Sulfate Ester Research Articles

Potential application of cellulose nanocrystals obtained from cultivated fibers in Amazon forest

The Amazon fibers, Jute (Corchorus capsularis L.) and Malva/Caesarweed (Urena lobata L.), obtained from Phoenix Amazon Project were scrutinized and the biomass components were quantified according to the TAPPI standards. The cellulose amount from jute and caesarweed was, respectively, around 49% and 41%. Scanning Electron Microscopy (SEM) analysis has evaluated the removal of lignin of the fiber through the micro holes located at holocellulose’s samples and the hemicellulose partial removal through the samples’ fibrillation at alphacellulose’s micrographs. The Fourier Transform Infrared spectroscopy (FTIR) results corroborated the delignification and hemicellulose removal through the alphacellulose obtention process. X-Ray Diffraction (XRD) patterns reiterate type I cellulose for the raw/holo samples, and type II cellulose for the bleached ones, with an increase of the crystallinity index from ~60% to ~85% for the samples. Thermogravimetry (TG) showed that the thermal stability of the samples increased until the bleaching process, and decreased after the cellulose nanocrystals (CNCs) extraction because of the ester sulphate groups insertion. The CNCs were successfully extracted, as can be seen on the Atomic Force Microscopy (AFM) images, and the aspect ratio and specific surface area calculated showed that these CNCs present some potential application in polymers matrices.

Phytochemistry Meets Geochemistry—Blumenol C Sulfate: A New Megastigmane Sulfate from Palicourea luxurians (Rubiaceae: Palicoureeae)

There is a previously neglected influence of geochemical conditions on plant phytochemistry. In particular, high concentrations of dissolved salts can affect their biosynthesis of natural products. Detoxification is most likely an important aspect for the plant, but additional natural products can also give it an expanded range of bioactivities. During the phytochemical analysis a Palicourea luxurians plant collected in a sulfate-rich environment (near the Río Sucio, Costa Rica) showed an interesting natural product in this regard. The structure of this compound was determined using spectroscopic and computational methods (NMR, MS, UV, IR, CD, optical rotation, quantum chemical calculations) and resulted in a megastigmane sulfate ester possessing a β-ionone core structure, namely blumenol C sulfate (1, C13H22O5S). The levels of sulfur and sulfate ions in the leaves of the plant were determined using elemental analysis and compared to the corresponding levels in comparable plant leaves from a less sulfate-rich environments. The analyses show the leaves from which we isolated blumenol C sulfate (1) to contain 35% more sulfur and 80% more sulfate than the other samples. Antimicrobial and antioxidant activities of compound 1 were tested against Escherichia coli, E. coli ampR and Bacillus subtilis as well as measured using complementary in vitro FRAP and ATBS assays, respectively. These bioactivities are comparable to those determined for structurally related megastigmanes. The sulfur and sulfate content of the plant leaves from the sulfate-rich environment was significantly higher than that of the other plants. Against this background of salt stress, we discuss a possible biosynthesis of blumenol C sulfate (1). Furthermore, there appears to be no benefit for the plant in terms of extended bioactivities. Hence, the formation of blumenol C sulfate (1) probably primarily serves the plant detoxification process.

G6PD promotes cell proliferation and dexamethasone resistance in multiple myeloma via increasing anti-oxidant production and activating Wnt/β-catenin pathway

