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Bao Z, Yu D, Fu J, Gu J, Xu J, Qin L, Hu H, Yang C, Liu W, Chen L, Wu R, Liu H, Xu H, Guo H, Wang L, Zhou Y, Li Q, Wang X. 2-Hydroxy-5-nitro-3-(trifluoromethyl)pyridine as a Novel Matrix for Enhanced MALDI Imaging of Tissue Metabolites. Anal Chem 2024; 96:5160-5169. [PMID: 38470972 DOI: 10.1021/acs.analchem.3c05235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), which is a label-free imaging technique, determines the spatial distribution and relative abundance of versatile endogenous metabolites in tissues. Meanwhile, matrix selection is generally regarded as a pivotal step in MALDI tissue imaging. This study presents the first report of a novel MALDI matrix, 2-hydroxy-5-nitro-3-(trifluoromethyl)pyridine (HNTP), for the in situ detection and imaging of endogenous metabolites in rat liver and brain tissues by MALDI-MS in positive-ion mode. The HNTP matrix exhibits excellent characteristics, including strong ultraviolet absorption, μm-scale matrix crystals, high chemical stability, low background ion interference, and high metabolite ionization efficiency. Notably, the HNTP matrix also shows superior detection capabilities, successfully showing 185 detectable metabolites in rat liver tissue sections. This outperforms the commonly used matrices of 2,5-dihydroxybenzoic acid and 2-mercaptobenzothiazole, which detect 145 and 120 metabolites from the rat liver, respectively. Furthermore, a total of 152 metabolites are effectively detected and imaged in rat brain tissue using the HNTP matrix, and the spatial distribution of these compounds clearly shows the heterogeneity of the rat brain. The results demonstrate that HNTP is a new and powerful positive-ion mode matrix to enhance the analysis of metabolites in biological tissues by MALDI-MSI.
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Affiliation(s)
- Zhibin Bao
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Dian Yu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Jinxiang Fu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Jianchi Gu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Jia Xu
- Department of Clinical Laboratory, Xiyuan Hospital, China Academy of Chinese Medical Sciences, #1 Xiyuangcaochang, Beijing 100091, China
| | - Liang Qin
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Hao Hu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Chenyu Yang
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Wenjuan Liu
- Department of Clinical Laboratory, Xiyuan Hospital, China Academy of Chinese Medical Sciences, #1 Xiyuangcaochang, Beijing 100091, China
| | - Lulu Chen
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Ran Wu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Haiqiang Liu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Hualei Xu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Hua Guo
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Lei Wang
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Yijun Zhou
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
| | - Qi Li
- Department of Clinical Laboratory, Xiyuan Hospital, China Academy of Chinese Medical Sciences, #1 Xiyuangcaochang, Beijing 100091, China
| | - Xiaodong Wang
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China
- Centre for Imaging & Systems Biology, College of Life and Environmental Sciences, Minzu University of China, #27 Zhongguancun South Avenue, Beijing 100081, China
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2
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Hanin A, Chollet C, Demeret S, Di Meglio L, Castelli F, Navarro V. Metabolomic changes in adults with status epilepticus: A human case-control study. Epilepsia 2024; 65:929-943. [PMID: 38339978 DOI: 10.1111/epi.17899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/12/2024] [Accepted: 01/16/2024] [Indexed: 02/12/2024]
Abstract
OBJECTIVE Status epilepticus (SE) is a life-threatening prolonged epileptic seizure that affects ~40 per 100 000 people yearly worldwide. The persistence of seizures may lead to excitotoxic processes, neuronal loss, and neuroinflammation, resulting in long-term neurocognitive and functional disabilities. A better understanding of the pathophysiological mechanisms underlying SE consequences is crucial for improving SE management and preventing secondary neuronal injury. METHODS We conducted a comprehensive untargeted metabolomic analysis, using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), on plasma and cerebrospinal fluid (CSF) samples from 78 adult patients with SE and 107 control patients without SE, including 29 with CSF for both groups. The metabolomic fingerprints were compared between patients with SE and controls. Metabolites with differences in relative abundances that could not be attributed to treatment or nutrition provided in the intensive care unit were isolated. Enrichment analysis was performed on these metabolites to identify the most affected pathways. RESULTS We identified 76 metabolites in the plasma and 37 in the CSF that exhibited differential expression in patients with SE compared to controls. The enrichment analysis revealed that metabolic dysregulations in patients with SE affected primarily amino acid metabolism (including glutamate, alanine, tryptophan, glycine, and serine metabolism), pyrimidine metabolism, and lipid homeostasis. Specifically, patients with SE had elevated levels of pyruvate, quinolinic acid, and keto butyric acid levels, along with lower levels of arginine, N-acetylaspartylglutamate (NAAG), tryptophan, uracil, and uridine. The tryptophan kynurenine pathway was identified as the most significantly altered in SE, resulting in the overproduction of quinolinic acid, an N-methyl-d-aspartate (NMDA) receptor agonist with pro-inflammatory properties. SIGNIFICANCE This study has identified several pathways that may play pivotal roles in SE consequences, such as the tryptophan kynurenine pathway. These findings offer novel perspectives for the development of neuroprotective therapeutics.
