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Mass Spectrometry Imaging

MALDI
MALDI
15T

Mass spectrometry imaging is used to investigate the spatial distribution of molecules within biological samples. The mass spectrometry imaging group of instruments comprises several "soft" sampling probes coupled to high-resolution mass spectrometers. Here, the term "soft" is used to highlight a gentle desorption and/or ionization mechanism that enables analysis of intact biomolecules. These instruments provide a unique capability to probe the sample surface chemistry on various spatial scales (from near-single-cell level to cell clusters) with high throughput and sensitivity. This capability gives us the distribution and the identity of hundreds of molecules in an untargeted fashion and enables comprehensive insight into biological and environmental processes across spatial scales.

Research application

  • Supporting the Structural Biology Integrated Research Platform, these resources provide insight into the distribution of small proteins and their proteoforms in the environmental systems. 
  • Supporting the Biomolecular Pathways Integrated Research Platform, these resources combine integrated-research-platforms, qualitative, and quantitative molecular information to study metabolic networks within and across specific locations. 
  • Supporting the Cell Signaling and Communication Integrated Research Platform, these resources allow quantitative analyses of metabolites in individual cells within communities or tissues.
  • Supporting the Rhizosphere Function Integrated Research Platform, these resources identify targeted molecules' localization in the plant tissue and surrounding environment and reveal molecules and molecular changes specific for different cells and cell types in the analyzed plant system. A new workflow developed at EMSL, “on target chemical derivatization (OTCD) for MALDI MS imaging,” uses 4-APEBA chemical derivatization to boost the sensitivity of MALDI analysis. This workflow enables insight into the cell-specific distribution of phytohormones, amino acids, aliphatic and aromatic organic acids, short aldehydes, and many other carbonyl-containing microbial and phytocompounds, even if they are present in low amounts (<fmole) in the sample.

Available instruments

  • MALDI-12T FTICR (Bruker): for untargeted and targeted imaging of small molecules, metabolites, lipids, and glycans. Maximal spatial resolution: 25 µm. Optimal mass range: 100-2,000 m/z. Provides high mass resolution and mass accuracy.
  • MALDI-Q-ToF (Synapt G2 Si, Waters): for targeted imaging of small and large metabolites. Maximal spatial resolution: 25 µm. Optimal mass range: 50–4,000 m/z. Pre-mass analysis ion mobility is optional for the analysis of some isomers. 
  • Triversa Nanomate (Advion): for Liquid Extraction Surface Analysis (LESA) of proteins, small molecules, and lipids. When coupled to ion mobility or liquid chromatography systems, this instrument provides more accurate molecular identification. Maximal spatial resolution 400 µm. Optimal mass range: 100–6,000 m/z (depending on mass spectrometry instrument utilized). 
  • LAESI-MS custom-built “molecular microscope”: for untargeted ambient imaging and high-throughput single cell metabolomics/lipodomics. A microscope is incorporated into the LAESI source enabling optically directed (brightfield/fluorescence: GFP, YFP, MCherry) MSI to be performed. Maximum spatial resolution: 30 µm. Optimal mass range: 100– 1,500 m/z (depending on mass spectrometry instrument utilized). 
  • SepQuant dropletProbe (HTX): for Liquid Extraction Surface Analysis (LESA) of small molecules and lipids. When coupled to nanoflow liquid chromatography systems, this instrument provides more accurate molecular identification. Maximal spatial resolution 300 µm. Optimal mass range: 100–6,000 m/z (depending on mass spectrometry instrument utilized).
  • MALDI-timsTOF (Bruker): for high-throughput targeted imaging of metabolites, lipids, peptides, and glycans. Maximal spatial resolution: 5um. Optimal mass range: 50-4,000 m/z. Provides moderate mass resolution and accuracy. Pre-mass analysis ion mobility is optional for the analysis of mass isomers and confident molecular identification.
  • MALDI-UHMR HF Orbitrap (Thermo Fisher Scientific): for untargeted imaging of lipids, large metabolites, glycans, peptides, proteins, and proteoforms. Maximal spatial resolution: 10 µm. Optimal mass range: m/z 500-5000 or m/z 2000-20000. Provides high resolution and mass accuracy.

Tips for success

  • For spatial metabolite and lipidomic analysis, we expect users to ship us fresh and frozen plant tissues (root, stem, fruit, leaf, etc.), and we will do the rest of the critical sample prep (embedding, cryo-sectioning, and mounting on specific target plates). Alternatively, users can send us already embedded samples in 2.5%–4% CMC or 7.5% HPMC.
  • For N-glycan mapping, samples should be formalin-fixed paraffin-embedded.
  • We analyze molecular communication between microbial cultures cultivated on solid agar. For these projects, agar should not contain more than 40% salt, optimal volume is 10 mL (for traditional (100 x 15 mm) Petri dishes), and samples should be sent overnight without freezing. We request at least one control (blank agar) and three bio-replicates of each condition (individual colonies, multiple colonies).

 

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