Immersion by rotation-based application of the matrix for fast and reproducible sample preparations and robust results in mass spectrometry imaging.

Johanna Schäfermann,Hanna Bednarz,Marco Giampà,Georg Kliewer,Karsten Niehaus,Jan Lösch

doi:10.1002/jms.4488

Johanna Schäfermann, Hanna Bednarz + Show 4 more

Open Access

https://doi.org/10.1002/jms.4488

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Abstract

Automated matrix deposition for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is crucial for producing reproducible analyte ion signals. Here we report an innovative method employing an automated immersion apparatus, which enables a robust matrix deposition within 5 minutes and with scalable throughput by using MAPS matrix and non-polar solvents. MSI results received from mouse heart and rat brain tissues were qualitatively similar to those from nozzle sprayed samples with respect to peak number and quality of the ion images. Overall, the immersion-method enables a fast and careful matrix deposition and has the future potential for implementation in clinical tissue diagnostics.

Highlights

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a molecular analytical technology for analyzing the spatial distribution of molecules directly in a tissue section.[1,2,3,4] Tissue slices are typically coated with a matrix-assisted laser desorption/ionization (MALDI) matrix in order to extract analytes of interest from the tissue
The comparison of MALDI-TOF mass spectra from MSI measurements of rat brain or mouse heart tissue processed by either immersion or spray-coating with maleic anhydride proton sponge (MAPS) matrix, which has been dissolved in toluene, shows no qualitative differences between the two sample preparations (Figure 2)
The MALDI-MSI images of the ion at m/z value 35 are displayed in Figure 3, which is tentatively identified as chloride because it was observed with a chloride-specific isotopic abundancy (Supporting information, Figure S1)

Summary

| INTRODUCTION

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a molecular analytical technology for analyzing the spatial distribution of molecules directly in a tissue section.[1,2,3,4] Tissue slices are typically coated with a MALDI matrix in order to extract analytes of interest from the tissue. In order to realize the implementation of MSI as standard application in translational medicine, the sample preparation must be robust, easy to be integrated into the clinical workflow routines and the throughput should be scalable. The usage of these automated systems is still demanding in terms of qualified personnel and high maintenance. In order to standardize the process of matrix application by immersion, an automated technique would be beneficial For this reason, we developed an innovative matrix deposition apparatus with an automatic rotation mechanism. This immersion device allows a feasible and low maintenance procedure of matrix deposition in about 5 minutes

| METHODS

| RESULTS

| DISCUSSION