Mass spectrometry

Weighing up surfaces

Mass spectrometry can be used to image a lipid membrane with 100 nm resolution based on its chemical composition

Credit: © 2006 AAAS

Mass spectrometry is an analytical technique that can be used to weigh molecules. Although many variations exist, the basic principles are the same; the sample of interest is ionized and the ions are separated, according to their mass-to-charge ratio, and counted. Now, researchers in the USA have shown how mass spectrometry can be used to map out the distribution of two different lipids in a membrane.

Steven Boxer and co-workers1 from Stanford University, the University of California, Davis, and Lawrence Livermore National Laboratory look at bilayers in which two different isotopically labelled lipids separate into domains. As a focused beam of caesium ions scans across the surface of a freeze-dried membrane, the lipid molecules fragment to form ions. These ‘secondary’ ions — which retain the isotopic signature of their parent lipids — are then detected and give a spatially resolved picture of the membrane.

Individual membrane components can be resolved at the molecular level with electron microscopy and optical imaging probes much larger length scales. Boxer’s technique falls in between, however, and can image the lateral organization of lipids within a membrane with 100 nm resolution as well as providing chemical composition data.


  1. 1

    Kraft, M. L. et al. Science (2006). 10.1126/science.1130279

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Cantrill, S. Weighing up surfaces. Nature Nanotech (2006).

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