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Mass spectrometry imaging of thin-layer chromatography plates using laser desorption/low-temperature plasma ionisation
摘要： Thin-layer chromatography (TLC) is a classic method for the separation and analysis of complex mixtures. Biological assays, chemical derivatisation and spectroscopy techniques are compatible with TLC and provide extra information about isolated compounds. However, coupling TLC to mass spectrometry is hampered by the difficulty to desorb the analytes from the silica surfaces. In this study, we used a multimodal ion source for laser desorption (LD) and low-temperature plasma (LTP) post-ionisation. Efficient desorption was reached by covering the TLC plates with activated carbon. Regions of interest can be analysed by spots, by lines or by area. We show the separation of methylxanthines from coffee, tea and cocoa preparations by TLC, with subsequent mass spectrometry imaging (MSI). Using a lateral resolution of 400 mm × 400 mm, allowed the acquisition of 21,895 spectra in 2.4 h (2.5 pixels/s). Further, we demonstrate the possibility of direct mass fragmentation studies and quantification. We mounted the system on an Open LabBot with a theoretical lateral resolution of 12.5 mm and performed the visualisation of ions of interest and the pixel-wise review of mass spectra with our free software RmsiGUI (https://bitbucket.org/lababi/rmsigui). This non-proprietary and modular platform enables the cost-efficient adaption of the system and further development by the community.
关键词： mass spectrometry imaging,thin-layer chromatography,low-temperature plasma,laser desorption,ambient ionisation
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia) - Bangkok, Thailand (2019.6.12-2019.6.14)] 2019 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia) - Development of Automated LED Light Compensation System for Lycopersicon Esculentum
摘要： The cells in an organism emit different amounts of proteins according to their clinical state (healthy/pathological, for instance). The resulting proteomic pro?le can be used for early detection, diagnosis, and therapy planning. In this paper, we study the classi?cation of a proteomic sample from the point of view of an inverse problem with a joint Bayesian solution, called inversion-classi?cation. We propose a hierarchical physical forward model and present encouraging results from both simulation and clinical data.
关键词： proteins,classi?cation algorithms,proteomics,Statistical signal processing,probability,liquid chromatography,mass spectrometry,selective reaction monitoring,inverse problems,mathematical modelling
更新于2025-09-19 17:13:59
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The Smallest Aromatic Tetracation Produced in Gas Phase by Intense Femtosecond Laser Pulses
摘要： We report the production of long-lived tetracation, which is the smallest aromatic tetracation hexafluorobenzene ever investigated, by 0.8 μm femtosecond laser pulses. The tetracation yield relative to that of trication radical is 0.11. Using the time-of-flight mass spectrometer equipped with the fast ion gate and the curved field reflectron, we estimate the lower limit of the lifetime of tetracation to be 9 μs. Confinement of multiple positive charges in a small organic molecule is unexpected; however, our finding is an answer of this fundamental concern.
关键词： multiply charged ion,tunnel ionization,time-of-flight mass spectrometry
更新于2025-09-19 17:13:59
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Nanocytotoxicity using matrix-assisted laser desorption ionization mass spectrometry
摘要： The analysis of bacteria species using MALDI-MS is simple and fast compared with traditional analysis methods such as cell culture, which requires days and sometime weeks.
关键词： nanocytotoxicity,matrix-assisted laser desorption ionization mass spectrometry,nanomedicine,antibacterials
更新于2025-09-19 17:13:59
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Silicon‐Based Laser Desorption Ionization Mass Spectrometry for the Analysis of Biomolecules: A Progress Report
摘要： Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is widely used in the biomedical field for the label-free analysis of molecules such as drugs, lipids, peptides, proteins, and biological tissues for molecular imaging. However, organic matrices used in traditional MALDI-MS applications introduce excessive interferences in the low m/z range. For this reason, nanostructured materials—and in particular silicon-based LDI strategies—have become a promising alternative, since they provide a much weaker background. Herein, the recent developments in fabrication, functionalization, and practical applications of silicon-based LDI-MS methods are reviewed. Also the basic requirements of silicon-based substrates for optimal LDI analysis by providing an overview of the LDI mechanisms that use silicon-based substrates instead of organic matrices are reported. Finally, the considerable potential of silicon-based substrates is discussed, giving suggestions for topics for future research.
