Preparation of Antibacterial Biobased Fibers by Triaxial Microfluidic Spinning Technology Using Ionic Liquids as the Solvents.

Bacterial infections have become a serious threat to public health. The utilization of antibacterial textiles offers an effective way to combat bacterial infections at the source, instead of relying solely on antibiotic consumption. Herein, efficient and durable antibacterial fibers based on quercetin and cellulose were prepared by a triaxial microfluidic spinning technology using ionic liquids (ILs) as the solvents. It was indicated that the structure and properties of the antibacterial fibers were affected by the type of IL and the flow rates during the triaxial microfluidic spinning process. Quercetin regenerated from [Emim]Ac underwent structural transformation and obtained an increased water solubility, while quercetin regenerated from [Emim]DEP remained unchanged, which was proven by FI-IR, XRD, and UV analyses. Furthermore, antibacterial fibers regenerated from [Emim]Ac exhibited the highest antibacterial activity of 96.9% against S. aureus, achieved by reducing the inner-to-outer flow rate ratio to 0 and concentrating quercetin at the center of fibers. On the other hand, when [Emim]DEP was used as the solvent, balancing the inner-to-outer flow rate ratio to concentrate quercetin in the middle layer of the fiber was optimal for achieving the best antibacterial activity of 93.3% because it promised both the higher encapsulation efficiency and release rate. Computational fluid dynamics (CFD) mathematically predicted the solvent exchange process during triaxial spinning, explaining the influence of IL types and flow rates on quercetin distribution and encapsulation efficiency. It was indicated that optimizing the distribution of antibacterial agents within the fibers can fully unleash its antibacterial potential while preserving the mechanical properties of the fiber. Therefore, the proposed simple triaxial spinning strategy provides valuable insights into the design of biomedical materials.

Exploring hydrogen-bond structures in cellulose during regeneration with anti-solvent through two-dimensional correlation infrared spectroscopy.

Cellulose, renowned for its excellent biocompatibility, finds extensive applications in both industrial and laboratory settings. However, few studies have specifically addressed the mechanistic evolution of hydrogen bond networks in cellulose during the dissolution and regeneration processes. In this research, the regeneration mechanism of cellulose in water and ethanol is investigated through molecular dynamics simulations. The results indicate that the ability of water molecules to disrupt hydrogen bonds between cellulose and ionic liquids is stronger than that of ethanol, which is more conducive to promoting the regeneration of cellulose. Besides, the Fourier transform infrared spectroscopy coupled with two-dimensional correlation infrared spectroscopy techniques are employed to unveil the evolution sequence of hydrogen bonds during dissolution and regeneration: ν(OH) (absorbed water) â†’ ν(O3-H3···O5) (intrachain) â†’ ν(O6-H6···O3') (interchain) â†’ ν(O2-H2···O6) (intrachain) â†’ ν(OH) (free). This study not only enhances our understanding of the intricate hydrogen bond dynamics in cellulose dissolution and regeneration but also provides a foundation for the expanded application of cellulose in diverse fields.

Structure and properties variations of regenerated cellulose fibers induced by metal ion impurity.

In the ionic liquids (ILs) method for processing regenerated cellulose fiber (RCF), which is a high-performance ecologically benign product, metal ion impurities (such as Fe3+ and Cu2+) of cellulose might inevitably remain in the recycled ILs and coagulation bath. The presence of metal ions might negatively impact the properties of the manufactured RCFs and obstruct their applications, which are urgent to be made clear. For this research, the solvent for dissolving wood pulp cellulose (WPC) was 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP) with various metal ion concentrations. The effect of metal ions in IL on the dissolution of cellulose was investigated by Molecular Dynamics simulations. Rheological analysis and degree of polymerization (DP) analysis were adopted to evaluate the influence on fiber spinnability of different spinning solution metal ion concentrations and various dissolving times. Further, the morphology and mechanical performances of the RCFs variation regulation were also thoroughly researched. The findings showed that the presence of metal ions in the spinning solution affected the DP, crystallinity, and orientation factor of RCFs, which will influence their stress more sensitively than the strain. These findings can serve as a practical guide for the commercial manufacture of emerging fiber.

An efficient method for improving the stability of Monascus pigments using ionic gelation.

