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ClpXP is a two-component mitochondrial matrix protease. The caseinolytic mitochondrial matrix peptidase chaperone subunit X (ClpX) recognizes and translocates protein substrates into the degradation chamber of the caseinolytic protease P (ClpP) for proteolysis. ClpXP degrades damaged respiratory chain proteins and is necessary for cancer cell survival. Despite the critical role of ClpXP in mitochondrial protein quality control, the specific degrons, or modifications that tag substrate proteins for degradation by human ClpXP, are still unknown. We demonstrated that phosphorylated serine (pSer) targets substrates to ClpX and facilitates their degradation by ClpXP in biochemical assays. In contrast, ClpP hyperactivated by the small-molecule drug ONC201 lost the preference for phosphorylated substrates. Hydrogen deuterium exchange mass spectrometry combined with biochemical assays showed that pSer binds the RKL loop of ClpX. ClpX variants with substitutions in the RKL loop failed to recognize phosphorylated substrates. In intact cells, ClpXP also preferentially degraded substrates with pSer. Moreover, ClpX substrates with the pSer were selectively found in aggregated mitochondrial proteins. Our work uncovers a mechanism for substrate recognition by ClpXP, with implications for targeting acute myeloid leukemia and other disorders involving ClpXP dysfunction., Competing Interests: Competing interests statement:A.D.S. has received research funding from Takeda Pharmaceuticals, BMS and Medivir AB, and consulting fees/honorarium from Takeda, Astra-Zeneca, BMS, and Novartis, Pharmaceuticals. A.D.S. is on the medical and scientific board of the Leukemia and Lymphoma Society of Canada. S.V. is the founder and Chief Scientific Officer of OncoMathica Inc. A.D.S. is named on a patent application for the use of DNT cells to treat AML.

Studying native protein structures at near-atomic resolution in a crowded environment presents challenges. Consequently, understanding the structural intricacies of proteins within pathologically affected tissues often relies on mass spectrometry and proteomic analysis. Here, we utilized cryoelectron microscopy (cryo-EM) and the Build and Retrieve (BaR) method to investigate protein complexes' structural characteristics such as post-translational modification, active site occupancy, and arrested conformational state in Alzheimer's disease (AD) using brain lysate from a rat model (TgF344-AD). Our findings reveal novel insights into the architecture of these complexes, corroborated through mass spectrometry analysis. Interestingly, it has been shown that the dysfunction of these protein complexes extends beyond AD, implicating them in cancer, as well as other neurodegenerative disorders such as Parkinson's disease, Huntington's disease, and schizophrenia. By elucidating these structural details, our work not only enhances our understanding of disease pathology but also suggests new avenues for future approaches in therapeutic intervention., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The enzyme complex KEOPS (Kinase, Endopeptidase and Other Proteins of Small size) installs the universally conserved and essential N 6 -threonylcarbamoyl adenosine modification (t 6 A) on ANN-decoding tRNAs in eukaryotes and in archaea. KEOPS consists of Cgi121, Kae1, Pcc1, Gon7 and the atypical kinase/ATPase Bud32. Except Gon7, all KEOPS subunits are needed for tRNA modification, and in humans, mutations in all five genes underlie the lethal genetic disease Galloway Mowat Syndrome (GAMOS). Kae1 catalyzes the modification of tRNA, but the specific contributions of Bud32 and the other subunits are less clear. Here we solved cryogenic electron microscopy structures of KEOPS with and without a tRNA substrate. We uncover distinct flexibility of KEOPS-bound tRNA revealing a conformational change that may enable its modification by Kae1. We further identified a contact between a flipped-out base of the tRNA and an arginine residue in C-terminal tail of Bud32 that correlates with the conformational change in the tRNA. We also uncover contact surfaces within the KEOPS-tRNA holo-enzyme substrate complex that are required for Bud32 ATPase regulation and t 6 A modification activity. Our findings uncover inner workings of KEOPS including a basis for substrate specificity and why Kae1 depends on all other subunits., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Metabolic dysfunction-associated steatohepatitis (MASH) has become the leading cause of chronic liver disease, but there has been no approved pharmacotherapy to date., Methods: We used a network analysis approach to delineate protein-protein interactions that contribute to the transition from steatosis to MASH, in order to identify and target this transition as a potential pharmacotherapeutic strategy. Acyl-CoA thioesterase 1 (ACOT1) was identified as a critical node in the protein-protein interaction (PPI) network of the transition from steatosis to MASH in patient samples. ACOT1 overexpression and silencing effects were tested in vivo on C57BL/6 mice exposed to high-fat diet (HFD) and inoculated with an adenoviral system to modulate ACOT1 expression. Transcriptomic and untargeted lipidomic profiles were performed on the mouse livers., Results: ACOT1 expression was 3-fold higher in MASH as compared to steatosis. In patient samples, ACOT1 was significantly correlated with the severity of MASH as reflected by the nonalcoholic fatty liver disease score. Experimental validation showed that downregulation of ACOT1 resulted in decreased lipid accumulation and prevention of MASH in vivo . Conversely, upregulation of ACOT1 via an adenoviral vector resulted in development of MASH, whereas control mice only developed steatosis. Lipidomic analysis revealed glycerophospholipids to be especially abundant in MASH accelerated by ACOT1 upregulation., Conclusion: These results suggest that ACOT1 contributes to the transition from steatosis to MASH through modulation of glycerophospholipid accumulation and its potential as a novel therapeutic target in MASH. This trial is registered with NCT02148471., Competing Interests: All authors declare no conflict of interest, financial or otherwise., (Copyright © 2024 Elisa Pasini et al.)

A combination of the dispersive liquid-liquid microextraction (DLLME) method based on the total vaporization procedure and cooling-assisted organic solvent-coated thin film microextraction (TFME) was applied for extracting chlorpyrifos (as the model compound). Based on the high thermal conductivity, a nickel foam thin film with the dimensions of 5.0 mm × 5.0 mm was used as a substrate for holding the organic solvent. Supporting thin film by organic solvent increases the thickness and contact area of the film relative to TFME or single drop microextraction (SDME) alone, resulting in a dramatic increase in the extraction efficiency. To protect the organic solvent and enhance the analyte distribution coefficient between the film and the vapor phase, a cooling system was applied. The proposed design was effective due to condensing the target analyte only on the uniform cooled thin film and not on the other regions in the extraction chamber. A corona discharge ionization source-ion mobility spectrometer was employed to identify the analyte. After optimizing the effective parameters, the limits of quantification (S/N = 10) and detection (S/N = 3) were calculated 0.1 and 0.03 μg L -1 , respectively, and the dynamic range was measured between 0.1 and 7.0 μg L -1 , with a determination coefficient of 0.9997. For three concentration levels of 0.1, 3.0, and 7.0 μg L -1 , the relative standard deviations (n = 3) as the repeatability index were to be 6 %, 5 %, and 4 % for intra-day and 9 %, 6 %, and 5 % for inter-day, respectively. The enrichment factor was also calculated to be 3630 for the analyte concentration of 1.0 μg L -1 . Well water, potato, and agricultural wastewater were analyzed as the real samples and the relative recovery values were measured between 92 % and 99 %. The accuracy of the proposed technique was validated by the European Standards EN 12393 method. In this approach, two steps of analyte extraction (DLLME and TFME) were used consecutively, resulting in better preconcentration and reduced matrix interference during cleaning-up., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

