Solvent Research Articles

History of the study of amyloidosis: from the Rokitansky’s theory to the present day

In the history of amyloidosis studying the concept of liquids dyscrasia has been predominated and finally it is resulted in accepting a serum protein-precursor as a leading amyloidogenic factor in the disease pathogenesis. Consequently basic diagnostic and treatment strategy was aimed to find and eliminate this protein from the blood and this approach evidenced high effectiveness in most frequent AA and AL-amyloidosis characterized with anomaly high levels of precursors in the blood. At the same time there are less frequent and slower progressing inheritant forms of systemic amyloidosis including transthyretin induced, which are less depending on amyloidogenecity of amyloid precursor and because of that, in example, the effectiveness of transthyretin stabilizers or blockers of its synthesis is limited comparing with the precursor elimination in AA or AL. Developed in the middle of XX century a theory of local synthesis by macrophages is more preferable to describe the pathogenesis of these forms. And modern proteome analysis using give rise to confirm the key meaning of macrophage in the amyloidogenesis and proves necessity to know deeply mechanisms of macrophagial autophagia – basic tool of maintaining intracellular protein homeostasis. That is why it is difficult to hope on high effectiveness of chemical amyloid solvents in vivo, which being under macrophages regulation never could realize its chemical activities.

Fluorinated natural rubber with enhanced strength and excellent resistance to ozone, organic solvent, and acid and alkali via in situ reactive melt extrusion

Natural rubber (NR), as a green and renewable industrial raw material, is applied in many fields. However, the relatively weak resistance originated from its unsaturated backbone structure restricts the further application in some harsh conditions. To incorporate the excellent resistance feature of the fluorinated components into NR, fluorinated natural rubber (FNR) was prepared with dodecafluoroheptyl methacrylate (DFHMA) via in situ melt extrusion reaction. The results indicated that fluorinated reaction of NR mainly happened at the α-H of double bond in backbone chain and that styrene could promote fluorination and increase the size of fluorinated side chain. The vulcanized FNR (VFNR) exhibited wonderful mechanical performance, remarkable hydrophobicity, and excellent resistance to ozone, organic solvent, acid and alkali. The water contact angles of VFNR increased from 89 ° to 104 °and the ozone aging cracking time of VFNR increased by one time longer than that of VNR. The swelling degree of VFNR in the full synthetic engine oil is only two-thirds that of VNR, and the retention of tensile strength after immersion in HCl, H2SO4, and NaOH solution was elevated by 13 %, 11 %, and 5 % compared to those of VNR, respectively. This work presents a simple and eco-friendly method to prepare the fluorinated natural rubber facilitating the industrial fabrication of green and high-performance NR via melt extrusion.

Characterization and Enhanced Production of Fungal Melanin from Aspergillus Species Isolated from Soil

This study aimed to isolate and identify fungi from soil samples, focusing on their ability to produce melanin. Eleven different genera of fungi were isolated and identified using lactophenol cotton blue staining and microscopic examination, referencing H.L. Barnett and Barry B. Hunter. Among these, only Aspergillus was found to produce melanin. Optimal melanin production conditions were determined to be a 1.5% tyrosine supplement in the growth medium, under shaking conditions (120 rpm) and dark incubation for three weeks, resulting in a yield of 21.08 mg/100 ml. Physiochemical characterization revealed that the extracted melanin was insoluble in organic solvents but soluble in alkaline solutions (NaOH, KOH), and partially soluble in DMSO. Spectrometric analysis using UV-Visible spectroscopy showed characteristic absorption peaks. FTIR indicated functional groups and Scanning Electron Microscopy (SEM) images displayed a granular and heterogeneous surface topology. The study also assessed the effects of different carbon and nitrogen sources, and trace elements on melanin production. Maltose and sucrose were the most effective carbon sources, while peptone was the most effective nitrogen source. Among trace elements, calcium significantly enhanced melanin yield, while copper and zinc had moderate effects. These findings provide valuable insights into optimizing fungal melanin production and its potential industrial applications. The study highlights the sustainable and scalable production of melanin from Aspergillus, contributing to the broader understanding of fungal metabolites and their commercial exploitation. Future research should focus on genetic and metabolic pathways to further enhance melanin biosynthesis and explore its diverse applications.