BACKGROUND: Monascus pigments (Mps) are easily impacted by heating, pH and light, resulting in degradation. In this study, Mps were encapsulated by the ionic gelation method with sodium alginate (SA) and sodium caseinate (SC), as well as CaCl2 as a crosslinker. The encapsulated Mps SA/SC in four proportions (SA/SC: 1/4, 2/3, 3/2, 4/1, w/w). Then, the encapsulation efficiency and particle size of the SA/SC-Mps system were evaluated to obtain the optimal embedding conditions. Finally, the effects of heating, pH, light and storage on the stability of non-capsulated Mps and encapsulated Mps were assessed. RESULTS: SA/SC = 2/3 (AC2) had higher encapsulation efficiency (74.30%) of Mps and relatively small particle size (2.02 mm). The AC2 gel beads were chosen for further investigating the stability of encapsulated Mps to heating, pH, light and storage. Heat stability experiments showed that the degradation of Mps followed first-order kinetics, and the encapsulated Mps had lower degradation rates than non-capsulated Mps. Encapsulation could reduce the effect of pH on Mps. The effects of ultraviolet light on the stability of Mps were considered, and showed that the retention efficiency of encapsulated Mps was 22.01% higher than that of non-capsulated Mps on the seventh day. Finally, storage stability was also evaluated under dark refrigerated conditions for 30 days, and the results indicated that encapsulation could reduce the degradation of Mps. CONCLUSION: This study has proved that AC2 gel beads can improve the stability of Mps. Thus, the ionic gelation method is a promising encapsulation method to improve the stability of Mps. © 2023 Society of Chemical Industry.

Effects of Glucose and Coagulant on the Structure and Properties of Regenerated Cellulose Fibers.

Regenerated cellulose fiber (RCF) is an environmentally friendly material with outstanding mechanical properties and recyclability, which has been used in a large number of applications. However, during the spinning process using ionic liquids (ILs) as solvents, the dissolved cellulose continues to degrade and even produces degradation products such as glucose, which can enter the recycled solvent and coagulation bath. The presence of glucose can seriously affect the performance of the produced RCFs and hinder their applications, so it has become critical to clarify the regulation and mechanism of this process. In this study, 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP) with different glucose contents was selected to dissolve wood pulp cellulose (WPC) and obtained RCFs in different coagulation baths. The effect of glucose content in spinning solution on fiber spinnability was investigated by rheological analysis, and the influence of coagulation bath composition and glucose content on the morphological characteristics and mechanical properties of the RCFs was also studied in depth. The results indicated that the morphology, crystallinity, and orientation factor of RCFs were influenced by the presence of glucose in the spinning solution or coagulation bath, resulting in corresponding changes in mechanical properties, which can provide practical reference and guidance for the industrial production of new type fiber.

Mechanical Properties and Mechanism Analysis of Graphite Tailings Environment-Friendly Concrete.

The development of tailings in concrete technology is not only conducive to the realization of the goal of reducing carbon emissions, but also conducive to the inhibition the occurrence of shortages of sand and gravel supplies. In this study, graphite tailings were used to replace sand in the range of 0~100%, and the mechanical mechanism of graphite tailings concrete was examined through compressive and flexural tests. The mechanical experimental results were evaluated and verified based on concrete macroscopic failure appearance, mesoscopic failure appearance, and physical characteristics of graphite tailings. The results revealed that the concrete strength increases first and then decreases with the increase of the graphite tailings content. Compared to GT00 (GT00 is a specimen with a graphite tailings content of 0%, and so on), GT10~GT60 exhibited better mechanical properties, of which 30% was recommended as the optimal replacement rate. The mechanical properties of GT10 and GT20 had an upward trend, and GT30 had low spalling, with aggregate fragmentation found on the fracture surface. GT30 showed the best resistance to bending and deformation. The mechanical properties of GT40~GT60 had a downward trend. When the graphite tailings content was higher than 70%, the interface defects of the aggregate matrix increased, thus making it easier for cracks to propagate along the interface. Furthermore, the mechanism of graphite tailings replacing sand verified the test results from different perspectives, which provides new analysis ideas for other tailings in environment-friendly concrete.

A Polydnavirus Protein Tyrosine Phosphatase Negatively Regulates the Host Phenoloxidase Pathway.

