Environmental Friendly Solvent Research Articles

Determination of parabens and bisphenol A in sludge samples using hydrophobic deep eutectic solvents by gas chromatography coupled to mass spectrometry and sample introduction via pyrolizer

This study reports on the development and use of hydrophobic deep eutectic solvents (HDES) as environmentally-friendly solvents to address the demand for low-toxicity materials for analysts and the environment. The study involved the application of HDES in environmental matrices for extracting emerging contaminants. In this case, HDESs were used as extraction solvents in dispersive liquid–liquid microextraction (DLLME) to determine parabens and bisphenol A from sludge samples. Gas chromatography-mass spectrometry (GC–MS) featuring a pyrolizer was used for sample introduction. Chemometric tools were utilized to optimize analysis conditions, considering the sample introduction and DLLME parameters. HDESs were characterized using Fourier-Transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). Univariate and multivariate strategies were employed to determine the optimal experimental conditions. In this case, the injection volume was fixed as 20 µL, with a temperature of 320 °C and a pyrolizer duration time of 0.5 min. For DLLME, full factorial design permitted identification of the best condition of each experimental variable, including the salting-out effect, pH, volume of dispersing solvent, and volume of extraction solvent. Optimal conditions for DLLME in sludge samples were determined as 300 µL of HDES, 350 µL of ACN, pH = 10, and the addition of NaCl at 27% m/v. Following optimization studies, a HDES was successfully applied as an extraction solvent to determine endocrine disruptors in sludge samples. Future work involves the analysis of additional sludge samples (both liquid and solid phases) using standard addition to quantify analytes using the developed methodology. The utilization of HDES within environmental samples facilitated the identification of emerging contaminants, aligning with the tenets of sustainable analytical chemistry. This was substantiated by applying the GREEnness Analytical (AGREE) evaluation metric system, yielding values of 0.72 and 0.76 for the employed methodology and sample preparation, respectively.

Experimental measurements, thermodynamic modeling and molecular dynamics simulation of the multiphase equilibria of {1-butanol + n-butyl acetate + [EMIM][EtSO4]} systems at 101.3 kPa

Ionic liquids (ILs) are organic salts with normal melting temperatures lower than 373 K and have interesting properties to be used as environment-friendly solvents, as low volatility, high thermal stability, and easy containing and recycling ability. Besides, they are versatile molecules whose anions and cations can be changed to solubilize different organic compounds. For these reasons, ionic liquids can be used in many industrial applications, such as in separation processes as azeotropic distillation and liquid–liquid extraction, and, because of that, it is important to know the phase equilibrium behavior for equipment design for these processes. However, experimental data for systems containing ionic liquids are very scarce. This work aimed to analyze the fluid phase behavior of the 1-butanol + n-butyl acetate + [EMIM][EtSO4] system in liquid–liquid (LLE), vapor–liquid (VLE) and vapor–liquid–liquid equilibria (VLLE) at 101.3 kPa. LLE was analyzed in glass-jacketed vessels and VLE and VLLE were analyzed in a modified Othmer ebuliometer. Compositions of each phase sample were obtained from calibration curves with built-in functions of the refractive index and density. Experimental data were submitted to thermodynamic consistency tests and the consistent points were modeled with the Group Contribution Volume Translated Peng-Robinson (GC-VT-PR) and Non-Random Two-Liquid (NRTL) models. Vapor pressure and saturated liquid density data for the ionic liquid, necessary for the determination of the pure component parameters, were obtained from analytical methods. For the LLE, a phase stability test was also done to evaluate the data consistency by the Gibbs energy of the mixing surface and to determine the plait point. Molecular dynamics (MD) simulations, performed by NAMD software, were also conducted to understand the behavior of the multiphase fluid equilibria, by analyzing the structural properties of the components. Results of the thermodynamic modeling in terms of the deviations of temperature and mole fractions showed that these models were adequate to study the phase behavior of systems containing ionic liquids, while the dynamic simulations suggested that the ionic liquid molecules strongly interact with 1-butanol molecules when compared with the n-butyl acetate molecules.

