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Palomino TV, Muddiman DC. Mass spectrometry imaging of N-linked glycans: Fundamentals and recent advances. MASS SPECTROMETRY REVIEWS 2024. [PMID: 38934211 DOI: 10.1002/mas.21895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 06/06/2024] [Accepted: 06/09/2024] [Indexed: 06/28/2024]
Abstract
With implications in several medical conditions, N-linked glycosylation is one of the most important posttranslation modifications present in all living organisms. Due to their nontemplate synthesis, glycan structures are extraordinarily complex and require multiple analytical techniques for complete structural elucidation. Mass spectrometry is the most common way to investigate N-linked glycans; however, with techniques such as liquid-chromatography mass spectrometry, there is complete loss of spatial information. Mass spectrometry imaging is a transformative analytical technique that can visualize the spatial distribution of ions within a biological sample and has been shown to be a powerful tool to investigate N-linked glycosylation. This review covers the fundamentals of mass spectrometry imaging and N-linked glycosylation and highlights important findings of recent key studies aimed at expanding and improving the glycomics imaging field.
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Affiliation(s)
- Tana V Palomino
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
| | - David C Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
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Joignant AN, Knizner KT, Xi Y, Muddiman DC. Evaluating the optimal tissue thickness for mass spectrometry imaging using infrared matrix-assisted laser desorption electrospray ionization. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9638. [PMID: 37817341 PMCID: PMC10881192 DOI: 10.1002/rcm.9638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/26/2023] [Accepted: 08/26/2023] [Indexed: 10/12/2023]
Abstract
RATIONALE Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) utilizes a 2970 nm mid-IR laser to desorb samples with depth resolutions (Z) on the order of micrometers. Conventionally, 5-20 μm thick tissue sections are used to characterize different applications of the IR-MALDESI source, but an optimal thickness has not been systematically investigated. METHODS Mouse liver was sectioned to various thicknesses and analyzed using IR-MALDESI mass spectrometry imaging (MSI). Height profiles of tissue sections of various cryosectioned thicknesses were acquired to affirm tissue thickness. Tissue sections of each thickness were measured using a Keyence microscope. Paraffin wax was cryosectioned, mounted on microscope slides, and measured using a chromatic confocal sensor system to determine the cryostat sectioning accuracy. RESULTS Analyzing sectioned tissues at higher thickness (>10 μm) leads to lower ion abundance, a decrease in signal over long analysis times, and more frequent instrument cleaning. Additionally, increasing tissue thickness above the optimum (7 μm) does not result in a significant increase in lipid annotations. CONCLUSIONS This work defines an optimal sample thickness for IR-MALDESI-MSI and demonstrates the utility of optimizing tissue thickness for MSI platforms of comparable Z resolution.
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Affiliation(s)
- Alena N. Joignant
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Kevan T. Knizner
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Ying Xi
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - David C. Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
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Joignant AN, Xi Y, Muddiman DC. Impact of wavelength and spot size on laser depth of focus: Considerations for mass spectrometry imaging of non-flat samples. JOURNAL OF MASS SPECTROMETRY : JMS 2023; 58:e4914. [PMID: 36916474 DOI: 10.1002/jms.4914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/09/2023] [Accepted: 02/19/2023] [Indexed: 06/18/2023]
Abstract
Biospecimens with nearly flat surfaces on a flat stage are typically required for laser-based mass spectrometry imaging (MSI) techniques. However, sampling stages are rarely perfectly level, and accounting for this and the need to accommodate non-flat samples requires a deeper understanding of the laser beam depth of focus. In ablation-based MSI methods, a laser is focused on top of the sample surface, ensuring that the sample is at the focal point or remains within depth of focus. In general, the depth of focus of a given laser is related to the beam quality (M2 ) and the wavelength (λ). However, because laser is applied on a biological sample, other variables can also impact the depth of focus, which could affect the robustness of the MSI techniques for diverse sample types. When the height of a sample ranges outside of the depth of focus, ablated area and the corresponding ion abundances may vary as well, increasing the variability of results. In this tutorial, we examine the parameters and equations that describe the depth of focus of a Gaussian laser beam. Additionally, we describe several approaches that account for surface roughness exceeding the depth of focus of the laser.