GCN2 is a stress response kinase that phosphorylates the translation initiation factor eIF2α to inhibit general protein synthesis when activated by uncharged tRNA and stalled ribosomes. The presence of a HisRS-like domain in GCN2, normally associated with tRNA aminoacylation, led to the hypothesis that eIF2α kinase activity is regulated by the direct binding of this domain to uncharged tRNA. Here we solved the structure of the HisRS-like domain in the context of full-length GCN2 by cryoEM. Structure and function analysis shows the HisRS-like domain of GCN2 has lost histidine and ATP binding but retains tRNA binding abilities. Hydrogen deuterium exchange mass spectrometry, site-directed mutagenesis and computational docking experiments support a tRNA binding model that is partially shifted from that employed by bona fide HisRS enzymes. These results demonstrate that the HisRS-like domain of GCN2 is a pseudoenzyme and advance our understanding of GCN2 regulation and function., Competing Interests: Declaration of interests F.S. is a founder and consultant of Repare Therapeutics and Induxion Therapeutics., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Heterotrimeric G proteins can be regulated by posttranslational modifications, including ubiquitylation. KCTD5, a pentameric substrate receptor protein consisting of an N-terminal BTB domain and a C-terminal domain, engages CUL3 to form the central scaffold of a cullin-RING E3 ligase complex (CRL3 KCTD5 ) that ubiquitylates Gβγ and reduces Gβγ protein levels in cells. The cryo-EM structure of a 5:5:5 KCTD5/CUL3 NTD /Gβ 1 γ 2 assembly reveals a highly dynamic complex with rotations of over 60° between the KCTD5 BTB /CUL3 NTD and KCTD5 CTD /Gβγ moieties of the structure. CRL3 KCTD5 engages the E3 ligase ARIH1 to ubiquitylate Gβγ in an E3-E3 superassembly, and extension of the structure to include full-length CUL3 with RBX1 and an ARIH1~ubiquitin conjugate reveals that some conformational states position the ARIH1~ubiquitin thioester bond to within 10 Å of lysine-23 of Gβ and likely represent priming complexes. Most previously described CRL/substrate structures have consisted of monovalent complexes and have involved flexible peptide substrates. The structure of the KCTD5/CUL3 NTD /Gβγ complex shows that the oligomerization of a substrate receptor can generate a polyvalent E3 ligase complex and that the internal dynamics of the substrate receptor can position a structured target for ubiquitylation in a CRL3 complex., Competing Interests: Competing interests statement:The authors declare no competing interest.

The world is confronting a severe water crisis. To clean up water from heavy metals, microorganisms, chemicals, and other types of pollutants, nanocomposites have been receiving great attention specifically due to the high surface area affording to work effectually even at low concentrations. In this research, we synthesized a new amino acid-modified MoS 2 nanocomposite by chemically immobilizing Mn (II). The synthesized absorbent MoS 2 -COOH/gly/Mn was identified by thermogravimetric analysis (TGA), nitrogen adsorption measurement, X-ray diffraction (XRD), analysis of energy dispersive X-ray mapping (EDAX and MAP), field emission scanning electron microscopy (FE-SEM), and Fourier Transform Infrared spectrometry (FT-IR). The nanocomposite was employed as an adsorbent through the solid phase microextraction (SPME) method while trifluralin herbicide was chosen as a model compound. For the monitoring of trifluralin molecules, we employed an ion mobility spectrometry apparatus featuring a corona discharge ionization source. The SPME method's effectiveness was examined by investigating the stirring rate and extraction time as two crucial parameters, aiming to achieve trace analysis of trifluralin. Under the optimized condition of the trifluralin extraction, the coefficient (R 2 ) and linear dynamic range (LDR) correlation were obtained at 0.9961 and 0.5-10 μg L -1 , respectively. Relative recovery values the described approach were obtained in the span of 96-97% for agricultural wastewater samples. The quantification (LOQ) and limit of detection (LOD) were calculated at 0.5 and 0.15 μg L -1 , respectively. The proposed nanocomposite absorbent has the capability to be applied as an efficient material for the extraction of trifluralin herbicide from different solutions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. As the authors of this article we hereby declare that have no financial and personal relationships with other people or organizations and there are no interests to declare. The disclosed information is correct and that no other situation of real, potential or apparent conflict of interest is known to me. We undertake to inform you of any change in these circumstances, including if an issue arises during the course of the meeting or work itself., (© 2024 The Authors.)

Acyl carrier protein (ACP) is the work horse of polyketide (PKS) and fatty acid synthases (FAS) and acts as a substrate shuttling domain in these mega enzymes. In fungi, FAS forms a 2.6 MDa symmetric assembly with six identical copies of FAS1 and FAS2 polypeptides. However, ACP spatial distribution is not restricted by symmetry owing to the long and flexible loops that tether the shuttling domain to its corresponding FAS2 polypeptide. This symmetry breaking has hampered experimental investigation of substrate shuttling route in fungal FAS. Here, we develop a protein engineering and expression method to isolate asymmetric fungal FAS proteins containing odd numbers of ACP domains. Electron cryomicroscopy (cryoEM) observation of the engineered complex reveals a non-uniform distribution of the substrate shuttling domain relative to its corresponding FAS2 polypeptide at 2.9 Å resolution. This work lays the methodological foundation for experimental study of ACP shuttling route in fungi., (© 2024. The Author(s).)

Rising drug resistance among pathogenic fungi, paired with a limited antifungal arsenal, poses an increasing threat to human health. To identify antifungal compounds, we screened the RIKEN natural product depository against representative isolates of four major human fungal pathogens. This screen identified NPD6433, a triazenyl indole with broad-spectrum activity against all screening strains, as well as the filamentous mold Aspergillus fumigatus. Mechanistic studies indicated that NPD6433 targets the enoyl reductase domain of fatty acid synthase 1 (Fas1), covalently inhibiting its flavin mononucleotide-dependent NADPH-oxidation activity and arresting essential fatty acid biosynthesis. Robust Fas1 inhibition kills Candida albicans, while sublethal inhibition impairs diverse virulence traits. At well-tolerated exposures, NPD6433 extended the lifespan of nematodes infected with azole-resistant C. albicans. Overall, identification of NPD6433 provides a tool with which to explore lipid homeostasis as a therapeutic target in pathogenic fungi and reveals a mechanism by which Fas1 function can be inhibited., Competing Interests: Declaration of interests L.E.C. and L.W. are co-founders and shareholders in Bright Angel Therapeutics, a platform company for development of novel antifungal therapeutics. L.E.C. is a Science Advisor for Kapoose Creek, a company that harnesses the therapeutic potential of fungi. S.C.L. is a principal scientist for Hexagon Bio, a biopharmaceutical company focused on developing targeted small molecule therapeutics., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Fatty acid synthase (FASN) catalyzes the de novo synthesis of palmitate, a 16-carbon chain fatty acid that is the primary precursor of lipid metabolism and an important intracellular signaling molecule. FASN is an attractive drug target in diabetes, cancer, fatty liver diseases, and viral infections. Here, we develop an engineered full-length human FASN (hFASN) that enables isolation of the condensing and modifying regions of the protein post-translation. The engineered protein enables electron cryo-microscopy (cryoEM) structure determination of the core modifying region of hFASN to 2.7 Å resolution. Examination of the dehydratase dimer within this region reveals that unlike its close homolog, porcine FASN, the catalytic cavity is close-ended and is accessible only through one opening in the vicinity of the active site. The core modifying region exhibits two major global conformational variabilities that describe long-range bending and twisting motions of the complex in solution. Finally, we solved the structure of this region bound to an anti-cancer drug, Denifanstat (i.e., TVB-2640), demonstrating the utility of our approach as a platform for structure guided design of future hFASN small molecule inhibitors., (© 2023. The Author(s).)

