), and triethyl phosphate (TEP) with different dipole moments. It is shown that the prepared composite films, with a maximum ME voltage coefficient of 35 mV cm^-1 Oe^-1 and a maximum sensitivity of 2.2 mV T^-1, are suitable for applications, highlighting the path for a new generation of more sustainable ME sensors.

Application of the Solute-Solvent Intermolecular Interactions as Indicator of Caffeine Solubility in Aqueous Binary Aprotic and Proton Acceptor Solvents: Measurements and Quantum Chemistry Computations

The solubility of caffeine in aqueous binary mixtures was measured in five aprotic proton acceptor solvents (APAS) including dimethyl sulfoxide, dimethylformamide, 1,4-dioxane, acetonitrile, and acetone. The whole range of concentrations was studied in four temperatures between 25 °C and 40 °C. All systems exhibit a strong cosolvency effect resulting in non-monotonous solubility trends with changes of the mixture composition and showing the highest solubility at unimolar proportions of organic solvent and water. The observed solubility trends were interpreted based on the values of caffeine affinities toward homo- and hetero-molecular pairs formation, determined on an advanced quantum chemistry level including electron correlation and correction for vibrational zero-point energy. It was found that caffeine can act as a donor in pairs formation with all considered aprotic solvents using the hydrogen atom attached to the carbon in the imidazole ring. The computed values of Gibbs free energies of intermolecular pairs formation were further utilized for exploring the possibility of using them as potential solubility prognostics. A semi-quantitative relationship (R² = 0.78) between caffeine affinities and the measured solubility values was found, which was used for screening for new greener solvents. Based on the values of the environmental index (EI), four morpholine analogs were considered and corresponding caffeine affinities were computed. It was found that the same solute–solvent structural motif stabilizes hetero-molecular pairs suggesting their potential applicability as greener replacers of traditional aprotic proton acceptor solvents. This hypothesis was confirmed by additional caffeine solubility measurements in 4-formylmorpholine. This solvent happened to be even more efficient compared to DMSO and the obtained solubility profile follows the cosolvency pattern observed for other aprotic proton acceptor solvents.

Structure and Dynamic Properties of a Glycerol-Betaine Deep Eutectic Solvent: When Does a DES Become an Aqueous Solution?

Deep eutectic solvents (DESs) are an emerging class of green solvents with a wide spectrum of potential applications whose properties may be further tailored through the addition of water. Here, we study, through molecular dynamics, the influence of water on the properties of a betaine-glycerol-water (B:G:W) DES (1:2:ζ; ζ = 0 to 100), aiming at getting insight into the structural and dynamic crossover between a DES and an aqueous solution. The density, shear viscosity, and diffusion coefficients are found to exhibit a non-linear dependence of ζ, similar to that observed for the solvation layers' composition. Each Gly and Bet are replaced, respectively, by ∼3 and ∼5 water molecules, with the highest rates of depletion being found for Gly around Bet and Gly around Gly. Above ζ = 7 (70 mol %; 29.5 wt %), a major structural transformation occurs, with the complete disruption of the second Bet-Gly solvation layer and the formation of a new second layer at a shorter distance, accompanied by a sudden change in the rate of increase of the components' diffusion. Nonetheless, opposite to other DES, our results indicate a smooth crossover between a DES and an aqueous solution.

Novel Oligomer Enables Green Solvent Processed 17.5% Ternary Organic Solar Cells: Synergistic Energy Loss Reduction and Morphology Fine-Tuning

