Mass Spectra Research Articles

Studying the Ξ(2030) as a predominantly K¯*Σ molecular state

Since its discovery in 1977, the spin parity of Ξ(2030) has not been fully determined experimentally. The latest Particle Data Group listing suggests it may be a baryon with J=5/2. Therefore, studying the mass spectrum and decay properties of Ξ(2030) has become a current hot topic to definitively establish its spin parity. As the three-quark model fails to explain Ξ(2030), we previously proposed it may be a molecule primarily composed of K¯*Σ with JP=5/2+, based on its mass spectrum study. To verify its molecular state interpretation, this work proposes studying the strong decays of Ξ(2030) assuming it is a P-wave JP=5/2+ meson-baryon molecule predominantly composed of K¯*Σ. We calculated all experimentally measured two-body and three-body final state decay widths of Ξ(2030), including Ξ(2030)→K¯Λ,K¯Σ,πΞ,πΞ*, and Ξ(2030)→ππΞ,πK¯Σ,πK¯Λ. The results indicate that both the total decay width and partial decay widths agree well with experimental values within the error margins. This supports that Ξ(2030) is a molecule with spin-parity JP=5/2+, predominantly composed of K¯*Σ. Compared to the experimental central values, our results are slightly smaller, which suggests that Ξ(2030) may contain additional components besides meson-baryon molecular components, such as three-quark structures. Published by the American Physical Society 2024

An Automated Analysis of Homocoupling Defects Using MALDI-MS and Open-Source Computer Software.

Conjugated organic polymers have substantial potential for multiple applications but their properties are strongly influenced by structural defects such as homocoupling of monomer units and unexpected end-groups. Detecting and/or quantifying these defects requires complex experimental techniques, which hinder the optimization of synthesis protocols and fundamental studies on the influence of structural defects. Mass spectrometry offers a simple way to detect these defects but a manual analysis of many complex spectra is tedious and provides only approximate results. In this work, we develop a computational methodology for analyzing complex mass spectra of organic copolymers. Our method annotates spectra similarly to a human expert and provides quantitative information about the proportions of signal assigned to each ion. Our method is based on the open-source Masserstein algorithm, which we modify to handle large libraries of reference spectra required for annotating complex mass spectra of polymers. We develop a statistical methodology to analyze the quantitative annotations and compare the statistical distributions of structural defects in polymer chains between samples. We apply this methodology to analyze commercial and lab-made samples of a benchmark polymer and show that the samples differ both in the amount and in the types of structural defects.

Preparation, Characterization, In Vitro Biological Evaluation, DFT Calculations, and Molecular Docking Investigations of 1H-Imidazole-2-Carboxylic acid and Histidine-Based Mixed-Ligand Complexes.

Mixed-ligand complexes incorporating 1H-Imidazole-2-Carboxylic acid (IMCA) and Histidine (LHIS) show promise for biomedical and biotechnological applications. This study synthesizes and characterizes FeIMCALHIS, CoIMCALHIS, and NiIMCALHIS coordination compounds using metal chloride salts (FeCl3.6H2O, CoCl2.6H2O, NiCl2.6H2O) in ethanolic solutions. The complexes are characterized by spectroscopic methods (IR, UV-vis, and mass spectra), elemental analysis, conductivity, magnetic, and thermal analysis. Molar conductivity indicates their non-electrolytic nature. UV-vis spectra reveal absorption bands with pathochromic shifts, and electronic spectra show characteristic metal-ligand transitions, indicating their structural configuration and coordination geometry. 3D geometry optimization shows six-coordination around Fe(III) and Co(II) in FeIMCALHIS and CoIMCALHIS, and four-coordination around Ni(II) in NiIMCALHIS. Analysis of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) suggests decreased electron donation ability upon coordination. Electronic structure parameters (HOMO, LUMO, ionization potential, energy gap, electron affinity, chemical potentials, and electronegativity) provide further insights into stability and reactivity. The metal complexes exhibit enhanced antimicrobial, antioxidant, and anti-inflammatory activity compared to individual ligands, with FeIMCALHIS showing notable antimicrobial activity. Molecular docking analysis reveals strong binding interactions with target proteins, highlighting their potential therapeutic applications.