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Affiliation(s)
- Alena N Joignant
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
| | - Ying Xi
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
| | - David C Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
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Bai H, Manni JG, Muddiman DC. Transforming a Mid-infrared Laser Profile from Gaussian to a Top-Hat with a Diffractive Optical Element for Mass Spectrometry Imaging. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:10-16. [PMID: 36542595 PMCID: PMC9975536 DOI: 10.1021/jasms.2c00203] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Many mass spectrometry imaging (MSI) applications such as infrared matrix-assisted electrospray ionization (IR-MALDESI) employ an infrared (IR) laser with a Gaussian profile where laser irradiance is highest in the center and decreases exponentially. To enable full ablation of a square region of interest, oversampling is often needed, which results in nonuniform ablation and leads to decreased image quality. A diffractive optical element (DOE) was integrated into the optical path to generate homogeneous intensity distributions while maintaining laser energy above the ablation threshold, to enable complete sample removal from laser pulses without oversampling. 2D and 3D imaging with the DOE inserted show clear and sharp ablation patterns with satisfactory biological signals gained. Further improvements will optimize the beam profile and generate a square top-hat laser beam for MSI application at higher spatial resolution.
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Affiliation(s)
- Hongxia Bai
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | | | - David C. Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
- Molecular Education, Technology, and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC 27695 USA
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Caleb Bagley M, Garrard KP, Muddiman DC. The development and application of matrix assisted laser desorption electrospray ionization: The teenage years. MASS SPECTROMETRY REVIEWS 2023; 42:35-66. [PMID: 34028071 DOI: 10.1002/mas.21696] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 05/24/2023]
Abstract
In the past 15 years, ambient ionization techniques have witnessed a significant incursion into the field of mass spectrometry imaging, demonstrating their ability to provide complementary information to matrix-assisted laser desorption ionization. Matrix-assisted laser desorption electrospray ionization is one such technique that has evolved since its first demonstrations with ultraviolet lasers coupled to Fourier transform-ion cyclotron resonance mass spectrometers to extensive use with infrared lasers coupled to orbitrap-based mass spectrometers. Concurrently, there have been transformative developments of this imaging platform due to the high level of control the principal group has retained over the laser technology, data acquisition software (RastirX), instrument communication, and image processing software (MSiReader). This review will discuss the developments of MALDESI since its first laboratory demonstration in 2005 to the most recent advances in 2021.
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Affiliation(s)
- Michael Caleb Bagley
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
| | - Kenneth P Garrard
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
- The Precision Engineering Consortium, North Carolina State University, Raleigh, North Carolina, USA
- Molecular Education, Technology, and Research Innovation Center (METRIC), North Carolina State University, Raleigh, North Carolina, USA
| | - David C Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
- Molecular Education, Technology, and Research Innovation Center (METRIC), North Carolina State University, Raleigh, North Carolina, USA
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
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6
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Joignant AN, Bai H, Manni JG, Muddiman DC. Improved spatial resolution of infrared matrix-assisted laser desorption electrospray ionization mass spectrometry imaging using a reflective objective. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2022; 36:e9392. [PMID: 36057935 PMCID: PMC9643617 DOI: 10.1002/rcm.9392] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
RATIONALE The level of visual detail of a mass spectrometry image is dependent on the spatial resolution with which it is acquired, which is largely determined by the focal diameter in infrared laser ablation-based techniques. While the use of mid-IR light for mass spectrometry imaging (MSI) has advantages, it results in a relatively large focal diameter and spatial resolution. The continual advancement of infrared matrix-assisted electrospray ionization (IR-MALDESI) for MSI warranted novel methods to decrease laser ablation areas and thus improve spatial resolution. METHODS In this work, a Schwarzschild-like reflective objective was incorporated into the novel NextGen IR-MALDESI source and characterized on both burn paper and mammalian tissue using an ice matrix. Ablation areas, mass spectra, and annotations obtained using the objective were compared against the current optical train on the NextGen system without modification. RESULTS The effective resolution was determined to be 55 μm by decreasing the step size until oversampling was observed. Use of the objective improved the spatial resolution by a factor of three as compared against the focus lens. CONCLUSIONS A Schwarzschild-like reflective objective was successfully incorporated into the NextGen source and characterized on mammalian tissue using an ice matrix. The corresponding improvement in spatial resolution facilitates the future expansion of IR-MALDESI applications to include those that require fine structural detail.