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Affiliation(s)
- Aurélie Hanin
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, USA
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié-Salpêtrière, Paris, France
- AP-HP, Epilepsy Unit and Clinical Neurophysiology Department, DMU Neurosciences, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Céline Chollet
- Université Paris Saclay, CEA, INRAE, Médicaments et Technologies pour la Santé (MTS), MetaboHUB, Gif-sur-Yvette, France
| | - Sophie Demeret
- AP-HP, Neuro-Intensive Care Unit, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Lucas Di Meglio
- AP-HP, Neuro-Intensive Care Unit, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Florence Castelli
- Université Paris Saclay, CEA, INRAE, Médicaments et Technologies pour la Santé (MTS), MetaboHUB, Gif-sur-Yvette, France
| | - Vincent Navarro
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié-Salpêtrière, Paris, France
- AP-HP, Epilepsy Unit and Clinical Neurophysiology Department, DMU Neurosciences, Hôpital de la Pitié-Salpêtrière, Paris, France
- Center of Reference for Rare Epilepsies, Epicare, Hôpital de la Pitié-Salpêtrière, Paris, France
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3
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Nestor L, De Bundel D, Vander Heyden Y, Smolders I, Van Eeckhaut A. Unravelling the brain metabolome: A review of liquid chromatography - mass spectrometry strategies for extracellular brain metabolomics. J Chromatogr A 2023; 1712:464479. [PMID: 37952387 DOI: 10.1016/j.chroma.2023.464479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 10/27/2023] [Accepted: 10/29/2023] [Indexed: 11/14/2023]
Abstract
The analysis of the brain extracellular metabolome is of interest for numerous subdomains within neuroscience. Not only does it provide information about normal physiological functions, it is even more of interest for biomarker discovery and target discovery in disease. The extracellular analysis of the brain is particularly interesting as it provides information about the release of mediators in the brain extracellular fluid to look at cellular signaling and metabolic pathways through the release, diffusion and re-uptake of neurochemicals. In vivo samples are obtained through microdialysis, cerebral open-flow microperfusion or solid-phase microextraction. The analytes of potential interest are typically low in concentration and can have a wide range of physicochemical properties. Liquid chromatography coupled to mass spectrometry has proven its usefulness in brain metabolomics. It allows sensitive and specific analysis of low sample volumes, obtained through different approaches. Several strategies for the analysis of the extracellular fluid have been proposed. The most widely used approaches apply sample derivatization, specific stationary phases and/or hydrophilic interaction liquid chromatography. Miniaturization of these methods allows an even higher sensitivity. The development of chiral metabolomics is indispensable, as it allows to compare the enantiomeric ratio of compounds and provides even more challenges. Some limitations continue to exist for the previously developed methods and the development of new, more sensitive methods remains needed. This review provides an overview of the methods developed for sampling and liquid chromatography-mass spectrometry analysis of the extracellular metabolome.