Integral fractionation of Arundo donax using biphasic mixtures of solvents derived from biomass: An environmentally friendly approach

Arundo donax, one of the most invasive plants in the world, but also a promising source of lignocellulose materials was employed as a feedstock for a biorefinery process. Water-extracted Arundo donax samples were subjected to one-step biphasic fractionation in catalyzed media containing water and 1-butanol, an environmentally-friendly solvent. The effects of selected operational variables (catalyst concentration, temperature and reaction time) on the measured effects (solid recovery yield and compositions of the solid, aqueous and organic phases resulting from treatments) were assessed using statistical methods. The results allowed a quantitative discussion on aspects regarding the selectivity of component separation (lignin, glucan, and hemicelluloses), the overall recovery of valuable products, and the selection of operational conditions enabling extensive delignification (around to 90 %) and high recovery rates of glucan and hemicellulose-derived sugars (above 80 % and 75 %, respectively). This study provides new insights into biphasic fractionation, highlighting the selective separation of hemicellulose, cellulose and lignin into a single and sustainable process, thereby by enhancing biomass resource while reducing environmental impact.

An environmentally benign process to synthesize vanillin and other substituted phenyl aldehydes using natural phenylpropenes

The limited vanillin (3a) production from plant sources requires identifying some renewable and sustainable approaches for its synthesis. This study aimed to develop an efficient, eco-friendly process for synthesizing vanillin (3a) from eugenol (1a) and eugenol-rich essential oils. The chemical methodology for vanillin (3a) synthesis involved base-mediated isomerization of eugenol (1a) to isoeugenol (2a), followed by OsO4/NaIO4 mediated oxidation of isoeugenol to vanillin (3a) using different additives such 1,4-diazabicyclo[2.2.2]octane (DABCO) and substituted pyridines in reusable environment-friendly solvents. Use of 2,6-dimethylpyridine and 2,6-dimethylpyridine N-oxide as additives in the oxidation step offered a significantly higher product yield (vanillin 3a, 70 %). The process synthesized vanillin (3a) irrespective of the cis/ trans stereochemistry of isoeugenol (2a). The peculiarity of the method relates to converting eugenol (1a) to vanillin (3a) without phenolic group protection, which offers step economy. Besides efficient vanillin (3a) synthesis, the process's general implications involve converting other naturally occurring phenylpropenes or phenylpropenes-enriched oils to the corresponding phenyl aldehydes (59–82 % yield).

Systematic study on date palm seeds (Phoenixdactylifera L.) extraction optimisation using natural deep eutectic solvents and ultrasound technique

Natural deep eutectic solvents (NADES) are emerging, environment-friendly solvents that have garnered attention for their application in extracting phenolic compounds. This study investigated the effects of four synthetic NADES on polyphenols extracted from date seeds (DS) using choline chloride (ChCl) as a hydrogen-bond acceptor and lactic acid (La), citric acid (Citri), glycerol (Gly), and fructose (Fruc) as hydrogen-bond donors, in comparison with DS extracts extracted by conventional solvents (water, 70% methanol, and 70% ethanol). The antioxidant activity (DPPH), total phenolic content (TPC) and 6 phenolic compounds were determined using HPLC. The results showed that the ChCl–La and ChCl–Citri systems exhibited a high extraction efficiency regarding TPC, and DPPH in the DS extracts extracted by NADES compare to those DS extracts extracted with conventional solvents (p ˂ 0.001). HPLC results demonstrated that DS extracted by ChCl–La contained all measured phenolic compounds. Also gallic acid and catechin were the major compounds identified in the DS extracts. In addition DS extracted by ChCl–Citri and ChCl–Gly had the highest concentration of catechin. In conclusion, combining NADES is a promising and environment-friendly alternative to the conventional solvent extraction of phenolic compounds from DS.

Exploration of the critical structural parameter of polyamide decisive for permeability based on SWRO membrane regulated by environmental-friendly solvent Gamma-valerolactone