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Affiliation(s)
- Alena N. Joignant
- FTMS Laboratory for Human Health Research, Department of ChemistryNorth Carolina State UniversityRaleighNCUSA
| | - Hongxia Bai
- FTMS Laboratory for Human Health Research, Department of ChemistryNorth Carolina State UniversityRaleighNCUSA
- Molecular Education, Technology and Research Innovation CenterNorth Carolina State UniversityRaleighNCUSA
| | | | - David C. Muddiman
- FTMS Laboratory for Human Health Research, Department of ChemistryNorth Carolina State UniversityRaleighNCUSA
- Molecular Education, Technology and Research Innovation CenterNorth Carolina State UniversityRaleighNCUSA
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Knizner KT, Guymon JP, Garrard KP, Bouvrée G, Manni J, Hauschild JP, Strupat K, Fort KL, Earley L, Wouters ER, Pu F, Radosevich AJ, Elsen NL, Williams JD, Pankow MR, Muddiman DC. Next-Generation Infrared Matrix-Assisted Laser Desorption Electrospray Ionization Source for Mass Spectrometry Imaging and High-Throughput Screening. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:2070-2077. [PMID: 36173393 PMCID: PMC9944128 DOI: 10.1021/jasms.2c00178] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is a hybrid, ambient ionization source that combines the advantages of electrospray ionization and matrix-assisted laser desorption/ionization, making it a versatile tool for both high-throughput screening (HTS) and mass spectrometry imaging (MSI) studies. To expand the capabilities of the IR-MALDESI source, an entirely new architecture was designed to overcome the key limitations of the previous source. This next-generation (NextGen) IR-MALDESI source features a vertically mounted IR-laser, a planar translation stage with computerized sample height control, an aluminum enclosure, and a novel mass spectrometer interface plate. The NextGen IR-MALDESI source has improved user-friendliness, improved overall versatility, and can be coupled to numerous Orbitrap mass spectrometers to accommodate more research laboratories. In this work, we highlight the benefits of the NextGen IR-MALDESI source as an improved platform for MSI and direct analysis. We also optimize the NextGen MALDESI source component geometries to increase target ion abundances over a wide m/z range. Finally, documentation is provided for each NextGen IR-MALDESI part so that it can be replicated and incorporated into any lab space.
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Affiliation(s)
- Kevan T. Knizner
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Jacob P. Guymon
- Precision Engineering Consortium, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh 27695, NC, USA
| | - Kenneth P. Garrard
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
- Precision Engineering Consortium, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh 27695, NC, USA
- Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC 27695, USA
| | - Guy Bouvrée
- GB Conseil & Services, 77170 Brie Comte Robert, France
| | | | | | - Kerstin Strupat
- Thermo Fisher Scientific (Bremen) GmbH, 28199 Bremen, Germany
| | - Kyle L. Fort
- Thermo Fisher Scientific (Bremen) GmbH, 28199 Bremen, Germany
| | - Lee Earley
- Thermo Fisher Scientific, San Jose, CA 95134, USA
| | | | - Fan Pu
- Drug Discovery Science and Technology, AbbVie Inc., North Chicago, IL 60064, USA
| | - Andrew J. Radosevich
- Drug Discovery Science and Technology, AbbVie Inc., North Chicago, IL 60064, USA
| | - Nathaniel L. Elsen
- Drug Discovery Science and Technology, AbbVie Inc., North Chicago, IL 60064, USA
| | - Jon D. Williams
- Drug Discovery Science and Technology, AbbVie Inc., North Chicago, IL 60064, USA
| | - Mark R. Pankow
- Precision Engineering Consortium, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh 27695, NC, USA
| | - David C. Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
- Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC 27695, USA
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Recent Advances of Ambient Mass Spectrometry Imaging and Its Applications in Lipid and Metabolite Analysis. Metabolites 2021; 11:metabo11110780. [PMID: 34822438 PMCID: PMC8625079 DOI: 10.3390/metabo11110780] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 11/08/2021] [Accepted: 11/11/2021] [Indexed: 01/02/2023] Open
Abstract
Ambient mass spectrometry imaging (AMSI) has attracted much attention in recent years. As a kind of unlabeled molecular imaging technique, AMSI can enable in situ visualization of a large number of compounds in biological tissue sections in ambient conditions. In this review, the developments of various AMSI techniques are discussed according to one-step and two-step ionization strategies. In addition, recent applications of AMSI for lipid and metabolite analysis (from 2016 to 2021) in disease diagnosis, animal model research, plant science, drug metabolism and toxicology research, etc., are summarized. Finally, further perspectives of AMSI in spatial resolution, sensitivity, quantitative ability, convenience and software development are proposed.
