Metal Oxide Laser Ionization Mass Spectrometry Imaging (MOLI MSI) Using Cerium(IV) Oxide.

TitleMetal Oxide Laser Ionization Mass Spectrometry Imaging (MOLI MSI) Using Cerium(IV) Oxide.
Publication TypeJournal Article
Year of Publication2019
AuthorsBasu SS, McMinn MH, Lopez BGimenez-Ca, Regan MS, Randall EC, Clark AR, Cox CR, Agar NYR
JournalAnal Chem
Volume91
Issue10
Pagination6800-6807
Date Published2019 05 21
ISSN1520-6882
Abstract

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a powerful technique for spatially resolved metabolomics. A variation on MALDI, termed metal oxide laser ionization (MOLI), capitalizes on the unique property of cerium(IV) oxide (CeO) to induce laser-catalyzed fatty acyl cleavage from lipids and has been utilized for bacterial identification. In this study, we present the development and utilization of CeO as an MSI catalyst. The method was developed using a MALDI TOF instrument in negative ion mode, equipped with a high frequency laser. Instrument parameters for MOLI MS fatty acid catalysis with CeO were optimized with phospholipid standards and fatty acid catalysis was confirmed using lipid extracts from reference bacterial strains, and sample preparation was optimized using mouse brain tissue. MOLI MSI was applied to the imaging of normal mouse brain revealing differentiable fatty acyl pools in myelinated and nonmyelinated regions. Similarly, MOLI MSI showed distinct fatty acyl composition in tumor regions of a patient derived xenograft mouse model of glioblastoma. To assess the potential of MOLI MSI to detect pathogens directly from tissue, a pseudoinfection model was prepared by spotting Escherichia coli lipid extracts on mouse brain tissue sections and imaged by MOLI MSI. The spotted regions were molecularly resolved from the supporting mouse brain tissue by the diagnostic odd-chained fatty acids and reflected control bacterial MOLI MS signatures. We describe MOLI MSI for the first time and highlight its potential for spatially resolved fatty acyl analysis, characterization of fatty acyl composition in tumors, and its potential for pathogen detection directly from tissue.

DOI10.1021/acs.analchem.9b00894
Alternate JournalAnal. Chem.
PubMed ID31025851
PubMed Central IDPMC6826256
Grant ListR01 CA201469 / CA / NCI NIH HHS / United States
T32 HL007627 / HL / NHLBI NIH HHS / United States
P41 EB015898 / EB / NIBIB NIH HHS / United States
R25 CA089017 / CA / NCI NIH HHS / United States
U54 CA210180 / CA / NCI NIH HHS / United States