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Improved spatial resolution of matrix-assisted laser desorption/ionization imaging of lipids in the brain by alkylated derivatives of 2,5-dihydroxybenzoic acid.
Stoyanovsky-DA; Sparvero-LJ; Amoscato-AA; He-RR; Watkins-S; Pitt-BR; Bayir-H; Kagan-VE
Rapid Commun Mass Spectrom 2014 Mar; 28(5):403-412
RATIONALE: Matrix-assisted laser desorption/ionization (MALDI) is one of the major techniques for mass spectrometry imaging (MSI) of biological systems along with secondary-ion mass spectrometry (SIMS) and desorption electrospray mass spectrometry (DESI). The inherent variability of MALDI-MSI signals within intact tissues is related to the heterogeneity of both the sample surface and the matrix crystallization. To circumvent some of these limitations of MALDI-MSI, we have developed improved matrices for lipid analysis based on structural modification of the commonly used matrix 2,5-dihydroxybenzoic acid (DHB). METHODS: We have synthesized DHB containing -C6H13 and -C12H25 alkyl chains and applied these matrices to rat brain using a capillary sprayer. We utilized a Bruker Ultraflex II MALDI-TOF/TOF mass spectrometer to analyze lipid extracts and tissue sections, and examined these sections with polarized light microscopy and differential interference contrast microscopy. RESULTS: O-alkylation of DHB yields matrices, which, when applied to brain sections, follow a trend of phase transition from crystals to an oily layer in the sequence DHB - DHB-C6H13 - DHB-C12H25 . MALDI-MSI images acquired with DHB-C12H25 exhibited a considerably higher density of lipids than DHB. CONCLUSIONS: Comparative experiments with DHB and DHB-C12H25 are presented, which indicate that the latter matrix affords higher lateral resolution than the former.
Mass-spectrometry; Biological-systems; Tissue-culture; Sample-preparation; Sampling; Lipids; Animals; Laboratory-animals; Microscopy
V. E. Kagan, Department of Environmental and Occupational Health, University of Pittsburgh, 100 Technology Drive, Pittsburgh, PA 15219
Issue of Publication
Rapid Communications in Mass Spectrometry
University of Pittsburgh at Pittsburgh
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division