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Plug-and-play laser ablation-mass spectrometry for molecular imaging by means of dielectric barrier discharge ionization. Anal Chim Acta 2021; 1177:338770. [PMID: 34482891 DOI: 10.1016/j.aca.2021.338770] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/24/2021] [Accepted: 06/14/2021] [Indexed: 11/22/2022]
Abstract
The plug-and-play hyphenation of UV-laser ablation (LA) and mass spectrometry is presented, using dielectric barrier discharge ionization (DBDI). The DBDI source employed here is characterized by its unique geometry, being directly mounted onto the inlet capillary of a mass spectrometer. In the literature, this particular kind of DBDI source is also referred to as active capillary plasma ionization. It has been commercialized as soft ionization by chemical reaction in transfer (SICRIT) and will be addressed as DBDI in this study. LA-DBDI-MS was used for the direct, molecule-specific and spatially resolved analysis of various solid samples, such as coffee beans and pain killer tablets without extensive sample preparation. The combination of fast washout UV-laser ablation and the principle of the DBDI source used here allowed for highly efficient soft ionization as well as high spatial resolution down to 10 μm for molecular imaging.
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Bai H, Linder KE, Muddiman DC. Three-dimensional (3D) imaging of lipids in skin tissues with infrared matrix-assisted laser desorption electrospray ionization (MALDESI) mass spectrometry. Anal Bioanal Chem 2021; 413:2793-2801. [PMID: 33388847 DOI: 10.1007/s00216-020-03105-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/22/2020] [Accepted: 11/30/2020] [Indexed: 12/14/2022]
Abstract
Three-dimensional (3D) mass spectrometry imaging (MSI) has become a growing frontier as it has the potential to provide a 3D representation of analytes in a label-free, untargeted, and chemically specific manner. The most common 3D MSI is accomplished by the reconstruction of 2D MSI from serial cryosections; however, this presents significant challenges in image alignment and registration. An alternative method would be to sequentially image a sample by consecutive ablation events to create a 3D image. In this study, we describe the use of infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) in ablation-based 3D MSI for analyses of lipids within fresh frozen skin tissue. Depth resolution using different laser energy levels was explored with a confocal laser scanning microscope to establish the imaging parameters for skin. The lowest and highest laser energy level resulted in a depth resolution of 7 μm and 18 μm, respectively. A total of 594 lipids were putatively detected and detailed lipid profiles across different skin layers were revealed in a 56-layer 3D imaging experiment. Correlated with histological information, the skin structure was characterized with differential lipid distributions with a lateral resolution of 50 μm and a z resolution of 7 μm.
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Affiliation(s)
- Hongxia Bai
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Keith E Linder
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, 27695, USA.,Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, 27695, USA
| | - David C Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA. .,Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, 27695, USA. .,Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC, 27695, USA.