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Affiliation(s)
- Liam Nestor
- Research group Experimental Pharmacology (EFAR), Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Dimitri De Bundel
- Research group Experimental Pharmacology (EFAR), Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Yvan Vander Heyden
- Department of Analytical Chemistry, Applied Chemometrics and Molecular Modelling (FABI), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Ilse Smolders
- Research group Experimental Pharmacology (EFAR), Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Ann Van Eeckhaut
- Research group Experimental Pharmacology (EFAR), Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
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4
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Lu W, Park NR, TeSlaa T, Jankowski CS, Samarah L, McReynolds M, Xing X, Schembri J, Woolf MT, Rabinowitz JD, Davidson SM. Acidic Methanol Treatment Facilitates Matrix-Assisted Laser Desorption Ionization-Mass Spectrometry Imaging of Energy Metabolism. Anal Chem 2023; 95:14879-14888. [PMID: 37756255 PMCID: PMC10568533 DOI: 10.1021/acs.analchem.3c01875] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 08/15/2023] [Indexed: 09/29/2023]
Abstract
Detection of small molecule metabolites (SMM), particularly those involved in energy metabolism using MALDI-mass spectrometry imaging (MSI), is challenging due to factors including ion suppression from other analytes present (e.g., proteins and lipids). One potential solution to enhance SMM detection is to remove analytes that cause ion suppression from tissue sections before matrix deposition through solvent washes. Here, we systematically investigated solvent treatment conditions to improve SMM signal and preserve metabolite localization. Washing with acidic methanol significantly enhances the detection of phosphate-containing metabolites involved in energy metabolism. The improved detection is due to removing lipids and highly polar metabolites that cause ion suppression and denaturing proteins that release bound phosphate-containing metabolites. Stable isotope infusions of [13C6]nicotinamide coupled to MALDI-MSI ("Iso-imaging") in the kidney reveal patterns that indicate blood vessels, medulla, outer stripe, and cortex. We also observed different ATP:ADP raw signals across mouse kidney regions, consistent with regional differences in glucose metabolism favoring either gluconeogenesis or glycolysis. In mouse muscle, Iso-imaging using [13C6]glucose shows high glycolytic flux from infused circulating glucose in type 1 and 2a fibers (soleus) and relatively lower glycolytic flux in type 2b fiber type (gastrocnemius). Thus, improved detection of phosphate-containing metabolites due to acidic methanol treatment combined with isotope tracing provides an improved way to probe energy metabolism with spatial resolution in vivo.
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Affiliation(s)
- Wenyun Lu
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Noel R. Park
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
| | - Tara TeSlaa
- Department
of Molecular and Medical Pharmacology, University
of California Los Angeles, Los Angeles, California 90095, United States
| | - Connor S.R. Jankowski
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
| | - Laith Samarah
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
| | - Melanie McReynolds
- Department
of Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Xi Xing
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Jessica Schembri
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
| | - Morgan T. Woolf
- Department
of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joshua D. Rabinowitz
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
- Rutgers
Cancer Institute of New Jersey (CINJ), Rutgers
University, New Brunswick, New Jersey 08901, United States
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Ludwig
Institute for Cancer Research, Princeton
University, Princeton, New Jersey 08544, United States
| | - Shawn M. Davidson
- Lewis
Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, United States
- Rutgers
Cancer Institute of New Jersey (CINJ), Rutgers
University, New Brunswick, New Jersey 08901, United States
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5
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Xu H, Hao Q, Liu H, Chen L, Wu R, Qin L, Guo H, Li J, Yang C, Hu H, Xue K, Feng J, Zhou Y, Liu B, Li G, Wang X. A concentration-descending washing strategy with methanol for the enhancement of protein imaging in biological tissues by MALDI-MS. Analyst 2023; 148:823-831. [PMID: 36637134 DOI: 10.1039/d2an01678h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a powerful approach that has been widely used for in situ detection of various endogenous compounds in tissues. However, there are still challenges with in situ analysis of proteins using MALDI-MSI due to the ion suppression effects of small molecules in tissue sections. Therefore, tissue-washing steps are crucial for protein MALDI tissue imaging to remove these interfering molecules. Here, we successfully developed a new method named the concentration-descending