Enhanced superhydrophobicity and durability of modified cotton cloth for efficient oil-water separation

The development of simple, low-cost, and efficient oil/water separation membranes is still a major challenge in the field of wastewater treatment. In this study, an oil/water separation membrane is prepared based on low-cost cotton cloth (CF) through a simple solution soaking treatment without using organic solvents. Pristine CF is treated first with concentrated alkali and then chemically grafted by sodium methyl silicate (SMS) onto the surface to obtain oil/water separation membrane (SMS-O-CF). This process not only increases the roughness of the CF but also endows the surface with superhydrophobicity due to the outward extension of methyl groups, resulting in a water contact angle (WCA) of 155° and good self-cleaning ability. The SMS-O-CF achieves efficient separation for various oil/water mixtures and maintains a separation efficiency up to 96 % and a flux of over 11,557 L·m−2·h−1 after 220 cycles under neutral conditions. Moreover, the modified CF also exhibits excellent acid/alkaline resistance and wear resistance. Regardless of the 12 h acid/base immersion, 100 min water wash, or 200-cycle mechanical abrasion, SMS-O-CF still exhibits high flux and separation efficiency. Raw material cost for preparing SMS-O-CF is as low as 1.0 dollar/m2. The preparation of SMS-O-CF has provided a green manufacturing method for developing low-cost and efficient oil–water separation membranes.

Synthesis of the polyethylene polyamine-based flexible covalent organic frameworks and their application for capturing and fluorescence sensing iodine

Effective uptake of radioactive steam waste in the fission process is of great vital for the safe use of nuclear energy. Nitrogen-rich polyethylenepolyamine provides effective adsorption sites for the capture of iodine, but triethylenediamine (TEDA)-impregnated activated carbon has the disadvantages of easy sublimation, poor safety, and poor regeneration capacity. Herein, we report five polyethylene polyamine-based (PEPA-based) flexible COFs for the first time which were synthesized by Schiff base polymerization reactions with the flexible knot [2,4,6-tris(4-formylphenoxy)-1,3,5-triazine (TPT–3–CHO)] and flexible linkers (PEPA). The PEPA-based flexible COFs possess large surface areas and strong iodine adsorption capacity, which can be reused. With the increase of the linker lengths, their BET-surface areas decreases, but their adsorption of iodine increase. When dispersed in polar organic solvents, the PEPA-based flexible COFs can fluorescently sense iodine through the electron transfer mechanism and the energy transfer mechanism.

Photolysis of tolfenamic acid in aqueous and organic solvents: a kinetic study.

Tolfenamic acid (TA) is a non-steroidal anti-inflammatory drug that was studied for its photodegradation in aqueous (pH 2.0-12.0) and organic solvents (acetonitrile, methanol, ethanol, 1-propanol, 1-butanol). TA follows first-order kinetics for its photodegradation, and the apparent first-order rate constants (k obs) are in the range of 0.65 (pH 12.0) to 6.94 × 10-2 (pH 3.0) min-1 in aqueous solution and 3.28 (1-butanol) to 7.69 × 10-4 (acetonitrile) min-1 in organic solvents. The rate-pH profile for TA photodegradation is an inverted V (∧) or V-top shape, indicating that the cationic form is more susceptible to acid hydrolysis than the anionic form of TA, which is less susceptible to alkaline hydrolysis. The fluorescence behavior of TA also exhibits a V-top-shaped curve, indicating maximum fluorescence intensity at pH 3.0. TA is highly stable at a pH range of 5.0-7.0, making it suitable for formulation development. In organic solvents, the photodegradation rate of TA increases with the solvent's dielectric constant and solvent acceptor number, indicating solute-solvent interactions. The values of k obs decreased with increased viscosity of the solvents due to diffusion-controlled processes. The correlation between k obs versus ionization potential and solvent density has also been established. A total of 17 photoproducts have been identified through LC-MS, of which nine have been reported for the first time. It has been confirmed through electron spin resonance (ESR) spectrometry that the excited singlet state of TA is converted into an excited triplet state through intersystem crossing, which results in an increased rate of photodegradation in acetonitrile.