Synthesis and evaluation of in vitro antioxidant, anticancer, and antibacterial properties of new benzylideneiminophenylthiazole analogues

A series of new benzylideneiminophenylthiazole analogues were designed and synthesized. Common spectroscopic methods, such as FT-IR, 1H-, 13C-NMR, and MASS spectra, and elemental analysis, were used to confirm the molecular structures. Then, the antioxidant, cytotoxicity, and anti-bacterial effects of synthesized analogues were assessed against 2,2-diphenyl-1-picrylhydrazyl (DPPH), three cancer cell lines, and two bacterial strains, respectively. Among the analogues, 7f was detected as the most potent compound for antioxidant activity. Moreover, the compounds 7b, 7f, and 7 g exhibited the maximum cytotoxicity activity against MCF-7, HepG-2, and A549 cell lines, respectively. Finally, 7e showed the highest anti-bacterial activity against both S. aureus and E. coli strains. It was concluded from the antioxidant, cytotoxicity, and anti-bacterial effects that the benzylideneiminophenylthiazoles might serve as candidate molecules for the development of small molecules with medicinal potential.

Towards a universal method for middle-down analysis of antibodies via proton transfer charge reduction-Orbitrap mass spectrometry.

Modern mass spectrometry technology allows for extensive sequencing of the ~ 25kDa subunits of monoclonal antibodies (mAbs) produced by IdeS proteolysis followed by disulfide bond reduction, an approach known as middle-down mass spectrometry (MD MS). However, the spectral congestion of tandem mass spectra of large polypeptides dramatically complicates fragment ion assignment. Here, we report the development and benchmark of an MD MS strategy based on the combination of different ion fragmentation techniques with proton transfer charge reduction (PTCR) to simplify the gas-phase sequencing of mAb subunits. Applied on the liquid chromatography time scale using an Orbitrap Tribrid mass spectrometer, PTCR produces easy-to-interpret mass spectra with limited ion signal overlap. We demonstrate that the accurate estimation of the number of charges submitted to the Orbitrap mass analyzer after PTCR allows for the detection of charge-reduced product ions over a wide mass-over-charge (m/z) window with low parts per million m/z accuracy. Therefore, PTCR-based MD MS analysis increases not only sequence coverage, number of uniquely identified fragments, and number of assigned complementary ion pairs, but also the general confidence in the assignment of subunit fragments. This data acquisition method can be readily applied to any class of mAbs without an apparent need for optimization, and benefits from the high resolving power of the Orbitrap mass analyzer to return sequence coverage of individual subunits exceeding 80% in a single run, and > 90% when just two experiments are combined.

Exploring the Potential of Novel 4-Thiazolidinone Derivatives as Dual Anti-inflammatory and Antioxidant Agents: Synthesis, Pharmacological Activity and Docking Analysis

A series of 4-thiazolidinone was synthesized and characterized by means of TLC, melting point, and spectral data like IR, 1H NMR, and Mass spectra. The anti-inflammatory activity of the synthesized compounds was determined via in vivo studies. The antioxidant properties of the synthesized compounds were determined by carrageenan-induced rat paw edema model. The synthesized compounds (A1-A14) showed significant anti-inflammatory and antioxidant activities. The most promising results for both antioxidant and antiinflammatory activity were exhibited by compound A8 which may emerge as a potent anti-inflammatory agent with potential free radical scavenging activity. Molecular docking studies were carried out to determine the interaction of compounds into the active site of COX-2 inhibitor (PDB ID: 3LN1), which suggested compound A8 to have the best docking score by showing interactions with ASP483 and LYS478.

Impact of smoking habit on the subgingival proteome in patients with periodontitis.