washing strategy (CDWS) with methanol (MeOH), i.e., washing of biological tissue with 100%, 95%, and 70% MeOH solutions, for the enhancement of endogenous in situ protein detection and imaging in tissues using MALDI-MS. The method of MeOH-based CDWS (MeOH-CDWS) led to the successful in situ detection of 272 ± 3, 185 ± 4, and 134 ± 2 protein ion signals from rat liver, rat brain, and germinating Chinese-yew seed tissue sections, respectively. By comparison, 161 ± 2, 121 ± 1, and 114 ± 2 protein ions were detected by three commonly used methods, i.e., Carnoy's wash, ethanol (EtOH)-based CAWS (i.e., concentration-ascending washing strategy, 70% EtOH followed by 90% EtOH/9% AcOH), and isopropanol (iPrOH)-based CAWS (70% iPrOH followed by 95% iPrOH), respectively, in rat liver tissue sections, indicating that 68.9 ± 3.1%, 124.8 ± 3.3%, and 138.6 ± 4.4% more protein ion signals could be detected by the use of MeOH-CDWS than the three abovementioned washing strategies. Our results show that the use of MeOH-CDWS improves the performance of MALDI-MSI for in situ protein detection such as the number and intensity of proteins. The use of MeOH-CDWS improves the fixation of proteins and thus reduces the loss of proteins, which significantly reduces protein delocalization in tissue and enhances the performance of MALDI tissue imaging of protein. Thus, the use of MeOH-CDWS improves the quality of protein images in tissue sections through MALDI-MSI and has the potential to be used as standard practice for MALDI tissue imaging of proteins.
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Affiliation(s)
- Hualei Xu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Qichen Hao
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Haiqiang Liu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Lulu Chen
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Ran Wu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Liang Qin
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Hua Guo
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Jinrong Li
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Chenyu Yang
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Hao Hu
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Kun Xue
- College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Jinchao Feng
- College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Yijun Zhou
- College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
| | - Biao Liu
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Nanjing 210042, China.
| | - Gaopeng Li
- General Surgery Department, Shanxi Bethune Hospital, Taiyuan 030032, China.
| | - Xiaodong Wang
- Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), State Ethnic Affairs Commission, Beijing 100081, China. .,College of Life and Environmental Sciences, Centre for Imaging & Systems Biology, Minzu University of China, Beijing 100081, China
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6
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018. MASS SPECTROMETRY REVIEWS 2023; 42:227-431. [PMID: 34719822 DOI: 10.1002/mas.21721] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.
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Affiliation(s)
- David J Harvey
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, UK
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7
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Zhang YX, Zhang YD, Shi YP. A reliable and effective sample preparation protocol of MALDI-TOF-MSI for lipids imaging analysis in hard and dry cereals. Food Chem 2023; 398:133911. [DOI: 10.1016/j.foodchem.2022.133911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 07/18/2022] [Accepted: 08/07/2022] [Indexed: 11/27/2022]
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8
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Liu Y, Li G, Gu TJ, Li L. Nanosecond Photochemical Reaction for Enhanced Identification, Quantification, and Visualization of Primary Amine-Containing Metabolites by MALDI-Mass Spectrometry. Anal Chem 2022; 94:3774-3781. [PMID: 35189681 DOI: 10.1021/acs.analchem.1c03840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many metabolites, including amino acids, neurotransmitters, and pharmaceuticals, contain primary amine functional groups. The analysis of these molecules by mass spectrometry (MS) plays an important role in the study of cancers and psychogenic diseases. However, the MS-based detection and visualization of these bioactive metabolites directly from real biological systems still suffer from challenges such as low ionization efficiency and/or matrix interference effects. Here, we introduce a simple and efficient strategy, the nanosecond photochemical reaction (nsPCR)-enabled fast chemical derivatization, enabling direct MS analysis of primary amine-containing metabolites, with enhanced detection sensitivity for numerous metabolites from cell culture medium and rat brain sections. Furthermore, this nsPCR-based chemical derivatization strategy was demonstrated to be a useful visualizing tool that could provide improved spatial information for these metabolites, potentially offering alternative tools for gaining novel insights into metabolic events.