Recovery of volatile fatty acids from anaerobic fermentation broth of baker’s yeast industry effluent by liquid−liquid extraction

As metabolic intermediates, volatile fatty acids (VFAs) can be recovered by separation and purification and contribute to the economy. It was necessary, however, to investigate the optimization of liquid–liquid extraction (LLE) in this study because of the technical difficulties encountered during the recovery of VFAs. For this reason, the organic solvents diethyl ether, trioctylamine, and toluene were investigated as LLE solvents to extract VFAs from Baker’s yeast industry effluent, which contains high levels of organic matter. An optimal pH value of 3 was determined by a pH scan performed between pH 2.5 and pH 7.5. Principal component analysis (PCA) was used to determine the effects of organic solvents and pH on extraction efficiency. The extraction efficiency was evaluated using the optimal pH and multi-stage extraction experiments. In a three-stage extraction, diethyl ether recovered 82% of the VFAs, making it a promising organic solvent for extracting VFAs from anaerobic fermentation broth. PCA revealed that an opposite correlation between VFA recovery and pH for each organic solvent. Based on the results of the cost analysis, it was determined that the costs of recovering VFAs were reduced by 90% per kilogram.

Enhancing Sustainable Analytical Chemistry in Liquid Chromatography: Guideline for Transferring Classical High-Performance Liquid Chromatography and Ultra-High-Pressure Liquid Chromatography Methods into Greener, Bluer, and Whiter Methods.

This review is dedicated to sustainable practices in liquid chromatography. HPLC and UHPLC methods contribute significantly to routine analytical techniques. Therefore, the transfer of classical liquid chromatographic methods into sustainable ones is of utmost importance in moving toward sustainable development goals. Among other principles to render a liquid chromatographic method green, the substitution of the organic solvent component in the mobile phase with a greener one received great attention. This review concentrates on choosing the best alternative green organic solvent to replace the classical solvent in the mobile phase for easy, rapid transfer to a more sustainable normal phase or reversed-phase liquid chromatography. The main focus of this review will be on describing the transfer of non-green to green and white chromatographic methods in an effort to elevate sustainability best practices in analytical chemistry. The greenness properties and greenness ranking, in addition to the chromatographic suitability of seventeen organic solvents for liquid chromatography, are mentioned to have a clear insight into the issue of rapidly choosing the appropriate solvent to transfer a classical HPLC or UHPLC method into a more sustainable one. A simple guide is proposed for making the liquid chromatographic method more sustainable.

Purification and structural analysis of tannase from novel bacteria of Bacillus cereus strain KMS3-1 isolated in marine sediment

Tannases are a family of esterases that catalyze the hydrolysis of ester and depside bonds of hydrolyzable tannins to release small compounds such as glucose. In this work, tannase production from Bacillus cereus strain KMS3-1 was purified and characterized. The standard methods, such as ammonium sulfate precipitation followed by gel filtration chromatography, were used to purify the enzyme tannase from KMS3-1. With 40% enzyme recovery, the purification process yielded a 1.93-fold increase in specific activity. Analysis using SDS-PAGE confirmed a molecular weight of about 40 kDa. Circular dichroism analysis revealed the secondary structure composition α-helix (12.03%), indicating a dominant role of β-turns (38.4%). A pH of 6.0 and a temperature between 50 and 60 °C were ideal for enzyme activity. Tannic acid has an enzyme Km value of 3.0 x 10−3 M and a Vmax of 4.45 U/mL. Surfactants, metal ions, organic solvents, and inhibitors significantly influence the enzyme activity. Cytotoxicity assays revealed the non-toxic nature of the purified enzyme on Vero cells and rat animal models. These results explore and contribute to a better understanding of tannase enzyme properties and their potential applications in the food and beverage industries.

Dual Roles of the Photooxidation of Organic Amines for Enhanced Triplet-Triplet Annihilation Upconversion in Nanoparticles.

Oxygen-mediated triplet-triplet annihilation upconversion (TTA-UC) quenching limits the application of such organic upconversion materials. Here, we report that the photooxidation of organic amines is an effective and versatile strategy to suppress oxygen-mediated upconversion quenching in both organic solvents and aqueous solutions. The strategy is based on the dual role of organic amines in photooxidation, i.e., as singlet oxygen scavengers and electron donors. Under photoexcitation, the photosensitizer sensitizes oxygen to produce singlet oxygen for the oxidation of alkylamine, reducing the oxygen concentration. However, photoinduced electron transfer among photosensitizers, organic amines, and oxygen leads to the production of superoxide anions that suppress TTA-UC. To observe oxygen-tolerating TTA-UC, we find that alkyl secondary amines can balance the production of singlet oxygen and superoxide anions. We then utilize polyethyleneimine (PEI) to synthesize amphiphilic polymers to encapsulate TTA-UC pairs for the formation of water-dispersible, ultrasmall, and multicolor-emitting TTA-UC nanoparticles.