Few investigations evaluated smoking's impact on the periodontal proteome. Therefore, this study aimed to analyse the influence of tobacco on the overall periodontal proteome and the differential expression of gingival crevicular fluid (GCF) proteins using sequential window acquisition of all theoretical mass spectra (SWATH-MS). GCF samples were collected from 40 periodontitis subjects (stages III-IV). These were separated based on smoking status into smokers (17), ex-smokers (10), and non-smokers (13). Samples were analysed using SWATH-MS, and proteins were identified using the UniProt human-specific database. Data are available via ProteomeXchange with the identifier PXD043474. Principal component analysis (PCA) was employed to examine the spectral mass distribution of the proteome. Protein expression was different for a p-value<0.05 and a log2 fold change ≥0.3 (upregulated) or ≤-0.3 (downregulated). The distribution of overall proteome did not differ between non-smokers, smokers, and ex-smokers. Considering protein expression, 23 were differentially expressed in smokers vs. non-smokers (16 upregulated and 7 downregulated), 17 in ex-smokers vs. non-smokers (2 upregulated and 15 downregulated), and only 8 in smokers vs. ex-smokers (7 upregulated and 1 downregulated). Smoking increased the expression of proteins related to epithelial hyperkeratinization (keratins type II cytoskeletal 4, type I cytoskeletal 13 and type I cytoskeletal 19, cornulin, and fatty acid-binding protein 5). However, multiple immunoglobulins were underexpressed when comparing smokers and ex-smokers to non-smokers. Although smoking does not significantly modify the overall GCF proteome associated with periodontitis, it alters the expression of several proteins compared to never-smokers and ex-smokers. Smoking is a critical risk factor for the development and progression of periodontitis. However, evidence of the effect of smoking on the subgingival proteome is scarce. Therefore, this study aimed to determine the impact of smoking on the overall proteome and differential expression of gingival crevicular fluid (GCF) proteins using the sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomic technique. For this purpose, GCF samples were collected from 40 subjects with periodontitis, of which 17 were smokers, 10 were ex-smokers, and 13 were non-smokers. These samples were analysed by SWATH-MS, and proteins were identified using the UniProt human-specific database. Analysis of the overall proteome showed that its distribution was not significantly different between smokers, ex-smokers, and non-smokers. However, several proteins were found to be differentially expressed according to the smoking status. Smoking can increase the expression of several keratins and proteins related to hyperkeratinization of the epithelium. However, in ex-smokers, these proteins return to similar levels to those of non-smokers. Moreover, smoking may induce a lower expression of proteins related to adaptive immunity, such as immunoglobulins. This immunosuppressive effect may persist in ex-smokers.

Reaping the Chemical Diversity of Morinagamyces vermicularis Using Feature-Based Molecular Networking.

Moringadepsin (6) and chaetone B (7) were isolated by us in the course of a conventional chemical screening of Morinagamyces vermicularis CBS 303.81, a fungus belonging to the relatively underexplored family Schizotheciaceae of the phylum Ascomycota. Since these metabolites did not account for the antifungal activity observed in a crude extract of this fungus, we utilized an MS/MS-based molecular networking approach to get a thorough insight into the secondary metabolites produced by this strain. Manual annotation of high-resolution fragmentation mass spectra by CANOPUS classified a major molecular family as putatively new thiodiketopiperazines. However, these results were opposite to the results of ChemWalker analysis based solely on MS/MS data, assigning these metabolites as various polyketides. Thus, targeted preparative HPLC isolation focusing on the most abundant features within this major molecular family resulted in the isolation of five secondary metabolites. Their structures were elucidated based on HRMS and NMR data as four new thiodiketopiperazine derivatives, botryosulfuranols D-G (1-4), alongside the known botryosulfuranol A (5). Compounds 1-3 and 5 exhibited moderate to weak antifungal activity against different test strains, accounting for the initial antifungal activity observed for its crude extract. Our study stressed the importance of full NMR-based structure elucidation for metabolomics research.

Identification of Omitted Pollutants in Environmental Water via In Situ Thin-Film Microextraction.

Sample preparation is an inevitable step in the screening workflow for the identification of unknown pollutants in the aquatic environment. However, the possible loss of pollutants during sample preparation has aroused serious concern but remains not effectively resolved. This study shows that high-risk pollutants omitted in solid-phase extraction (SPE) can be identified via in situ thin-film microextraction (TFME) coupled with high-resolution mass spectrometry. It was observed that a total of 541 features showed higher mass spectrometry signal intensity by using in situ TFME in comparison with SPE. Subsequently, 28 compounds were identified from the features with higher intensity by comparing the recorded tandem mass spectra with the online database and validating with standards. Notably, six out of these compounds were completely omitted using SPE, including a dye, drug, and industrial product. It was confirmed that the lower extraction efficiencies of SPE were attributed to the limited sample volumes, the losses of compounds during sample transportation and storage, and the entrapment of compounds in SPE columns. This study demonstrates that in situ TFME should be used as a supplementary technique to SPE for extending the coverage of pollutants in the screening workflows.