The intrinsic structure of the aromatic polyamide (APA) layer which is decisive for permeability and permselectivity of the state-of-art thin film composite (TFC) reverse osmosis (RO) membranes should be analyzed precisely in-depth. In this work, seawater reverse osmosis (SWRO) membranes with different APA microstructures are prepared by introducing the environmental-friendly solvent Gamma-valerolactone (GVL) into the organic phase to modulate the diffusion rate of m-phenylenediamine (MPD), thereby altering the packing density and morphology of APA aggregates. Small-angle X-ray scattering is utilized to obtain the fractal dimension of APA aggregates which quantitatively reflects the irregularity and complexity of the APA aggregates based on the principle of statistics. Confirmed by the cross-section images, fractal dimensions of APA aggregates transform from pseudo-1-dimension to pseudo-2-dimension structures due to the weakened folding property and the enhanced structural flexibility of the APA colloid particles, along with the looser stacking morphology of the APA aggregates. By correlation analysis, the fractal dimension possessed strong linear and positive correlation with water permeability coefficient A (R2=0.9945), together with strong linear and negative correlation with water-salt permselectivity A/B (R2=0.9896). As a demonstration, parameter of fractal dimension was supposed to be the critical structural parameter which played the most important role in water permeability of SWRO membranes, and the permeability and the permselectivity of SWRO membranes could only be simultaneously improved on the basis of the fractal dimension infinitely close to 1-dimension with the nodular and linear structures of the APA aggregated mostly maintained.

Environmentally-friendly solvent pulping and grafting strategies for better foamability of poly(lactic acid)/agricultural waste biocomposites

In this study, the foamability of poly (lactic acid) (PLA) through a continuous extrusion process was enhanced by using an agricultural waste, environmentally friendly pulping methods, and reactive compatibilization of the lignocellulosic filler with matrix in the extrusion flow field. Both applied solvent-pulping methods by using chemicals with low safety and toxicity risks were considerably successful in purifying the micron-sized cellulosic fibers of rice straw (RS). The interface of PLA matrix with RS pulp fibers was modified by applying reactive compatibilizers containing maleic anhydride (MA) and epoxy functional groups. Both compatibilizers had the ability to simultaneously react with the hydroxyl groups of RS pulp fibers and end groups of PLA chains during the melt-compounding process. As a result of RS pulping and PLA/RS pulp compatibilizing reactions, the processability of PLA in an extrusion foaming process was substantially enhanced, in a way that the void fraction and cell density of PLA foam increased more than seven and two times, respectively. The extruded lightweight all-green biocomposite foams can be applied in construction and packaging applications.

Accomplishing High-Performance Organic Solar Sub-Modules (≈55 cm2) with >16% Efficiency by Controlling the Aggregation of an Engineered Non-Fullerene Acceptor.

The fabrication of environmentally benign, solvent-processed, efficient, organic photovoltaic sub-modules remains challenging due to the rapid aggregation of the current high performance non-fullerene acceptors (NFAs). In this regard, design of new NFAs capable of achieving optimal aggregation in large-area organic photovoltaic modules has not been realized. Here, an NFA named BTA-HD-Rh is synthesized with longer (hexyl-decyl) side chains that exhibit good solubility and optimal aggregation. Interestingly, integrating a minute amount of new NFA (BTA-HD-Rh) into the PM6:L8-BO system enables the improved solubility in halogen-free solvents (o-xylene:carbon disulfide (O-XY:CS2)) with controlled aggregation is found. Then solar sub-modules are fabricated at ambient condition (temperature at 25±3 °C and humidity: 30-45%). Ultimately, the champion 55 cm2 sub-modules achieve exciting efficiency of >16% in O-XY:CS2 solvents, which is the highest PCE reported for sub-modules. Notably, the highest efficiency of BTA-HD-Rh doped PM6:L8-BO is very well correlated with high miscibility with low Flory-Huggins parameter (0.372), well-defined nanoscale morphology, and high charge transport. This study demonstrates that a careful choice of side chain engineering for an NFA offers fascinating features that control the overall aggregation of active layer, which results in superior sub-module performance with environmental-friendly solvents.

Greening the supply chain: Sustainable approaches for rare earth element recovery from neodymium iron boron magnet waste

The increasing demand for modern technologies has led to a growing reliance on rare earth elements (REEs). To address this issue, recycling used products such as permanent magnet waste containing REEs. However, this approach necessitates the development of advanced extraction and separation techniques to ensure high yields and purity of the REEs extracted. This review provides an overview of the latest extraction and separation technologies, with a particular focus on the hydrometallurgical approach for extracting REEs from secondary sources, notably permanent magnets. Hydrometallurgy, which involves leaching followed by solvent extraction for purification, has gained widespread use for obtaining REEs from secondary sources, as evidenced by its reported high recovery efficiencies. We found that the recovery of REEs using chemical leaching varied between 80% and 99%, influenced by factors such as type of source material, leaching solvent, leaching conditions, impurities, reaction kinetics and solid-liquid ratio. However, effectively employing this process on a larger scale still faces certain challenges due to the excessive use of corrosive solvents for leaching magnet waste and the generation of toxic chemicals as end products in the form of leachate. Additionally, the current process exhibits deficiencies in the targeted recovery of REEs from magnet waste, specifically in achieving purity and selectivity by eliminating iron impurities. This article concludes that the future prospects for the selective recovery of REEs from neodymium iron boron magnet waste lie in green and environment-friendly solvents. One such approach revolves around the utilization of biodegradable organic acids and salt aqua regia for leaching. These solvents are less corrosive and have high dissolution efficiency, which results in less chemical consumption and an overall environment-friendly and cost-effective recovery process.