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Affiliation(s)
- Yuan Liu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Gongyu Li
- Research Center for Analytical Science and Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Ting-Jia Gu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Lingjun Li
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.,Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
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9
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Lai W, Du D, Chen L. Metabolomics Provides Novel Insights into Epilepsy Diagnosis and Treatment: A Review. Neurochem Res 2022; 47:844-859. [PMID: 35067830 DOI: 10.1007/s11064-021-03510-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/04/2021] [Accepted: 12/14/2021] [Indexed: 02/05/2023]
Abstract
Epilepsy is one of the most common diseases of the central nervous system. The diagnosis of epilepsy mainly depends on electroencephalograms and symptomatology, while diagnostic biofluid markers are still lacking. In addition, approximately 30% of patients with epilepsy (PWE) show a poor response to the currently available anti-seizure medicines. An increasing number of studies have reported alterations in the blood, brain tissue, cerebrospinal fluid and urine metabolome in PWE and animal models of epilepsy. The aim of this review was to identify potential metabolic biomarkers and pathways that might facilitate diagnostic, therapeutic and prognostic determination in PWE and the understanding of the pathogenesis of the disease. The PubMed and Embase databases were searched for metabolomic studies of PWE and epileptic models published before December 2020. The study objectives, types of models and reported differentially altered metabolites were examined and compared. Pathway analyses were performed using MetaboAnalyst 5.0 online software. Thirty-five studies were included in this review. Metabolites such as glutamate, lactate and citrate were disturbed in both PWE and epileptic models, which might be potential biomarkers of epilepsy. Metabolic pathways including alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism; glycerophospholipid metabolism; glyoxylate and dicarboxylate metabolism; and arginine and proline metabolism were involved in epilepsy. These pathways might play important roles in the pathogenesis of the disease. This review summarizes metabolites and metabolic pathways related to epilepsy and provides a novel perspective for the identification of potential biomarkers and therapeutic targets for epilepsy.
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Affiliation(s)
- Wanlin Lai
- Department of Neurology, West China Hospital of Sichuan University, No.37 Guoxue Alley, Chengdu, 610041, People's Republic of China
| | - Dan Du
- West China-Washington Mitochondria and Metabolism Center, Advanced Mass Spectrometry Centre, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital of Sichuan University, No.37 Guoxue Alley, Chengdu, 610041, People's Republic of China
| | - Lei Chen
- Department of Neurology, West China Hospital of Sichuan University, No.37 Guoxue Alley, Chengdu, 610041, People's Republic of China.
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10
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Pathmasiri KC, Nguyen TTA, Khamidova N, Cologna SM. Mass spectrometry-based lipid analysis and imaging. CURRENT TOPICS IN MEMBRANES 2021; 88:315-357. [PMID: 34862030 DOI: 10.1016/bs.ctm.2021.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mass spectrometry imaging (MSI) is a powerful tool for in situ mapping of analytes across a sample. With growing interest in lipid biochemistry, the ability to perform such mapping without antibodies has opened many opportunities for MSI and lipid analysis. Herein, we discuss the basics of MSI with particular emphasis on MALDI mass spectrometry and lipid analysis. A discussion of critical advancements as well as protocol details are provided to the reader. In addition, strategies for improving the detection of lipids, as well as applications in biomedical research, are presented.
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Affiliation(s)
- Koralege C Pathmasiri
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, United States
| | - Thu T A Nguyen
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, United States
| | - Nigina Khamidova
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, United States
| | - Stephanie M Cologna
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, United States; Laboratory of Integrated Neuroscience, University of Illinois at Chicago, Chicago, IL, United States.
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11
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Merdas M, Lagarrigue M, Vanbellingen Q, Umbdenstock T, Da Violante G, Pineau C. On-tissue chemical derivatization reagents for matrix-assisted laser desorption/ionization mass spectrometry imaging. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 56:e4731. [PMID: 34080257 DOI: 10.1002/jms.4731] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 03/26/2021] [Accepted: 04/13/2021] [Indexed: 05/27/2023]
Abstract
Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a key tool for the analysis of biological tissues. It provides spatial and quantitative information about different types of analytes within tissue sections. Despite the increasing improvements of this technique, the low detection sensitivity of some compounds remains an important challenge to overcome. Poor sensitivity is related to weak ionization efficiency, low abundance of analytes and matrix ions, or endogenous interferences. On-tissue chemical derivatization (OTCD) has proven to be an important solution to these issues and is increasingly employed in MALDI MSI studies. OTCD reagents, synthesized or commercially available, have been essentially used for the detection of small exogenous or endogenous molecules within tissues. Optimally, an OTCD reaction is performed in mild conditions, in an acceptable range of time, preserves the integrity of the tissues, and prevents the delocalization. In addition to their reactivity with a targeted chemical function, some OTCD reagents can also be used as a matrix, which simplifies the sample preparation procedure. In this review, we present an exhaustive overview of OTCD reagents and methods used in MALDI MSI studies.
