Mass Spectrometry Reviews最新文献

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has rapidly advanced in biomedical research, enabling label-free, untargeted spatial detection of metabolites, lipids, proteins, and glycans in tissue sections. However, challenges such as low ionization efficiency and chemical instability limit the detection of certain molecules. To address these issues, on-tissue chemical derivatization (OTCD) has been widely applied as an effective strategy to enhance imaging capabilities. This review systematically summarizes the development of derivatization reagents targeting different reactive functional groups and their applications in MALDI-MSI, including strategies for the derivatization of amines, carbonyls, carboxyls, double bonds, hydroxyls, thiols, and platinum-based drugs. Particular attention is given to how these derivatization reagents enhance the detection range and biological relevance by increasing molecular weight, improving ionization efficiency, and reducing background noise interference. Additionally, we explore the application of OTCD in various biological samples and discuss challenges related to experimental workflows, derivatization efficiency, and tissue integrity. This review provides important theoretical support for the advancement of MSI technology and highlights its broad potential applications in biomedical research.

Tannins are widespread specialized plant metabolites that contribute significantly to the polyphenol content of plant-based diets. Their effects on human and animal health vary depending on their structure, with potential benefits including antioxidative, antimicrobial, anthelmintic, and anticarcinogenic properties. Understanding tannin composition and quantity in plant products is essential, as their bioactivities are influenced by their functional groups. Mass spectrometry-based techniques excel in tannin analysis, offering both qualitative and quantitative insights. Combining ultrahigh-performance liquid chromatography with electrospray ionization and high-resolution and triple quadrupole mass analyzers is optimal for comprehensive tannin profiling. Such an approach enables precise analysis and helps predict tannin bioactivities. This review highlights the mass spectrometric analysis of proanthocyanidins and hydrolysable tannins, addressing ionization techniques, interpretation of multiply charged ions, characteristic fragmentations, and reaction monitoring. Applications related to tannin bioactivities are also briefly discussed, demonstrating the utility of mass spectrometry in tannin analysis in complex sample matrices.

Glycosylation, the enzymatic addition of carbohydrate moieties to proteins, is essential for immune recognition, protein folding, and disease progression. The structural complexity of glycans and the heterogeneity of glycosylation sites present significant challenges towards accurate identification and quantification, necessitating advanced methodologies for comprehensive characterization. Tandem MS (MS/MS) has emerged as the primary analytical platform for glycomics and glycoproteomics. This review highlights the recent developments in fragmentation techniques, ranging from well-established techniques such as CID/HCD and ETD, to newer and more advanced techniques such as electron-based methods (EThcD), photodissociation strategies (UVPD, IRMPD), and hybrid approaches (sceHCD, EThcD-sceHCD, HCD-pd-ETD), each providing distinct advantages towards glycan structure elucidation and glycosite mapping. This review also discusses emerging computational strategies, especially deep learning for automated interpretation of complex glycomics and glycoproteomics data.

The review examines the evolution of chemical ionization mass spectrometry (CI-MS), a technique developed in 1966 by Field and Munson. CI is a soft-ionization method that produces more intense molecular ions with less fragmentation than electron ionization (EI). CI-MS is widely utilized across various fields, including atmospheric chemistry, environmental science, and biomedical research. The article highlights different CI-MS types, such as proton transfer reaction mass spectrometry (PTR-MS), which is renowned for its ability to analyze volatile organic compounds in real-time; negative ion CI-MS, which provides insights into anions; selected ion flow tube mass spectrometry (SIFT-MS), and ion-drift chemical ionization mass spectrometry (ID-CIMS), techniques that allow for the direct analysis of trace gases with high sensitivity and specificity. The article discusses advancements in chromatography with CI-MS, particularly atmospheric pressure chemical ionization (APCI) and liquid electron ionization (LEI) interface. The ongoing exchange of data between fundamental ion/molecule studies and specific applications has significantly boosted the growth of CI-MS in recent decades. In recent years, no extensive review has been published on CI-MS. This article provides an overview of CI-MS technique, its applications, and its evolution over the years, highlighting its importance in advancing scientific research and understanding the chemistry of various environments.

Because matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) induces selective cleavage on the peptide backbone, this technique allows reliable identification of peptides and proteins. In the last 15 years, several new matrices have been developed that more efficiently induce MALDI-ISD, opening new research avenues. Fragmentation of peptides by MALDI-ISD can be divided into two categories: reducing and oxidizing matrices induce selective cleavage of N-Cα and Cα-C bonds, respectively. Regarding the dissociation mechanism, MALDI-ISD was believed, until recently, to be initiated by "hydrogen atom" transfer between an analyte peptide and the matrix. Based on this hypothesis, the origin of the hydrogen atoms would be the aniline group of the matrix in MALDI with a reducing matrix and the amide nitrogen of the peptide backbone in MALDI-ISD with an oxidizing matrix. MALDI-ISD involves homolytic cleavage of N-H bonds, though the N-H bond is generally stronger than O-H and C-H bonds. Notably, mass spectrometry experiments cannot distinguish between "hydrogen atom transfer" and "electron transfer and subsequent proton transfer." Recent well-designed experiments and quantum chemistry calculations have strongly suggested that electron transfer between the peptide and matrix is likely to be the initial step of the MALDI-ISD process. Reducing and oxidizing matrices for MALDI-ISD induce fragmentation through peptide radical anions and cations, respectively. The generated fragment ions and radicals subsequently undergo reactions within the MALDI plume, leading to the formation of stable even-electron ions that are detectable in the mass spectrum. As a result, MALDI-ISD fragments are observed as both positively and negatively charged ions, despite MALDI-ISD entailing the fragmentation of peptide radical anions and cations. The proposed mechanism offers a robust framework for understanding the MALDI-ISD process. A more comprehensive understanding of this process is essential to fully harness the potential of the MALDI-ISD technique and would pave the way for further development of methodologies advancing the field of analytical chemistry based on finding new matrices.

Phytocannabinoids are bioactive metabolites derived from the Cannabis sativa plant. They have garnered attention due to their recreational uses and therapeutic potential. Although various analytical strategies have been employed for their analysis, mass spectrometry (MS) coupled to chromatographic separation is superior due to its sensitivity and selectivity. Various MS-based strategies, namely Gas chromatography (GC-MS) and liquid chromatography - MS (LC-MS) are reviewed with focus on the analysis of phytocannabinoids in vascular matrices. These include plasma, serum, whole blood, and dried blood spots (DBS). Applications, advantages and challenges associated with each MS strategy in vascular matrices are evaluated and critically discussed. In addition, the review outlines the challenges in DBS spot analysis, such as hematocrit bias, versus plasma/serum and whole blood processing, which involves protein removal, extraction and cleanup steps.