Fabrication of Carbon Dots with Singlet Oxygen Generation and Their Potential Photodynamic Therapy Applications.

Due to the unique chemical and biomedical properties of carbon dots (CDs), they have increasingly obtained the attention in many research fields, for example, bioimaging, fluorescence sensing, and drug delivery, etc. Recently, it was found that, under light excitation, CDs can also be exploited as a novel photosensitizer to prepare reactive oxygen species (ROS), which expand their applications in the field of photodynamic therapy for cancer treatment. Nevertheless, the high cost and complex fabrication approach of CDs significantly limit their applications. To address this issue, bottom-up routes usually utilize sustainable and inexpensive carbon precursor as starting materials, employed N,N-dimethylformamide (DMF) or ethanol as an environmental-friendly solvent. Bottom-up approach was energy efficient, and the purification process was relatively simple by dialysis. Therefore, carbon dots (CDs) were facilely fabricated in a one-pot solvothermal process using 1-aminoanthraquinone as a precursor, and their application as photosensitizers for in vitro antitumor cells, especially photodynamic therapy (PDT) was established. Then the photophysical and nanoscale dimensions properties of the fabricated CDs were characterized via TEM, UV-visible, fluorescence, and FT-IR spectroscopy. The synthesized N-doped CDs can easily dissolve in water, possess very low biotoxicity, yellow-light emission (maximum peak at 587nm). More importantly, PDT studies demonstrated that the obtained CDs possess a high singlet oxygen yield of 35%, and exhibit significant phototoxicity to cancer cells upon 635nm laser irradiation. These studies highlight that N-doped CDs can be facilely synthesized from only one precursor, and are a potentially novel theranostic agent for in vivo PDT.

Catalytic Conversion of Oil Shale over Fe or Ni Catalysts under Sub-Critical Water

Sub-critical water is an environment-friendly solvent. It is widely used for the extraction of various organic compounds. It can be used to dissolve and transport organic matter in oil shale. In this study, the conversion of oil shale was synergistically catalyzed by the addition of Fe or Ni to the Fe inherent in samples under sub-critical water conditions. Oil shale can be converted to gas, oil and residues of oil. Thermogravimetric (TG) analysis results presented that the weight loss of raw oil shale was up to 15.85%. After sub-critical water extraction, the weight loss rate of the residues was reduced to 8.41%. With the application of a metal catalyst, Fe or Ni, the weight loss of residues was further reduced to 7.43% and 6.57%, respectively. According to DTG curves, it was found that there were two weight-loss rate peaks. The decomposition process of kerogen in oil shale could be divided into two cracking processes. One is decomposed at a high velocity at around 420 °C, and another is decomposed at a low velocity at around 515 °C. Gas chromatography (GC) results of gas products indicated that Fe or Ni could contribute to producing normal alkanes, such as methane, ethane, propane, etc., which are produced by the hydrogenation of alkenes via hydrogen transfer during the conversion process of kerogen. Gas chromatography-mass spectrometry (GC–MS) was conducted to analyze the components of the liquid products. The results showed that n-alkanes, iso-alkane, oxygenated hydrocarbons and aromatic compounds were the major components of the kerogen cracking products. When Ni was introduced as a catalyst, the contents of aromatic compounds and oxygenated hydrocarbons in the liquid products were increased from 19.55% and 6.87% to 22.38% and 13.77%, respectively. This is due to the synergistic effect of the addition of Ni with the inherent Fe in oil shale under sub-critical water which ensures kerogen is more easily cracked to produce aromatic compounds and oxygenated hydrocarbons.