Polydnavirus (PDV) is a parasitic factor of endoparasitic wasps and contributes greatly to overcoming the immune response of parasitized hosts. Protein tyrosine phosphatases (PTPs) regulate a wide variety of biological processes at the post-transcriptional level in mammals, but knowledge of PDV PTP action during a parasitoid−host interaction is limited. In this study, we characterized a PTP gene, CvBV_12-6, derived from Cotesia vestalis bracovirus (CvBV), and explored its possible regulatory role in the immune response of the host Plutella xylostella. Our results from qPCR show that CvBV_12-6 was highly expressed in hemocytes at an early stage of parasitization. To explore CvBV_12-6 function, we specifically expressed CvBV_12-6 in Drosophila melanogaster hemocytes. The results show that Hml-Gal4 > CvBV_12-6 suppressed the phenoloxidase activity of hemolymph in D. melanogaster, but exerted no effect on the total count or the viability of the hemocytes. In addition, the Hml-Gal4 > CvBV_12-6 flies exhibited decreased antibacterial abilities against Staphylococcus aureus. Similarly, we found that CvBV_12-6 significantly suppressed the melanization of the host P. xylostella 24 h post parasitization and reduced the viability, but not the number, of hemocytes. In conclusion, CvBV_12-6 negatively regulated both cellular and humoral immunity in P. xylostella, and the related molecular mechanism may be universal to insects.

Synthesis of alkyl polyglycosides using SO3H-functionalized ionic liquids as catalysts.

An effective process for synthesis of alkyl polyglycosides (APG) was developed using SO3H-functionalized ionic liquids (SFILs) as catalysts. Four SFILs, [PSmim][HSO4], [PSmim][pTSA], [PSPy][HSO4] and [PSPy][pTSA], were designed and synthesized for APG synthesis. The results indicated that [PSmim][HSO4] shows the best catalytic performance among these four SFILs, which has a great agreement with the order of their acidities. When the [PSmim][HSO4] was used as catalyst, the reaction time could be decreased from 24 h to 8 h, and molar ration of n-octanol to glucose could be decreased from 5 : 1 to 3 : 1 under the optimization reaction conditions. In addition, the [PSmim][HSO4] could be easily regenerated and recycled at least 5 times with slight decrease in catalytic activity. Moreover, the catalytic mechanism of [PSmim][HSO4] was further investigated by molecular simulation. The high catalytic activity of [PSmim][HSO4] is attributed to hydrogen bonds between [PSmim][HSO4] and glucose and n-octanol, which could accelerate the protonation of glucose and removal of hydrogen ions from the hydroxyl in n-octanol.

A Mn-N3 single-atom catalyst embedded in graphitic carbon nitride for efficient CO2 electroreduction.

Developing effective catalysts based on earth abundant elements is critical for CO2 electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO (jCO) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N3 site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a jCO of 14.0 mA cm-2 at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher jCO of 29.7 mA cm-2 is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N3 site, which facilitates the formation of the key intermediate COOH* through a lowered free energy barrier.

Aromatic Ester-Functionalized Ionic Liquid for Highly Efficient CO2 Electrochemical Reduction to Oxalic Acid.

Electrochemical reduction of CO2 into valuable chemicals is a significant route to utilize CO2 resources. Among various electroreduction products, oxalic acid (H2 C2 O4 ) is an important chemical for pharmaceuticals, rare earth extraction, and metal processing. Here, an aprotic aromatic ester-functionalized ionic liquid (IL), 4-(methoxycarbonyl) phenol tetraethylammonium ([TEA][4-MF-PhO]), was designed as an electrolyte for CO2 electroreduction into oxalic acid. It exhibited a large oxalic acid partial current density of 9.03 mA cm-2 with a faradaic efficiency (FE) of 86 % at -2.6 V (vs. Ag/Ag+ ), and the oxalic acid formation rate was as high as 168.4 µmol cm-2 h-1 , which is the highest reported value to date. Moreover, the results of density functional theory calculations demonstrated that CO2 was efficiently activated to a -COOH intermediate by bis-active sites of the aromatic ester anion via the formation of a [4-MF-PhO-COOH]- adduct, which finally dimerized into oxalic acid.

Highly Selective Oxygen/Nitrogen Separation Membrane Engineered Using a Porphyrin-Based Oxygen Carrier.

Air separation is very important from the viewpoint of the economic and environmental advantages. In this work, defect-free facilitated transport membranes based on poly(amide-12-b-ethylene oxide) (Pebax-2533) and tetra(p-methoxylphenyl)porphyrin cobalt chloride (T(p-OCH3)PPCoCl) were fabricated in systematically varied compositions for O2/N2 separation. T(p-OCH3)PPCoCl was introduced as carriers that selectively and reversibly interacted with O2 and facilitated O2 transport in the membrane. The T(p-OCH3)PPCoCl had good compatibility with the Pebax-2533 via the hydrogen bond interaction and formed a uniform and thin selective layer on the substrate. The O2 separation performance of the thin film composite (TFC) membranes was improved by adding a small amount of the T(p-OCH3)PPCoCl and decreasing the feed pressure. At the pressure of 0.035 MPa, the O2 permeability and O2/N2 selectivity of the 0.6 wt % T(p-OCH3)PPCoCl/Pebax-2533 was more than 3.5 times that of the Pebax-2533 TFC membrane, which reached the 2008 Robeson upper bound. It provides a candidate membrane material for O2/N2 efficient separation in moderate conditions.

