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Dual Laser and Desorption Electrospray Ionization Mass Spectrometry Imaging Using the Same Interface
摘要： For a more comprehensive characterization of molecular heterogeneities of matter, multi-modal mass spectrometry imaging must be developed to take advantage of the complementarity of information available through different ionization mechanisms. We report the design, implementation, and performance validation of a laser desorption imaging interface comprised of add-on components that adapt a commercial Desorption Electrospray Ionization Mass Spectrometry (DESI-MS) imaging interface for dual imaging of Picosecond Infrared Laser Mass Spectrometry (PIRL-MS) with DESI-MS. The interface utilizes hardware elements and data analysis pipelines already established for DESI-MS imaging, and was further validated in cancer margin assessments using human medulloblastoma cancers. The PIRL-MS images were robust and reproducible across multiple experimental runs on independently prepared xenograft tumours, and could be segmented into cancer and healthy regions in concordance with pathology using a variety of supervised and unsupervised clustering methods. The spectral quality and complexity obtained with this interface were examined with infiltrating and non-infiltrating tumours, and were comparable to other mass spectrometry analysis interfaces. The average PIRL-MS spectra from spatially resolved images could be used for robust cancer m/z model building to classify medulloblastoma cancer from healthy tissue without any misclassifications, an observation that held true over close to 70 sampling data points. While the unsupervised spectral analysis methods suggested a slight suppression of signal in the phospholipid range compared to the hand-held configuration, these changes were insufficient to hamper utility in cancer margin assessment with spatially resolved data obtained with our interface. Dual PIRL-MS and DESI-MS imaging of consecutive sections, as suggested by multivariate loading plots, revealed highly complementary molecular information with m/z values identifiable with one desorption method sufficient to reveal cancer regions being absent in another, further emphasising the need for effective hardware and software interfaces for dual mass spectrometry imaging.
关键词： mass spectrometry imaging,laser desorption,DESI-MS,PIRL-MS,medulloblastoma,cancer margin assessment
更新于2025-09-19 17:13:59
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Mass Spectrometry Imaging of Triglycerides in Biological Tissues by Laser Desorption Ionization from Silicon Nanopost Arrays
摘要： Mass spectrometry imaging (MSI) is used increasingly to simultaneously detect a broad range of biomolecules, while mapping their spatial distributions within biological tissue sections. Matrix-assisted laser desorption ionization (MALDI) is recognized as the method-of-choice for MSI applications due in part to its broad molecular coverage. In spite of the remarkable advantages offered by MALDI, imaging of neutral lipids, such as triglycerides (TGs), from tissue has remained a significant challenge due to ion suppression of TGs by phospholipids, e.g., phosphatidylcholines (PCs). To help overcome this limitation, silicon nanopost array (NAPA) substrates were introduced to selectively ionize TGs from biological tissue sections. This matrix-free laser desorption ionization (LDI) platform was previously shown to provide enhanced ionization of certain lipid classes, such as hexosylceramides (HexCers) and phosphatidylethanolamines (PEs) from mouse brain tissue. In this work, we present NAPA as an MSI platform offering enhanced ionization efficiency for TGs from biological tissues relative to MALDI, allowing it to serve as a complement to MALDI-MSI. Analysis of a standard lipid mixture containing PC(18:1/18:1) and TG(16:0/16:0/16:0) by LDI from NAPA provided an ~49 and ~227-fold higher signal for TG(16:0/16:0/16:0) relative to MALDI, when analyzed without and with the addition of a sodium acetate, respectively. In contrast, MALDI provided an ~757 and ~295-fold higher signal for PC(18:1/18:1) compared to NAPA, without and with additional Na+. Averaged signal intensities for TGs from MSI of mouse lung and human skin tissues exhibited an ~105 and ~49-fold increase, respectively, with LDI from NAPA compared to MALDI. With respect to PCs, MALDI provided an ~2 and ~19-fold increase in signal intensity for mouse lung and human skin tissues, respectively, when compared to NAPA. The complementary coverage obtained by the two platforms demonstrates the utility of using both techniques to maximize the information obtained from lipid MS or MSI experiments.
关键词： laser desorption ionization,Mass spectrometry imaging,NAPA,nanopost array,lipids,triglycerides
更新于2025-09-19 17:13:59
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Fundamentals and Applications of Fourier Transform Mass Spectrometry || Fourier transform ion cyclotron resonance mass spectrometry and laser: A versatile tool
摘要： The coupling of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with laser combines the attributes of laser mass spectrometry with the analytical capabilities of a mass spectrometer having high resolution, high mass measurement accuracy, long ion-observation times, and exceptional ion isolation capabilities required for ion-molecule reaction or ion fragmentation studies [1–3]. The laser may be used for different purposes in mass spectrometry. The most standard one is to generate ions from the surface of the laser-irradiated sample. Two regimes have to be considered in respect with the laser fluence (energy deposit per surface unit in J/cm2) or the laser power density also named irradiance (power density deposit per surface unit in W/cm2). At low laser fluence, laser desorption/ionization (LDI) may take place. When the laser fluence increases, the regime of laser–matter interaction is modified and laser ablation (LA) occurs. In both cases, the ionization phenomenon and the transfer of the atoms or molecules to the gas phase are the direct result of the laser matter interaction. LDI and LA are well suited to the analysis of a wide range of organic, inorganic and also biological compounds. For complex matrices, it is important to note that information may be obtained on both organic and inorganic species. This is of first importance for the study of environmental or composite samples for example, in which organics, inorganics and/or polymers are intimately associated.
