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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
Author(s) -
Stoyanovsky D. A.,
Sparvero L. J.,
Amoscato A. A.,
He R. R.,
Watkins S.,
Pitt B. R.,
Bayir H.,
Kagan V. E.
Publication year - 2014
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6796
Subject(s) - chemistry , mass spectrometry , mass spectrometry imaging , maldi imaging , desorption , matrix (chemical analysis) , matrix assisted laser desorption/ionization , resolution (logic) , alkyl , analytical chemistry (journal) , fourier transform ion cyclotron resonance , electrospray ionization , chromatography , organic chemistry , adsorption , artificial intelligence , computer science
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 ‐C 6 H 13 and ‐C 12 H 25 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‐C 6 H 13 → DHB‐C 12 H 25 . MALDI‐MSI images acquired with DHB‐C 12 H 25 exhibited a considerably higher density of lipids than DHB. CONCLUSIONS Comparative experiments with DHB and DHB‐C 12 H 25 are presented, which indicate that the latter matrix affords higher lateral resolution than the former. Copyright © 2014 John Wiley & Sons, Ltd.