BackgroundGlucose-6-phosphate dehydrogenase (G6PD) as the rate-limiting enzyme in the pentose phosphate pathway (PPP) is well-established as an aberrantly expressed protein in numerous clinical diseases; however, its role in cancer, specifically in multiple myeloma (MM) remains elusive.MethodsIn this study, serum metabolites in 70 normal people and 70 newly diagnosed MM patients were analyzed using untargeted metabolomics and the results were verified using ELISA. The survival analysis of multiple clinical datasets was performed to identify a potential target gene in MM. The oncogenic role of G6PD was investigated using lentivirus-based overexpression or knockdown of G6PD using RNAi or an inhibitor in vitro, and in a xenograft mouse model in vivo. The mechanisms of induced Dexamethasone (Dexa)-resistance of G6PD were further explored using the above established MM cell lines in vitro.ResultsBased on the screening of potential genes, PPP was shown to be involved in the occurrence of MM, which was evidenced by the differential expression of serum metabolites of G6P and Dehydroepiandrosterone sulfate (DHEAS, the more stable sulfate ester form of an endogenously uncompetitive G6PD inhibitor known as DHEA). Elevated G6PD promoted MM cell proliferation. Mechanistically, high G6PD expression enhanced enzymatic generation of the antioxidant NADPH via the PPP and decreased the production of reactive oxygen species (ROS), thus inducing the proliferation and Dexa resistance in MM cells. Furthermore, canonical Wnt/β-catenin signaling also participated in regulating G6PD-induced drug resistance and cellular redox levels of ROS. Intriguingly, DHEA treatment could enhance the sensitivity of MM cells to Dexa primarily through augmenting cellular oxidative stress.ConclusionsOur data demonstrate that G6PD enhances the generation of the enzymatic anti-oxidant NADPH and decreases ROS generation, thereby promoting resistance to Dexa-induced apoptosis via the enzymatic PPP and non-enzymatic Wnt/β-catenin signaling pathway in MM. Targeting G6PD to harness cellular redox may serve as a promising novel strategy for the management of MM.

Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry

Abstract. Aircraft-borne in situ measurements of the chemical aerosol composition were conducted in the Asian tropopause aerosol layer (ATAL) over the Indian subcontinent in the summer of 2017, covering particle sizes below ∼3 µm. We have implemented a recently developed aerosol mass spectrometer, which adopts the laser desorption technique as well as the thermal desorption method for quantitative bulk information (i.e., a modified Aerodyne AMS), aboard the high-altitude research aircraft M-55 Geophysica. The instrument was deployed in July and August 2017 during the StratoClim EU campaign (Stratospheric and upper tropospheric processes for better Climate predictions) over Nepal, India, Bangladesh, and the Bay of Bengal, covering altitudes up to 20 kma.s.l. For particles with diameters between 10 nm and ∼3 µm, the vertical profiles of aerosol number densities from the eight research flights show significant enhancements in the altitude range of the ATAL. We observed enhancements in the mass concentrations of particulate nitrate, ammonium, and organics in a similar altitude range between approximately 13 and 18 km (corresponding to 360 and 410 K potential temperature). By means of the two aerosol mass spectrometry techniques, we show that the particles in the ATAL mainly consist of ammonium nitrate (AN) and organics. The single-particle analysis from laser desorption and ionization mass spectrometry revealed that a significant particle fraction (up to 70 % of all analyzed particles by number) within the ATAL results from the conversion of inorganic and organic gas-phase precursors, rather than from the uplift of primary particles from below. This can be inferred from the fact that the majority of the particles encountered in the ATAL consisted solely of secondary substances, namely an internal mixture of nitrate, ammonium, sulfate, and organic matter. These particles are externally mixed with particles containing primary components as well. The single-particle analysis suggests that the organic matter within the ATAL and in the lower stratosphere (even above 420 K) can partly be identified as organosulfates (OS), in particular glycolic acid sulfate, which are known as components indicative for secondary organic aerosol (SOA) formation. Additionally, the secondary particles are smaller in size compared to those containing primary components (mainly potassium, metals, and elemental carbon). The analysis of particulate organics with the thermal desorption method shows that the degree of oxidation for particles observed in the ATAL is consistent with expectations about secondary organics that were subject to photochemical processing and aging. We found that organic aerosol was less oxidized in lower regions of the ATAL (<380 K) compared to higher altitudes (here 390–420 K). These results suggest that particles formed in the lower ATAL are uplifted by prevailing diabatic heating processes and thereby subject to extensive oxidative aging. Thus, our observations are consistent with the concept of precursor gases being emitted from regional ground sources, subjected to rapid convective uplift, and followed by secondary particle formation and growth in the upper troposphere within the confinement of the Asian monsoon anticyclone (AMA). As a consequence, the chemical composition of these particles largely differs from the aerosol in the lower stratospheric background and the Junge layer.

