Multimodal Imaging: Elements & Molecules in Biological Samples
Catia Costa & Melanie J. Bailey
Why multimodal imaging?

We are developing analytical strategies to combine MeV ion beam elemental mapping with mass spectrometry imaging (MSI).

This will help to understand (e.g.) the impact of…

☐  Metal nanoparticles
☐  Elemental accumulation/depletion
☐  Metal containing drugs
… on the local chemistry (e.g. metabolites, proteins, lipids).

But…

… we want to perform sequential measurements on a single sample, because features are not always accurately reproduced in sequential sections.

What are the challenges?

☐  Expertise and   instrumentation are not               normally co-located
☐  Different sample handling requirements
☐  Techniques are potentially destructive                 (what is the correct workflow?)
☐  Different data handling strategies

What techniques have we combined?
Desorption electrospray ionisation (DESI) and particle induced X-ray emission (PIXE)

☐  Using a spray solvent consisting of 50:50 (%v/v) methanol:ethanol           enables sequential molecular (DESI) elemental (PIXE) mapping out         on the same tissue section.

☐  This novel spray solvent mixture does not cause measurable loss or         delocalisation of elemental signatures.

☐  This is desirable to allow accurate correlation of elemental and               molecular features since regions of interest are not always                       accurately reproduced in sequential sections.  In this work, the new         solvent system produced similar, if not better, lipid coverage and             sensitivity in positive ion mode when compared to the conventional       methanol:water solvent.

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