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Graphene-Coated Glass Substrate for Continuous Wave Laser Desorption and Atmospheric Pressure Mass Spectrometric Imaging of Live Hippocampal Tissue
摘要： Atmospheric pressure mass spectrometric (AP-MS) imaging technology combined with an inverted optical microscopic system is a powerful tool for determining the presence and spatial distributions of specific biomolecules of interest in live tissues. Efficient desorption and ionization are essential to acquire mass spectrometric (MS) information in an ambient environment. In this study, we demonstrate a new and efficient desorption process using a graphene-coated glass substrate and a continuous wave (CW) laser for high-resolution AP-MS imaging of live hippocampal tissue. We found that desorption of biomolecules in a live tissue slice was possible with the aid of a graphene-coated glass substrate and indirect application of a 532 nm CW-laser on the graphene substrate. Interestingly, the desorption efficiency of live tissue on the graphene-coated substrate was strongly dependent on the number of graphene layers. Single-layer graphene was found to be the most sensitive substrate for efficient desorption and reproducible high-resolution hippocampal tissue imaging applications. The subsequent ionization process using nonthermal plasma generated sufficient amounts of molecular ions to obtain high-resolution 2-dimensional MS images of the cornu ammonis (CA) and the dentate gyrus (DG) regions of the hippocampus. Therefore, graphene-coated substrates could be a promising platform to induce an efficient desorption process essential for highly reproducible ambient MS imaging.
关键词： Hippocampal tissue,Mass spectrometry imaging,Laser desorption,Graphene-coated substrate,Ambient mass spectrometry
更新于2025-11-25 10:30:42
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Graphene quantum dots enhanced ToF-SIMS for single-cell imaging
摘要： Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has shown promising applications in single-cell analysis owing to its high spatial resolution molecular imaging capability. One of the main drawbacks hindering progress in this field is the relatively low ionization efficiency for biological systems. The complex chemical micro-environment in single cells typically causes severe matrix effects, leading to significant signal suppression of biomolecules. In this work, we investigated the signal enhancement effect of graphene quantum dots (GE QDs) in ToF-SIMS analysis. A × 160 magnification of ToF-SIMS signal for amiodarone casted on glass slide was observed by adding amino-functionalized GE QDs (amino-GE QDs), which was significantly higher than adding previously reported signal enhancement materials and hydroxyl group-functionalized GE QDs (hydroxyl-GE QDs). A possible mechanism for GE QD-induced signal enhancement was proposed. Further, effects of amino-GE QDs and hydroxyl-GE QDs on amiodarone-treated breast cancer cells were compared. A significant signal improvement for lipids and amiodarone was achieved using both types of GE QDs, especially for amino-GE QDs. In addition, ToF-SIMS chemical mapping of single cells with better quality was obtained after signal enhancement. Our strategy for effective ToF-SIMS signal enhancement holds great potential for further investigation of drug metabolism pathways and the interactions between the cell and micro-environment.
关键词： Signal enhancement,Single-cell analysis,Graphene quantum dots,Time-of-flight secondary ion mass spectrometry
更新于2025-11-14 15:32:45
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Structural, morphological and opticalproperties of spray-formed silver-doped zinc sulphide thin films
摘要： The study focused on the qualities of spray-formed Silver-doped Zinc sulphide (ZnS) thin films sprayed on soda-lime glass (slg) substrate. Silver-doped and undoped ZnS thin films with 0%, 1%, 3% and 5% Silver concentrations were deposited. The qualities of the synthesized films were investigated using x-ray diffractometry, scanning electron microscopy, Fourier transforms infrared (FTIR) spectrometry, UV-VIS spectrophotometry, Raman spectrometry and contact angle techniques. The x-ray diffraction data identified cubic structures for the thin films. Scanning electron microscopy shows the presence of agglomerates of nanoparticles and pores in the thin films. The thin films’ crystallite size ranges between 3.107 and 4.103 nm. FTIR revealed the chemical bonds in the film. The transmittance of the thin films is between 42.35 and 81.86% at 550 nm, the energy gap is observed within a range of 3.11 and 3.60 eV while the indices of refraction are in the range of 1.52 to 3.81 at 550 nm wavelength. Photoluminescence result shows Sulphur vacancies. A hydrophilic surface feature of the film was revealed by the contact angle measurement.
