Credit: © 2009 Wiley

Two-dimensional imaging mass-spectrometry has become a useful tool in biology for looking at the distribution of molecules such as lipids or drugs in cells and tissue. One of the benefits of using mass spectrometry for imaging is that it doesn't require the use of staining dyes or radioactive labelling. The technique identifies molecules on a surface and three-dimensional images can be reconstructed from several sections.

Graham Cooks and colleagues from Purdue University have now developed a new technique that allows these sections to be quickly examined under ambient conditions, rather than the vacuum normally required1. They used desorption electrospray ionization to liberate molecules from the samples, which then pass through the mass spectrometer. They optimized the conditions to provide the high-quality signal intensity and increased-quality two-dimensional images required to make up reliable three-dimensional models.

To test the technique, they looked at specific lipids in sections of mouse brain. Two characteristic lipids are distributed evenly in either the grey- or white-matter regions, so mapping only these rapidly built up a picture of the whole brain. Although this is only an approximation, the technique could be extended to look for other molecules and other organs. This could help build an 'atlas' that precisely correlates the presence of molecules to organ function.