Charge Distribution between Different Classes of Glycerophospolipids in MALDI-MS Imaging

Boskamp, Marcel S.; Soltwisch, Jens

doi:10.1021/acs.analchem.9b05761

Cited by 60 publications

(89 citation statements)

References 56 publications

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“…With more complex samples as with tissue homogenates, ion suppression effects based on lipid class may affect ion yield. 43 While NOR performed well with MALDI-2, DHB had the highest increase in lipids detected with MALDI-2 from the tissue homogenates compared with other matrices. The number of lipids detected in each lipid class for DHB and NOR is displayed in is optimal for non-polar lipid studies and DHB is better applied to increased sensitivity of phospholipids.…”

Section: Lipidomic Comparisons Across Multiple Tissue Typesmentioning

confidence: 90%

“…Data presented in Table 1 shown that MALDI-2 may correct for ion suppression effects to enable detection of these protonated species. 43 MALDI-2 increased protonated lipid coverage with all matrices but the species detected with MALDI-2 varied based on the matrix. The TG species, for example, was detected only with MALDI-2 for CHCA, DHB, and NOR but was not detected with DHA.…”

Section: Analysis Of Lipid Standardsmentioning

confidence: 94%

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Effect of MALDI Matrices on Lipid Analyses of Biological Tissues Using MALDI-2 Post-Ionization Mass Spectrometry

McMillen¹,

Fincher²,

Klein³

et al. 2020

Preprint

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<p>Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) allows for highly multiplexed, untargeted detection of many hundreds of analytes from tissue. Recently, laser post-ionization (MALDI-2) has been developed for increased ion yield and sensitivity for lipid IMS. However, the dependence of MALDI-2 performance on the various lipid classes is largely unknown. To understand the effect of the applied matrix on MALDI-2 analysis of lipids, samples including an equimolar lipid standard mixture, various tissue homogenates, and intact rat kidney tissue sections were analyzed using the following matrices: α-cyano-4-hydroxycinnamic acid (CHCA), 2’,5’-dihydroxyacetophenone (DHA), 2’,5’-dihydroxybenzoic acid (DHB), and norharmane (NOR). Lipid signal enhancement of protonated species using MALDI-2 technology varied based on the matrix used. Although signal improvements were observed for all matrices, the most dramatic effects using MALDI-2 were observed using NOR and DHB. For lipid standards analyzed by MALDI-2, NOR provided the broadest coverage, enabling the detection of all 13 protonated standards, including non-polar lipids, whereas DHB gave less coverage but gave the highest signal increase for those lipids recorded. With respect to tissue homogenates and rat kidney tissue, mass spectra were compared and showed that the number and intensity of neutral lipids tentatively identified with MALDI-2 using NOR increased significantly (e.g. 5-fold intensity increase for triacylglycerol). In the cases of DHB with MALDI-2, the number of protonated lipids identified from tissue homogenates doubled with 152 on average compared to 76 with MALDI alone. High spatial resolution imaging (~20 µm) of rat kidney tissue showed similar results using DHB with 125 lipids tentatively identified from MALDI-2 spectra versus just 72 using standard MALDI. From the four matrices tested, NOR provided the greatest increase in sensitivity for neutral lipids (triacylglycerol, diacylglycerol, monoacylglycerol, cholesterol ester) and DHB provided the highest overall number of lipids detected using MALDI-2 technology. </p>

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Section: Lipidomic Comparisons Across Multiple Tissue Typesmentioning

confidence: 90%

Section: Analysis Of Lipid Standardsmentioning

confidence: 94%

Effect of MALDI Matrices on Lipid Analyses of Biological Tissues Using MALDI-2 Post-Ionization Mass Spectrometry

McMillen¹,

Fincher²,

Klein³

et al. 2020

Preprint

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“…MSI lipid class coverage in the mouse cerebellum. As the ionization of many lipid classes suffers from a known suppression effect, 47 the coverage of lipid classes in mouse cerebellum tissue was evaluated to assess the suitability of BzPy for comprehensive lipid coverage in MSI studies. In total, 508/365 lipids were annotated in the positive/negative ion mode, respectively.…”

Section: Resultsmentioning

confidence: 99%

Multifunctional Reactive MALDI Matrix Enabling High-Lateral Resolution Dual Polarity MSI and Lipid C=C Position-Resolved MS2I

