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- 摘要
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- 实验方案
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Study of the Synthetic Potential of the Reaction of Benzimidazole with Bis(iodomethyl)tetramethyldisiloxane by Matrix-Free Laser Desorption/Ionization Mass Spectrometry
摘要： According to the matrix-free laser desorption/ionization time-of-flight mass spectrometric data, the reaction of benzimidazole with bis(iodomethyl)tetramethyldisiloxane at different temperatures leads to the formation of linear and cyclic organosilicon systems containing benzimidazole fragments. The structures of the major and minor products were determined by analysis of the fragmentation patterns in the field-free space.
关键词： bis(iodomethyl)tetramethyldisiloxane,benzimidazole,insertion,fragmentation,alkylation,silanone,laser desorption/ionization
更新于2025-09-23 15:21:01
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High-Throughput Fingerprinting of Rhizobial Free Fatty Acids by Chemical Thin-Film Deposition and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry
摘要： Fatty acids (FAs) represent an important class of metabolites, impacting on membrane building blocks and signaling compounds in cellular regulatory networks. In nature, prokaryotes are characterized with the most impressing FA structural diversity and the highest relative content of free fatty acids (FFAs). In this context, nitrogen-fixing bacteria (order Rhizobiales), the symbionts of legumes, are particularly interesting. Indeed, the FA profiles influence the structure of rhizobial nodulation factors, required for successful infection of plant root. Although FA patterns can be assessed by gas chromatography—(GC-) and liquid chromatography—mass spectrometry (LC-MS), sample preparation for these methods is time-consuming and quantification suffers from compromised sensitivity, low stability of derivatives and artifacts. In contrast, matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) represents an excellent platform for high-efficient metabolite fingerprinting, also applicable to FFAs. Therefore, here we propose a simple and straightforward protocol for high-throughput relative quantification of FFAs in rhizobia by combination of Langmuir technology and MALDI-TOF-MS featuring a high sensitivity, accuracy and precision of quantification. We describe a step-by-step procedure comprising rhizobia culturing, pre-cleaning, extraction, sample preparation, mass spectrometric analysis, data processing and post-processing. As a case study, a comparison of the FFA metabolomes of two rhizobia species—Rhizobium leguminosarum and Sinorhizobium meliloti, demonstrates the analytical potential of the protocol.
关键词： bacteria,metabolic fingerprinting,matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS),barium monocarboxylates,free fatty acids (FFAs),chemical deposition technique,Langmuir film technology,rhizobia
更新于2025-09-23 15:21:01
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Laser Mass Spectrometry
摘要： Mass spectrometry (MS) has been used in a broad range of applications, in chemical, biochemical, pharmaceutical, and environmental fields. Lasers have many uses in MS, such as laser desorption (LD), laser desorption ionization (LDI), matrix-assisted laser desorption ionization (MALDI), and multiphoton ionization (MPI). Herein, recent developments and applications of mass spectrometry with laser beams, including laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), are introduced.
关键词： laser desorption,matrix-assisted laser desorption ionization,multiphoton ionization,Laser abrasion,laser desorption/ionization
更新于2025-09-23 15:19:57
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Co Incorporated Mesoporous Carbon Material Assisted Laser Desorption/Ionization Ion Source as an on-line Interface of in vivo Microdialysis Coupled with Mass Spectrometry
摘要： The combination of microdialysis and mass spectrometry (MS) provides the potential for rapidly monitoring diverse metabolites in vivo. Unfortunately, the high concentration of salt in biological microdialysates hindered the sensitive and on-line detection of these small molecular compounds. In this study, we synthesized Co incorporated mesoporous carbon material (Co-NC), and developed Co-NC assisted laser desorption/ionization (LDI) ion source as an on-line interface of in vivo microdialysis coupled with MS for direct analysis of diverse metabolites in microdialysates. The Co-NC could be used as matrix for surface assisted laser desorption/ionization mass spectrometry (SALDI MS) analysis of small molecular compounds, even under high concentration of salt conditions. The Co-NC possessed the adsorption ability for small molecular compounds, and it was believed that the adsorption ability of Co-NC might separate the analytes from the salt in microdialysates at a microscopic level, which might facilitate the desorption and ionization of the analytes and finally improved the salt-tolerance ability as matrix. Furthermore, the Co-NC assisted LDI ion source as a novel interface of in vivo microdialysis coupled with MS has been applied to the on-line monitoring of liver metabolites from the CCl4-induced liver injury rat model for the first time.