Sustainable combination of ionic liquid and deep eutectic solvent for protecting and preserving of the protein structure: The synergistic interaction of enzymes and eco-friendly hybrid ionic fluids

Hybrid ionic fluids (HIFs) are one of the emerging and fascinating sustainable solvent media, a novel environment-friendly solvent for biomolecules. The HIFs have been synthesized by combining a deep eutectic solvent (DES), an ionic liquid (IL) having a common ion. The stability and activity of hen's egg white lysozyme (Lyz) in the presence of a recently designed new class of biocompatible solvents, HIFs have been explored by UV–visible, steady-state fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR) along with dynamic light scattering (DLS) measurements. This work emphasizes the effect of DES synthesized by using 1:2 choline chloride and glycerol [Glyn], ILs (1-butly-3-methylimidazolium chloride [BMIM]Cl and choline acetate [Chn][Ac]) and their corresponding HIFs on the structure and functionality of Lyz. Moving forward, we also studied the secondary structure, thermal stability and enzymatic activity and thermodynamic profile of Lyz at pH = 7 in the presence of varying concentrations (0.1 to 0.5) M of [BMIM]Cl, [Chn][Ac] ILs, [Glyn] DES and [Glyn][BMIM]Cl (hybrid ionic fluid1) as well as [Glyn][Chn][Ac] (hybrid ionic fluid2). Spectroscopic results elucidate that ILs affect the activity and structural stability of Lyz, whereas the stability and activity are increased by DES and are maintained by HIFs at all the studied concentrations. Overall, the experimental results studied elucidate expressly that the properties of Lyz are maintained in the presence of hybrid ionic fluid1 while these properties are intensified in hybrid ionic fluid2. This work has elucidated expressly biocompatible green solvents in protein stability and functionality due to the alluring properties of DES, which can counteract the negative effect of ILs in HIFs.

Facile synthesis of highly stable and efficient MAPbI3 perovskite quantum dots: Spectroscopic characterization and defect analysis

The hybrid methylammonium-based perovskite quantum dots (PQDs) have attracted tremendous attraction for display devices due to their low cost, high luminescence, and color purity. The large-scale production of PQDs is constrained due to the use of toxic and hazardous solvents such as dimethylformamide (DMF) in the synthesis process. Here, a novel approach to prepare PQDs using an environment-friendly solvent, gamma-valerolactone (GVL), is proposed. The synthesized PQDs were found to be uniform with less defect states as compared to the conventionally used DMF solvents, confirmed by different characterizing techniques. The stability of GVL-based PQDs was also found to be improved and proved the efficiency of the present method. Photoluminescence quantum yield (PLQY) of 98 % and single tetragonal CH3NH3PbI3 phase of GVL-derived sample retained over 15 days while the decomposition and degradation were observed in the DMF-derived sample within a short duration. A protocol for the preparation of CH3NH3PbI3 PQDs with less intrinsic defects and uniform optoelectronic properties is presented and paves the way for further modifications and applications.

A key parametric study of ultrasonic exfoliation of 2D TiB2 using DI water as a unique medium

Liquid Phase Exfoliation (LPE) is a very effective technique for the synthesis of few layered two dimensional (2D) nanosheets. There is a surge to find environment friendly solvents for efficient exfoliation of layered materials to produce 2D nanosheets. TiB2 is an important layered material with very little reported work on its 2D nanosheets. The present work is about successful LPE of TiB2 using deionized (DI) water as a clean, green and low cost dispersion medium to make TiB2 nanosheets. The impact of ultrasonication conditions i.e. input power and treatment duration for efficient synthesis of few layered 2D nanosheets in DI water is studied by Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It is found that by increasing input power, the layer thickness is reduced from bulk to 34 nm with lateral dimensions as huge as up to 5 μm. The increased treatment duration has further reduced the layer thickness to 21 nm associated with a decrease in lateral dimensions to about 1 μm. The mechanism of variation in the aspect ratio of the 2D nanosheets with ultrasonication power and treatment duration is explained. The optimum conditions for the fabrication of high aspect ratio 2D nanosheets of TiB2 owe to a greater acoustic cavitation intensity, an optimum treatment duration and a homogenous distribution of the cavitation events while using an appropriate size of the sonotrode in the sonicated volume during ultrasonication.