关键词： laser,Fourier transform ion cyclotron resonance mass spectrometry,laser desorption/ionization,organic compounds,mass spectrometry imaging,inorganic compounds,laser ablation
更新于2025-09-16 10:30:52
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Mass spectrometry imaging (MSI) of fresh bones using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI)
摘要： We report an effective strategy for direct analysis and two-dimensional (2D) infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI) of mouse bones that underwent no chemical treatments prior to analysis. To unravel the chemistry in bones under near-physiological conditions, we cut a flash-frozen bone in half longitudinally, placed it in a mold facing flat side down, and poured Plaster of Paris on top of and around the bone. After Plaster of Paris had set, the bone with embedding material was removed from the mold, and placed on the IR-MALDESI imaging stage. Plaster of Paris acted as a fixture to keep every spot on the sample surface the same distance away from the laser focus. To demonstrate the feasibility of IR-MALDESI MSI for analyses of unmodified bones, we imaged bones derived from healthy and stroke-affected mice and generated ion heatmaps showing the spatial distribution of putatively annotated features.
关键词： mouse bones,IR-MALDESI,direct analysis,Plaster of Paris,Mass spectrometry imaging
更新于2025-09-16 10:30:52
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Distribution of Flavan-3-ol Species in Ripe Strawberry Fruit Revealed by Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging
摘要： Flavan-3-ols, which comprise proanthocyanidins and their monomers, are major ?avonoids in strawberries, and they have a wide range of biological activities and health bene?ts. However, their spatial distribution in strawberry fruit remains poorly understood. Therefore, we performed matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI), to visualize ? ?avan-3-ols in ripe strawberry fruit. Peaks matching the m/z values of ?avan-3-ols [M ? H] ions were detected in the negative ion mode using 1,5-diaminonaphthalene as matrix. Catechin and/or epicatechin, three B-type procyanidins, and two B-type propelargonidins were identi?ed by MALDI-tandem MS. These ?avan-3-ols were mainly distributed in the calyx, in and around the vascular bundles, and in the skin. In-source fragmentation of proanthocyanidins was determined using their standards, suggesting their distribution was mixed ion images of themselves, and fragment ions generated from those had a higher degree of polymerization. B-type procyanidins were predominantly distributed in the vascular bundles than in the skin, whereas B-type propelargonidins were almost equally distributed between the vascular bundles and skin, suggesting that their distribution patterns are di?erent from the type of their ?avan-3-ol monomers. Flavan-3-ols, especially B-type procyanidins, may help prevent pathogen infection not only in the skin but also in and around the vascular bundles.
关键词： mass spectrometry imaging (MSI),propelargonidins,procyanidins,proanthocyanidins,?avan-3-ols,strawberry,matrix-assisted laser desorption/ionization (MALDI)
更新于2025-09-16 10:30:52
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Anti-Myocardial Infarction Effects of Radix Aconiti Lateralis Preparata Extracts and Their Influence on Small Molecules in the Heart Using Matrix-Assisted Laser Desorption/Ionization–Mass Spectrometry Imaging
摘要： Radix Aconiti Lateralis Preparata (fuzi) is the processed product of Aconitum carmichaelii Debeaux tuber, and has great potential anti-myocardial infarction e?ects, including improving myocardial damage and energy metabolism in rats. However, the e?ects of Radix Aconiti Lateralis Preparata extracts in a rat model of myocardial infarction have not yet been fully illustrated. Herein, Radix Aconiti Lateral Preparata was used to prepare Radix Aconiti Lateralis Preparata extract (RAE), fuzi polysaccharides (FPS), and fuzi total alkaloid (FTA). Then, we aimed to compare the e?ects of RAE, FPS, and FTA in MI rats and further explore their in?uence on small molecules in the heart. We reported that Radix Aconiti Lateralis Preparata extract (RAE) and fuzi total alkaloid (FTA) signi?cantly improved left ventricular function and structure, and reduced myocardial damage and infarct size in rats with myocardial infarction by the left anterior descending artery ligation. In contrast, fuzi polysaccharides (FPS) was less e?ective than RAE and FTA, indicating that alkaloids might play a major role in the treatment of myocardial infarction. Moreover, via matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI–MSI), we further showed that RAE and FTA containing alkaloids as the main common components regulated myocardial energy metabolism-related molecules and phospholipids levels and distribution patterns against myocardial infarction. In particular, it was FTA, not RAE, that could also regulate potassium ions and glutamine to play a cardioprotective role in myocardial infarction, which revealed that an appropriate dose of alkaloids generated more obvious cardiotonic e?ects. These ?ndings together suggested that Radix Aconiti Lateralis Preparata extracts containing an appropriate dose of alkaloids as its main pharmacological active components exerted protective e?ects against myocardial infarction by improving myocardial energy metabolism abnormalities and changing phospholipids levels and distribution patterns to stabilize the cardiomyocyte membrane structure. Thus, RAE and FTA extracted from Radix Aconiti Lateralis Preparata are potential candidates for the treatment of myocardial infarction.
