title: Multigrid MALDI mass spectrometry imaging (mMALDI MSI).
abstract: Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is an important technique for the spatially resolved molecular analysis of tissue sections. The selection of matrices influences the resulting mass spectra to a high degree. For extensive and simultaneous analysis, the application of different matrices to one tissue sample is desirable. To date, only a single matrix could be applied to a tissue section per experiment. However, repetitive removal of the matrix makes this approach time-consuming and damaging to tissue samples. To overcome these drawbacks, we developed a multigrid MALDI MSI technique (mMALDI MSI) that relies on automated inkjet printing to place differing matrices onto predefined dot grids. We used a cooled printhead to prevent cavitation of low viscosity solvents in the printhead nozzle. Improved spatial resolution of the dot grids was achieved by using a triple-pulse procedure that reduced droplet volume. The matrices can either be applied directly to the thaw-mounted tissue sample or by precoating the slide followed by mounting of the tissue sample. During the MALDI imaging process, we were able to precisely target different matrix point grids with the laser to simultaneously produce distinct mass spectra. Unlike the standard method, the prespotting approach optimizes the spectra quality, avoids analyte delocalization, and enables subsequent hematoxylin and eosin (H&E) staining. Graphical Abstract Scheme of the pre-spotted multigrid MALDI MSI workflow.
authors.affiliation: Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.|Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.
authors.forename: Annett
authors.initials: A
authors.lastname: Urbanek
authors.affiliation: Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.|Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hölzer
authors.affiliation: Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.|Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Knop
authors.affiliation: Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany. ulrich.schubert@uni-jena.de.|Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany. ulrich.schubert@uni-jena.de.
authors.forename: Ulrich S
authors.initials: US
authors.lastname: Schubert
authors.affiliation: Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743, Jena, Germany.|Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.|ENT Department, Jena University Hospital, Lessingstrasse 2, 07743, Jena, Germany.|Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, 07745, Jena, Germany.
authors.forename: Ferdinand
authors.initials: F
authors.lastname: von Eggeling
mesh_terms: D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013194:Staining and Labeling
keywords: Inkjet printing; Mass spectrometry imaging; Multigrid; Multiplex; Simultaneous analysis; Sub-pixel