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Affiliation(s)
- Mira Merdas
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail) - UMR_S 1085, Rennes, F-35042, France
- Protim, Univ Rennes, Rennes, F-35042, France
- DMPK Department, Technologie Servier, Orléans, 45007, France
| | - Mélanie Lagarrigue
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail) - UMR_S 1085, Rennes, F-35042, France
- Protim, Univ Rennes, Rennes, F-35042, France
| | | | | | | | - Charles Pineau
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail) - UMR_S 1085, Rennes, F-35042, France
- Protim, Univ Rennes, Rennes, F-35042, France
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12
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Wang Y, Hummon AB. MS imaging of multicellular tumor spheroids and organoids as an emerging tool for personalized medicine and drug discovery. J Biol Chem 2021; 297:101139. [PMID: 34461098 PMCID: PMC8463860 DOI: 10.1016/j.jbc.2021.101139] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/22/2022] Open
Abstract
MS imaging (MSI) is a powerful tool in drug discovery because of its ability to interrogate a wide range of endogenous and exogenous molecules in a broad variety of samples. The impressive versatility of the approach, where almost any ionizable biomolecule can be analyzed, including peptides, proteins, lipids, carbohydrates, and nucleic acids, has been applied to numerous types of complex biological samples. While originally demonstrated with harvested organs from animal models and biopsies from humans, these models are time consuming and expensive, which makes it necessary to extend the approach to 3D cell culture systems. These systems, which include spheroid models, prepared from immortalized cell lines, and organoid cultures, grown from patient biopsies, can provide insight on the intersection of molecular information on a spatial scale. In particular, the investigation of drug compounds, their metabolism, and the subsequent distribution of their metabolites in 3D cell culture systems by MSI has been a promising area of study. This review summarizes the different ionization methods, sample preparation steps, and data analysis methods of MSI and focuses on several of the latest applications of MALDI-MSI for drug studies in spheroids and organoids. Finally, the application of this approach in patient-derived organoids to evaluate personalized medicine options is discussed.
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Affiliation(s)
- Yijia Wang
- Department of Chemistry and Biochemistry, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA
| | - Amanda B Hummon
- Department of Chemistry and Biochemistry, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA.
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13
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Wang N, Dartois V, Carter CL. An optimized method for the detection and spatial distribution of aminoglycoside and vancomycin antibiotics in tissue sections by mass spectrometry imaging. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 56:e4708. [PMID: 33586279 PMCID: PMC8032321 DOI: 10.1002/jms.4708] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/20/2021] [Accepted: 01/26/2021] [Indexed: 05/08/2023]
Abstract
Suboptimal antibiotic dosing has been identified as one of the key drivers in the development of multidrug-resistant (MDR) bacteria that have become a global health concern. Aminoglycosides and vancomycin are broad-spectrum antibiotics used to treat critically ill patients infected by a variety of MDR bacterial species. Resistance to these antibiotics is becoming more prevalent. In order to design proper antibiotic regimens that maximize efficacy and minimize the development of resistance, it is pivotal to obtain the in situ pharmacokinetic-pharmacodynamic profiles at the sites of infection. Mass spectrometry imaging (MSI) is the ideal technique to achieve this. Aminoglycosides, due to their structure, suffer from poor ionization efficiency. Additionally, ion suppression effects by endogenous molecules greatly inhibit the detection of aminoglycosides and vancomycin at therapeutic levels. In the current study, an optimized method was developed that enabled the detection of these antibiotics by MSI. Tissue spotting experiments demonstrated a 5-, 15-, 35-, and 54-fold increase in detection sensitivity in the washed samples for kanamycin, amikacin, streptomycin, and vancomycin, respectively. Tissue mimetic models were utilized to optimize the washing time and matrix additive concentration. These studies determined the improved limit of detection was 40 to 5 μg/g of tissue for vancomycin and streptomycin, and 40 to 10 μg/g of tissue for kanamycin and amikacin. The optimized protocol was applied to lung sections from mice dosed with therapeutic levels of kanamycin and vancomycin. The washing protocol enabled the first drug distribution investigations of aminoglycosides and vancomycin by MSI, paving the way for site-of-disease antibiotic penetration studies.