关键词： silver,Thin film,zinc sulphide,Raman spectrometry
更新于2025-11-14 15:16:37
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Mass Spectrometric Imaging Reveals Photocatalytic Degradation Intermediates of Aromatic Organochlorines Resulting from Interfacial Photoelectron Transfer and Hydroxyl Radical Abstraction on Semiconductor Nanoparticles
摘要： Organochlorines are highly persistent and toxic contaminants that are widely distributed and accumulated in various aquatic or soil environments as well as food chains. Heterogeneous photocatalytic degradation of such pollutants by using semiconductor nanoparticles has been recognized as one of the effective purification ways. Understanding of degradation mechanisms and designing of highly efficient semiconductor nanoparticles require structural identification of various degradation intermediates that are difficult to achieve with current spectroscopic techniques. Herein a mass spectrometric approach was developed to tackle interfacial photoelectron transfer and hydroxyl radical abstraction on different semiconductor nanoparticles. Chlorobenzenes (including hexachlorobenzene and chlorothalonil) adsorbed on the surfaces of nanoparticles were found to instantly undergo dechlorination and ring dissociation through photoelectron capture dissociation and abstraction of a chlorine atom from aromatic C-Cl bond by hydroxyl radicals. Different intermediates have been unambiguously identified with experimental evidences provided by a Q-TOF mass spectrometer. It has been demonstrated that both electron density around atoms and steric effects of side chains contribute to the site selectivity for photoelectron capture and hydroxyl radical abstraction. But the energies needed for chemical bond cleavages and the stabilization of acquired charges play important roles in degradation efficiency. By using mass spectrometric imaging, photocatalytic differences of different semiconductor nanoparticles have been revealed.
关键词： Photoelectron Capture Dissociation,Interfacial Photoelectron Transfer,Chlorobenzenes,Mass Spectrometry,Hydroxyl Radical
更新于2025-09-23 15:23:52
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A novel method for simultaneous determination of zinc, nickel, cobalt and copper based on UV–vis spectrometry
摘要： A novel method based on UV–vis spectrometry is developed for simultaneous determination of zinc, nickel, cobalt and copper without any separation steps. The method studied in this paper is the combination of ratio spectra derivative and kalman filtering spectrophotometry. First, using absorbance of zinc standard solution as divisor, the ratio spectra derivative obtained can completely eliminate the interference of zinc on trace ions. Second, the trace ions are simultaneously determined by kalman filtering spectrophotometry. Last, based on obtaining trace ion concentrations, a calibration curve for zinc is established. The linear determination ranges are 10-70mg/L for zinc, 0.2-1.4mg/L for trace ions of nickel, cobalt and copper. The results show that the predicted results of zinc, nickel, cobalt and copper by this proposed method is superior to PLS method. The work reported here is an effective attempt for the simultaneous determination of zinc, nickel, cobalt and copper in industrial wastewater of zinc hydrometallurgy, and will have more applications.
关键词： Zinc hydrometallurgy,Ratio spectra derivative,Kalman filtering spectrophotometry,UV–vis spectrometry
更新于2025-09-23 15:23:52
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Online photochemical derivatization enables comprehensive mass spectrometric analysis of unsaturated phospholipid isomers
摘要： Mass spectrometry-based lipidomics is the primary tool for the structural analysis of lipids but the effective localization of carbon–carbon double bonds (C=C) in unsaturated lipids to distinguish C=C location isomers remains challenging. Here, we develop a large-scale lipid analysis platform by coupling online C=C derivatization through the Paternò-Büchi reaction with liquid chromatography-tandem mass spectrometry. This provides rich information on lipid C=C location isomers, revealing C=C locations for more than 200 unsaturated glycerophospholipids in bovine liver among which we identify 55 groups of C=C location isomers. By analyzing tissue samples of patients with breast cancer and type 2 diabetes plasma samples, we find that the ratios of C=C isomers are much less affected by interpersonal variations than their individual abundances, suggesting that isomer ratios may be used for the discovery of lipid biomarkers.