The large non-radiative recombination is the main factor that limits state-of-the-art organic solar cells (OSCs). In this work, two novel structurally similar oligomers (named 5BDTBDD and 5BDDBDT) with D-A-D-A-D and A-D-A-D-A configuration are synthesized for high-performance ternary OSCs with low energy loss. As third components, these PM6 analogue oligomers effectively suppress the non-radiative recombination in OSCs. Although the highest occupied molecular orbital (HOMO) levels of 5BDTBDD and 5BDDBDT are higher than that of PM6, the oligomers enabled ultra-high electroluminescence quantum efficiency (EQE_EL ) of 0.05% and improved V_OC , indicating suppressing non-radiative recombination overweighs the common belief of deeper HOMO requirement in third component selection. Moreover, the different compatibility of 5BDTBDD and 5BDDBDT with PM6 and BTP-BO4Cl fine-tunes the active layer morphology with synergistic effects. The ternary devices based on PM6:5BDTBDD:BTPBO4Cl and PM6:5BDDBDT:BTP-BO4Cl achieve a significantly improved PCEs of 17.54% and 17.32%, representing the state-of-the art OSCs processed by green solvent of o-xylene. The strategy using novel oligomer as third component also has very wide composition tolerance in ternary OSCs. This is the first work that demonstrates novel structurally compatible D-A type oligomers are effective third components, and provides new understanding of synergetic energy loss mechanisms towards high performance OSCs.

Effect of Ultrasound-Assisted Extraction of Carotenoids from Papaya (Carica papaya L. cv. Sweet Mary) Using Vegetable Oils

By-products from fruits and are of great interest for their potential use in the food industry due to their high content of bioactive compounds. Herein, we examined the ultrasound-assisted extraction (UAE) of carotenoid and carotenoid esters from papaya pulp and peel using soybean oil and sunflower oil as alternative green solvents. Response surface methodology (RSM) was established to optimize the UAE process. Three independent variables, ultrasonic amplitude (20–60%), time (10–60 min), and co-solvent percentage (ethanol) (5–20%, v/v), were applied. The highest total carotenoid content in the UAE extracts was obtained from papaya pulp extracts (58.7 ± 1.6 and 56.0 ± 1.5 μg carotenoids/g oil) using soybean oil and sunflower oil, respectively (60% amplitude/ 10 min/ 20% ethanol). On the other hand, the highest carotenoid content (52.0 ± 0.9 μg carotenoids/g oil) was obtained from papaya peel using soybean oil applying the UAE process (20% amplitude/ 77 min/ 20% ethanol); a minor content of 39.3 ± 0.5 μg carotenoids/g oil was obtained from papaya peel using sunflower oil at 60% amplitude/ 60 min/ 5% ethanol. Lycopene was the most abundant carotenoid among all individual carotenoids observed in papaya oil extracts, obtaining the highest yields of this carotenoid when papaya pulp and peel were extracted using soybean oil (94% and 81%, respectively) and sunflower oil (95% and 82%, respectively). Great extraction of xanthophyll esters was detected using 20% of ethanol in the vegetable oil extraction solvent (v/v). High correlations (>0.85) was obtained between total carotenoid content and color determination in the UAE oil extracts. UAE vegetable oil extracts enriched with carotenoids from papaya by-products could be useful to formulate new food ingredients based on emulsions with interesting potential health benefits.

Continuous Counter-Current Ionic Liquid Metathesis in Mixer-Settlers: Efficiency Analysis and Comparison with Batch Operation

Following the initial cation formation, the synthesis of ionic liquids (ILs) often involves an anion-exchange or metathesis reaction. For hydrophobic ILs, this is generally performed through several cross-current contacts of the IL with a fresh salt solution of the desired anion. However, if a large number of contacts is required to attain an adequate conversion, this procedure is not economical because of the large excess of the reagent that is consumed. In this study, the metathesis of an IL, Aliquat 336 or [A336][Cl], to ILs with other anions ([A336][X] with X = HSO4 -, Br-, NO3 -, I-, and SCN-) was studied in a continuous counter-current mixer-settler setup. McCabe-Thiele diagrams were constructed to estimate the required number of stages for quantitative conversion. Significantly higher IL conversions were achieved, combined with reduced reagent consumption and waste production. This improvement in efficiency was most pronounced for anions placed low in the Hofmeister series, for example, HSO4 -, Br-, and NO3 -, which are difficult to exchange. The performance of the counter-current experiments was compared with the conventional multistep cross-current batch process by calculating the reaction mass efficiency (RME) and the environmental factor (E-factor). The RMEs of the cross-current experiments were notably smaller, that is, 38-78% of the values observed for the counter-current experiments. The E-factors of the counter-current experiments were a factor of 2.0-6.8 smaller than those of the cross-current experiments. These sustainability metrics indicate a highly efficient reagent use and a considerable, simultaneous decrease in waste production for the counter-current IL metathesis reactions.