Functionalized ionic liquid membranes for CO2 separation.

It is imperative to develop efficient, reversible and economic technologies for separating CO2 which mainly comes from flue gas, natural gas and syngas. Membranes based on functionalized ionic liquids (ILs) have attracted much attention from researchers in recent years, and have been considered as a very promising technology. This feature article focuses on the research progress in CO2 separation using functionalized IL membranes. The recent advances in the preparation, separation performance, and separation mechanism of supported IL membranes (SILMs), pure poly(ionic liquid) (PIL) membranes, PIL-copolymer membranes, PIL-IL composite membranes and polymer-IL composite membranes for CO2 separation have been reviewed. In addition, the future directions and prospects for CO2 separation using functionalized IL membranes are given.

Insights into Carbon Dioxide Electroreduction in Ionic Liquids: Carbon Dioxide Activation and Selectivity Tailored by Ionic Microhabitat.

Electroreduction of carbon dioxide (CO2 ) into high value-added products is a potential solution to a reduction in CO2 levels and its utilization. One major challenge is the lack of an efficient system that can highly selectively reduce CO2 into desirable products with low energy consumption. Ionic liquids (ILs) have been used as electrolytes for the electroreduction of CO2 , and it has been proven that the CO2 -cation complex results in a low-energy pathway. In this work, an ionic microhabitat (IMH) has been built for CO2 electroreduction, and a novel anion-functionalized IL, 1-butyl-3-methylimidazolium 1,2,4triazolide ([Bmim][124Triz]), has been designed as the reaction medium. The results showed that the IMH played a key role in enhancing the performance of CO2 electroreduction, especially in dominating the product selectivity, which is recognized to be a great challenge in an electroreduction process. New insights into the role of the IMH in higher CO2 solubility, bending linear CO2 by forming the [124Triz]-CO2- adduct, and transferring activated CO2 into the cathode surface easily were revealed. The Faradaic efficiency for formic acid is as high as 95.2 %, with a current density reaching 24.5 mA cm-2 . This work provides a promising way for the design of robust and highly efficient ILs for CO2 electroreduction.

[Study on the pH-sensitive secondary structure of gamma-PGA embedded with magnetite nanoparticles].

The conformational transition of poly gamma-glutamic acid (gamma-PGA) embedded with magnetite nanoparticles under various pH conditions was investigated by Fourier transform infrared spectroscopy (FTIR). The secondary structure content was determined through the analysis of amide I bands of Fourier deconvolution spectra, secondary derivative spectra and the Gaussian curve fitting of the original infrared spectra. The results showed that the conformation of the gamma-PGA was affected by solution pH. The total contents of beta-sheet and beta-turn were higher than 65%, while alpha-helix and random coil were low. The content of beta-turn increased with increasing pH, while the beta-sheet decreased. Additionally, the zeta potential results showed that the pH-sensitive secondary structure of gamma-PGA had influence on the stability of suspension of magnetic gamma-PGA nanospheres. The minimum value of zeta potential (-35. 4 mV) was obtained at pH 10.2.

In situ magnetic separation and immobilization of dibenzothiophene-desulfurizing bacteria.

In situ cell separation and immobilization of bacterial cells for biodesulfurization were developed by using superparamagnetic Fe(3)O(4) nanoparticles (NPs). The Fe(3)O(4) NPs were synthesized by coprecipitation followed by modification with ammonium oleate. The surface-modified NPs were monodispersed and the particle size was about 13 nm with 50.8 emu/g saturation magnetization. After adding the magnetic fluids to the culture broth, Rhodococcus erythropolis LSSE8-1 cells were immobilized by adsorption and then separated with an externally magnetic field. The maximum amount of cell mass adsorbed was about 530 g dry cell weight/g particles to LSSE8-1 cells. Analysis showed that the nanoparticles were strongly absorbed to the surface and coated the cells. Compared to free cells, the coated cells not only had the same desulfurizing activity but could also be easily separated from fermentation broth by magnetic force. Based on the adsorption isotherms and Zeta potential analysis, it was believed that oleate-modified Fe(3)O(4) NPs adsorbed bacterial cells mainly because of the nano-size effect and hydrophobic interaction.