Mechanical-vibration-driven piezocatalytic degradation of organic pollutants over microcrystalline SnSe with selenium vacancies

Two-dimensional piezoelectric materials are attractive candidates to trigger piezoelectric catalytic reactions for organics degradation. Microcrystalline structures can endow them with enhanced piezocatalytic activity due totheir large surface area and abundant defect structures. In this work, microcrystalline SnSe with selenium vacancies (mc-SeVs SnSe) was synthesized and employed for piezocatalytic degradation of aqueous organics for the first time. Various instrumental testing results demonstrated that this unique microcrystalline SnSe has strong piezoelectric responses, abundant selenium vacancy defects and large active edges. Compared with crystalline SnSe, mc-SeVs SnSe showed superior piezocatalytic activity for the degradation of various organics in water. More importantly, mc-SeVs SnSe could induce the piezoelectric effect through mild mechanical energy to facilitate the efficient degradation of organic pollutants. The degradation efficiency of Crystal violet, p-nitrophenol, Malachite green, Congo red and Rhodamine B approached 100 % within 60 min reaction time. Superoxide and hydroxyl radicals were detected as the main reactive oxygen species generated in the piezocatalytic process. The degradation pathways of Rhodamine B were proposed based on high performance liquid chromatography-quadrupole-time of flight mass spectrum. The impact of strain on the alterations of dipole moment and electronic structure was investigated using density functional theory. The change in electron band structure induced by the polarized electric field was the underlying reason for the generation of hydroxyl radicals. This work will enrich the piezoelectric materials for organics degradation and provide fresh light on the mechanism of mechanically driven piezoelectric catalytic reactions.

Effect of Hydrophilic Function Groups on the Properties of Short‐Chain Fluorocarbon Surfactants

AbstractShort‐chain fluorocarbon surfactants grafted with alcohol, carboxyl and ester functional groups were prepared by quaternization with short‐chain perfluorobutyl sulfonyl fluoride as raw material. The structures of surfactants were characterized by infrared spectroscopy, nuclear magnetic resonance and mass spectrum. The surface activity, micelle formation process and micelle aggregation behavior of surfactants were studied by surface tensiometer, dynamic light scattering particle size analyzer and fluorescent spectrophotometer. The results show that the critical micelle concentration (CMC) of surfactants are 19.3, 7.8 and 2.2 mmol L−1, and the surface tension of the surfactant solution at CMC are as low as 17.3, 19.2 and 18.5 mN m−1, respectively. The standard Gibbs free energy ( ) values of surfactants are negative, and the absolute values of are less than the standard Gibbs adsorption energy ( ), illustrating that the adsorption process is easier than the micelle formation process. In addition, the size distribution of the aggregates is much larger than that of spherical micelles, showing that the surfactant self‐assembled into larger aggregates in solution. The grafted hydrophilic functional groups show a significant effect on the performance of surfactants. The ester‐based surfactant has a lower CMC value, which has the advantages of small dosage, good economy and excellent application value.

Revisiting Dissolved Organic Matter Analysis Using High-Resolution Trapped Ion Mobility and FT-ICR Mass Spectrometry.

The molecular level characterization of complex mixtures remains an analytical challenge. We have shown that the integration of complementary, high-resolution, gas-phase separations allows for chemical formula level isomeric content description. In the current work, we revisited the current challenges associated with the analysis of dissolved organic matter using high-resolution trapped ion mobility separation (TIMS) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In particular, we evaluated the separation capabilities provided by TIMS-MS compared to MS alone, the use of ICR complementary data acquisition (DAQ) systems and transient processing strategies, ICR cell geometries (e.g., Infinity cell vs harmonized cell), and magnetic field strengths (7 T vs 9.4 T vs 21 T) for the case of a Harney River DOM sample. Results showed that the external high-performance DAQ enables direct representation of mass spectra in absorption mode FT (aFT), doubling the MS resolution compared to the default magnitude mode FT (mFT). Changes between half- vs full-apodization result in greater MS signal/noise vs superior MS resolving power (RP); in the case of DOM analysis, a 45% increase in assigned formulas is observed when employing the DAQ half (Kaiser-type)-apodization window and aFT when compared to the default instrument mFT. Results showed the advantages of reprocessing 2D-TIMS-FT-ICR MS data with higher RP and magnetic field chemical formulas generated list acquired (e.g., 21 T led to a 24% increase in isomers reported) or the implementation of alternative strategies.

Dynamics of the Aspiration of Charged Droplets into a LC-ESI-MS System.

