Sodium-Doped Gold-Assisted Laser Desorption Ionization for Enhanced Imaging Mass Spectrometry of Triacylglycerols from Thin Tissue Sections

Abstract

The deposition of sodium salts followed by a sputtered layer of gold has been demonstrated to be a power combination for the analysis of triacylglycerols (TAGs) from tissue sections by laser desorption ionization (LDI) imaging mass spectrometry (IMS). Various sodium salts were tested for their capability to ionize TAGs and their ability to produce fast drying, small crystals (≤3 μm). The spray deposition of a sodium acetate and carbonate buffer mixture at pH 10.3 on which a 28 ± 3 nm sputtered layer of gold (Au-CBS) is subsequently deposited was found to provide the most effective combination for TAG analysis by high imaging resolution IMS. Under these conditions, a 30-fold increase in TAG signal intensity was observed when compared to matrix-assisted LDI (MALDI) methods using 2,5-dihydrobenzoic acid as matrix. Furthermore, Au-CBS led to an increase in the number of detected TAG species from ∼7 with DHB to more than 25 with the novel method, while few phospholipid signals were observed. These results were derived from the IMS investigation of fresh frozen mouse liver and rabbit adrenal gland tissue sections with a range of higher spatial resolutions between 35 and 10 μm. Au-CBS-LDI MS presents a highly sensitive and specific alternative to MALDI MS for imaging of TAGs from tissue sections. This novel approach has the potential to provide new biological insights on the role of TAGs in both health and disease.

Gold nanoparticles for enhanced ionization and fragmentation of biomolecules using LDI‐MS

“…Other lipids (e.g., phospholipids, sphingomyelin, fatty acids, etc.) also consistently formed silver-analyte adducts, and some species further fragmented in experiments by Muller et al 13 Sputtered gold has been utilized for ionization of cholesterol, 63 but this is only the second report of in solution AuNP sample preparation, giving an opportunity to further probe fundamental ionization effects. 64 It has now been shown that 20-nm AgNPs, 2-nm AuNPs, and 5-nm AuNPs effectively 4,32 Assuming that thermal heating plays an important role in the ionization mechanism, these differences in NP size give an opportunity to probe the potential zones of ionization.…”

High‐Spatial Resolution Mass Spectrometry Imaging: Toward Single Cell Metabolomics in Plant Tissues

“…This resulted in partial success, although some aggregation was apparent and caused signal loss, especially as the time between suspension preparation and spray deposition increased. An alternative to NP suspensions is the use of physical vapor deposition (PVD) (or sputter coating) to create NPs in situ, which has been demonstrated for Pt,, Au,, and Ag . We are currently working to compare several metal NPs produced via PVD for their efficacy in small molecule analysis.…”

Mild Methylenetetrahydrofolate Reductase Deficiency Alters Inflammatory and Lipid Pathways in Liver

“…Consistent with decreased expression of Scd1, analysis of the FA composition of liver using molecular profiling of tissue sections [22][23][24] by MS revealed a marked increase in saturated FA content of TG and phospholipids in HFAT compared to CD mice for Mthfr +/+ (Figure 6) as well as Mthfr +/− mice (Table S4, Supporting Information). This was also observed in another independent set of mice (data not shown).…”