关键词： C=C location isomers,biomarker discovery,Paternò-Büchi reaction,mass spectrometry,lipidomics
更新于2025-09-23 15:23:52
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Native mass spectrometry reveals the conformational diversity of the UVR8 photoreceptor
摘要： UVR8 is a plant photoreceptor protein that regulates photomorphogenic and protective responses to UV light. The inactive, homodimeric state absorbs UV-B light, resulting in dissociation into monomers, which are considered to be the active state and comprise a β-propeller core domain and intrinsically disordered N- and C-terminal tails. The C terminus is required for functional binding to signaling partner COP1. To date, however, structural studies have only been conducted with the core domain where the terminal tails have been truncated. Here, we report structural investigations of full-length UVR8 using native ion mobility mass spectrometry adapted for photoactivation. We show that, while truncated UVR8 photoconverts from a single conformation of dimers to a single monomer conformation, the full-length protein exists in numerous conformational families. The full-length dimer adopts both a compact state and an extended state where the C terminus is primed for activation. In the monomer the extended C terminus destabilizes the core domain to produce highly extended yet stable conformations, which we propose are the fully active states that bind COP1. Our results reveal the conformational diversity of full-length UVR8. We also demonstrate the potential power of native mass spectrometry to probe functionally important structural dynamics of photoreceptor proteins throughout nature.
关键词： intrinsically disordered proteins,plant photoreception,UVR8,native mass spectrometry,ion mobility
更新于2025-09-23 15:23:52
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Chemical and topographical single-cell imaging by near-field desorption mass spectrometry
摘要： Simultaneous acquiring chemical and topographical information within a single cell at nanoscale resolutions is vital to cellular biology, yet it remains a great challenge for current techniques due to limited lateral resolutions and detection sensitivities. Here we report the development of near-field desorption mass spectrometry for co-registered chemical and topographical imaging, thereby bridging the gap between laser-based MS methods and multimodal single-cell imaging. Using this integrated platform, imaging resolution of 250 nm and 3D topographically reconstructed chemical single-cell imaging were achieved. This technique offers more in-depth cellular information than is currently possible with micrometre-range laser-based MS imaging methods. Considering the simplicity and compact size of the near-field device, this technique can be introduced to matrix-assisted laser desorption ionization MS, expanding the multimodal abilities of MS at nanoscale resolutions across wide disciplines.
关键词： single-cell analysis,analytical methods,multimodal imaging,mass spectrometry,near-field desorption
更新于2025-09-23 15:23:52
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An LDI-MSI approach for targeted and untargeted differentiation and assessment of pharmaceutical formulations
摘要： Falsified, counterfeit and adulterated medicines are an endemic problem worldwide that results in both monetary and health-related losses. Developing fast and reliable methods that are able to present a timely result based on the drug’s spectral profile is an effort that is sure to benefit those involved in the whole distribution chain. We propose herein a Laser Desorption/Ionization imaging-based method that provides simple and minimal sample preparation; this method is capable of providing specific markers that characterize adulterations, using as proof of concept one of the most adulterated drug products for oral use, sildenafil. Our approach is able to provide quality markers, which can be applied in the fast screening of any product within the same molecular class. This same strategy may be a useful alternative to provide accurate measurements with high specificity for unraveling contaminants and/or byproducts in virtually any given pharmaceutical product.
关键词： mass spectrometry imaging,LDI,direct analysis,spectral profiles,Falsified medicines
更新于2025-09-23 15:23:52
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In-Situ Measurement of Outgassing Generated from EUV Metal Oxide Nanoparticles Resist During Electron Irradiation
摘要： In this study, we prepared the EUV metal resist, which included ZrO2 nano-particle and three type ligands as 2-methyl-2-propenoic acid (MAA), 2-methylpropanoic acid (IBA) and vinylbenzoic acid (VBA). Each resist was prepared by blending each material separately for evaluating the outgassing from EUV resist materials. We prepared three-type samples of ZrO2-MAA, ZrO2-IBA and ZrO2-VBA by coating each resist, and evaluated the outgassing from these samples during irradiation of 2 keV electron by in-situ mass spectrometry. From the results of mass spectrum, we could observe the outgassing of PAG as unique peaks. And each ligand peak was distributed over the low mass range. On the other hand, the ZrO2 peaks could not be observe in mass spectrum of each sample. Thus, we guess that ZrO2 nano-particles might not be evaporating during 2 keV electron irradiation.
关键词： Ligand,EUV metal resist,Electron irradiation,Mass spectrometry,In-situ outgas measurement,ZrO2
更新于2025-09-23 15:22:29