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Affiliation(s)
- Ning Wang
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Véronique Dartois
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Department of Medical Sciences, Hackensack School of Medicine, Nutley, New Jersey, USA
| | - Claire L. Carter
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
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14
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Zahraei A, Guo G, Perwick RD, Donaldson PJ, Demarais NJ, Grey AC. Mapping glucose metabolites in the normal bovine lens: Evaluation and optimisation of a matrix-assisted laser desorption/ionisation imaging mass spectrometry method. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 56:e4666. [PMID: 33089566 DOI: 10.1002/jms.4666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/02/2020] [Accepted: 09/25/2020] [Indexed: 06/11/2023]
Abstract
The spatial resolution of microdissection-based analytical methods to detect ocular lens glucose uptake, transport and metabolism are poor, whereas the multiplexing capability of fluorescence microscopy-based approaches to simultaneously detect multiple glucose metabolites is limited in comparison with mass spectrometry-based methods. To better understand lens glucose transport and metabolism, a more highly spatially resolved technique that maintains the fragile ocular lens tissue is required. In this study, a sample preparation method for matrix-assisted laser desorption/ionisation imaging mass spectrometry (MALDI IMS) analysis of ocular lens glucose uptake and metabolism has been evaluated and optimised. Matrix choice, tissue preparation and normalisation strategy were determined using negative ion mode MALDI-Fourier transform-ion cyclotron resonance MS of bovine lens tissue and validation performed using gas chromatography-MS. An internal standard was applied concurrently with N-(1-naphthyl)ethylenediamine dihydrochloride (NEDC) matrix to limit cracking of the fresh frozen lens tissue sections. MALDI IMS data were collected at a variety of spatial resolutions to detect both endogenous lens metabolites and stable isotopically labelled glucose introduced by ex vivo lens culture. Using this approach, initial steps in important metabolic processes that are linked to diabetic cataract formation were spatially mapped in the bovine lens. In the future, this method can be applied to study the dynamics of glucose uptake, transport and metabolic flux to aid in the study of diabetic lens cataract pathophysiology.
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Affiliation(s)
- Ali Zahraei
- School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - George Guo
- School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Rebecca D Perwick
- School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J Donaldson
- School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Nicholas J Demarais
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Angus C Grey
- School of Medical Sciences, University of Auckland, Auckland, New Zealand
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15
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Zhang D, Bian Q, Zhou Y, Huang Q, Gao J. The application of label-free imaging technologies in transdermal research for deeper mechanism revealing. Asian J Pharm Sci 2020; 16:265-279. [PMID: 34276818 PMCID: PMC8261078 DOI: 10.1016/j.ajps.2020.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/23/2020] [Accepted: 07/06/2020] [Indexed: 12/13/2022] Open
Abstract
The penetration behavior of topical substances in the skin not only relates to the transdermal delivery efficiency but also involves the safety and therapeutic effect of topical products, such as sunscreen and hair growth products. Researchers have tried to illustrate the transdermal process with diversified theories and technologies. Directly observing the distribution of topical substances on skin by characteristic imaging is the most convincing approach. Unfortunately, fluorescence labeling imaging, which is commonly used in biochemical research, is limited for transdermal research for most topical substances with a molecular mass less than 500 Da. Label-free imaging technologies possess the advantages of not requiring any macromolecular dyes, no tissue destruction and an extensive substance detection capability, which has enabled rapid development of such technologies in recent years and their introduction to biological tissue analysis, such as skin samples. Through the specific identification of topical substances and endogenous tissue components, label-free imaging technologies can provide abundant tissue distribution information, enrich theoretical and practical guidance for transdermal drug delivery systems. In this review, we expound the mechanisms and applications of the most popular label-free imaging technologies in transdermal research at present, compare their advantages and disadvantages, and forecast development prospects.