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11
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Garrard KP, Ekelöf M, Khodjaniyazova S, Bagley MC, Muddiman DC. A Versatile Platform for Mass Spectrometry Imaging of Arbitrary Spatial Patterns. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:2547-2552. [PMID: 32539373 PMCID: PMC8761386 DOI: 10.1021/jasms.0c00128] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A vision-system driven platform, RastirX, has been constructed for mass spectrometry imaging (MSI) of arbitrary two-dimensional patterns. The user identifies a region of interest (ROI) by drawing on a live video image of the sample with the computer mouse. Motion commands are automatically generated to move the sample to acquire scan data for the pixels in the ROI. Synchronization of sample stage motion with laser firing and mass spectrometer (MS) scan acquisition is fully automated. RastirX saves a co-registered optical image and the scan location information needed to convert raw MS data into imzML format. Imaging an arbitrarily shaped ROI instead of the minimal enclosing rectangle reduces contamination from off-sample material and significantly reduces acquisition time.
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Affiliation(s)
- Kenneth P. Garrard
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
- Precision Engineering Consortium, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
- Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Måns Ekelöf
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Sitora Khodjaniyazova
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - M. Caleb Bagley
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - David C. Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
- Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, North Carolina 27695, United States
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12
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Bagley MC, Pace CL, Ekelöf M, Muddiman DC. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging analysis of endogenous metabolites in cherry tomatoes. Analyst 2020; 145:5516-5523. [PMID: 32602477 PMCID: PMC7423647 DOI: 10.1039/d0an00818d] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We report the spatially resolved metabolic profiling of cherry tomatoes using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI), a mass spectrometry imaging (MSI) technique that operates at ambient conditions and requires no sample derivatization. Tomatoes were flash frozen, cryosectioned and imaged with adequate spatial resolution to distinguish between the major tissue structures of a tomato including the skin, mesocarp, endocarp, locular tissue, septum, placenta, seed and seed coating. Metabolites were imaged from 100-1200 m/z, enabling significant coverage of a diverse array of metabolites including amino acids and lipids along with the major secondary metabolite classes: terpenes, phenolics, glycosides, and alkaloids. During the metabolic profiling, we found endogenous carotenoid hydrocarbons, namely lycopene or its structural isomer β-carotene, ionized as radical cations. To our knowledge, this is the first demonstration of ionizing hydrocarbons in the MSI field.
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Affiliation(s)
- M Caleb Bagley
- FTMS Laboratory for Human Health Research, Department of Chemistry, USA.
| | - Crystal L Pace
- FTMS Laboratory for Human Health Research, Department of Chemistry, USA.
| | - Måns Ekelöf
- FTMS Laboratory for Human Health Research, Department of Chemistry, USA.
| | - David C Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, USA. and Department of Plant and Microbial Biology, USA and Molecular Education, Technology, and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC 27695, USA
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13
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Ekelöf M, Dodds J, Khodjaniyazova S, Garrard KP, Baker ES, Muddiman DC. Coupling IR-MALDESI with Drift Tube Ion Mobility-Mass Spectrometry for High-Throughput Screening and Imaging Applications. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:642-650. [PMID: 31971795 PMCID: PMC7263366 DOI: 10.1021/jasms.9b00081] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Because of its high degree of selectivity and chemical resolution, mass spectrometry (MS) is rapidly becoming the analytical method of choice for high-throughput evaluations and clinical diagnostics. While advances in MS resolving power have increased by an order of magnitude over the past decade, advances in sample introduction are still needed for high-throughput screening applications where the time frame of chromatographic separation would limit the duty cycle. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is an ambient ionization source that has been shown to be applicable for direct analyses and mass spectrometry imaging (MSI) of complex biological samples in a high-throughput manner. To increase a range of detectable features in IR-MALDESI experiments, we integrated the home-built ion source with a commercially available drift tube ion mobility spectrometer-mass spectrometer (IMS-MS) and analyzed small polar molecules, lipids, carbohydrates, and intact proteins. We also describe in detail how the pulsed ionization source was synchronized with IMS-MS.
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Affiliation(s)
- Måns Ekelöf
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - James Dodds
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Sitora Khodjaniyazova
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Kenneth P Garrard
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
- Precision Engineering Consortium, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27606, United States
| | - Erin S Baker
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - David C Muddiman
- FTMS Laboratory for Human Health Research, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
- Molecular Education, Technology, and Research Innovation Center (METRIC), North Carolina State University, Raleigh, North Carolina 27695, United States
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