Wäldchen¹,

Mohr²,

Wagner³

et al. 2020

Preprint

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Local lipid variations in tissues are readily revealed with mass spectrometry imaging (MSI) methods and resulting lipid distributions serve as bioanalytical signatures to reveal cell- or tissue-specific lipids. Comprehensive MSI lipid mapping requires measurements in both ion polarities. Additionally, structural lipid characterization is necessary to link lipid structure to lipid function. Whereas some structural elements of lipids are readily derived from high-resolution mass spectrometry (MS) and tandem-MS (MSn), the localization of C=C double bonds (DBs) requires specialized fragmentation and/or functionalization methods. In this work, we identify a multifunctional matrix-assisted laser desorption/ionization (MALDI) matrix for spatially-resolved lipidomics investigations that reacts with lipids in Paternò-Büchi (PB) reactions during laser irradiation facilitating DB position assignment and allows dual polarity high-resolution MALDI-MSI and MALDI MS2I studies. By screening twelve compounds for improved ionization efficiency in positive/negative ion mode and PB functionalization yield compared to the previously introduced reactive MALDI matrix benzophenone, benzoylpyridine (BzPy) is identified as the best candidate. The multifunctional character of the new matrix enables DB localization of authentic standards belonging to twelve lipid classes and helps to assign 506/365 lipid features in positive/negative ion mode from mouse cerebellum tissue. The analytical capabilities of BzBy as a multifunctional MALDI-MSI matrix are demonstrated by imaging endogenous and PB-functionalized lipids in mouse kidney sections with 7 µm lateral resolution in both ion modes. Tracking diagnostic lipid DB position fragment ions in mouse pancreas tissue with down to 10 µm pixel size allows to identify islets of Langerhans associated lipid isomer upregulation or depletion. <br>

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“…In the context of membrane lipids, PC has been reported to heavily suppress all other GPL classes in the positive ion mode [16]. Recently published results by Boskamp and Soltwisch describe additional ISE between other GPL classes and also point out an inverse ion promotion effect, where the presence of a second GPL boosts ion signal intensity [15]. A variation of strongly suppressing or promoting molecular species between different types of tissue could therefore be the root cause of the observed bias in intensity response.…”

Section: Ion Suppression Effectsmentioning

confidence: 99%

“…fraction of desorbed molecules is ionized [6][7][8][9][10][11][12][13]. Ion yields strongly depend on the chemical properties of the matrix and the analyte itself but also on the overall composition of the sample [12,14,15]. For glycerophospholipids (GPL), for example, it has been shown that the presence of small quantities of phosphatidylcholine (PC) can effectively quench ion yields for other GPL classes like phosphatidylethanolamine (PE) [15,16].…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Validation of MALDI-MS imaging data of selected membrane lipids in murine brain with and without laser postionization by quantitative nano-HPLC-MS using laser microdissection

2020

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MALDI mass spectrometry imaging (MALDI-MSI) is a widely used technique to map the spatial distribution of molecules in sectioned tissue. The technique is based on the systematic generation and analysis of ions from small sample volumes, each representing a single pixel of the investigated sample surface. Subsequently, mass spectrometric images for any recorded ion species can be generated by displaying the signal intensity at the coordinate of origin for each of these pixels. Although easily equalized, these recorded signal intensities, however, are not necessarily a good measure for the underlying amount of analyte and care has to be taken in the interpretation of MALDI-MSI data. Physical and chemical properties that define the analyte molecules’ adjacencies in the tissue largely influence the local extraction and ionization efficiencies, possibly leading to strong variations in signal intensity response. Here, we inspect the validity of signal intensity distributions recorded from murine cerebellum as a measure for the underlying molar distributions. Based on segmentation derived from MALDI-MSI measurements, laser microdissection (LMD) was used to cut out regions of interest with a homogenous signal intensity. The molar concentration of six exemplary selected membrane lipids from different lipid classes in these tissue regions was determined using quantitative nano-HPLC-ESI-MS. Comparison of molar concentrations and signal intensity revealed strong deviations between underlying concentration and the distribution suggested by MSI data. Determined signal intensity response factors strongly depend on tissue type and lipid species.

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Charge Distribution between Different Classes of Glycerophospolipids in MALDI-MS Imaging

Cited by 60 publications

References 56 publications

Effect of MALDI Matrices on Lipid Analyses of Biological Tissues Using MALDI-2 Post-Ionization Mass Spectrometry

Effect of MALDI Matrices on Lipid Analyses of Biological Tissues Using MALDI-2 Post-Ionization Mass Spectrometry

Multifunctional Reactive MALDI Matrix Enabling High-Lateral Resolution Dual Polarity MSI and Lipid C=C Position-Resolved MS2I

Validation of MALDI-MS imaging data of selected membrane lipids in murine brain with and without laser postionization by quantitative nano-HPLC-MS using laser microdissection

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