title: Enhanced sensitivity for high spatial resolution lipid analysis by negative ion mode matrix assisted laser desorption ionization imaging mass spectrometry.
abstract: We have achieved enhanced lipid imaging to a ~10 μm spatial resolution using negative ion mode matrix assisted laser desorption ionization (MALDI) imaging mass spectrometry, sublimation of 2,5-dihydroxybenzoic acid as the MALDI matrix, and a sample preparation protocol that uses aqueous washes. We report on the effect of treating tissue sections by washing with volatile buffers at different pHs prior to negative ion mode lipid imaging. The results show that washing with ammonium formate, pH 6.4, or ammonium acetate, pH 6.7, significantly increases signal intensity and number of analytes recorded from adult mouse brain tissue sections. Major lipid species measured were glycerophosphoinositols, glycerophosphates, glycerolphosphoglycerols, glycerophosphoethanolamines, glycerophospho-serines, sulfatides, and gangliosides. Ion images from adult mouse brain sections that compare washed and unwashed sections are presented and show up to 5-fold increases in ion intensity for washed tissue. The sample preparation protocol has been found to be applicable across numerous organ types and significantly expands the number of lipid species detectable by imaging mass spectrometry at high spatial resolution.
authors.affiliation: Mass Spectrometry Research Center and Department of Biochemistry, Vanderbilt University Medical Center, 465 21st Avenue South, MRB III Suite 9160, Nashville, Tennessee 37232, USA.
authors.forename: Peggi M
authors.initials: PM
authors.lastname: Angel
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Spraggins
authors.forename: H Scott
authors.initials: HS
authors.lastname: Baldwin
authors.forename: Richard
authors.initials: R
authors.lastname: Caprioli
mesh_terms: D000085:Acetates / Q000737:chemistry; D000818:Animals; D001921:Brain / Q000378:metabolism; D005561:Formates / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D008055:Lipids / Q000032:analysis*; D051379:Mice; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000085:Acetates; D005561:Formates; D007477:Ions; D008055:Lipids; C030544:formic acid; C018824:ammonium acetate