Probing cell chemistry with time‐of‐flight secondary ion mass spectrometry: development and exploitation of instrumentation for studies of frozen‐hydrated biological material

Abstract

Imaging static secondary ion mass spectrometry (SIMS) offers a powerful method of obtaining molecular information from biological systems with good spatial resolution. However, the technique needs further development to make it suitable for routine analysis of cells. We report here the development of a new freeze-facture device to facilitate the manipulation and analysis of biological cell material, with the cell chemistry preserved intact by rapid freezing. We illustrate performance characteristics with high-contrast images of freeze-fractured, frozen-hydrated liposomes with the drug clofazamine constrained within the lipid bilayer providing a marker to determine the fracture plane across the liposome structure. By monitoring and imaging clofazamine on the surface of yeast cells in the frozen-hydrated state, and demonstrating its absence within molecular information from a cell fractured to reveal the cell ultrastructure, we demonstrate that the molecule does not penetrate the cell wall.

The Magic of Cluster SIMS

“…Several labs have achieved single-cell bioimaging with atomic primary projectiles (23)(24)(25). Although the images have been plagued by low signal from the diverse array of membrane molecules, lipid rearrangements at highly curved membrane junctions have been followed.…”

ToF‐SIMS imaging of lipids in cell membranes

“…Further interesting developments are the interface of imaging SIMS mass spectrometers with other instruments. For example, SIMS combined with fluorescence, 47 FT-IR 77 or MALDI 23,64 imaging or even built-in cryosectioning or freezefracture devices. 78,79 It seems that for the next several years, the imaging SIMS instruments suitable for biomedicine will have as many or more capabilities as today's instruments for materials science.…”

Secondary Ion MS Imaging To Relatively Quantify Cholesterol in the Membranes of Individual Cells from Differentially Treated Populations

“…1 Numerous analytical techniques, including electrochemical detection, 2-6 separation-based methods, 7-9 fluorescence microscopy, 10-13 and mass spectrometry [14][15][16][17][18][19][20][21][22][23][24] have been used to surmount the inherent difficulties of measurements down to the μm-, pL-, and zmole-scale to study the intricate chemistry that exists within single cells.…”