Synthetic extremophiles via species-specific formulations improve microbial therapeutics.

Microorganisms typically used to produce food and pharmaceuticals are now being explored as medicines and agricultural supplements. However, maintaining high viability from manufacturing until use remains an important challenge, requiring sophisticated cold chains and packaging. Here we report synthetic extremophiles of industrially relevant gram-negative bacteria (Escherichia coli Nissle 1917, Ensifer meliloti), gram-positive bacteria (Lactobacillus plantarum) and yeast (Saccharomyces boulardii). We develop a high-throughput pipeline to define species-specific materials that enable survival through drying, elevated temperatures, organic solvents and ionizing radiation. Using this pipeline, we enhance the stability of E. coli Nissle 1917 by more than four orders of magnitude over commercial formulations and demonstrate its capacity to remain viable while undergoing tableting and pharmaceutical processing. We further show, in live animals and plants, that synthetic extremophiles remain functional against enteric pathogens and as nitrogen-fixing plant supplements even after exposure to elevated temperatures. This synthetic, material-based stabilization enhances our capacity to apply microorganisms in extreme environments on Earth and potentially during exploratory space travel.

Nitenpyram in tea: Eco-friendly detection methodology and residue behavior

Studies on nitenpyram determination and behavior within tea remain limited despite its widespread use as a neonicotinoid. An organic-saving analytical approach tailored for the detection of nitenpyram in tea was established. Nitenpyram was extracted by boiling water and cleaned up by Cleanert PCX solid-phase. The average recoveries were 75.1–94.5 %, with relative standard deviations (RSDs) of 0.7–8.6 % for saving 34.5–88.6 % organic solvent. The limits of quantification (LOQs) were 0.002 mg·kg−1 in fresh tea shoots, 0.005 mg·kg−1 in made tea, and 0.001 mg·L-1 in tea brew, satisfying the current minimum Maximum Residue Limit (MRL). Nitenpyram dissipated rapidly with half-lives of 1.2–1.4 days at the recommended dosage (27 g a.i. ha−1) in two locations. Remarkably, 20–110 % of nitenpyram was leached out from made tea in different brewing modes. This work provides insights into nitenpyram’s rational application in tea cultivation and offers considerations to institutions tasked with unestablished MRLs in tea.

Palladium-Catalyzed Amination of Aryl Halides with Aqueous Ammonia and Hydroxide Base Enabled by Ligand Development.

The conversion of aryl halides to primary arylamines with a convenient and inexpensive source of ammonia has been a long-standing synthetic challenge. Aqueous ammonia would be the most convenient and least expensive form of ammonia, but such a palladium-catalyzed amination reaction with a high concentration of water faces challenges concerning catalyst stability and competing hydroxylation, and palladium-catalyzed reactions with this practical reagent are rare. Further, most reactions with ammonia to form primary amines are conducted with tert-butoxide base, but reactions with ammonium hydroxide would contain hydroxide as base. Thus, ammonia surrogates, ammonia in organic solvents, and ammonium salts have been used under anhydrous conditions instead with varying levels of selectivity for the primary amine. We report the palladium-catalyzed amination of aryl and heteroaryl chlorides and bromides with aqueous ammonia and a hydroxide base to form the primary arylamine with high selectivity. The palladium catalyst containing a new dialkyl biheteroaryl phosphine ligand (KPhos) suppresses both the formation of aryl alcohol and diarylamine side products. Mechanistic studies with a soluble hydroxide base revealed turnover-limiting reductive elimination of the arylamine and an equilibrium between arylpalladium amido and hydroxo complexes prior to the turnover-limiting step.