Environmentally friendly solvent debinding technique of POM binder system for titanium injection molding

An environment-friendly solvent debinding process for polyoxymethylene (POM) for metal injection molding (MIM) is presented as an alternative to the traditional catalytic debinding method. This study investigated the influence of various acid solvents and debinding temperature. The optimal debinding parameters were 5 M nitric acid solution at 60 °C. Based on the calculation of effective diffusivity and activation energy, the solvent-debinding mechanism for POM is proposed. The removal of POM was controlled by three processes: dissolution, diffusion, and chemical reaction. The resulting final titanium parts have a high density of over 95% and an ultimate tensile strength of 406 MPa.

Evaluate the aluminum concentrations in whey milk samples of cows from different areas using deep eutectic solvent-based ultrasound-assisted dispersive liquid-liquid microextraction method

This study investigates the contamination of cow milk with aluminum (Al) and its potential health implications, particularly for children. Cow milk samples were collected from both nonexposed and exposed areas in Sindh, based on the source of livestock drinking water (fresh canals and groundwater). An environmental friendly deep eutectic solvent (DES) was used with ultrasonic-assisted dispersive liquid-liquid microextraction (UDLLμE) to enrich trace amounts of Al in whey milk and water samples. The enriched samples were then analyzed using inductively coupled plasma optical emission spectrometry. Certified reference materials were employed to validate the methodology, and the experimental results exhibited acceptable conformity. The DES-based dispersive liquid-liquid microextraction method was environmental friendly, devoid of acids and oxidizing agents, and used safe and inexpensive components for routine trace metal analysis in diverse samples. The resulting data revealed that Al in whey milk samples was observed in the range of 31–45 %, corresponding to (160–270) μg L−1 and (700–1035) μg L−1 in nonexposed and exposed whole cow milk samples, respectively. Additionally, it was observed that milk boiling in Al utensil for 10–20 min enhanced the Al levels from 3 to 8% of its total contents in milk samples.

A zinc porphyrin-amidine as a green carbon-based electron transport material for organic-light emitting diodes

Charge injection and transport interlayers based on artificial green carbon materials are imperative for a sustainable future of many classes of optoelectronic devices, including organic light-emitting diodes (OLEDs). Especially, porphyrin derivatives can act as efficient energy and charge funnels mimicking their successful photosynthetic function. Here, we report on the application of a novel green carbon material, in particular, a zinc porphyrin derivative bearing an amidine functional group (referred to as ZnP-amidine), as an electron transport material in fluorescent OLEDs based on a green-yellow co-polymer emitter. ZnP-amidine is processed from environmental friendly solvents without any annealing requirements thus being suitable for low-cost sustainable optoelectronics. It is applies as an ultra-thin interlayer between the aluminum cathode and the emissive layer to enable efficient electron transport and stable performance. This work paves the path towards low-cost green carbon materials inspired by natural processes for organic optoelectronics.

Comparative assessment of phenolic composition profile and biological activities of green extract and conventional extracts of Salvia sclarea

In recent years, there have been an attempt to develop safe and environmental friendly solvents to replace conventional solvents, and use for extraction bioactive compounds from natural sources. A current investigation involved the preparation of green, methanolic, and ultrasonic extracts of S. sclarea, and compared their phenolic profiling using HPLC–DAD, antibacterial, antioxidant, and enzyme inhibition activities. The HPLC–DAD analysis revealed that Rosmarinic acid was the main content in all extracts, with Ellagic acid only present in the green extract. The green extract exhibited superior anti-biofilm activity against S. Aureus and E. Faecalis compared to the other extracts at MIC concentration. Furthermore, the green extract also displayed the highest inhibition of swarming motility in P. Aeruginosa with inhibition range 68.0 ± 2.1 (MIC) to 19.5 ± 0.6 (MIC/4). and better enzyme inhibitory activity against BChE (with IC50 = 131.6 ± 0.98 µg/mL) and AChE (with inhibition 47.00 ± 1.50%) compared to the other extracts; while, the ultrasonic extract showed strong inhibition of violacein production by C. Violaceum with a inhibition range 05.5 ± 0.1 (MIC/32) to 100 ± 0.00 (MIC), followed by the green extract with a inhibition range 15.0 ± 0.5 (MIC/8) to 100 ± 0.00 (MIC), additionally, the ultrasonic and methanoic extracts showed significant activity against urease enzyme with (IC50 = 171.6 ± 0.95 µg/mL and IC5 0 = 187.5 ± 1.32 µg/mL) respectively. Both the green and methanolic extracts showed considerable antioxidant activities, as β-carotene-linoleic acid (IC50 = 5.61 ± 0.47 µg/mL and 5.37 ± 0.27 µg/mL), DPPH· (IC50 = 19.20 ± 0.70 µg/mL and 16.31 ± 0.23 µg/mL), ABTS·+(IC50 = 8.64 ± 0.63 µg/mL and 6.50 ± 0.45 µg/mL) and CUPRAC (A0.5 = 17.22 ± 0.36 µg/mL and 12.28 ± 0.12 µg/mL) respectively, likewise the green extract performing better in metal chelating compared to the other extracts. The green extraction is reported as a cost effective and solvent free method for extracting natural products that produces compounds free of toxic chemicals. This could be the method to be used in the industries as a renewable method.