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Affiliation(s)
- Danping Zhang
- Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Qiong Bian
- Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yi Zhou
- Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Qiaoling Huang
- The Third People's Hospital of Hangzhou, Hangzhou 310012, China
| | - Jianqing Gao
- Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Jiangsu Engineering Research Center for New-Type External and Transdermal Preparations, Changzhou 213000, China
- Corresponding author.
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16
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Sun C, Liu W, Ma S, Zhang M, Geng Y, Wang X. Development of a high-coverage matrix-assisted laser desorption/ionization mass spectrometry imaging method for visualizing the spatial dynamics of functional metabolites in Salvia miltiorrhiza Bge. J Chromatogr A 2020; 1614:460704. [DOI: 10.1016/j.chroma.2019.460704] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 11/09/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022]
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17
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Sun C, Li Z, Ma C, Zang Q, Li J, Liu W, Zhao H, Wang X. Acetone immersion enhanced MALDI-MS imaging of small molecule metabolites in biological tissues. J Pharm Biomed Anal 2019; 176:112797. [DOI: 10.1016/j.jpba.2019.112797] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 07/28/2019] [Accepted: 07/31/2019] [Indexed: 12/22/2022]
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18
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Rzagalinski I, Kovačević B, Hainz N, Meier C, Tschernig T, Volmer DA. Toward Higher Sensitivity in Quantitative MALDI Imaging Mass Spectrometry of CNS Drugs Using a Nonpolar Matrix. Anal Chem 2018; 90:12592-12600. [PMID: 30260620 DOI: 10.1021/acs.analchem.8b02740] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tissue-specific ion suppression is an unavoidable matrix effect in MALDI mass spectrometry imaging (MALDI-MSI), the negative impact of which on precision and accuracy in quantitative MALDI-MSI can be reduced to some extent by applying isotope internal standards for normalization and matrix-matched calibration routines. The detection sensitivity still suffers, however, often resulting in significant loss of signal for the investigated analytes. An MSI application considerably affected by this phenomenon is the quantitative spatial analysis of central nervous system (CNS) drugs. Most of these drugs are low molecular weight, lipophilic compounds, which exhibit inefficient desorption and ionization during MALDI using conventional polar acidic matrices (CHCA, DHB). Here, we present the application of the (2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile) matrix for high sensitivity imaging of CNS drugs in mouse brain sections. Since DCTB is usually described as an electron-transfer matrix, we provide a rationale (i.e., computational calculations of gas-phase proton affinity and ionization energy) for an additional proton-transfer ionization mechanism with this matrix. Furthermore, we compare the extent of signal suppression for five different CNS drugs when employing DCTB versus CHCA matrices. The results showed that the signal suppression was not only several times lower with DCTB than with CHCA but also depended on the specific tissue investigated. Finally, we present the application of DCTB and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry to quantitative MALDI imaging of the anesthetic drug xylazine in mouse brain sections based on a linear matrix-matched calibration curve. DCTB afforded up to 100-fold signal intensity improvement over CHCA when comparing representative single MSI pixels and >440-fold improvement for the averaged mass spectrum of the adjacent tissue sections.
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Affiliation(s)
- Ignacy Rzagalinski
- Institute of Bioanalytical Chemistry , Saarland University , 66123 Saarbrücken , Germany
| | - Borislav Kovačević
- Group for Computational Life Sciences , Ruđer Bošković Institute , 10000 Zagreb , Croatia
| | - Nadine Hainz
- Institute of Anatomy and Cell Biology , Saarland University , 66421 Homburg , Germany
| | - Carola Meier
- Institute of Anatomy and Cell Biology , Saarland University , 66421 Homburg , Germany
| | - Thomas Tschernig
- Institute of Anatomy and Cell Biology , Saarland University , 66421 Homburg , Germany
| | - Dietrich A Volmer
- Department of Chemistry , Humboldt University of Berlin , 12489 Berlin , Germany
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