Sialic acids linked to glycoproteins and glycolipids are important mediators of cell and protein recognition events. These sugar residues are removed by neuraminidases (sialidases). Neuraminidase-1 (sialidase-1 or NEU1) is a ubiquitously expressed mammalian sialidase located in lysosomes and on the cell membrane. Because of its modulation of multiple signaling processes, it is a potential therapeutic target for cancers and immune disorders. Genetic defects in NEU1 or in its protective protein cathepsin A (PPCA, CTSA) cause the lysosomal storage diseases sialidosis and galactosialidosis. To further our understanding of this enzyme's function at the molecular level, we determined the three-dimensional structure of murine NEU1. The enzyme oligomerizes through two self-association interfaces and displays a wide substrate-binding cavity. A catalytic loop adopts an inactive conformation. We propose a mechanism of activation involving a conformational change in this loop upon binding to its protective protein. These findings may facilitate the development of selective inhibitor and agonist therapies.

Candida species are among the most prevalent causes of systemic fungal infection, posing a growing threat to public health. While Candida albicans is the most common etiological agent of systemic candidiasis, the frequency of infections caused by non -albicans Candida species is rising. Among these is Candida auris, which has emerged as a particular concern. Since its initial discovery in 2009, it has been identified worldwide and exhibits resistance to all three principal antifungal classes. Here, we endeavored to identify compounds with novel bioactivity against C. auris from the Medicines for Malaria Venture's Pathogen Box library. Of the five hits identified, the trisubstituted isoxazole MMV688766 emerged as the only compound displaying potent fungicidal activity against C. auris, as well as other evolutionarily divergent fungal pathogens. Chemogenomic profiling, as well as subsequent metabolomic and phenotypic analyses, revealed that MMV688766 disrupts cellular lipid homeostasis, driving a decrease in levels of early sphingolipid intermediates and fatty acids and a concomitant increase in lysophospholipids. Experimental evolution to further probe MMV688766's mode of action in the model fungus Saccharomyces cerevisiae revealed that loss of function of the transcriptional regulator HAL9 confers resistance to MMV688766, in part through the upregulation of the lipid-binding chaperone HSP12 , a response that appears to assist in tolerating MMV688766-induced stress. The novel mode of action we have uncovered for MMV688766 against drug-resistant fungal pathogens highlights the broad utility of targeting lipid homeostasis to disrupt fungal growth and how screening structurally-diverse chemical libraries can provide new insights into resistance-conferring stress responses of fungi. IMPORTANCE As widespread antimicrobial resistance threatens to propel the world into a postantibiotic era, there is a pressing need to identify mechanistically distinct antimicrobial agents. This is of particular concern when considering the limited arsenal of drugs available to treat fungal infections, coupled with the emergence of highly drug-resistant fungal pathogens, including Candida auris. In this work, we demonstrate that existing libraries of drug-like chemical matter can be rich resources for antifungal molecular scaffolds. We discovered that the small molecule MMV688766, from the Pathogen Box library, displays previously undescribed broad-spectrum fungicidal activity through perturbation of lipid homeostasis. Characterization of the mode of action of MMV688766 provided new insight into the protective mechanisms fungi use to cope with the disruption of lipid homeostasis. Our findings highlight that elucidating the genetic circuitry required to survive in the presence of cellular stress offers powerful insights into the biological pathways that govern this important phenotype.

In this work, dispersive liquid-liquid microextraction (DLLME) based on high-density extraction solvent was applied as a simple, fast and sensitive method for extraction and preconcentration of methamphetamine from human plasma and urine samples. The efficiency of positive corona discharge ionization ion mobility spectrometry was investigated for direct analysis of the extracted analyte. Effective parameters on the extraction efficiency, such as type and volume of the extraction and disperser solvents, centrifugation time, and sample solution pH were optimized. Trichloromethane and isopropanol were selected as the extracting and disperser solvents, respectively. Under the optimized conditions, the linear dynamic range (R 2  = 0.9969) was found to be 0.5-18 µg/L, and 0.15 µg/L was calculated as the limit of detection. The relative standard deviations of intra- and inter-day were obtained 4 and 10%, respectively, and finally, in the analysis of human plasma and urine samples, the extraction recovery was obtained 104%., (© 2022. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

In this paper, modified polyacrylonitrile/silica aerogel fibers were prepared and used as an adsorbent for thin-film microextraction of chlorpyrifos. The extracted analyte was analyzed by corona discharge ion mobility spectrometry. The electrospinning method was applied for the preparation of polyacrylonitrile fibers. The alkaline hydrolyzation technique was used to modify the electrospun film surface. Silica aerogel was synthesized on the surface of modified electrospun polyacrylonitrile fibers by the in situ growth technique. To access a high extraction yield, effective synthesis and extraction parameters such as NaOH concentration, reaction temperature and time, thin-film pretreatment, gelation time, solution pH, ionic strength, and extraction time were studied. The linearity range and the limit of detection of the method were 1-100 μg L -1 and 0.3 μg L -1 , respectively. The precision of the method was 4 and 12% for the concentration levels of 5 and 60 μg L -1 , respectively. Chlorpyrifos was successfully determined by the method in well water, river water, agricultural wastewater, and tangerine samples.

Viruses evade the innate immune response by suppressing the production or activity of cytokines such as type I interferons (IFNs). Here we report the discovery of a mechanism by which the SARS-CoV-2 virus coopts an intrinsic cellular machinery to suppress the production of the key immunostimulatory cytokine IFN-β. We reveal that the SARS-CoV-2 encoded nonstructural protein 2 (NSP2) directly interacts with the cellular GIGYF2 protein. This interaction enhances the binding of GIGYF2 to the mRNA cap-binding protein 4EHP, thereby repressing the translation of the Ifnb1 mRNA. Depletion of GIGYF2 or 4EHP significantly enhances IFN-β production, which inhibits SARS-CoV-2 replication. Our findings reveal a target for rescuing the antiviral innate immune response to SARS-CoV-2 and other RNA viruses.

Some alcoholic modifier gases were applied to separate isomer peaks in ion mobility spectrometry (IMS). Different mechanisms have been investigated on the separation, such as collision cross-section and analyte-modifier cluster formation. In this regard, some parameters that affected the cluster formation, such as dipole moment, electron affinity, the position of functional groups, and the modifier structure, were evaluated. On the other hand, some effective experimental parameters, including cell temperature and the flow rates of the drift and modifier gases, were also optimized. The combination of dispersive liquid-liquid microextraction with thin-film evaporation (DLLME-TFE) was used as a sample preparation method for the extraction of 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) isomers (as the target analytes). Isobutanol was selected as the alcoholic modifier to separate the ion molecular peaks of these isomers. The limit of detection and the limit of quantification obtained were 15 and 50 μg L -1 , and the linear dynamic range (50-700 μg L -1 ) with coefficient of determination of 0.9941 and 0.9914 were obtained for 2,4-DNT and 2,6-DNT, respectively. The intra- and inter-day relative standard deviations were obtained between 3% and 5%. For validation of the method, determination of the isomers was accomplished for a red wastewater field sample, resulting in relative recovery values of about 96%., (© 2022 John Wiley & Sons Ltd.)