Multivariate optimization results in an edible extract from Ilex paraguariensis unexplored residues with a high amount of phenolic compounds

Ilex paraguariensis A. St. Hil. plants are used for the preparation of food and drinks which are widely consumed worldwide. During the harvest season of these plants, 2-5 ton hec^-1 of agricultural residue is generated, which remains underutilized. Therefore, this study aimed to obtain an edible extract with high content of bioactive compounds and antimicrobial properties from the agricultural residue of I. paraguariensis for industrial use in food applications. The extraction conditions were optimized through a multivariate experimental design using ethanol:water. The extracted compounds were characterized by HPLC-ESY-QTOF-MS. In the optimal extraction conditions, 55 compounds were extracted, including 8 compounds that were not previously reported in I. paraguariensis. The method proved to be simple, fast, economical and environmentally friendly, with the use of green solvents. This optimization allowed for the extraction of 15.07 g of phenolic compounds per 100 g of residue. The extract showed high antioxidant activity and the capacity to inhibit Staphylococcus aureus. Results indicate that it is possible to obtain an edible extract with a high content of bioactive compounds, particularly phenolic compounds, from the I. paraguariensis residue, which has high prospects for the valorization of unexplored natural resources.

Experimental Design and Optimization of Recovering Bioactive Compounds from Chlorella vulgaris through Conventional Extraction

Microalgae contain an abundance of valuable bioactive compounds such as chlorophylls, carotenoids, and phenolics and, consequently, present great commercial interest. The aim of this work is the study and optimization of recovering the aforementioned components from the microalgae species Chlorella vulgaris through conventional extraction in a laboratory-scale apparatus using a "green" mixture of ethanol/water 90/10 v/v. The effect of three operational conditions-namely, temperature (30-60 °C), duration (6-24 h) and solvent-to-biomass ratio (20-90 mL_solv/g_biom), was examined regarding the extracts' yield (gravimetrically), antioxidant activity, phenolic, chlorophyll, and carotenoid contents (spectrophotometric assays), as well as concentration in key carotenoids, i.e., astaxanthin, lutein, and β-carotene (reversed-phase-high-performance liquid chromatography (RP-HPLC)). For this purpose, a face-centered central composite design (FC-CCD) was employed. Data analysis resulted in the optimal extraction conditions of 30 °C, for 24 h with 37 mL_solv/g_biom and validation of the predicted models led to 15.39% w/w yield, 52.58 mg_extr/mg_DPPH (IC50) antioxidant activity, total phenolic, chlorophyll, and carotenoid content of 18.23, 53.47 and 9.92 mg/g_extr, respectively, and the total sum of key carotenoids equal to 4.12 mg/g_extr. The experimental data and predicted results were considered comparable, and consequently, the corresponding regression models were sufficiently reliable for prediction.

Advances in Lipid Extraction Methods-A Review

Extraction of lipids from biological tissues is a crucial step in lipid analysis. The selection of appropriate solvent is the most critical factor in the efficient extraction of lipids. A mixture of polar (to disrupt the protein-lipid complexes) and nonpolar (to dissolve the neutral lipids) solvents are precisely selected to extract lipids efficiently. In addition, the disintegration of complex and rigid cell-wall of plants, fungi, and microalgal cells by various mechanical, chemical, and enzymatic treatments facilitate the solvent penetration and extraction of lipids. This review discusses the chloroform/methanol-based classical lipid extraction methods and modern modifications of these methods in terms of using healthy and environmentally safe solvents and rapid single-step extraction. At the same time, some adaptations were made to recover the specific lipids. In addition, the high throughput lipid extraction methodologies used for liquid chromatography-mass spectrometry (LC-MS)-based plant and animal lipidomics were discussed. The advantages and disadvantages of various pretreatments and extraction methods were also illustrated. Moreover, the emerging green solvents-based lipid extraction method, including supercritical CO2 extraction (SCE), is also discussed.