关键词： silicon nanostructures,laser desorption ionization (LDI),surface functionalization,mass spectrometry imaging (MSI)
更新于2025-09-19 17:13:59
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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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Development of ZnO Nanoparticles as an Efficient Zn Fertilizer: Using Synchrotron-Based Techniques and Laser Ablation to Examine Elemental Distribution in Wheat Grain
摘要： Zinc (Zn) deficiency is an important problem worldwide, adversely impacting human health. Using a field trial in China, we compared the foliar-application of both ZnO nanoparticles (ZnO-NPs) and ZnSO4 on winter wheat (Triticum aestivum L.) for increasing the Zn concentration within the grain. We also used synchrotron-based X-ray fluorescence microscopy (μ-XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to examine the distribution of Zn within the grain. We found that ZnO-NPs increase the Zn concentration in the wheat grain, increasing from 18 mg·kg-1 in the control up to 40 mg·kg-1 when the ZnO-NPs were applied four times. These grain Zn concentrations in the ZnO-NP-treated grains are similar to those recommended for human consumption. However, the ZnO-NPs were similar in their effectiveness to ZnSO4. When examining trace element distribution in the grain, the trace elements were found to accumulate primarily in the aleurone layer and the crease region across all treatments. Importantly, Zn concentrations in the grain endosperm increased by nearly 30-fold relative to the control, with this markedly increasing Zn within the edible portion. These results demonstrate that ZnO-NPs is a suitable fertilizer for increasing Zn within wheat grain and can potentially be used to improve human nutrition.
关键词： X-ray fluorescence microscopy (μ-XRF),foliar application,wheat,Zn biofortification,laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS),ZnO-NPs
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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An approach to analysis of primary amines by a combination of thin‐layer chromatography and matrix‐assisted laser desorption ionization mass spectrometry in conjunction with post‐chromatographic derivatization
摘要： On-spot derivatization has been suggested for the modification of primary amine containing compounds for their analysis by thin-layer chromatography hyphenated with matrix-assisted laser desorption ionization mass spectrometry. The proposed approach was based on post-chromatographic treatment of separated analytes inside the chromatographic zones on the thin-layer chromatography plates by tris(2,6-dimethoxyphenyl)methilium reagent. The derivatives, containing permanent positive charge, reveal exceptionally intense peaks of their cationic moieties and high signal/noise ratio in mass spectra recorded directly from the plates. The method was tested on a series of aliphatic, aromatic, and amine-containing pharmaceuticals.
关键词： thin-layer chromatography,mass spectrometry,primary amines,matrix-assisted laser desorption/ionization,derivatization
更新于2025-09-19 17:13:59
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Enrichment and Identification of Metallothionein by Functionalized Nano-Magnetic Particles and Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry
摘要： As a low molecular weight protein with the ability of binding metal ions and high inducibility, metallothionein (MT) is often regarded as an important biomarker for assessment of heavy metal pollution in water environment. In the light of that the traditional process of enrichment and identification is time-consuming and complicated, we prepared a core-shell nanoparticle, gold-coated iron oxide nanoparticles (Fe3O4@Au NPs) herein. It possessed the advantages of fast response to magnetic fields and optical properties attributing to Fe3O4 and Au nanoparticles, respectively. The Fe3O4@Au nanoparticles could be used to enrich MT simply through Au–S interaction, and the purified proteins were determined by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS). The results showed that the Fe3O4@Au nanoparticles could directly enrich MT from complex solutions and the detection limit could be as low as 10 fg mL?1.
关键词： Core-shell structure,Mass spectrometry,Low-abundant,Metallothionein,Gold nanoparticles,Magnetic nanomaterials
更新于2025-09-19 17:13:59