Novel porous covalent organic framework (COF) based on condensation reaction between cyanuric chloride, 4,4'-ethylendianiline, and 3,4,9,10-perylenetetracarboxylic dianhydride was synthesized via sealed tube condition. The results COF was used as a new adsorbent for solid-phase microextraction (SPME) for extracting trifluralin and chlorpyrifos from vegetables, fruit samples, and wastewater. Gas chromatograph with a corona discharge-ion mobility spectrometer as the detector was also used for analyzing the target analytes. Some parameters that affected the extraction, such as stirring rate, time and temperature of extraction and pH were investigated, exhaustively. The detection limits were 0.13, and 0.15 µg/L and the linear ranges of 0.45-20 and 0.50-25 µg/L with a linearity coefficient of 0.9965 and 0.9987 were also obtained for trifluralin and chlorpyrifos, respectively. The method was applied successfully to analyze some real samples of cucumber, carrot, grape, and agriculture wastewater, and the results showed a relative recovery in the range of 87% to 110%., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In this paper, a helical copper wire, coated with copper-benzene-1,4-dicarboxylic acid metal-organic framework (Cu-BDC) was used as a sorbent for stir-bar sorptive extraction of fenthion from water and fruit samples. The homogenous coating was fabricated through two simple and fast steps. The chemical conversion of copper substrate to copper hydroxide nanotubes (Cu(OH) 2 NTs) was performed in an alkaline solution and then Cu-BDC was formed through a neutralization reaction. Corona discharge ion mobility spectrometry in positive mode was applied for the detection of fenthion. To improve the sensitivity of the method, some synthesis and extraction parameters affecting the extraction efficiency such as benzene-1,4-dicarboxylic acid concentration, ionic strength, sample pH, stirring rate, extraction temperature, and extraction time were investigated. The linear dynamic range between 0.5 and 80 μg L -1 and detection limit of 0.1 μg L -1 were obtained under optimal conditions. The intra- and inter-day relative standard deviations were less than 6.4 and 8.6%, respectively. The applicability of the method was examined for the analysis of different samples (i.e., well water, agricultural wastewater, and orange). The recovery for the determination of fenthion in spiked samples varied from 88 to 111%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier B.V.)

A mesh screen was electrochemically coated with polypyrrole and used as a sorptive extractor device, for the first time. This configuration acts in such a way that it is self-rotating in the presence of a magnetic force and can be used for extraction and concentration of analytes. Actually, applying a mesh screen instead of a bar or plate in sorptive extraction provided a more effective contact area between the sorptive materials and sample solution, resulting in higher sorption efficiency. The device performance was assessed by using chlorpyrifos pesticide as a model analyte. A thermal desorption unit was coupled to an ion mobility spectrometer and applied for evaporating the extracted analyte. Different parameters affecting the extraction efficiency during the electro-polymerization and the extraction process, including the time of electrodeposition, the concentration of pyrrole, oxalic acid and salt, temperature and time of extraction, and the stirring rate of the extractor device were investigated and optimized, simultaneously. The detection and quantification limits of the method were calculated to be 0.035 and 0.1 μg L -1 , respectively. The linear dynamic range obtained was from 0.1 to 20 μg L -1 , with a determination coefficient of 0.9984. The intra-day and inter-day-relative standard deviations (RSD, n = 3) were lower than 3% and 8%, respectively. Under the optimal conditions, the absolute recovery and the enrichment factor were found to be 97% and 5820, respectively. Finally, the relative recoveries of the proposed method were calculated to be in the range of 86-111% for spiked water, wastewater, and apple samples. The results obtained from the method were validated by EPA method 622.

Tuberous sclerosis protein complex (pTSC) nucleates a proteinaceous signaling hub that integrates information about the internal and external energy status of the cell in the regulation of growth and energy consumption. Biochemical and cryo-electron microscopy studies of recombinant pTSC have revealed its structure and stoichiometry and hinted at the possibility that the complex may form large oligomers. Here, we have partially purified endogenous pTSC from fasted mammalian brains of rat and pig by leveraging a recombinant antigen binding fragment (F ab ) specific for the TSC2 subunit of pTSC. We demonstrate F ab -dependent purification of pTSC from membrane-solubilized fractions of the brain homogenates. Negative stain electron microscopy of the samples purified from pig brain demonstrates rod-shaped protein particles with a width of 10 nm, a variable length as small as 40 nm, and a high degree of conformational flexibility. Larger filaments are evident with a similar 10 nm width and a ≤1 μm length in linear and weblike organizations prepared from pig brain. Immunogold labeling experiments demonstrate linear aggregates of pTSC purified from mammalian brains. These observations suggest polymerization of endogenous pTSC into filamentous superstructures.

The enzymes β-galactosidase (GLB1) and neuraminidase 1 (NEU1; sialidase 1) participate in the degradation of glycoproteins and glycolipids in the lysosome. To remain active and stable, they associate with PPCA [protective protein cathepsin A (CTSA)] into a high-molecular weight lysosomal multienzyme complex (LMC), of which several forms exist. Genetic defects in these three proteins cause the lysosomal storage diseases GM1-gangliosidosis/mucopolysaccharidosis IV type B, sialidosis, and galactosialidosis, respectively. To better understand the interactions between these enzymes, we determined the three-dimensional structure of the murine LMC core. This 0.8-MDa complex is composed of three GLB1 dimers and three CTSA dimers, adopting a triangular architecture maintained through six copies of a unique GLB1-CTSA polar interface. Mutations in this contact surface that occur in GM1-gangliosidosis prevent formation of the LMC in vitro. These findings may facilitate development of therapies for lysosomal storage disorders., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Fabricating suitable adsorbents with low-cost and high efficiency extraction for measurement of very small amounts of agricultural pesticides in food and water is playing a vital key role in personal and environmental health. Here, a new composite of zeolitic imidazolate framework-67@magnesium aluminate spinel (ZIF-67@MgAl 2 O 4 ) has been fabricated by a simple method at room temperature with different weight ratios. Several techniques such as FE-SEM, BET, XRD, and TGA have been used to confirm the structural characterization of the obtained materials. The obtained ZIF-67@MgAl 2 O 4 was utilized as an adsorbent in the solid phase microextraction technique to extract and preconcentrate the herbicide molinate (as an analyte) in aqueous solution. Corona discharge ionization-ion mobility spectrometry (CD-IMS) was applied for quantification of the analyte molecules. Extraction temperature, extraction time, stirring rate, and sample pH as the main parameters that affected the extraction proficiency were chosen and considered. Under optimal conditions, the linear dynamic range (LDR) of the various concentrations of the molinate and correlation coefficient were 10.0-100.0 μg L -1 and 0.9961, respectively. The limit of quantification (LOQ) and method detection limit (MDL) were 10.0 μg L -1 and 3.0 μg L -1 , respectively. The relative standard deviation (RSD) of the ZIF-67@MgAl 2 O 4 for extracting the molinate molecules (molinate concentration; 50 μg L -1 ) was calculated to be 4% and the enrichment factor (EF) was ∼5., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