Synthesis and properties of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide

The present work continues a systematic study to find efficient and accessible methods for the synthesis ofN-sulfonylimines of polyhaloaldehydes and to analyze their properties. In the reaction of N,N-dichlorobenzene sulfon-amide with tribromoethylene, N-(2,2,2-tribromoethylidene)amide of 4-chlorobenzenesulfonic acid was obtained for the first time with a quantitative yield at boiling water bath temperature in carbon tetrachloride medium. The infrared spectra of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide reveal the absorption bands of sulfonic (1360 and 1165 cm-1) and NH (3275 cm-1) groups, while the 1H NMR spectra show a signal for azomethine protons within the region of 8.3–8.6 ppm. The 13C NMR spectra exhibit a signal for the CBr3 group within the region of ~31–43 ppm, while the signal characteristic of the CBr2Сl group within the region of ~53–56 ppm is absent. This means that no imine of dibromochloroacetic aldehyde is formed during the reaction. Thus, an efficient method for the synthesis of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide was developed, and the chemoselectivity of this reaction was found to depend on the process temperature. It was shown that N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide has amidoalkylating properties. A reaction of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide with benzene, toluene, anisole, and 2-chlorothiophene in the presence of an acid catalyst yielded p-substituted aromatic derivatives and 2,5-substituted thiophene derivatives. Infrared spectroscopy and NMR spectroscopy (1H, 13C) revealed that the substitution reaction proceeds regioselectively. All the obtained products were isolated in pure form as powders soluble in polar organic solvents and insoluble in water. The yields of 4-chloro-N-(1-phenyl-2,2,2-tribromoethyl)-benzenesulfonamide, 4-chloro-N-[1-(4-methylphenyl)-2,2,2-tribromoethyl]-benzenesulfonamide, 4-chloro-N-[1-(4-methoxyphenyl)-2,2,2-tribromoethyl]-benzene-sulfonamide, and 4-chloro-N-[2,2,2-tribromoethyl-1-(5-chloro-2-thienyl)ethyl]-benzenesulfonamide amounted to 74, 72, 64, and 74 %, respectively.

Task-specific design of protic metal-based deep eutectic solvents for efficient separation of HCl/SO2

Efficient separation and recovery of hydrogen chloride (HCl) from HCl tail gas containing impurities such as sulfur dioxide (SO2) is very important from the viewpoint of economy and environment. However, due to the similar dissolution ability of SO2 and HCl, most solvents, including organic solvents, ionic liquids and deep eutectic solvents (DESs), show low SO2/HCl selectivity near 1.0 and are thus incompetent to separate SO2/HCl. To address this, we firstly reported the task-specific design of a novel class of protic metal-based DESs (PM-DESs) containing hydrochloride, metal chloride and sulfolane, which have good SO2 affinity but much inhibited HCl uptake, for the separation of HCl/SO2. The solubility data of SO2 and HCl in PM-DESs were determined and correlated by Krichevsky-Пiinskaya (K-I) equation. Among these PM-DESs, N,N-dimethylaniline hydrochloride (DMA·HCl) + zinc chloride (ZnCl2) + sulfolane exhibits satisfactory recyclability and selectivity up to 2.669 (100 kPa, 313.2 K), which is the highest value reported so far. Absorption of HCl/SO2 (50/50) mixed gas was also tested, with a high SO2/HCl selectivity of 3.250 obtained. In addition, the NMR and FTIR spectroscopic characterizations paired with quantum chemistry calculation were utilized to investigate the absorption mechanism from the perspective of atomic level. The DESs developed in the present work have the potential to separate and recycle HCl from SO2 owing to their good selectivity and desirable reversibility, and the strategy proposed in this work may offer new guidance for designing green media for HCl recovery.

Solubility of 2,5-Furandicarboxylic Acid in Pure and Mixed Organic Solvent Systems at 293 K Predicted Using Hansen Solubility Parameters.