Electrospray ionization (ESI) enables coupling between liquid chromatography (LC) and mass spectrometry (MS). Since it is a gentle ionization method, it is frequently used for the analysis of large biomolecules. In recent years, several experimental setups have demonstrated that the use of ESI results in the formation of charged droplets that are aspirated into the vacuum systems of mass spectrometers. This results in a variety of consequences, such as instrument contamination, which can impede the analytical performance. We investigate the signatures of aspirated charged droplets with a commercial LC-ESI-MS system at analytical conditions. Previous observations without LC coupling are reproduced and show that significant droplet aspiration is probably taking place at analytical LC-ESI-MS conditions. This common phenomenon likely decreases the instrument sensitivity. Analyte can be released by isolation and fragmentation of droplet fragments; thus, aspirated droplets can mask analyte even in the mass analyzer region. The complex morphology of droplet MS/MS mass spectra is highly reproducible at the same experimental conditions. This implies the existence of distinct molecular reaction pathways of the droplet fragments. To assess the effect of droplet aspiration on analytical applications, relevant method and ion source parameters, which are commonly varied during method optimization, were investigated. Further variations of the solvent composition revealed that the aspirated droplets and their fragmentation are particularly sensitive to the solvent composition and thus also to the LC solvent gradient in an analytical experiment.

Purely leptonic decays of heavy-flavored charged mesons

We study the purely leptonic decays of heavy-flavored charged pseudoscalar (P) and vector (V) mesons (D(s)(*)+, B(c)(*)+) in the relativistic independent quark (RIQ) model based on an average flavor-independent confining potential in an equally mixed scalar-vector harmonic form. We first compute the mass spectra of the ground-state-mesons and fix the model parameters necessary for the present analysis. Using the meson wave functions derivable in the RIQ model, and model parameters so fixed from hadron spectroscopy, we predict the decay constants: fP(V), ratios of decay constants: fV/fP, fP1/fP2, fV1/fV2, and the branching fractions (BFs): B(P(V)→l+νl), l=e, μ, τ, which agree with the available experimental data and other Standard Model (SM) predictions. For the unmeasured decay constants, especially in the purely leptonic decays of the charged vector mesons, our predictions could be tested in the upcoming Belle-II, SCTF, CEPC, FCC-ee, and LHCb experiments in the near future. Published by the American Physical Society 2024

Synthesis, molecular docking, and anti-breast cancer study of 1-H-indol-3-Carbohydrazide and their derivatives

A prominent heterocyclic system found in medications and natural goods is indoles. Due to the significance of this important ring system, a fresh batch of unique indole derivatives was created using indole carbohydrazide. The triazole moiety of indole derivative (3) is produced by reacting carbohydrazide with carbon disulfide in alkaline conditions, followed by hydrazine treatment. In addition to synthesizing additional derivatives, indole-bearing triazole (3) was condensed with aromatic aldehydes to create the indole derivatives (4a–c). Mass spectra, 1HNMR, 13CNMR, and infrared spectroscopy were used to diagnose all produced derivatives. An MTT assay was employed to test the derivatives against MCF-7 cells. The findings demonstrated the inhibitory action of compounds 5a and 5b, with IC50 values of 42.6 ± 0.33 µM and 27.3 ± 0.28, respectively. Affinity energy and the interaction between the investigated chemicals and receptor (CDK4 ID: 2w96) were ascertained by studying molecular docking. The chemical structure-physicochemical-pharmacokinetic relationship provides useful insight for medicinal chemists to design indole-triazole derivatives with acceptable drug-like and pharmacokinetic properties.

Are Hydroxyl Radicals Spontaneously Generated in Unactivated Water Droplets?

Spontaneous ionization/breakup of water at the surface of aqueous droplets has been reported with evidence ranging from formation of hydrogen peroxide and hydroxyl radicals, indicated by ions at m/z 36 attributed to OH•‐H3O+ or (H2O‐OH2)+• as well as oxidation products of radical scavengers in mass spectra of water droplets formed by pneumatic nebulization. Here, aqueous droplets are formed both by nanoelectrospray, which produces highly charged nanodrops with initial diameters ~100 nm, and a vibrating mesh nebulizer, which produces 2 – 20 µm droplets that are less highly charged. The lifetimes of these droplets range from 10s of µs to 560 ms and the surface‐to‐volume ratios span ~100‐fold range. No ions at m/z 36 are detected with pure water, nor are significant oxidation products for the two radical scavengers that were previously reported to be formed in high abundance. These and other results indicate that prior conclusions about spontaneous hydroxyl radical formation in unactivated water droplets are not supported by the evidence and that water appears to be stable at droplet surfaces over a wide range of droplet size, charge and lifetime.