A tandem microextraction method, centrifuge free dispersive liquid-liquid microextraction and thin-film microextraction (DLLME-TFME), was used for analyzing molinate in environmental samples by ion mobility spectrometry (IMS). Considering the IMS as a competitive detection system, coupling these two popular sample preparation methods reduces the effect of solvent interference and improves the sensitivity of the technique. Trichloromethane and methanol were used as the extraction, and dispersive solvents for the DLLME method and electrospun polyacrylonitrile/copper-benzene-1,4-dicarboxylic acid fibers were used as a sorbent in the TFME method. Some effective experimental variables influencing the extraction efficiency of an analyte such as type and volume of dispersive and extraction solvents, solution pH, ionic strength, sonication time, and extraction time were studied. The linear dynamic range of 0.5-50 μg L -1 and the limit of detection of 0.1 μg L -1 were obtained under optimized conditions. The relative standard deviations for intra-and inter-day analysis were calculated less than 10%. The present method was used for the determination of molinate in different real samples such as agricultural wastewater, well water, river water, and apple, and the recovery was obtained between 82% and 113%, for the spiked samples., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Co-MOF-based zeolitic imidazolate frameworks (ZIF-67) with various morphologies were prepared via an innovative way under distinct reaction conditions. By changing the reaction conditions, including the cobalt source, solvent, time, temperature, and linking agent to the cobalt ions, the morphological evolution of Co-MOF-based ZIF-67 was investigated. The Co-MOF-based ZIF-67 was applied as an adsorbent fiber in the solid-phase microextraction (SPME) technique for extracting a herbicide, namely molinate (as a test compound), in aqueous samples. For recognizing the molinate molecules, drift tube ion mobility spectrometry (IMS) was employed as a sensitive, rapid, and simple detection technique. Two essential parameters, namely extraction temperature and extraction time, influenced the extraction efficiency, and these parameters were also analyzed and optimized. The linear dynamic range (LDR) and the determination coefficient were found to be 0.5-20.0 μg L -1 and 0.9990, respectively. In this regard, the limit of quantification (LOQ) and the detection limit (LOD) were calculated and found to be 0.5 μg L -1 and 0.15 μg L -1 , respectively. Finally, the effect of the adsorbent with different morphologies on the extraction efficiency was compared., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

A novel covalent triazine-based framework (CTF)-grafted phenyl-functionalized fibrous silica nanosphere, KCC-1 (named as RS-2) was synthesized via a simple and effective Friedel-Crafts approach. The microporous CTF with fluorene backbone was coupled and grown uniformly on the surface of phenyl-functionalized KCC-1 to prepare a hybrid extended porous framework. The prepared materials were characterized, and FE-SEM and TEM images revealed a flower-like structure for RS-2. The synthesized RS-2 showed excellent thermal stability, so the weight loss was about 30% at 800 °C. RS-2 was applied as a new coating in the solid-phase microextraction procedure to extract chlorpyrifos and fenthion pesticides from water, wastewater, and fruit samples, before determining by corona discharge-ion mobility spectrometry. Some experimental factors affecting the extraction yield of the analytes, including ionic strength, stirring rate, sample pH, extraction temperature, and extraction time, were investigated. Under optimum conditions, the linear dynamic ranges were 0.1-10 μg L -1 and 1.0-70 μg L -1 , and the limits of detection were 0.05 and 0.55 μg L -1 for chlorpyrifos and fenthion, respectively. The proposed method showed recovery values in the range 86-117% with a precision of 3.0-7.1% for real samples. Covalent triazine-based framework (CTF)-grafted phenyl-functionalized fibrous silica nanosphere (named as RS-2) was synthesized. RS-2 was applied as a sorbent for solid-phase microextraction (SPME) of chlorpyrifos and fenthion from fruit and water samples followed by corona discharge ionization ion mobility spectrometry (CD-IMS).

The acyl carrier protein (ACP) domain shuttles substrates and reaction intermediates in type I fungal fatty acid synthases via transient protein-protein interactions. Here, using electron cryo-microscopy (cryoEM), we report the structure of a fungal FAS stalled at the dehydration reaction, which precedes the final enoyl reduction in the fatty acid biosynthesis cycle. This conformation revealed multiple contact sites between ACP and the dehydratase (DH) and enoyl reductase (ER) domains that occluded the ACP binding to the adjacent ER domain. Our data suggests a minimal path from the DH to the ER reaction site that requires minute changes in the coordinates of the structured N- and C- termini of the ACP domain.

A biomass-derived sponge-like carbonaceous aerogel was prepared through a two-step procedure, including hydrothermal carbonization and freeze-drying process. The aerogel was employed as the solvent holder for liquid-phase microextraction of organophosphorus pesticides, ethion, and chlorpyrifos (as the model compounds), prior to determination by secondary electrospray ionization-ion mobility spectrometry. The carbonaceous aerogel is an appropriate candidate to be used as the solvent holder due to some properties such as three-dimensional structure, porous nature, and very low density. So, the aerogel, including extraction solvent, can tumble on the top of the sample solution, without loss of solvent during its agitation. A comparison of the extraction efficiency was performed at similar conditions between the proposed method and single-drop microextraction, as well as hollow-fiber solvent bar microextraction. Different parameters affecting the extraction efficiency, such as stirring rate, salt concentration, temperature, and extraction time were investigated by using the response surface methodology. The linear dynamic range was in the ranges 1-30 and 1-70 μg L -1 with regression coefficients of 0.9973 and 0.9956 for ethion and chlorpyrifos, respectively. The limit of detection was 0.09 and 0.21 μg L -1 for ethion and chlorpyrifos, respectively. The method was used for extracting analytes from environmental water and vegetable samples, with the spiking recoveries in the range 80-121%. Graphical abstract Schematic representation of three-dimensional biomass-derived carbonaceous aerogel as the solvent holder in solvent bar microextraction (as a mode of the liquid-phase microextraction method). It was used for the extraction of two kinds of organophosphorus pesticides prior to the determination by ion mobility spectrometry.

Here, a three-dimensional reduced graphene oxide-polyaniline nanocomposite was synthesized and applied as a sorbent for solid-phase microextraction of ethion from water samples followed by negative corona discharge ionization ion mobility spectrometry. The nanocomposite was synthesized via a fast and facile two-step electrochemical method. The prepared sorbent was characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and thermogravimetric analysis. The main experimental parameters in the preparation of the fiber including concentration of graphene oxide, electrodeposition time, aniline concentration, and electropolymerization time were investigated. Also, parameters affecting the extraction process (i.e., salt addition, sample stirring rate, solution pH, extraction temperature and extraction time) were studied. Under the optimal conditions, the linearity and limit of detection were found to be 1.0-70 and 0.4 μg L -1 , respectively. The method presented good precision (intra-day and inter-day, n = 3), ranged from 1.7 to 4.7%. The analyte recovery obtained using spiked real water samples were in the range of 84-98%., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Propoxur insecticide as a thermally unstable compound (decomposed at its boiling point) could not be analyzed by traditional sample introduction systems based on the thermal desorption. In this study, an ultrasonic piezoelectric nebulizing injection port was applied for evaporating this compound prior to its determination by corona discharge ionization ion mobility spectrometry (CD-IMS). The target analyte was extracted from different water samples by using the extraction method of dispersive liquid-liquid microextraction. Methanol and trichloromethane were utilized as the disperser and extraction solvents, respectively. The effective variables included the volume of the disperser and the extraction solvents, the pH, and the centrifugation time were studied by a Fractional Factorial Design to identify the important parameter(s) and their interaction. To that end, a Central Composite Design was performed to achieve optimum levels of each effective parameter. The results showed that the optimum conditions were 78 μL of the extraction solvent, and 1.2 mL for the disperser solvent; centrifugation time was 1 min at 1010g, and finally pH 7. A detection limit of 2.1 μg L -1 , a linear range of 2.5 - 80 μg L -1 , and a relative standard deviation of 7% were obtained. Different water samples were analyzed by the proposed technique, and the propoxur amounts were successfully determined. The obtained results revealed satisfactory relative recovery values of between 91 and 105%.

