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Water-assisted laser desorption/ionization mass spectrometry for minimally invasive in vivo and real-time surface analysis using SpiderMass
摘要： Rapid, sensitive, precise and accurate analysis of samples in their native in vivo environment is critical to better decipher physiological and physiopathological mechanisms. SpiderMass is an ambient mass spectrometry (MS) system designed for mobile in vivo and real-time surface analyses of biological tissues. The system uses a fibered laser, which is tuned to excite the most intense vibrational band of water, resulting in a process termed water-assisted laser desorption/ionization (WALDI). The water molecules act as an endogenous matrix in a matrix-assisted laser desorption ionization (MALDI)-like scenario, leading to the desorption/ionization of biomolecules (lipids, metabolites and proteins). The ejected material is transferred to the mass spectrometer through an atmospheric interface and a transfer line that is several meters long. Here, we formulate a three-stage procedure that includes (i) a laser system setup coupled to a Waters Q-TOF or Thermo Fisher Q Exactive mass analyzer, (ii) analysis of specimens and (iii) data processing. We also describe the optimal setup for the analysis of cell cultures, fresh-frozen tissue sections and in vivo experiments on skin. With proper optimization, the system can be used for a variety of different targets and applications. The entire procedure takes 1–2 d for complex samples.
关键词： mass spectrometry,SpiderMass,real-time surface analysis,Water-assisted laser desorption/ionization,in vivo analysis
更新于2025-09-16 10:30:52
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Chemical analysis of a lunar meteorite by laser ablation mass spectrometry
摘要： The lunar meteorite Sayh al Uhaymir 169, that contains KREEP rich material, was investigated with our miniature laser ablation time-of-flight mass spectrometer to simulate the expected performance of in-situ measurements on the surface of a planetary body. The abundances of the major elements on the KREEP part of the rock were measured and plotted on a two-dimensional surface map to identify different mineral phases in the sample. The element distribution maps reveal the grain boundaries and allow identification of individual minerals and their major and trace element compositions. In the second measurement campaign the instrument was coupled with a HV pulser to increase sensitivity of the measurements. It could be shown that the detection sensitivity for heavy trace elements can be significantly improved while removing light elements from the analyzed ion beam. This study provides also measurements of U, Th and Pb elements present inside a single zircon grain. With the abundances of U and Pb in the zircon grain a preliminary age estimation of the zircon could be made and was found to be in reasonable agreement with ages reported in literature. Moreover, from the Ti concentration in the zircon grain a crystallization temperature was derived. Thus, by employing such an instrument on a planetary surface, scientific useful in-situ measurements on the element composition, the mineralogy, petrology and dating of surface samples can be accomplished.
关键词： Lunar meteorite,Trace elements,Laser ablation mass spectrometry,Crystallization temperature,KREEP material,Zircon
更新于2025-09-12 10:27:22
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[ACS Symposium Series] Fundamentals and Applications of Phosphorus Nanomaterials Volume 1333 || Phosphorus Clusters and Quantum Dots
摘要： Cluster is characterized by its unique role in chemistry and physics due to the fact that it bridges isolated atoms and bulk counterparts. It is also found that the structures and properties of clusters change dramatically with their sizes. Characterized by its diverse bonding patterns, phosphorus clusters have attracted many interests in past years. With the help of laser ablation mass spectrometry and other relative technologies, many kinds of phosphorus clusters have been generated, identified and studied. Their structures and properties are also widely studied by theoretical calculations. This chapter reviews both experimental and theoretical progresses about phosphorus clusters and relative species. On the other hand, the phosphorus quantum dots have attracted a great deal of attention due to its unique structures, properties, and applications in recent years. A quick overview on this topic is also included in the chapter, in order to attract more interests from broad research fields and make a bridge across the cluster study and nanomaterials to benefit scientists in both fields.