Comprehensive analysis of local and nonlocal amplitudes in the B0→ K*0μ+μ− decay

A comprehensive study of the local and nonlocal amplitudes contributing to the decay B0 → K*0(→ K+π−)μ+μ− is performed by analysing the phase-space distribution of the decay products. The analysis is based on pp collision data corresponding to an integrated luminosity of 8.4 fb−1 collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient C9\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{C}}_9 $$\\end{document}, responsible for vector dimuon currents, exhibits a 2.1σ deviation from the Standard Model expectation. The Wilson Coefficients C10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{C}}_{10} $$\\end{document}, C9′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{C}}_9^{\\prime } $$\\end{document} and C10′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{C}}_{10}^{\\prime } $$\\end{document} are all in better agreement than C9\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{C}}_9 $$\\end{document} with the Standard Model and the global significance is at the level of 1.5σ. The model used also accounts for nonlocal contributions from B0→ K*0[τ+τ−→ μ+μ−] rescattering, resulting in the first direct measurement of the bsττ vector effective-coupling C9τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{C}}_{9\ au } $$\\end{document}.

Streamlining LC-MS Characterization of Pharmaceutical Polymers by Fourier-Transform-Based Deconvolution and Macromolecular Mass Defect Analysis.

Polymer conjugation has risen in importance over the past three decades as a means of increasing the in vivo half-life of biotherapeutics, with benefits including better stability, greater drug efficacy, and lower toxicity. However, the intrinsic variability of polymer synthesis results in products with broad distributions in chain length and branching structure, complicating quality control for successful functionalization and downstream conjugation. Frequently, a combination of several analytical techniques is required for comprehensive characterization. While liquid chromatography-mass spectrometry (LC-MS) is a powerful platform that can provide detailed molecular features of polymers, the mass spectra are inherently challenging to interpret due to high mass polydispersity and overlapping charge distributions. Here, by leveraging Fourier transform-based deconvolution and macromolecular mass defect analysis, we demonstrate a new way to streamline pharmaceutical polymer analysis, shedding light on polymer size, composition, branching, and end-group functionalization with the capability for reaction monitoring.

Natural α-Methylene-γ-Butyrolactone Analogues: Synthesis and Evaluation of Isoaurone Derivatives as Antifungal Agents.

In order to develop novel, efficient and green fungicides, a series of novel isoaurone derivatives were designed and synthesized, which were characterized by 1H and 13C NMR, high-resolution mass spectra and melting points. The target compounds showed different inhibitory activities against seven plant pathogenic fungi. Compounds 1, 12, 17, 20, 22, 24 and intermediate A showed more than 90% inhibition rates against S. s at 50 mg/L. Interestingly, compound 22 and intermediate A showed the great inhibitory effect against S. s with EC50 values of 4.65 and 4.24 mg/L, which were better than the lead compound isoaurone (EC50 = 15.62 mg/L). The EC50 values of compounds 17 and 24 against B. c were 13.94 and 22.13 mg/L. Moreover, compound 19 displayed significant antifungal activity against G. g with the EC50 value of 11.88 mg/L. Theoretical calculations by DFT revealed that the α, β-unsaturated carbonyl bond and the benzyl ring are very importantly linked to the strength of the fungicidal activity. Therefore, this study identified a valuable antifungal lead compound for further development of green fungicides.

Nanopore ion sources deliver individual ions of amino acids and peptides directly into high vacuum

Electrospray ionization is widely used to generate vapor phase ions for analysis by mass spectrometry in proteomics research. However, only a small fraction of the analyte enters the mass spectrometer due to losses that are fundamentally linked to the use of a background gas to stimulate the generation of ions from electrosprayed droplets. Here we report a nanopore ion source that delivers ions directly into high vacuum from aqueous solutions. The ion source comprises a pulled quartz pipette with a sub-100 nm opening. Ions escape an electrified meniscus by ion evaporation and travel along collisionless trajectories to the ion detector. We measure mass spectra of 16 different amino acid ions, post-translationally modified variants of glutathione, and the peptide angiotensin II, showing that these analytes can be emitted as desolvated ions. The emitted current is composed of ions rather than charged droplets, and more than 90% of the current can be recovered in a distant collector.