During fatty acid biosynthesis, acyl carrier proteins (ACPs) from type I fungal fatty acid synthase (FAS) shuttle substrates and intermediates within a reaction chamber that hosts multiple spatially-fixed catalytic centers. A major challenge in understanding the mechanism of ACP-mediated substrate shuttling is experimental observation of its transient interaction landscape within the reaction chamber. Here, we have shown that ACP spatial distribution is sensitive to the presence of substrates in a catalytically inhibited state, which enables high-resolution investigation of the ACP-dependent conformational transitions within the enoyl reductase (ER) reaction site. In two fungal FASs with distinct ACP localization, the shuttling domain is targeted to the ketoacyl-synthase (KS) domain and away from other catalytic centers, such as acetyl-transferase (AT) and ER domains by steric blockage of the KS active site followed by addition of substrates. These studies strongly suggest that acylation of phosphopantetheine arm of ACP may be an integral part of the substrate shuttling mechanism in type I fungal FAS.

In this paper, a flexible and efficient nano-reinforced polymer inclusion membrane (PIM) was fabricated and used for cyanide (CN - ) extraction from water samples. Aliquat 336 (a liquid anion exchanger) was embedded in poly(vinyl chloride) (PVC) support as the extractant. Mg-Al-CO 3 layered double hydroxide (LDH) with high surface area and anion exchange ability was applied to promote the extraction efficiency of PIM. A PIM comprising 56% PVC, 40% Aliquat 336, and 4% Mg-Al-CO 3 LDH showed the best extraction efficiency. A single beam ultraviolet-visible spectrophotometer was used for the detection of cyanide. Surface morphology of the PIM was studied by field emission scanning electron microscopy. The experimental parameters influencing the extraction process were investigated and optimized. The intra- and inter-day relative standard deviations at two different concentrations were in the range of 2.8-7.6%. The dynamic range of the method was in the range of 5-500 μg L -1 , and the detection limit was 1.4 μg L -1 . The LDH reinforced PIM showed proper characteristics for the extraction of cyanide from real water and wastewater samples with recoveries between 82 and 115%.

Molecularly imprinted-electrospun nanofibers based on the use of poly(vinyl alcohol) were fabricated and used as a new sorbent for solid-phase microextraction of chlorpyrifos. The molecularly imprinted nanofibers were prepared by electrospinning and direct molecular imprinting of polymeric nanofibers. Poly(vinyl alcohol) was used as the functional and electrospun polymer. Chlorpyrifos was used as a template molecule, and glutaraldehyde as the cross-linker. Detection was performed by ion mobility spectrometry equipped with a secondary electrospray ionization source. The molecularly imprinted fiber has a selectivity and extraction efficiency better than the fiber fabricated using the conventional method of encapsulating MIP particles in electrospun nanofibers. Parameters affecting the extraction efficiency such as ionic strength, stirring rate, extraction time, and temperature were evaluated. The dynamic range of the method was in the range of 0.5-200 μg L -1 with the limit of detection of 0.1 μg L -1 . The intra- and inter-day relative standard deviations of the method were 4 and 9%, respectively. The fiber-to-fiber reproducibility for three different fibers is 5%. The spiking recoveries from spiked apple, cucumber, and water samples were in the range of 82-112%. Graphical abstract Molecularly imprinted-electrospun nanofibers were fabricated based on the direct molecular imprinting technique and used as a new SPME fiber coating for selective extraction of chlorpyrifos from fruits and water samples prior its determination by secondary electrospray ionization-ion mobility spectrometry.

A porous graphite sheet modified by a molecularly imprinted polymer (MIP) was directly used as the spray ionization source for ion mobility spectrometry (IMS). Therefore, it was possible to selectively analyze samples extracted by the molecularly imprinted polymer. This obviates the need for the steps of elution, solvent evaporation, dissolution and injection. To prepare the sheet, the graphite surface was first modified by electrodeposition of a molecularly imprinted polypyrrole film. This polypyrrole film was fabricated in a three-electrode electrochemical system using cyclic voltammetry. The electropolymerization of the graphite sheet was carried out with LiClO 4 as a supporting electrolyte in the reaction solution. The effects of the amount of monomer, the level of template concentrations, and the time of polymerization on the extraction efficiency of the MIP film were evaluated. The extraction conditions including extraction time, the extraction temperature, the pH values, the salt concentrations, and the stirring rate were also studied. Methanol was selected as the most suitable solvent for both desorption and ionization which occur simultaneously. The pesticide propoxur (acting as a test compound) was extracted from water samples and directly analyzed using IMS. The analytical parameters (working range: 1.0 to 250 ng·mL -1 ; detection limit: 0.3 ng·mL -1 ) indicated that the direct coupling of MIP and IMS has a great potential in terms of reproducibility, and speed of the analysis, while maintaining acceptable sensitivity. Graphical abstract Schematic presentation of molecularly imprinted graphite spray ionization coupled with ion mobility spectrometry (IMS) for rapid/selective extraction and ionization: Application to the pre-concentration of propoxur prior to its quantification by IMS.

Carbon sheets were attached to magnetite (Fe 3 O 4 ) nanoparticles. The resulting nanocomposite is shown to be a viable sorbent for use in magnetic dispersive solid-phase microextraction of three organophosphorus pesticides. The sorbent was synthesized via the sol-gel process followed by calcination and was characterized by an X-ray diffractometer, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and Raman spectrometry techniques. The affecting parameters in the adsorption and desorption steps were assessed and optimized via response surface methodology. Following desorption with dichloromethane, the OPPs were quantified by gas chromatography along with ion mobility spectrometry detection. Under optimized conditions, the limits of detection were 1.00, 0.46 and 0.85 μg L -1 for fenthion, malathion and chlorpyrifos, respectively. Response is linear in the concentration range of 2-500 μg L -1 for fenthion and malathion, and 2-1000 μg L -1 for chlorpyrifos with the determination coefficient larger than 0.9969. The intra-day and inter-day precision were from 3 to 9% and 5 to 16%, respectively. The enrichment factor was greater than 142 for all the studied pesticides. The sorbent was used for analyze spiked water and vegetable samples and gave relative recovery higher than 82%. Graphical abstract A flowchart of the synthesis of porous magnetized carbon sheet nanocomposites and the process of the magnetic dispersive solid-phase microextraction (MD-μ-SPE) of three organophosphorus pesticides prior to analysis by gas chromatography-ion mobility spectrometry (GC-IMS).