关键词： theoretical calculations,laser ablation mass spectrometry,quantum dots,phosphorus clusters,nanomaterials
更新于2025-09-12 10:27:22
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Membrane‐type frizzled‐related protein regulates lipidome and transcription for photoreceptor function
摘要： Molecular decision-makers of photoreceptor (PRC) membrane organization and gene regulation are critical to understanding sight and retinal degenerations that lead to blindness. Using Mfrprd6 mice, which develop PRC degeneration, we uncovered that membrane-type frizzled-related protein (MFRP) participates in docosahexaenoic acid (DHA, 22:6) enrichment in a manner similar to adiponectin receptor 1 (AdipoR1). Untargeted imaging mass spectrometry demonstrates cell-specific reduction of phospholipids containing 22:6 and very long-chain polyunsaturated fatty acids (VLC-PUFAs) in Adipor1?/? and Mfrprd6 retinas. Gene expression of pro-inflammatory signaling pathways is increased and gene-encoding proteins for PRC function decrease in both mutants. Thus, we propose that both proteins are necessary for retinal lipidome membrane organization, visual function, and to the understanding of the early pathology of retinal degenerative diseases.
关键词： RPE cell,retinal degenerations,Adipor1,inflammatory signaling,VLC-PUFAs,matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS)
更新于2025-09-12 10:27:22
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Estimation of Flexible and Rigid Residues of Disulfide-Bridged and Phosphorylated Proteins Using Matrix-Assisted Laser Desorption/Ionization in-Source Decay Mass Spectrometry
摘要： Flexible and rigid residues in disul?de-bridged and phosphorylated proteins have been estimated by using MALDI in-source decay mass spectrometry (ISD MS). The MALDI-ISD spectra of bovine α-lactoalbumin, β-lactoglobulin A, and β-casein predict that the backbone amide of Xxx-Asp/Asn/Cys/Ser/pSer and Gly-Xxx residues has higher hydrogen accessibility than other residues, while Xxx-Ile/Val residues have less accessibility. The higher hydrogen-accessible and lower accessible residues as measured by MALDI-ISD are consistent with the ?exible and rigid residues determined by X-ray, nuclear magnetic resonance, and ?uorescence decay methods. The disul?de bridges and phosphate groups do not prevent the estimation of ?exible or rigid residues, whereas some other disul?de bridges inhibit the identi?cation because of decreased sensitivity of ISD fragment ions. The estimation of ?exible and rigid residues by means of the matrix-hydrogen accessibility can be explained by exposure or lack thereof to the hydrogen-accessible sites of intact proteins. It is proposed that MALDI-ISD is a powerful tool for identifying ?exible and rigid residues of posttranslational modi?ed proteins without the conformation information of the protein data bank.
关键词： flexible and rigid residues,phosphorylated proteins,disul?de-bridged proteins,hydrogen accessibility,MALDI in-source decay mass spectrometry
更新于2025-09-12 10:27:22
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Mass separated particle flux from a laser-ablation metal cluster source
摘要： Flux waveforms of aluminum cluster beams supplied from a laser-ablation cluster source were precisely investigated under various source conditions such as background pressure, ablation laser intensity, and nozzle structure. A time-of-flight mass spectroscopy revealed that aluminum clusters with sizes up to 200 were generated and the amount of the clusters could be maximized by choosing a proper background pressure (～2 MPa) and an ablation laser fluence (～40 mJ/cm2). Flux waveforms of clusters having specific sizes were carefully reconstructed from the observed mass spectra. It is found that the pulse widths of the aluminum cluster beams were typically about 100 μs and much smaller than that of the monoatomic aluminum beam, indicating that the cluster formation was limited in a relatively small volume in the laser-ablated vapor. Introducing a conical nozzle having a large open angle was also found to enhance the cluster beam velocity and reduce its pulse width. A velocity measurement of particles in the cluster beam was conducted to examine the velocity spread of the supplied clusters. We found that the aluminum clusters were continuously released from the source for about 100 μs and this release time mainly determined the pulse width of the cluster beam, suggesting that controlling the behavior of an ablated vapor plume in the waiting room of the cluster source holds the key to drastically improving the cluster beam flux.
