High definition ion-mobility mass spectrometry and imaging for metabolomics, lipidomics and glycomics

We propose to purchase a high-end mass spectrometer system that is capable of identifying thousands of unique small molecules at a time. This is achieved by the combination of accurate mass measurements, which enables the calculation of molecular formulae, and the ability of the mass spectrometer to separate molecules on the basis of their mass and shape. This last ability - separation on the basis of shape - is achieved using a technique known as ion mobility, which is not standard on most commercially available mass spectrometers. Ion mobility techniques allow molecules that have identical masses and formulae to be separated. This ability is crucial for the correct identification and measurement of several classes of biologically important molecules, including small molecules, lipids, and carbohydrates. We propose two main front-end interfaces that will make full use of the mass spectrometer's capabilities. The first is an imaging interface, where plant or animal tissue slices can be automatically sampled in a two-dimensional plane to build up a picture of where molecules are localised in the sample. As one input to this imaging pipeline, we will also use the output from our newly acquired, separately funded quantitative phase imaging microscope, which enables cell types and behaviours in tissue slices to be visualised and measured without prior staining or fixing. This pipeline - from visible features to mass spectrometry imaging on the same sample - will enable us to relate visible changes observed within tissues to the underlying biochemical processes. Applications range from tracking drug movements between cell types in medical treatments, to locating the sites of plant cell wall degradation in studies where the focus is on optimizing biofuel generation from waste biomass. The second interface uses separation by high-performance liquid chromatography of biological extracts before the mass spectrometer. This will enable us to characterize very complex mixtures, for example from understanding how the lipid make-up of cell membranes in industrially important microbes contributes to robust fermentation, to measuring fine changes in branched carbohydrate structures that are important signalling and recognition molecules in human disease. A common thread in all the different applications will be the complexity and multi-dimensionality of the data produced. All data will require careful filtering and annotation to provide biologically meaningful conclusions; this is not trivial and more often than not requires significant expert manual input and is a productivity bottleneck. To address this often overlooked area, together with the instrument manufacturers, we are committing resources to develop software tools for efficient data analysis.