Resolving the Complexity of Spatial Lipidomics Using MALDI TIMS Imaging Mass Spectrometry

18 August 2020, Version 3
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Lipids are a structurally diverse class of molecules with important biological functions including cellular signaling and energy storage. Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) allows for direct map-ping of biomolecules in tissue. Fully characterizing the structural diversity of lipids remains a challenge due to the presence of isobaric and isomeric species, which greatly complicates data interpretation when only m/z information is available. Integrating ion mobility separations aids in deconvoluting these complex mixtures and addressing the challenges of lipid IMS. Here we demonstrate that a MALDI quadrupole time-of-flight (Q-TOF) mass spectrometer with trapped ion mobility spectrometry (TIMS) enables approximately a ~270% increase in the peak capacity during IMS experiments. MALDI TIMS-MS separation of lipid isomer standards, including sn-backbone isomers, acyl chain isomers, as well as double bond positional and geometric isomers are demonstrated. As a proof-of-concept, in situ separation and imaging of lipid isomers with distinct spatial distributions was performed using tissue sections from a whole-body mouse pup.

Keywords

lipidomics methods
lipidomics
imaging mass spectrometry
imaging mass spectrometry techniques
TIMS
Trapped ion mobility spectrometry
Trapped Ion Mobility Spectrometry
ion mobility
ion mobility spectroscopy technology
MALDI
matrix assisted laser desorption/ionization mass spectrometry

Supplementary materials

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200813 Supplemental v2 FINAL
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