Central to the production of polyethylene furanoate (PEF), a bioplastic that could potentially replace petroleum-derived plastics, is 2,5-furandicarboxylic acid (FDCA). FDCA is a chemical derived from biomass that has low solubility in traditionally used solvents such as water. Thus, identifying solvents that can solubilize significant amounts of FDCA could allow for lower PEF production costs. In this study, FDCA solubility was investigated in nine pure solvents including H2O, acetonitrile (ACN), γ-valerolactone (GVL), γ-butyrolactone (GBL), ethanol (EtOH), methanol (MeOH), dimethyl sulfoxide (DMSO), sulfolane (SULF), and tetrahydrofuran (THF), eight binary, and three ternary solvent blends at 293 K. For all binary systems excluding DMSO and MeOH, the solubility of FDCA increased 1.5-65 times compared to the pure organic solvent, and the FDCA solubility was at least 10 times higher when compared to pure water. Specifically, the 20/80 w/w H2O/DMSO system solubilized 23.1 wt % FDCA, the highest of any binary blend studied, and 190 times more solubility than in pure water. In 20/80 w/w H2O/THF, the FDCA solubility was 60 times higher than pure water. In ternary blends that included DMSO, H2O, and either GVL, THF, or SULF, solubility increased by at least 6.6 times relative to the pure secondary organic component and 54 times relative to pure water. Using Hansen solubility parameters (HSPs), the radius of interaction (R i,j ) was found to be more strongly correlated to FDCA solubility than individual HSPs or the total solubility parameter. A MATLAB-based optimization code was developed and successful in minimizing the R i,j of a solvent blend to maximize FDCA solubility in binary and ternary aqueous solvents.

Assessment of organic solvents for 2,5-furandicarboxylic acid (FDCA) and distribution in water/cyclohexanone biphasic system

2,5-furandicarboxylic acid (FDCA) is one of the most promising sugar-derived building blocks aimed to produce greener polymers, such as the 100 % recyclable bioplastic polyethylene furanoate (PEF). One incipient field of research is the development of liquid–liquid biphasic systems for FDCA production from 5-hydroxymethylfurfural (HMF) to increase selectivity and minimize undesirable by-product formation. In this work, we first performed an assessment of potential organic green solvents to form biphasic systems considering operability, along with safety, health, and environmental implications. This analysis guided the selection of eight organic solvents in which the solubility of FDCA was measured: cyclohexanone, diethyl ether, isobutyl acetate, methyl isobutyl ketone, methyl ethyl ketone, methoxycyclopentane, tert-butylmethyl ether, and octan-1-ol. The results revealed the superior performance of cyclohexanone as a solvent for the organic phase/water FDCA distribution owing to its higher FDCA solubility (1.364 g/L at 293.15 K). Thus, the FDCA distribution coefficient (KFDCA) between water and cyclohexanone was examined at several temperatures (293.15–313.15 K) and various initial aqueous concentrations to gain deeper insight into the thermodynamics of the phase transfer process and the influence of pH on FDCA distribution between water and cyclohexanone. The resulting enthalpy and entropy of transfer were −15.3 ± 1.0 kJ mol−1 and −44.9 ± 4.6 J K−1 mol−1, thus the highest value of KFDCA (4.83) was obtained at 293.15 K, together with a very high separation factor (81.5) which shows the great potential of cyclohexanone to extract FDCA from aqueous solutions.

The role of the cation and anion in aqueous liquid chromatography with sodium dodecyl sulphate and imidazolium-based ionic liquids as mobile phase reagents

BackgroundIn reversed-phase liquid chromatography, solute retention is primarily influenced by interactions between a nonpolar stationary phase and a moderately polar hydro-organic mobile phase, based on the solute lipophilicity. However, challenges regarding retention and peak tailing can arise due to ionic interactions between positively charged analytes and free silanols present on silica-based stationary phases. To address these challenges, incorporating surfactants and ionic liquids (ILs) into the mobile phase offers an effective solution. These additives synergistically enhance chromatographic performance through electrostatic and lipophilic interactions, which enable fine-tuning of selectivity and improved separation efficiency. ResultsThis study explores the chromatographic behaviour of several basic compounds in aqueous mixtures containing the anionic surfactant sodium dodecyl sulphate (SDS), above its critical micellar concentration, combined with various 1-alkyl-3-methylimidazolium-based ionic liquids (ILs) featuring chloride, tetrafluoroborate, and hexafluorophosphate anions, all without the addition of organic solvents. Specifically, this research investigates the influence of different anion types within the ILs and considers the impact of the IL cations. Analysis of solute peak profiles reveals narrow and symmetrical peaks. By introducing tetrafluoroborate and hexafluorophosphate IL anions into a mobile phase that contains an anionic surfactant, the study sheds light on the interactions occurring within the chromatographic column. This enhanced understanding of the combined effects of surfactants and ILs contributes to refining chromatographic methodologies. SignificanceThis research highlights the importance of carefully selecting the appropriate IL when incorporating it into a micellar mobile phase alongside SDS. This combination results in practical retention times that surpass the performance achieved with either the surfactant or IL alone in the mobile phase. The study particularly emphasises the impact of the IL anion, especially in the absence of SDS and organic solvents. This unveils interactions that are otherwise obscured in micellar and hydro-organic media, providing new insights into chromatographic dynamics.

