MALDI imaging of lipids after matrix sublimation/deposition

Mass spectrometric techniques have been developed to record mass spectra of biomolecules including lipids as they naturally exist within tissues and thereby permit the generation of images displaying the distribution of specific lipids in tissues, organs, and intact animals. These techniques are based on matrix-assisted laser desorption/ionization (MALDI) that requires matrix application onto the tissue surface prior to analysis. One technique of application that has recently shown significant advantages for lipid analysis is sublimation of matrix followed by vapor deposition directly onto the tissue. Explanations for enhanced sensitivity realized by sublimation/deposition related to sample temperature after a laser pulse and matrix crystal size are presented. Specific examples of sublimation/deposition in lipid imaging of various organs including brain, ocular tissue, and kidney are presented. This article is part of a Special Issue entitled: Lipodomics and Imaging Mass Spectrom.

Research highlights
► Sublimation/deposition purifies matrix and minimizes lateral diffusion of lipids.
► Sublimation results in small matrix crystals, which increases lipid signal strength.
► Examples of MALDI IMS using sublimation include brain, lens, retina, kidney tissues.