High-Resolution TOF-SIMS Imaging of Eukaryotic Cells Preserved in a Trehalose Matrix

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Abstract
A novel, trehalose-glycerol matrix was utilized to generate high-resolution, TOF-SIMS images of macrophages and glial cells. Viable cells incubated in 50 mM trehalose, then lyophilized in a 50 mM trehalose, 10−15% (w/w) glycerol rinse, are preserved and chemically profiled. These experiments demonstrate the utility of the disaccharide matrix as an efficient, cost-effective alternative to cryogenics for SIMS and other ultrahigh-vacuum (UHV) analyses of biological species. Cellular processes on oligodendrocytes and astrocytes, 1−3 μm in width, were well resolved for cells in the trehalose−glycerol matrix. The viscous cell matrixes were fractured and analyzed at room temperature and maintained their three-dimensional integrity under UHV. Images have been generated with a Au primary ion source near the static limit of 1012 ions/cm2. Though these nucleated cells do not remain viable after desiccation, TOF-SIMS imaging and subsequent rehydration reveals structural and morphological preservation. Eliminating the inherent obstacles associated with cryogenic analysis opens the door to greater utility of SIMS as a bioanalytical tool, such as lipid mapping of single cells in the nervous system.