关键词： microdialysis,Co incorporated mesoporous carbon material,metabolites,mass spectrometry,laser desorption/ionization,salt-tolerance
更新于2025-09-23 15:19:57
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Application of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging for Evaluating the Quality of Fish Fillets
摘要： Consumption of fish is rapidly increasing worldwide. It is important to evaluate fish fillet quality because fish undergoes physical and chemical changes during frozen storage. Fish fillets exhibit formaldehyde (FA) accumulation from the decomposition of trimethylamine N-oxide. FA is a powerful protein denaturant; thus, it is important to avoid FA buildup during fish processing to preserve fish quality, especially texture. To determine where FA accumulates, in order to maintain the quality of fish fillets, we performed matrix-assisted laser desorption/ionization mass spectrometry imaging, aiming to identify muscle-derived peptides, which reflect conditions such as denaturation and/or aggregation. We used frozen sections from which lipophilic molecules were washed out and detected various peptide peaks. Furthermore, we tried to identify indices to represent fish fillet softening by protease treatment. We could detect characteristic peaks owing to FA and protease treatment; the findings were consistent with the results of texture profiles showing fish fillet’s real solidity. These molecules might thus serve as effective markers to evaluate fish fillet quality.
关键词： mass spectrometry imaging,peptide,matrix-assisted laser desorption/ionization,protease,formaldehyde
更新于2025-09-23 15:19:57
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HCN emission by a Polydesmid Millipede Detected Remotely by Reactive Adsorption on Gold Nanoparticles Followed by Laser Desorption/Ionization Mass Spectrometry (LDI-MS)
摘要： Hydrocyanic acid (HCN) is a well-known defensive allomone in the chemical arsenal of millipedes in the order Polydesmida. The presence of HCN in the headspace vapor of adult Xystocheir dissecta (Wood, 1867), a common millipede from the San Francisco Bay Area, was traced by laser desorption/ionization-mass spectrometry (LDI-MS). To accomplish this, the headspace vapor surrounding caged, live millipedes was allowed to diffuse passively over gold-nanoparticle (AuNP) deposits placed at various distances from the emitting source. The stainless steel plates with AuNP deposits were removed and irradiated by a 355-nm laser. The gaseous ions generated in this way were detected by time-of-flight mass spectrometry. The intensity of the mass spectrometric peak detected at m/z 249 for the Au(CN)2? complex anion was compared to that of the residual Au? signal (m/z 197). Using this procedure, HCN vapors produced by the live millipedes could be detected up to 50 cm away from the source. Furthermore, the addition of H2O2, as an internal oxygen source for the gold cyanidation reaction that takes place in the AuNP deposits, significantly increased the detection sensitivity. Using the modified H2O2 addition procedure, HCN could now be detected at 80 cm from the source. Moreover, we found a decreasing intensity ratio of the Au(CN)2?/Au? signals as the distance from the emitting source increased, following an exponential-decay distribution as predicted by Fick’s law of diffusion.
关键词： Gold nanoparticles (AuNP),Polydesmida,Laser desorption/ionization (LDI),Millipedes,Hydrogen cyanide (HCN),Hydrogen peroxide (H2O2),Allomones
更新于2025-09-23 15:19:57
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Unique Distribution of Diacyl-, Alkylacyl-, and Alkenylacyl-Phosphatidylcholine Species Visualized in Pork Chop Tissues by Matrix-Assisted Laser Desorption/Ionizationa??Mass Spectrometry Imaging
摘要： Phosphatidylcholine (PC) is the major phospholipid in meat and in?uences meat qualities, such as healthiness. PC is classi?ed into three groups based on the bond at the sn-1 position: Diacyl, alkylacyl, and alkenylacyl. To investigate their composition and distribution in pork tissues, including longissimus thoracis et lumborum (loin) spinalis muscles, intermuscular fat, and transparent tissues, we performed matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI–MSI). Eleven diacyl-, seven alkylacyl-, and six alkenylacyl-PCs were identi?ed using liquid chromatography (LC)-tandem MS (MS/MS) analysis. Despite many alkylacyl- and alkenylacyl-PC species sharing identical m/z values, we were able to visualize these PC species using MALDI–MSI. Diacyl- and alkylacyl- and/or alkenylacyl-PC species showed unique distribution patterns in the tissues, suggesting that their distribution patterns were dependent on their fatty acid compositions. PCs are a major dietary source of choline in meat, and the amount was signi?cantly higher in the muscle tissues. Consumption of choline mitigates age-related memory decline and neurodegenerative diseases; therefore, the consumption of pork muscle tissues could help to mitigate these diseases. These results support the use of MALDI–MSI analysis for assessing the association between PC species and the quality parameters of meat.
关键词： mass spectrometry imaging (MSI),lipid distribution,phosphatidylcholines,liquid chromatography-tandem mass spectrometry (LC-MS/MS),pork,matrix-assisted laser desorption/ionization (MALDI)
更新于2025-09-23 15:19:57
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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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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