Effect of sodium alkyl sulfate chain length on foam stability: A molecular dynamics study

The alkyl chain length of surfactant plays an important role on its own performance. In this paper, the effect of sodium alkyl sulfate (SAS) with different alkyl chain lengths on the stability of foam film was studied by molecular dynamics (MD) method. The results showed that the increase of alkyl chain length enhances the interaction between SAS molecules, and increases the thickness of hydrated shell around the polar head. To investigate the effect of alkyl chain length on the drainage and rupture process of foam film, the steered molecular dynamics (SMD) study of foam liquid film with two external forces was also carried out. One external force is parallel to Z-axis and perpendicular to the liquid film, which can reflect the difficulty of foam drainage. The other is parallel to the horizontal direction of X-axis, which represents the stability of foam film. It was found that the longer the alkyl chain of SAS, the greater the external force required to destroy the foam surface. In addition, the free energy change profile of SAS from aqueous phase to SAS layer further indicates that the growth of alkyl chain can enhance the stability of foam film. This work aims to further understand the mechanism of foam film rupture and explore industrial methods to control foam stability.

Chemical characterization and biological activities of ulvan extracted from Ulva fasciata (Chlorophyta)

Ulvan is a sulfated heteropolysaccharide present in the cell wall of Ulva species with a unique structure and biological potential used in various fields. Chemical characterization was carried out to determine the structure of ulvan from Ulva fasciata Delile collected from Eastern Harbor, Alexandria coast, Egypt. Ulva contains 31.5% carbohydrate with a total ulvan content of 43.66% of total carbohydrate (13.75 g/100 g DW) and sulfate content of 20.45% of ulvan. FTIR spectrum presented signals of the sulfate ester (C–O–S) and sulfate groups (S=O), typical for ulvan. GC–MS revealed that ulvan was mainly composed of rhamnose and fucose. 1H-NMR spectra of ulvan showed identical behavior of monosaccharides nature with peaks characteristic of sulfated polysaccharides at 3.2–5.3 ppm region. Scanning electron micrographs (SEM) demonstrated amorphous architecture, and the sulfated nature of polysaccharides was emphasized by EDX analysis. The extracted ulvan showed significant antimicrobial activity against human and fish pathogens as well as antifouling bacteria with minimum inhibitory concentrations (MIC) of 8 µg/mL. The extracted ulvan exhibited potent antioxidant activity with a scavenging effect of 84.93% for 2,2-diphenyl-1-picrylhydrazy free radical (DPPH). Moreover, it showed anti-arthritic properties for the first time with a maximum inhibition of 86.04% with IC50 of 43.21%, indicating their potential value for the health and food industry.

Noble metal nanoparticles dispersed on nanocellulose: a green platform for catalytic organic transformations

In recent years, plant-derived biomaterials, typically cellulose, acting as catalytic supports have a great impact on heterogeneous catalysis thanks to their biodegradability, non-toxicity, low-cost, availability and easy-implementation. As the most abundant biopolymer found in nature, cellulose consists of repeating cellobiose units which are built up from two anhydroglucose rings and linked by a β-1,4 glycosidic bond. The term of “nanocellulose” has been widely used to describe cellulose nano-objects, involving cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs) and bacterial cellulose (BC). Nanocellulose features high specific surface area and controllable surface chemistry, high crystalline structure, superior mechanical strength and thermal stability, resulting in its applications in food, cosmetics, pharmaceutical, biomedical and paper industries. Concerning to catalytic support application, the nanocellulose surface possesses the hydroxyl (in nature) or the sulfate ester groups (modified via acid hydrolysis), facilitating metal ions reduction towards the corresponding metal nanoparticles. In addition, the supramolecular structure of cellulose permits to disperse metal nanoparticles and prevent their agglomerations. In this context, nanocellulose is introduced as matrices for immobilizing noble metal nanoparticles and then applied to catalytic organic transformations.

Shear exfoliated few-layer graphene and cellulose nanocrystal composite as biocompatible anode with efficient charge transfer

Electroconductive composites of graphene and cellulose nanocrystals (CNC) were prepared by direct exfoliation of natural flake graphite in CNC suspensions. Using the scalable high-shear exfoliation method, we show that the environmentally friendly CNC is an excellent graphene stabilizer as we prepared aqueous graphene-CNC dispersions with a high concentration (4.0 mg ml−1) and yield (4.0%) after only 2 h exfoliation time. With this fast and facile method, we exfoliated graphite using CNC with different amounts of negatively charged sulfate ester groups. We found that the graphene concentration is proportional to zeta potential of the CNC suspension suggesting that electrostatic repulsion plays a key role in graphene stabilization. Albeit the insulating nature of CNC, the spray-coated composite films were electrically conductive with conductivity up to 280 S m−1, depending on the CNC amount. Cyclic voltammetry measurements showed a reversible redox response for the Fe(CN)63-/4− couple proving that the electron transfer was efficient in the composite film. Furthermore, biocompatibility studies with photosynthetic microorganisms revealed no toxic effects as the cells maintained their photosynthetic performance and growth when placed in direct contact with the composite. The cytocompatibility, electroactivity and good water-stability make the composite film a promising anode for bioelectrochemical applications.

