Cellular Imaging Using Matrix-Enhanced and Metal-Assisted SIMS

Imaging mass spectrometry (IMS) allows the direct investigation of both the identity and the spatial distribution of the entire molecular content directly in tissue sections, single cells, and many other biological surfaces. We describe here the steps required to retrieve the molecular information from tissue sections using matrix-enhanced (ME) and metal-assisted (MetA) secondary ion mass spectrometry (SIMS). Surface metallization by plasma coating enhances desorption/ionization of membrane components such as lipids and sterols in imaging time-of-flight (ToF) SIMS of tissues and cells. High-resolution images of cholesterol and other membrane components can be obtained for single neuroblastoma cells and reveal subcellular details. Alternatively, in ME-SIMS, 2,5-dihydroxybenzoic acid electrosprayed on neuroblastoma cells allows intact molecular ion imaging of phosphatidylcholine (PC) and sphingomyelin (SM) at the cellular level.