MALDI-Imaging MS of Lipids on Mouse Brain Tissue Sections Using Negative Ion Mode
The main biological functions of lipids include energy storage, signaling, and acting as structural components of cell membranes. Not only their chemical composition and structures but also the distributions in biological body are important for biochemistry. Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-Imaging MS) is a powerful tool for the biochemical analyses of surfaces. Different lipid types are observed in positive or negative-ion MALDI mass spectra, depending on the presence of polar functional groups. Phosphatidyl cholines and galactosyl ceramides were mainly observed in the MALDI-Imaging MS of positive ion mode using JMS-S3000 SpiralTOF.
In this work, we report the use of the SpiralTOF for negative-ion MALDI-Imaging MS of sulfatides. High-resolution, accurate mass data and MS/MS data obtained under high-energy CID conditions provide information about structures, elemental compositions, and localization of many types of sulfatides.
A mouse brain tissue section was placed on an ITO conductive glass slide plate (Fig. 1). The matrix compound 9-aminoacridine was sprayed on the surface of the tissue and then the sample was introduced to the mass spectrometer. The imaging MS measurements were performed in negative-ion mode on the whole brain tissue section (6.3 mm × 9.24 mm ) with 60 μm spatial resolution. The images consisted of 16170 mass spectra equivalent to the accumulation of 500 laser shots for each mass spectrum.