Transcription level and phylogeny analyses of Chlamydomonas reinhardtii arylsulfatases.

Sulfur is a required macroelement for all organisms, and sulfate deficiency causes growth and developmental defects. Arylsulfatases (ARS) hydrolyze sulfate from sulfate esters and make sulfate bioavailable for plant uptake. These enzymes are found in microorganisms and animals; however, plant genomes do not encode any ARS gene. Our database searches found nineteen ARS genes in the genome of Chlamydomonas reinhardtii. Among these, ARS1 and ARS2 were studied in the literature; however, the remaining seventeen gene models were not studied. Our results show that putative polypeptide sequences of the ARS gene models all have the sulfatase domain and sulfatase motifs found in known ARSs. Phylogenetic analyses show that C. reinhardtii proteins are in close branches with Volvox carterii proteins while they were clustered in a separate group from Homo sapiens and bacterial species (Pseudomonas aeruginosa and Rhodopirellula baltica SH1), except human Sulf1, Sulf2, and GNS are clustered with algal ARSs. RT-PCR analyses showed that transcription of ARS6, ARS7, ARS11, ARS12, ARS13, ARS17, and ARS19 increased under sulfate deficiency. However, this increase was not as high as the increase seen in ARS2. Since plant genomes do not encode any ARS gene, our results highlight the importance of microbial ARS genes.

OH Group Orientation Leads to Organosulfate Formation at the Liquid Aerosol Surface.

Organosulfates (OSs) are well-known and ubiquitous constituents of atmospheric aerosol particles and have been used as secondary organic aerosol markers in many field studies. Hence, it is imperative to understand the formation of OS species in the atmosphere. Recently, hydroxy acids (HAs) and hydroxy acid sulfates have been extensively detected in the atmospheric environment. However, the reaction mechanism of HAs to form OSs is much less understood. In this work, we have mainly investigated the reaction of typical α-HAs, including glycolic acid (GA) and lactic acid (LA), and SO3 at the liquid aerosol surface using quantum chemistry calculations and Born-Oppenheimer molecular dynamics simulations. The OH group orientation of α-HAs at the air-water interface is found to exert a significant impact on the formation of OSs. The OH group pointing to the gas phase is obviously beneficial to the formation of OSs. Two key factors are discovered important to the reaction of α-HAs adsorbed on the liquid surface with SO3: (a) the exposure position of the active site to the gas phase and (b) the reactivity of the exposed site to the attracted SO3 molecule. Moreover, we found that the air-water interface exerts a significant influence on the physicochemical behaviors of GA and LA, especially on their OH group orientation, and thus leads to their different properties for the SO3 colliding reaction. The presented reaction mechanism provides a new feasible pathway for the production of OSs at the liquid aerosol surface, which may have important impacts on the formation of organic aerosols.

Designer Cathode Additive for Stable Interphases on High-Energy Anodes.

Rechargeable lithium-based batteries built with high-energy anode materials (e.g., silicon-based and silicon-derivative materials) are considered a feasible solution to satisfy the stringent requirements imposed by emerging markets, including electric vehicles and grid storage, due to their higher energy density compared to contemporary lithium-ion batteries. The robustness of the solid electrolyte interphase (SEI) layer on high-energy anodes is critical to achieve long-term and stable cycling performances of the batteries. Herein, we propose a new type of designer cathode additive (DCA), i.e., an ultrathin coating layer of elemental sulfur on the cathode, for the in situ formation of a thin and robust SEI layer on various types of high-energy anodes. The DCA elemental sulfur undergoes simultaneous oxidation and reduction paths, forming lithium alkyl sulfate (R-OSO2OLi) and poly(ethylene oxide) (PEO)-like polymers on the anode surface. The as-formed R-OSO2OLi/PEO-modified SEI layer has good lithium cation (Li+) permeability to facilitate fast ion transportation across the interphases and superior elasticity to adapt to large volume changes, which is particularly effective for improving the cycling efficiency of high-energy anodes (e.g., ca. 14-35% increase in capacity retention for the silicon-carbon composite (SiC) or silicon-tin alloy (Si-Sn)||LiFePO4 cells). The present work opens a new avenue toward the practical deployment of high-energy rechargeable lithium-based batteries.