关键词： mass spectrometry,laser ablation,molecular beam,Cluster
更新于2025-09-12 10:27:22
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Matrix Assisted Laser Desorption Ionization-Time-of-Flight mass spectrometry identification of <i>Mycobacterium bovis </i>in Bovinae
摘要： In this study, Matrix Assisted Laser Desorption Ionization-Time-of-Flight (MALDI-TOF) mass spectrometry was used to identify Mycobacterium bovis from cattle and buffalo tissue isolates from the North and South regions of Brazil, grown in solid medium and previously identified by Polymerase Chain Reaction (PCR) based on Region of Difference 4 (RD4), sequencing and spoligotyping. For this purpose, the protein extraction protocol and the mass spectra reference database were optimized for the identification of 80 clinical isolates of mycobacteria. As a result of this optimization, it was possible to identify and differentiate M. bovis from other members of the Mycobacterium tuberculosis complex with 100% specificity, 90.91% sensitivity and 91.25% reliability. MALDI-TOF MS methodology described herein provides successful identification of M. bovis within bovine/bubaline clinical samples, demonstrating its usefulness for bovine tuberculosis diagnosis in the future.
关键词： Matrix Assisted Laser Desorption Ionization-Time-of-Flight (MALDI-TOF) mass spectrometry,bovine tuberculosis,Mycobacterium tuberculosis complex,Mycobacterium bovis
更新于2025-09-12 10:27:22
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Definitive production of intact organic pentacation radical: Octafluoronaphthalene ionized in intense femtosecond laser fields
摘要： We demonstrate the production of long-lived octafluoronaphthalene pentacation radical in gas phase by tunneling ionization using 1.4 μm femtosecond laser pulses. Multiply charged molecular cations are definitively identified by their m/z, isotopic structure, and peak shape using time-of-flight mass spectrometry. The tetracation yield relative to the trication radical yield is 0.33 that is the highest value obtained to date. The yield of pentacation radical relative to tetracation is 0.025. Our results show that the use of perfluoro-aromatics is the promising way to approach intact highly charge states.
关键词： Tunnel ionization,Time-of-flight,Mass spectrometry,Femtosecond laser
更新于2025-09-12 10:27:22
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Proteomics of human glomerulonephritis by laser microdissection and liquid chromatography‐tandem mass spectrometry
摘要： Aim: Laser microdissection (LMD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) enable clinicians to analyse proteins from tissue sections. In nephrology, these methods are used to diagnose diseases of abnormal protein deposition, such as amyloidosis, but they are seldom applied to the diagnosis and pathophysiological understanding of human glomerular diseases. Methods: Renal biopsy specimens were obtained from five patients with IgA nephropathy (IgAN), five patients with membranous nephropathy (MN) and five kidney transplant donors (as controls). From 10-μm-thick sections of formalin-fixed, paraffin-embedded specimens, 0.3-mm2 samples of glomerular tissue were subjected to LMD. The samples were analysed by LC-MS/MS and investigated clinically and histologically. Results: From the control glomeruli, we identified more than 300 types of proteins. In patients with IgAN, we detected significant increases not only in IgA1 and in C3 but also in the factors related to oxidative stress and cell proliferation in comparison to the controls. In patients with MN, levels of IgG1, IgG4, C3, C4a, and phospholipase-A2-receptor were significantly elevated in comparison to the controls, as were the aforementioned factors related to oxidative stress and cell proliferations detected in IgAN. Conclusion: Application of LMD and LC-MS/MS to renal biopsy specimens enabled us to identify not only pathognomonic proteins for the diagnosis but also several factors possibly involved in the pathogenesis of human glomerular diseases.
关键词： glomerulonephritis,IgA nephropathy,membranous nephropathy,laser microdissection,mass spectrometry
更新于2025-09-12 10:27:22
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Three-Dimensional Composition Analysis of SnAg Solder Bumps Using Ultraviolet Femtosecond Laser Ablation Ionization Mass Spectrometry
摘要： The application of a novel UV fs Laser Ablation Ionization Mass Spectrometry approach for chemical depth profiling of low-melting point, high surface roughness SnAg solder bump features is presented. The obtained resolved three-dimensional compositional submicrometer data reveal unprecedented information on the distribution of individual elements inside the solder bump matrix. Moreover, the determination of matrix-matched relative sensitivity coefficients allows the first report on quantitative assessment of the SnAg alloy composition. These results significantly contribute to an in-depth understanding of the SnAg plating process. This experimental procedure may find application in future additive performance screening.
关键词： three-dimensional compositional analysis,chemical depth profiling,SnAg solder bumps,UV fs Laser Ablation Ionization Mass Spectrometry,matrix-matched relative sensitivity coefficients
更新于2025-09-12 10:27:22