Combining MALDI‐2 and transmission geometry laser optics to achieve high sensitivity for ultra‐high spatial resolution surface analysis

Spivey, Eric C.; McMillen, Josiah; Ryan, Daniel; Spraggins, Jeffrey M.; Caprioli, Richard M.

doi:10.1002/jms.4335

Cited by 50 publications

(58 citation statements)

References 16 publications

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“…The Spectroglyph source has a MALDI-2 laser setup as described previously. 46 Briefly, the MALDI-2 laser (266 nm, FQSS266-200-STA, CryLaS GmbH, Berlin, Germany) is aligned parallel to the sample surface to irradiate the initial MALDI-1 plume at ~400 µm above the sample surface. A delay time was set to be 20 µs between the initial MALDI-1 event and the MALDI-2 laser irradiation.…”

Section: Instrument/acquisition Parametersmentioning

confidence: 99%

“…44 Early studies showed that a dramatic increase in signal could be produced with MALDI-2 while operating MALDI-1 energy at or below the ionization threshold,. 36,46 Here, we operated the MALDI-1 laser well above the ionization threshold to obtain maximum lipid signal without MALDI-2.…”

Section: Analysis Of Lipid Standardsmentioning

confidence: 99%

“…Thus far, MALDI-2 has proven to improve sensitivity for certain molecular classes including liposoluble vitamins, mono-and oligosaccharides, certain lipid classes, and exogenous drugs. 34,36,[38][39][40][41][42][43]45,46 Lipid classes that have been shown to have dramatically increased ion intensities in positive ion mode include hexosylceramides (HexCers), phosphatidylethanolamines (PEs), phosphatidylinositols (PIs), phosphatidylglycerols (PGs), phosphatidylserines (PSs), triacylglycerols (TGs), and cholesterol esters (CEs). 34 Interestingly, other classes of lipids such as phosphatidylcholines (PCs) were not shown to increase significantly with MALDI-2.…”

Section: Introductionmentioning

confidence: 99%

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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: Instrument/acquisition Parametersmentioning

confidence: 99%

Section: Analysis Of Lipid Standardsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

McMillen¹,

Fincher²,

Klein³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Thus far, MALDI-2 has proven to improve sensitivity for certain molecular classes including liposoluble vitamins, monosaccharide and oligosaccharide, certain lipid classes, and exogenous drugs. 34,36,[38][39][40][41][42][43]45,46 Lipid classes that have been shown to have dramatically increased ion intensities in positive ion mode include hexosylceramides (HexCers), phosphatidylethanolamines (PEs), phosphatidylinositols (PIs), phosphatidylglycerols (PGs), phosphatidylserines (PSs), triacylglycerols (TGs), and cholesterol esters (CEs). 34 Interestingly, other classes of lipids such as phosphatidylcholines (PCs) were not shown to increase significantly with MALDI-2.…”

Section: Introductionmentioning

confidence: 99%

Effect of MALDI matrices on lipid analyses of biological tissues using MALDI‐2 postionization mass spectrometry

et al. 2020

View full text Add to dashboard Cite

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 postionization (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, 2′,5′‐dihydroxyacetophenone, 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 nonpolar 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., fivefold 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 with 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, and cholesterol ester), and DHB provided the highest overall number of lipids detected using MALDI‐2 technology.

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“…Although MALDI IMS is a rapidly developing field with dramatic improvements in instrument mass resolving power and scan speed introduced (Prentice et al, 2018;Spraggins et al, 2016), and the improvement of spatial resolution (Spivey et al, 2019), there are particular challenges for protein imaging (Heeren et al, 2009). Specifically, imaging and identification of low abundance and high molecular weight proteins is challenging (Ryan et al, 2019a).…”

Section: Introductionmentioning

confidence: 99%

Localization of the Lens Intermediate Filament Switch by Imaging Mass Spectrometry

Wang

Ryan²,

Schey³

2020

Preprint

Self Cite

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Imaging mass spectrometry (IMS) enables targeted and untargeted visualization of the spatial localization of molecules in tissues with great specificity. The lens is a unique tissue that contains fiber cells corresponding to various stages of differentiation that are packed in a highly spatial order. The application of IMS to lens tissue localizes molecular features that are spatially related to the fiber cell organization. Such spatially resolved molecular information assists our understanding of lens structure and physiology; however, protein IMS studies are typically limited to abundant, soluble, low molecular weight proteins. In this study, a method was developed for imaging low solubility cytoskeletal proteins in the lens; a tissue that is filled with high concentrations of soluble crystallins. Optimized tissue washes combined with on-tissue enzymatic digestion allowed successful imaging of peptides corresponding to known lens cytoskeletal proteins. The resulting peptide signals facilitated segmentation of the bovine lens into molecularly distinct regions. A sharp intermediate filament transition from vimentin to lens-specific beaded filament proteins was detected in the lens cortex. MALDI IMS also revealed the region where posttranslational myristoylation of filensin occurs and the results indicate that truncation and myristoylation of filensin starts soon after filensin expression increased in the inner cortex. From intermediate filament switch to filensin truncation and myristoylation, multiple remarkable changes occur in the narrow region of lens cortex. MALDI images delineated the boundaries of distinct lens regions that will guide further proteomic and interactomic studies.

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Combining MALDI‐2 and transmission geometry laser optics to achieve high sensitivity for ultra‐high spatial resolution surface analysis

Cited by 50 publications

References 16 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

Effect of MALDI matrices on lipid analyses of biological tissues using MALDI‐2 postionization mass spectrometry

Localization of the Lens Intermediate Filament Switch by Imaging Mass Spectrometry

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