Affinity and putative entrance mechanisms of alkyl sulfates into the β-CD cavity

Cyclodextrins (CDs) are novel pharmaceutical excipients and are widely used in the pharmaceutical industry and drug delivery due to their ability to form host–guest complexes. There are countless structural features of guest molecules responsible for the efficiency of guest–CD interactions. Among these factors, the hydrophobic moieties of a guest and their size are commonly considered to govern its binding affinity to CD molecules. Experimentally, it is often challenging to extract structural and dynamic information at the atomic scale about CD inclusion complexes, especially in the aqueous phase. Therefore, this study consisted of experimental (isothermal titration calorimetry and conductometric titration) and in silico analysis to rigorously characterize the interactions of β -CD with three alkyl sulfates of different hydrophobic chain lengths: sodium dodecyl sulfate (S12S), sodium decyl sulfate (S10S) and sodium octyl sulfate (S8S) in aqueous solutions. We find that the hydrophobic interactions are not always a key factor leading to the formation of stable inclusion complexes. Our results demonstrate that van der Waals interactions contribute more to complexation efficiency for sulfates with a longer hydrophobic tail, whereas electrostatic interactions are more pronounced for sulfates with shorter ones. Furthermore, we propose and discuss for the first time the putative mechanisms of the guest entering the host cavity conditioned by the lengths of hydrocarbon chains of alkyl sulfates. Finally, we prove that different types of inclusion complexes can exist in a conformational equilibrium depending on the size of a guest tail.

Iota-carrageenan as sustainable bio-adsorbent for the removal of europium ions from aqueous solutions

The use of algae cell-wall polysaccharides to adsorb heavy metals from wastewaters has motivated a lot of work in the field. Though these molecules possess properties that seem to render them applicable as metal adsorbents, their full potential has yet to be realized. To that end, we developed a simple and straightforward technique to remove europium ions from aqueous solutions by using three representative polysaccharides: guar gum, xanthan gum and iota-carrageenan. The sorption yield increased in correlation with the acidity of the functional groups on these representative polysaccharides. A comparison of the Fourier-transform infrared spectra of the guar gum/xanthan gum/iota-carrageenan hydrogels formed following the europium adsorption to that of pristine polysaccharides indicated that they comprised different transmission bands, suggesting that europium ion adsorption occurs via interactions with the functional groups on the polysaccharides. Furthermore, scanning electron microscopy of iota-carrageenan hydrogel confirming that the europium was adsorbed to the iota-carrageenan and the europium:sulfur ratio of about 2.8:1 suggest that europium was linked to ~3 ester sulfate groups by inter/intramolecular forces via the oxygen atom. In addition, X-ray photoelectron analysis showed that the ratio of the peaks Eu+2/Eu+3in iota-carrageenan hydrogel were markedly intensified relative to its respective ratio in Eu(NO3)3⋅6 H2O.

Immunomodulatory Activity In Vitro and In Vivo of a Sulfated Polysaccharide with Novel Structure from the Green Alga Ulvaconglobata Kjellman

Algae accumulate large amounts of polysaccharides in their cell walls or intercellular regions. Polysaccharides from algae possess high potential as promising candidates for marine drug development. In this study, a sulfated polysaccharide, UCP, from the green alga Ulva conglobata Kjellman was obtained by water extraction, anion-exchange, and size-exclusion chromatography purification, and its structure was characterized by a combination of chemical and spectroscopic methods. UCP mainly consisted of →4)-α/β-l-Rhap-(1→, →4)-β-d-Xylp-(1→ and →4)-β-d-GlcAp-(1→ residues. Sulfate ester groups were substituted mainly at C-3 of →4)-l-Rhap-(1→ and C-2 of →4)-β-d-Xylp-(1→. Partial glycosylation was at C-2 of →4)-α-l-Rhap-(1→ residues. UCP possessed a potent immunomodulatory effect in vitro, evaluated by the assays of lymphocyte proliferation and macrophage phagocytosis. The immunomodulatory activity of UCP in vivo was further investigated using immunosuppressive mice induced by cyclophosphamide. The results showed that UCP markedly increased the spleen and thymus indexes and ameliorated the cyclophosphamide-induced damage to the spleen and thymus. UCP could increase the levels of white blood cells, lymphocytes, and platelets, and improve the hematopoietic inhibition caused by cyclophosphamide. Moreover, UCP significantly promoted the secretions of the immunoglobulin (Ig)G, IgE, and IgM. The data demonstrated that UCP is a novel sulfated polysaccharide and may be a promising immunomodulatory agent.

