An in situ fracture device to image lipids in single cells using ToF‐SIMS

Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) imaging yields molecule‐specific images showing the spatial distribution of specific lipids with submicron resolution, making it a potentially powerful method for studying a variety of biological questions in single cells. In order to make possible the analysis of hydrated cells in vacuum, we have designed a device for in situ freeze‐fracture of cell samples. PC12 cells are frozen between two silicon shards in a sandwich geometry, and the fracture is conducted under vacuum inside the analysis chamber of the instrument. After freeze‐fracture, ToF‐SIMS analysis was carried out using a Bi cluster ion source, providing high‐resolution images of single cells. We also show that when combining freeze‐fracture and cluster SIMS imaging, low abundant biologically important lipids, specifically PE, PC and non‐SM PC, can be imaged in single cells. Finally, K + ion localization was used as a diagnostic to identify fracture planes through the cell for these fractured samples.