Overcoming Challenges of Lignin Nanoparticles: Expanding Opportunities for Scalable and Multifunctional Nanomaterials.

ConspectusThe increasing demand for polymeric materials derived from petroleum resources, along with rising concerns about climate change and global plastic pollution, has driven the development of biobased polymeric materials. Lignin, which is the second most abundant biomacromolecule after cellulose, represents a promising renewable raw material source for the preparation of advanced materials. The lucrative properties of lignin include its high carbon content (>60 atom %), high thermal stability, biodegradability, antioxidant activity, absorbance of ultraviolet radiation, and slower biodegradability compared to other wood components. Moreover, the advent of lignin nanoparticles (LNPs) over the last ten years has circumvented many well-known shortcomings of technical lignins, such as heterogeneity and poor compatibility with polymers, thereby unlocking the great potential of lignin for the development of advanced functional materials.LNPs stand out owing to their well-defined spherical shape and excellent colloidal stability, which is due to the electrostatic repulsion forces of carboxylic acid and phenolic hydroxyl groups enriched on their surface. These forces prevent their aggregation in aqueous dispersions (pH 3-9) and provide a high surface area to mass ratio that has been exploited to adsorb positively charged compounds such as enzymes or polymers. Consequently, it is not surprising that LNPs have become a prominent player in applied research in areas such as biocatalysis and polymeric composites, among others. However, like all ventures of life, LNPs also face certain challenges that limit their potential end-uses. Solvent instability remains the most challenging aspect due to the tendency of these particles to dissolve or aggregate in organic solvents and basic or acidic pH, thus limiting the window for their chemical functionalization and applications. In addition, the need for organic solvent during their preparation, the poor miscibility with hydrophobic polymeric matrices, and the nascent phase regarding their use in smart materials have been identified as important challenges that need to be addressed.In this Account, we recapitulate our efforts over the past years to overcome the main limitations mentioned above. We begin with a brief introduction to the fundamentals of LNPs and a detailed discussion of their associated challenges. We then highlight our work on: (i) Preparation of lignin-based nanocomposites with improved properties through a controlled dispersion of LNPs within a hydrophobic polymeric matrix, (ii) Stabilization of LNPs via covalent (intraparticle cross-linking) and noncovalent (hydration barrier) approaches, (iii) The development of an organic-solvent-free method for the production of LNPs, and (iv) The development of LNPs toward smart materials with high lignin content. Finally, we also offer our perspectives on this rapidly growing field.

The Role of the Polyethylene Glycol in the Organization of Gold Nanorods at the Air-Water and Air-Solid Interfaces.

The organization of metallic nanoparticles into assembled films is a complex process. The type of nanoparticle stabilizing ligand and the method for creating an organized layer can profoundly affect the optical properties of the resulting nanoparticle assembly. Investigations of the ligand structure and nanoparticle interactions can provide a greater understanding of the design of the assembly process and the quality of the resulting materials. One of the functionalization methods in the preparation of specific gold nanorods is the utilization of thiol-terminated poly(ethylene glycol). This generates gold nanorods capable of forming stable monolayers at the air-water interface upon dispersion in a suitable organic solvent. Herein, we show that depending on the molecular weight of the poly(ethylene glycol), the structures obtained at the air-water and air-solid interfaces differ in the arrangement. The studied structures were characterized by using spectroscopic and microscopic techniques, and the structural type was correlated with the polymer type. Insoluble and stable Langmuir monolayers composed of higher-molecular-weight gold nanorods with poly(ethylene glycol) were formed only in the presence of an additional stabilizer that prevented the formation of gold nanorods in aqueous solutions. At the air-solid interface, conformational changes in poly(ethylene glycol) induced the aggregation of gold nanorods, which became closely packed under the influence of surface pressure. The presented results suggested that the arrangement of two-dimensional layers of gold nanorods could be tailored using poly(ethylene glycol) of various molecular weights.