MALDI-TOF Mass Spectrometric Detection of SARS-CoV-2 Using Cellulose Sulfate Ester Enrichment and Hot Acid Treatment.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the ongoing coronavirus disease 2019 (COVID-19) pandemic. Here we report a novel strategy for the rapid detection of SARS-CoV-2 based on an enrichment approach exploiting the affinity between the virus and cellulose sulfate ester functional groups, hot acid hydrolysis, and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Virus samples were enriched using cellulose sulfate ester microcolumns. Virus peptides were prepared using the hot acid aspartate-selective hydrolysis and characterized by MALDI-TOF MS. Collected spectra were processed with a peptide fingerprint algorithm, and searching parameters were optimized for the detection of SARS-CoV-2. These peptides provide high sequence coverage for nucleocapsid (N protein) and allow confident identification of SARS-CoV-2. Peptide markers contributing to the detection were rigorously identified using bottom-up proteomics. The approach demonstrated in this study holds the potential for developing a rapid assay for COVID-19 diagnosis and detecting virus variants from a variety of sources, such as sewage and nasal swabs.

Two Laminaria japonica polysaccharides with distinct structure characterization affect gut microbiota and metabolites in hyperlipidemic mice differently

Our previous study found dietary mannogluconic acid (MA) and fucogalactan sulfate (FS) from Laminaria japonica have distinct structure characterization and potential hypolipidemic effects in vitro. Herein, we compared the benefits of MA and FS on hyperlipidemia. The result showed only FS treatment decreased body weight and serum cholesterol levels. Compared with MA, FS was more effective in mitigating hepatic fat accumulation, promoting GSH-Px activity, reducing the MDA formation, and lowering the level of TNF-α in liver. Gut microbiota and metabolism analysis revealed that FS increased the relative abundance of beneficial bacteria and boosted the level of short chain fatty acids. Particularly, taurine and 3α,7α,12α-trihydroxy-24-oxo-5-β-cholestanoyl CoA were upregulated by FS, which might attribute to the increased Oscillibacter and thus affect the enterohepatic circulation of bile acids and serum TC level. Therefore, FS with more branches and sulfate ester groups could be a good lipid-lowering dietary supplement.

Sulfated glycan recognition by carbohydrate sulfatases of the human gut microbiota.

Sulfated glycans are ubiquitous nutrient sources for microbial communities that have co-evolved with eukaryotic hosts. Bacteria metabolise sulfated glycans by deploying carbohydrate sulfatases that remove sulfate esters. Despite the biological importance of sulfatases, the mechanisms underlying their ability to recognise their glycan substrate remain poorly understood. Here, we utilise structural biology to determine how sulfatases from the human gut microbiota recognise sulfated glycans. We reveal 7 new carbohydrate sulfatase structures span four S1 sulfatase subfamilies. Structures of S1_16 and S1_46 represent the first structures of these subfamilies. Structures of S1_11 and S1_15 demonstrate how non-conserved regions of the protein drive specificity towards related but distinct glycan targets. Collectively, these data reveal that carbohydrate sulfatases are highly selective for the glycan component of their substrate. These data provide new approaches for probing sulfated glycan metabolism, whilst revealing the roles carbohydrate sulfatases play in host-glycan catabolism.

