ABSTRACT
Matrix-assisted laser desorption-ionization mass spectrometry imaging in transmission-mode geometry (t-MALDI-MSI) can provide molecular information with a pixel size of 1 µm and smaller, which makes this label-free method highly interesting for characterizing the chemical composition of tissues and cells on a (sub)cellular level. However, a major hindrance for wider use of the technology is the reduced ion abundance at small pixel sizes. Here we mitigate this problem by use of laser-induced post-ionization (MALDI-2) and by adapting a t-MALDI-2 ion source to an Orbitrap mass analyzer. We demonstrate the crucial sensitivity and accuracy boosts that are achieved with this combination by visualizing the distribution of numerous phospho- and glycolipids in mouse cerebellum and kidney slices, and in cultured Vero B4 cells. With brain tissue, a pixel size of 600 nm was achieved. Our method could constitute a valuable new tool for research in cell biology and biomedicine.
Subject(s)
Brain/metabolism , Epithelial Cells/metabolism , Image Processing, Computer-Assisted/methods , Kidney/metabolism , Molecular Imaging/methods , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Animals , Chlorocebus aethiops , Female , Lasers , Mice , Mice, Inbred C57BL , Vero CellsABSTRACT
Coupling laser post-ionisation with a high resolving power MALDI Orbitrap mass spectrometer has realised an up to â¼100-fold increase in the sensitivity and enhanced the chemical coverage for MALDI-MS imaging of lipids relative to conventional MALDI. This could constitute a major breakthrough for biomedical research.