Photoelectrochemical aptasensing withmethylene blue filled Ni-MOFs nanocomposite by spatial confinement for microcystin-LR detection.

Microcystin LR (MC-LR) is a hazardous cyanotoxin produced by cyanobacteria during freshwater eutrophication, which can cause liver cancer. Here, a photoelectrochemical (PEC) aptasensor based on methylene blue (MB)-loaded Ni-MOF composite (Ni-MOF/MB) with spatial confinement was constructed for the sensitive detection of MC-LR. Ni-MOF with two-dimensional sheet structure was prepared via a liquid-liquid interface synthesis method with environmental-friendly solvent and milder reaction conditions. Benefiting from the uniform pore size, Ni-MOF acted as reaction platform to anchor the photosensitive molecule MB. The electron donor, ascorbic acid (AA), was produced by alkaline phosphatase (ALP) loaded on DNA strand catalyzing ascorbic acid phosphate. The generated AA was absorbed by Ni-MOF/MB, thereby effectively improving the utilization of AA and avoiding the external environment interferences to enlarge the photocurrent of MB. For analysis, ALP-labeled aptamer can specifically recognize MC-LR by forming acomplex to strip from aptasensor, thus leading to a decreased photocurrent. Thedeveloped PEC aptasensor offered a linear range of 10 fM-100 pM with a detection limit of 6 fM. It was successfully employed for detecting MC-LR in farm water and fish meat, and the results were validated by ultrahigh-performance liquid chromatography-mass spectrometry. This method presents a new idea of MOF-limited domain for PEC aptasensing.

Aromatic vs alicyclic: Hydrophobicity of the ionic liquid on protein stability and fibril formation

Ionic liquids (ILs) are environment-friendly solvents with potential applications in biochemical reactions and as pharmaceutical ingredients. They are used to stabilize proteins and act as anti-aggregation agents in which the hydrophobic effect of ILs is suggested to have a primary role. To understand the differences in the effect of aromatic and alicyclic cations of ILs on thermal stability and fibrillation propensity of proteins, the effect of two alicyclic (butyl-1-methylpyrrolidinium and butyl-1-methylpiperidinium) and two aromatic (butyl-4-methylpyridinium and butyl-3-methylimidazolium) ILs on lysozyme was investigated by spectroscopy, densitometry, and molecular dynamics simulation. The results suggest that all the ILs switch the fibrillation pathway from nucleation-independent to nucleation-dependent mechanism at ≥200 mM. The fibrillation is slowed down by 28–35-fold in 500 mM of ILs, exceptionally pyrrolidinium-IL delays the fibrillation by ∼70-fold. All the ILs destabilize the protein during thermal denaturation. Though in all cases the unfolding is enthalpy-driven, pyridinium-IL at higher concentrations exhibits an entropy-driven unfolding effect. The volumetric analysis shows a higher thermal expansion coefficient for Lyz in pyridinium-IL which might be due to the increased internal cavity volume of the protein upon binding of the IL. These results corroborate with the computational studies that the preferential interaction coefficient of aromatic-ILs is more, particularly at a higher concentration (200 mM). Four preferable binding sites for ILs on the protein could be identified that includes the amyloidogenic regions, β-hairpin and the hydrophobic cluster 5. Also, the ILs are found to preferably interact with the protein through their alicyclic/aromatic ring and alkyl sidechain. These results suggest that the binding of ILs to the amyloidogenic region inhibits the fibril formation which has a similar effect for both alicyclic and aromatic ILs whereas aromatic-ILs show a larger destabilization effect than alicyclic-ILs at higher concentrations.