Imaging of lipids in rat heart by MALDI-MS with silver nanoparticles

Abstract

Lipids are a major component of heart tissue and perform several important functions such as energy storage, signaling, and as building blocks of biological membranes. The heart lipidome is quite diverse consisting of glycerophospholipids such as phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), phosphatidylinositols (PIs), phosphatidylglycerols (PGs), cardiolipins (CLs), and glycerolipids, mainly triacylglycerols (TAGs). In this study, mass spectrometry imaging (MSI) enabled by matrix implantation of ionized silver nanoparticles (AgNP) was used to map several classes of lipids in heart tissue. The use of AgNP matrix implantation was motivated by our previous work showing that implantation doses of only 1014/cm2 of 2 nm gold nanoparticulates into the first 10 nm of the near surface of the tissue enabled detection of most brain lipids (including neutral lipid species such as cerebrosides) more efficiently than traditional organic MALDI matrices. Herein, a similar implantation of 500 eV AgNP− across the entire heart tissue section results in a quick, reproducible, solvent-free, uniform matrix concentration of 6 nm AgNP residing near the tissue surface. MALDI-MSI analysis of either positive or negative ions produce high-quality images of several heart lipid species. In negative ion mode, 24 lipid species [16 PEs, 4 PIs, 1 PG, 1 CL, 2 sphingomyelins (SMs)] were imaged. Positive ion images were also obtained from 29 lipid species (10 PCs, 5 PEs, 5 SMs, 9 TAGs) with the TAG species being heavily concentrated in vascular regions of the heart.

Multi-matrix, dual polarity, tandem mass spectrometry imaging strategy applied to a germinated maize seed: toward mass spectrometry imaging of an untargeted metabolome

“…27,28 However, at least for the current tissue sample of a germinated maize seed, they were not as efficient for It is interesting to note that large oligosaccharides (e.g., Hex7; the same for Hex3 to Hex9, images not shown) are localized in the endosperm area whereas small oligosaccharides (i.e., Hex, Hex2) are localized in the embryo area. This suggests that starch is broken down in the endosperm and then small sugars are transported to the embryo.…”

Imaging mass spectrometry increased resolution using 2-mercaptobenzothiazole and 2,5-diaminonaphtalene matrices: application to lipid distribution in human colon

“…Usually, solvent-free deposition methods are advisable [18][19][20][21], as they ensure that the molecules in the tissue are not perturbed during this step. So far, matrix sublimation and the new ion implanters used by some groups seem to yield the best results [22][23][24].…”

Development of a mass-spectrometry-based lipidomics platform for the profiling of phospholipids and sphingolipids in brain tissues

“…For the lipid species detected by their class-specific head groups, the fatty acid information was further acquired from their MS/ MS spectrum obtained in negative ion mode. PC in both mouse brain and duck brain was characterized by a predominance of 16:0/18:1 at m/z 761.0 (about 24.1 % and 27.2 % in mouse brain and duck brain, respectively), 16:0/16:0 at m/z 734.9 (19.4 % and 16 % in mouse brain and duck brain, respectively), and 18:0/18:1 at m/z 789.0 (14.9 % and 14.7 % in mouse brain and duck brain, respectively), whereas PC in salmon brain was dominated by 16 PA and PG species with 34-36 carbons and one or four double bonds were the major species in mouse and duck brains, whereas PA species with 38 carbons and four to six double bonds and PG species with 36 carbons and one and four double bonds were the major species in salmon brain. In addition to the aforementioned PL species, in all samples the ones in minor amounts could be identified, as could the lyso forms.…”

“…Owing to its high sensitivity and high specificity, massspectrometric analysis of complex lipid mixtures via soft ionization techniques (electrospray ionization, ESI, and matrixassisted laser desorption ionization) has been developed and widely applied over the past 20 years [12][13][14][15][16][17]. Shotgun ESI mass spectrometry (MS) using direct infusion and liquid chromatography (LC)-MS using various chromatographic modes are two common analytical platforms used for lipid profiling [17][18][19][20][21][22].…”