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submitted on 03.07.2020 and posted on 06.07.2020by Daisy Unsihuay, ruichuan yin, Daniela Mesa Sanchez, Yingju Li, Xiaofei Sun, Sudhansu Dey, Julia Laskin
Simultaneous spatial localization and structural characterization of
molecules in complex biological samples currently represents an analytical
challenge for mass spectrometry imaging (MSI) techniques. In this study, we
describe a novel experimental platform, which substantially expands the
capabilities and enhances the depth of chemical information obtained in high
spatial resolution MSI experiments performed using nanospray desorption
electrospray ionization (nano-DESI). Specifically, we designed and constructed
a portable nano-DESI MSI platform and coupled it with a drift tube ion mobility
spectrometer-mass spectrometer (IM-MS). Separation of biomolecules observed in
MSI experiments based on their drift times provides unique molecular
descriptors necessary for their identification by comparison with databases. Furthermore,
it enables isomer-specific imaging, which is particularly important for
unraveling the complexity of biological systems. Imaging of day 4 pregnant
mouse uterine sections using the newly developed nano-DESI-IM-MSI system demonstrates
rapid isobaric and isomeric separation
and reduced chemical noise in MSI experiments. A direct comparison of the
performance of the new nano-DESI-MSI platform operated in the MS mode with the
more established nano-DESI-Orbitrap platform indicates a comparable performance
of these two systems. A spatial resolution of better than ~16 µm and similar molecular
coverage was obtained using both platforms.
The structural information provided by the ion mobility separation
expands the molecular specificity of high-resolution MSI necessary for the
detailed understanding of biological systems.