Nature-derived highly tribopositive ϰ-carrageenan-agar composite-based fully biodegradable triboelectric nanogenerators

Biodegradable triboelectric nanogenerators (TENGs) have been studied for powering biotransient electronics in past years. For stable powering, developing biodegradable materials which have high tribopositive properties as well as high biocompatibility is crucially required. Here, we investigate a nature-derived ϰ-carrageenan-agar (ϰC-Agar) composite as high-performing triboelectric friction material for biodegradable TENG. We found that the composite shows greatly enhanced electron-donating property. At an optimized ϰC concentration of 80 wt%, the surface potential at most 57.5% increases compared to bare materials. We validated that the enhancement was caused by increased charge trapping sites consisting of Ca2+ cations and sulfate ester groups in the composite. In addition, we found that the ϰC-Agar composite has high intrinsic biocompatibility as it shows high cell viability in MTT assay and subdermal implant causes little noticeable inflammation, contributed by the high hydrophilicity of the composite. We further demonstrate a fully biodegradable TENG using an optimized ϰC-Agar composite. Very thin (0.3 mm) and flexible our device generates high output root-mean-square (RMS) current of 0.45 mA·m−2 and output RMS power of 0.15 mW·m−2 at optimized impedance. Our work provides a basis for the development of high-performance biodegradable TENGs for self-powered transient electronics.

The influence of alkyl substitution on the in vitro metabolism and mutagenicity of benzo[a]pyrene

In recent years concerns over consumer exposure to mineral oil aromatic hydrocarbons (MOAH), especially those containing alkylated polycyclic aromatic hydrocarbons (PAHs), have emerged. This is especially due to the fact that some PAHs are known to be genotoxic and carcinogenic upon metabolic activation. However, available toxicological data on PAHs mainly relate to non-substituted PAHs with limited data on alkyl substituted PAHs. Therefore, the aim of the present study was to characterize in more detail the effect of alkyl substitution on the metabolism and mutagenicity of benzo[a]pyrene (B[a]P), a PAH known to be genotoxic and carcinogenic. To this end, the oxidative metabolism and mutagenicity of B[a]P and a series of its alkyl substituted analogues were quantified using in vitro microsomal incubations and the Ames test. The results obtained reveal that upon alkylation the metabolic oxidation shifts to the aliphatic side chain at the expense of aromatic ring oxidation. The overall metabolism, including metabolism via aromatic ring oxidation resulting potentially in bioactivation, was substantially reduced with elongation of the alkyl side chain, with metabolism of B[a]P with an alkyl substituent of >6 C atoms being seriously hampered. In the Ames test upon metabolic activation, the methyl substitution of B[a]P resulted in an increase or decrease of the mutagenic potency depending on the substitution position. The relevant pathways for mutagenicity of the selected monomethyl substituted B[a]P may involve the formation of a 7,8-dihydrodiol-9,10-epoxide, a 4,5-oxide and/or a benzylic alcohol as an oxidative side chain metabolite which subsequently may give rise to an unstable and reactive sulfate ester conjugate. It is concluded that alkylation of B[a]P does not systematically reduce its mutagenicity in spite of the metabolic shift from aromatic to side chain oxidation.

Influence of organic and inorganic precipitators on the efficiency of surfactants extraction from wastewater by flotation

The chemical structure of surfactants causes their accumulation on the surface of water sources and leads to the formation of stable foam, which prevents the access of oxygen to the water and leads to the death of hydrobionts and deterioration in water quality. Therefore, the extraction of surfactants from wastewater is an urgent task. Increase the efficiency of flotation extraction of cationic surfactants, namely hexadecyl pyridinium chloride [C 16 H 33 NC 5 H 5]Cl (CHDP) and surfactants based on it - cetazol, by introducing organic – (sodium alkyl sulfate (SAS), CnH 2n+1 OSO 3 Na, n=10-16), and inorganic - potassium hexacyanoferrate (II, III) precipitators. The solubility of the products of interaction of cationic surfactants with SAS (sublates) was determined, which are extracted from solutions at different temperatures and impurities of electrolytes. The Gibbs free energy (), enthalpy (), and entropy (), which take place in the process of dissolution, are calculated. The low value of the heat of dissolution (2.1-16.6 kJ/mol) indicates a small effect of temperature on the solubility of sublates. The thermodynamic analysis of the process of formation of sublates allows determining the optimal length of the hydrocarbon radical of the precipitator. It is established that the extraction of the studied cationic surfactants should be extracted from water solutions and wastewater by the method of precipitation flotation using organic and inorganic precipitators. The presence of electrolytes and an increase in temperature leads to an increase in the degree of extraction hexadecyl pyridinium alkyl sulphonates sublates.