Recent advances in matrix-assisted laser desorption
ionization (MALDI) mass spectrometry imaging (MSI) have led to the direct
analysis of tissue slices. The major advantage of MSI is its capability of
simultaneously localizing and identifying a parent molecule and its metabolites
without any labeling or any prior knowledge. MSI has been extensively employed
to detect the differentiated pattern of lipids in various organs in different
diseases, such as brains in Alzheimer’s disease. Poor reproducibility of MALDIMSI analysis due to the heterogeneity of the matrix-analyte crystals, hindersits use on quantitative analysis. In addition, discontinuous ion flow due to
quickly consumption of the samples under laser irradiation on specific site
affects its ability in qualitative analysis. Although electrospray ionization
mass spectrometry (ESI-MS) cannot directly be used for imaging, ESI tandem mass
spectrometry (LC/ESI-MS/MS) can separate and distinguish gangliosides.
Zhang et al. have presented a promising workflow for
qualitative, semi-quantitative and in situ analysis of gangliosides bycombining the MALDI MSI and ESI-MS. Following obtaining the brain from the
mice, fresh-frozen murine brain sections were prepared and coated with matrix
for subsequent MALDI MSI analysis.
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