Thin film nanofibers containing ZnTiO 3 nanoparticles were used for rapid and efficient evaporation of solvents as used to extract analytes by dispersive liquid-liquid microextraction (DLLME). The method is referred to as thin film evaporation (TFE). A combination of DLLME and TFE was applied to the extraction and preconcentration of the pesticide chlorpyrifos (as a model compound) prior to analysis by ion mobility spectrometry. The ZnTiO 3 nanoparticles were placed on polyacrylonitrile nanofibers which increases the porosity and surface area in the TFE process, thus causing fast and complete evaporation of solvents. The effects of sample pH value, extraction solvent and its volume, disperser solvent and volume, centrifugation time, evaporation time, and desorption temperature were optimized. The relative standard deviations of intra- and inter-day analyses were found to be 3% and 7%, respectively. The method has a linear dynamic range that covers the 0.10-3.0 μg.L -1 chlorpyrifos concentration range, the limit of detection is 0.04 μg.L -1 , and the enrichment factor is up to 5400 in case of spiked samples. Some spiked field samples were analyzed and the relative recoveries ranged between 99 and 111%. When applied along with ion mobility spectrometry, the interferences caused by solvent are found to be reduced in the ionization source. This makes it possible to select a variety of solvents as needed for sample extraction. Graphical abstract Schematic presentation of dispersive liquid-liquid microextraction (DLLME) combined with thin film evaporation (TFE) for rapid vaporization of extraction solvent: Application to the pre-concentration of chlorpyrifos prior to its quantification by corona discharge-ion mobility spectrometry (CD-IMS).

This paper reports on a novel ultrasonic injection port designed and constructed to analyze thermally unstable chemical compounds using corona discharge ion mobility spectrometry (CD-IMS). In order to achieve the highest possible efficiency with the device, some parameters such as the solvent type, carrier gas flow rate and sample volume were exhaustively investigated. Through a comparative study conducted, it was revealed that unlike the thermal desorption system, the proposed ultrasonic injection port could easily be used for the analysis of some thermally unstable compounds such as carbaryl, propoxur and vitamin B 1 , by means of CD-IMS. To evaluate the potential of the device, carbaryl, extracted from different samples by dispersive liquid-liquid microextraction technique, was quantitatively analyzed. The CD-IMS-based results brought forth the detection limit of 0.03 mg L -1 , and dynamic range of 0.1-10.0 mg L -1 with the determination coefficient of 0.9981. The relative standard deviations for one day and three consecutive days were 4 and 6%, respectively. Further, the spiked samples of agricultural wastewater, underground water, and tomato analyzed culminated in the recovery values of 83%, 98% and 82%, respectively. The satisfactory results proved an acceptable capability of the sample introduction system, to be conveniently used for routine analysis of thermally unstable compound, without any tedious derivatization., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this work, a porous graphite sheet is introduced as the substrate in a spray ionization source for ion mobility spectrometry (PGSI-IMS) for the first time. This ionization source has some important advantages in comparison with the hollow needle, which is conventionally used in electrospray ionization. In order to prepare the hydrophilic surface needed to load samples on a graphite substrate, the graphite sheet was treated with hot sulfuric acid solution for 2 hours. Some parameters affecting the ionization efficiency were studied, and the optimized conditions were found to be 3.5-kV graphite voltage, 24-μL methanol flow rate, 500 mL min -1 the gas flow rate, and graphite sheet with a 60° tip angle and 3-mm distance from the counter electrode. Finally, analyses of some test compounds (imipramine, diclofenac, codeine, morphine, and ethion) were conducted to evaluate the capability of the new ionization source in the positive and negative modes. The satisfactory results proved the capability of the graphite sheet spray ionization, to be conveniently used for routine analysis of chemical compounds by IMS., (© 2018 John Wiley & Sons, Ltd.)

Carbon-silica hybrid nanofibers as high performance coatings for solid-phase microextraction fibers were used for analyzing some pesticides by using gas chromatography-corona discharge ion mobility spectrometry. To that end, the fibers were prepared by carbonizing sol-gel based on electrospun polyacrylonitrile and tetraethyl orthosilicate nanofibers as carbon and silica precursors, respectively. Different parameters affecting the electrospinning and the extraction processes including spinning distance, voltage, feeding rate, stirring rate, salt concentration, temperature and extraction time were optimized by response surface methodology. The method involved deionized water samples spiked with pesticides at different concentration levels. The calibration curves were linear in the ranges of 0.1-20 and 0.05-20 μg L -1 with determination coefficients (R 2 ) of 0.9976 and 0.9928 for malathion and chlorpyrifos, respectively. The limits of detection of 0.032 and 0.019 μg L -1 and the limits of quantification of 0.1 and 0.05 μg L -1 were found for malathion and chlorpyrifos, respectively. Acceptable reproducibility values were obtained with relative standard deviations (RSD, n = 3) lower than 6 and 15%, for intra-day and inter-day precision, respectively. Finally, the relative recoveries of the proposed method were calculated in the range of 80-111% for real samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, we developed zirconium dioxide-reduced graphene oxide nanocomposite (ZrO 2 -rGO), as a novel coating for stir bar sorptive extraction (SBSE), prior to analysis by negative corona discharge ion mobility spectrometry (NCD-IMS). Ethion was selected as a test compound to evaluate the method. A stir bar was coated with the ZrO 2 -rGO nanocomposite using the sol-gel technique. ZrO 2 has a high tendency towards the phosphonate group, hence its ability in absorbing ethion with high efficiency. On the other hand, graphene is a good sorbent for polar and semi-polar chemical compounds. Parameters affecting SBSE including extraction temperature, salt effect, stirring rate, desorption temperature, and extraction time were evaluated. The detection limit of this method for ethion was calculated to be 1.5 μg L -1 , and the good linear range of 5.0-200 μg L -1 was obtained. The inter-day and intra-day relative standard deviations were 9% and 6%, respectively. This method was used to determine ethion in spiked river water and agricultural wastewater samples, and the obtained spiking recoveries were in the range of 93-97%., (Copyright © 2018 Elsevier B.V. All rights reserved.)