关键词： myocardial infarction,left anterior descending artery ligation,phospholipid,energy metabolism,matrix-assisted laser desorption/ionization–mass spectrometry imaging,Radix Aconiti Lateralis Preparata
更新于2025-09-16 10:30:52
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Internal Energy Deposition in Infrared Matrix-Assisted Laser Desorption Electrospray Ionization With and Without the Use of Ice as a Matrix
摘要： The internal energy deposited into analytes during the ionization process largely influences the extent of fragmentation, thus the appearance of the resulting mass spectrum. The internal energy distributions of a series of para-substituted benzyl pyridinium cations in liquid and solid-state generated by infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) were measured using the survival yield method, of which results were subsequently compared with conventional electrospray ionization (ESI). The comparable mean internal energy values (e.g., 1.8–1.9 eV at a collision energy of 15 eV) and peak widths obtained with IR-MALDESI and ESI support that IR-MALDESI are essentially a soft ionization technique where analytes do not gain considerable internal energy during the laser-induced desorption process and/or lose energy during uptake into charged electrospray droplets. An unusual fragment ion, protonated pyridine, was only found for solid IR-MALDESI at relatively high collision energies, which is presumably resulted from direct ionization of the pre-charged analytes in form of salts. Analysis of tissue with an ice layer consistently yielded ion populations with higher internal energy than its counterpart without an ice layer, likely due to a substantially enhanced number of IR absorbers with ice. Further measurements with holo-myoglobin show that IR-MALDESI-MS retains the noncovalently bound heme-protein complexes under both native-like and denaturing conditions, while complete loss of the heme group occurred in denaturing ESI-MS, showing that the softness of IR-MALDESI is equivalent or superior to ESI for biomolecules.
关键词： Ambient ionization,Survival yield method,Internal energy deposition,Mass spectrometry imaging,Thermometer ions,IR-MALDESI
更新于2025-09-11 14:15:04
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Rapid Diagnosis Of Drug Agglomeration And Crystallinity In Pharmaceutical Preparations By Electrospray Laser Desorption Ionization Mass Spectrometry Imaging
摘要： In this study we evaluate the applicability of electrospray laser desorption ionization mass spectrometry imaging (ELDI-MSI) to interrogate tablet formulations for the spatial distributions of ingredients. Tablet formulations with varying amounts of crystalline acetaminophen (the active pharmaceutical ingredient, API) were analyzed to determine if crystallinity could be evaluated via ELDI-MSI. ELDI-MSI concurrently imaged the API, binders, and surfactants. The spatial distributions of amorphous API were very similar to that of the surfactants and different from that of crystalline API. The higher the crystallinity in the tablet formulation, the more agglomeration of the active ingredient was observed by ELDI-MSI. This study shows the capability of ELDI-MSI to diagnose agglomeration and crystallinity content in pharmaceutical preparations with little to no sample preparation. The ability to concurrently image APIs with other components provides valuable information as to their form in the tablet.
关键词： ELDI,crystallinity,mass spectrometry imaging,pharmaceuticals,agglomeration
更新于2025-09-11 14:15:04
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Discriminating Normal Regions within Cancerous Hen Ovarian Tissue Using Multivariate Hyperspectral Image Analysis
摘要： Identification of subregions under different pathological conditions on cancerous tissue is of great significance for understanding cancer progression and metastasis. Infrared matrix-assisted laser desorption electrospray ionization mass spectrometry (IR-MALDESI-MS) can be potentially used for the diagnostic purpose since it can monitor spatial distribution and abundance of metabolites and lipids in biological tissues. However, the large size and high dimensionality of hyperspectral data make analysis and interpretation challenging. To overcome these barriers, multivariate methods were applied to IR-MALDESI data for the first time, aiming at efficiently resolving mass spectral images, from which these results were then used to identify normal regions within cancerous tissue.
关键词： Mass Spectrometry Imaging,Multivariate curve resolution-Alternating Least Squares,IR-MALDESI,Ovarian Cancer,Principle Component Analysis
更新于2025-09-10 09:29:36
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NOVEL MATRIX SUBLIMATION DEVICE FOR MALDI MASS SPECTROMETRY IMAGING
摘要： Sublimation is a widely used method for matrix deposition in imaging mass spectrometry experiments. Still, most of the time standard glass sublimators are used for this purpose, which do not enable optimal matrix deposition reproducibility, compromising inter-experiment comparison of the results. Here we present an in-house designed stainless steel sublimator in which the parameters that have the strongest influence over matrix deposition reproducibility can be easily monitored. Using sections of human colon biopsies we demonstrate the capabilities of this new prototype.
关键词： mass spectrometry imaging,matrix sublimation,stainless steel sublimator,reproducibility,MALDI
更新于2025-09-09 09:28:46