High-resolution TOF-SIMS imaging of eukaryotic cells preserved in a trehalose matrix

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.