An appropriate injection port was designed and constructed for direct analysis of stir-bar sorptive extractions using an ion mobility spectrometry (IMS). The novel design of the port offers great simplicity in use, high sensitivity, and high thermal and mechanical stability. The sol-gel technique was applied to prepare polydimethylsiloxane absorbent on a stir-bar. The parameters affecting extraction efficiency including stirring rate, extraction temperature, extraction time, salt addition and desorption temperature were optimized. The detection limit of the method was calculated to be 1.5μgL -1 , for diazinon, an organophosphorus pesticide selected as a test compound. The linear dynamic range was obtained to be 5.0-200.0μgL -1 with a determination coefficient of 0.9991 for the test compound. The intra- and inter-day relative standard deviations were calculated to be 4% and 5%, respectively. Agricultural wastewater, well water, and apple were selected as real samples. The detection limit was calculated to be 1.5μgL -1 and 7.5μgkg -1 for the real water samples and the apple sample, respectively. The recovery values (%) were 105 ± 6, 107 ± 3 and 96 ± 6 for the spiked agricultural wastewater, well water and apple samples, respectively. The results revealed that the injection port can be used for direct analysis of samples extracted by any sorbent support, without any further sample preparation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A cellulose paper was modified with an aptamer against methamphetamine on either carbon dots (CDs) or on multichannel carbon nanotubes (CNTs). The resulting sorbent was applied to the extraction of METH from blood or saliva. The METH-loaded paper than also was directly applied as a paper spray ionization source in ion mobility spectrometry. The carbon nanomaterial enhances sensitivity, and the aptamer enhances selectivity. The materials were covalently bound to the paper on one side, while the aptamer was immobilized on the other. After optimization of the extraction process and instrumental parameters, the limits of detection when using the aptamer-CNT modified paper are 0.6 ng·mL -1 for saliva, and 0.45 ng·mL -1 for plasma. The respective values when using aptamer-CD modified paper are 1.5 ng·mL -1 for saliva and 0.9 ng·mL -1 for plasma. Calibration plots are linear in the 2 to 150 ng·mL -1 METH concentration range for saliva, and in the 1.5 to 200 ng·mL -1 concentration ranges for blood when using the aptamer-CNT based method. When using the aptamer-CDs, the dynamic ranges extend from 5 to 200 ng·mL -1 and from 3 to 250 ng·mL -1 , respectively. The method was applied to the determination of METH in real samples of saliva and blood, and the accuracy of the method was confirmed by comparison of the results with data analyzed by GC-MS. Graphical abstract ᅟ.

Dual-template magnetic molecularly imprinted polymer nanoparticles were synthesized and used for the solid-phase extraction of acetaminophen and codeine before simultaneous determination by corona discharge ion mobility spectrometry. The magnetic molecularly imprinted polymer nanoparticles were prepared using silica-coated magnetic nanoparticles as supporters, acetaminophen and codeine as template molecules, 3-aminopropyltriethoxysilane and phenyltriethoxysilane as functional monomers, and tetraethoxysilane as a cross-linker. The obtained molecularly imprinted polymer was characterized by transmission electron microscopy, x-ray diffraction and Fourier-transform infrared spectroscopy. The adsorption performance of the imprinted polymers was studied by a series of experiments, indicating a satisfactory recognition ability of products for acetaminophen and codeine. The detection limits of 0.05 and 0.12 μg mL -1 , and the dynamic range of 0.20 - 2.0 and 0.40 - 3.0 μg mL -1 were achieved for acetaminophen and codeine, respectively. The proposed method was used for simultaneous determinations of acetaminophen and codeine in urine samples, and the corresponding recoveries were calculated in the range of 87 - 94%. These satisfactory results revealed the ability of the method for a routine analysis of acetaminophen and codeine, simultaneously.

In this work, the microextraction in packed syringe technique combined with corona discharge ion mobility spectrometry was used for determining diazinon in water samples. A new porous composite of nanoclay and polysiloxane was prepared using a sol-gel process. An amount of 2.0 mg of the sorbent was packed in a 250 μL syringe and used for extraction. A volume of 2 mL of the sample was passed through the sorbent bed, and the entrapped analyte was eluted by 25 μL of methanol. Important parameters influencing the extraction performance were investigated. Under optimum experimental conditions, the detection limit for diazinon was 0.07 ng/mL. The intra- and inter-day relative standard deviations were 5.0 and 12.3%, respectively. The calibration curve was linear in the concentration range from 0.2 to 20.0 ng/mL (r 2  = 0.999). The applicability of the method was demonstrated by analyzing spiked real water samples and the spiking recoveries were in the range of 95 to 106%., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

CD22 maintains a baseline level of B-cell inhibition to keep humoral immunity in check. As a B-cell-restricted antigen, CD22 is targeted in therapies against dysregulated B cells that cause autoimmune diseases and blood cancers. Here we report the crystal structure of human CD22 at 2.1 Å resolution, which reveals that specificity for α2-6 sialic acid ligands is dictated by a pre-formed β-hairpin as a unique mode of recognition across sialic acid-binding immunoglobulin-type lectins. The CD22 ectodomain adopts an extended conformation that facilitates concomitant CD22 nanocluster formation on B cells and binding to trans ligands to avert autoimmunity in mammals. We structurally delineate the CD22 site targeted by the therapeutic antibody epratuzumab at 3.1 Å resolution and determine a critical role for CD22 N-linked glycosylation in antibody engagement. Our studies provide molecular insights into mechanisms governing B-cell inhibition and valuable clues for the design of immune modulators in B-cell dysfunction.The B-cell-specific co-receptor CD22 is a therapeutic target for depleting dysregulated B cells. Here the authors structurally characterize the ectodomain of CD22 and present its crystal structure with the bound therapeutic antibody epratuzumab, which gives insights into the mechanism of inhibition of B-cell activation.

This paper introduces a novel approach to overcome the solvent interference in corona discharge-ion mobility spectrometry (CD-IMS) based on the time-resolved signals of the solvent and the analyte. To that end, a short Teflon tube was filled with a low amount of squalene or OV-1, which was prepared and located between the injection port and the entrance of the CD-IMS cell. Through this procedure, a sufficient delay (~5s) was obtained between the introduction of the solvent and the analyte into the reaction region of IMS. This resulted in removing the proton by solvent molecules, as well as increasing the effective collision during the analyte ionization, thereby providing an analysis with more sensitivity, accuracy, and precision. To show the column efficiency, ethion and diazinon (organophosphorus pesticides) were selected as the test compounds and their solutions were analyzed by the proposed method. The amount of sorbent, carrier gas flow rate, and the sorbent temperature affecting the sorbent efficiency were optimized by employing the response surface methodology and the central composite design. The proposed method was exhaustively validated in terms of sensitivity, linearity, and repeatability. In particular, the feasibility of direct injection was successfully verified by the satisfactory results, as compared with those achieved without the prior column. The methodology used in this study is very simple and inexpensive, which can overcome the solvent interference when a solution is directly injected into the CD-IMS., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Halloysite nanotubes were modified in three simple steps including etching, hydroxylation and amino grafting. The sol-gel technique was used for the chemical bonding of the modified halloysite nanotubes (MHNTs) to fused-silica support. The MHNTs, as a novel adsorbent was applied as a SPME coating. Diazinon, parathion and fenthion were selected as the model compounds to study the extraction efficiency of the coating. Gas chromatography-corona discharge ion mobility spectrometry was applied for the analysis of the extracted analytes. The parameters influencing the extraction efficiency of the method, such as stirring rate, salt effect, extraction temperature and time were optimized. The results showed that the MHNTs fiber had better extraction efficiency than the commercial SPME (PA, PDMS, and PDMS-DVB), bare silica, silica-based HNTs and HNTs-titanium dioxide fibers. The limits of detection were found to be in the range of 0.01-0.03 μg L -1 . The limits of quantification were in the range of 0.03-0.07 μg L -1 . Also, a good linearity in the range of 0.03-3.0, 0.07-2.0 and 0.03-3.0 μg L -1 , was found for diazinon, fenthion and parathion, respectively. The method precision was lower than 7.0 and 8.7% as the intra- and inter-day relative standard deviations, respectively. Agricultural wastewater, cucumber and apple were chosen as the real samples. The spiking recovery values were between 84 (±9) and 97% (±6). The results showed that the method was applicable and suitable for real samples analysis., (Copyright © 2017 Elsevier B.V. All rights reserved.)