Novel Blotting Method for Mass Spectrometry Imaging of Metabolites in Strawberry Fruit by Desorption/Ionization Using Through Hole Alumina Membrane.

Hirofumi Enomoto,Masahiro Kotani,Takayuki Ohmura

doi:10.3390/foods9040408

Hirofumi Enomoto, Masahiro Kotani + Show 1 more

Open Access

https://doi.org/10.3390/foods9040408

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Abstract

Mass spectrometry imaging (MSI) using matrix-assisted laser desorption/ionization (MALDI) is a powerful technique for visualizing metabolites in the strawberry fruit. During sample preparation for MALDI-MSI, sectioning of the samples is usually required. In general, MALDI-MSI analysis of strawberry fruits that are larger than a single glass slide is difficult because thin sections cannot be prepared. In this study, we attempted to visualize metabolites in large strawberry fruits by MSI, employing a blotting method that uses desorption ionization using a through-hole alumina membrane (DIUTHAME) chip. Large strawberry fruits were cut and a DIUTHAME chip was set on the cross-section to blot the metabolites. After drying the DIUTHAME chip, the metabolites were measured in positive and negative ion modes using a commercial MALDI-type mass spectrometer. Several peaks were detected in both the ion modes. Various metabolites related to food quality, such as sugars, organic acids, and anthocyanins, were detected and successfully visualized by blotting on a DIUTHAME chip in MSI. These results suggest that blotting using a DIUTHAME chip in MSI is useful for visualizing the metabolites present in the strawberry fruit.

Highlights

Various separation techniques, such as liquid chromatography-electrospray ionization (ESI)-mass spectrometry, are commonly used for qualitative and quantitative analyses of metabolites [1]
We metabolites onto the cross section of strawberry fruit on the used chip, which wasblotted used for metabolite analysis by section of strawberry on than the DIUTHAME
Derived from the metabolites present in the sample. These results suggested that various types of is a matrix free ionization method different from matrix-assisted laser desorption/ionization (MALDI) [23], in which the detected peaks are usually metabolites in strawberry fruit were detected both ion modes our blotting method with the derived from the metabolites present in the in sample

Summary

Introduction

Various separation techniques, such as liquid chromatography-electrospray ionization (ESI)-mass spectrometry, are commonly used for qualitative and quantitative analyses of metabolites [1] They are used to investigate the analyte distribution by dividing samples into different tissues; the spatial resolution depends on the fineness of tissue differentiation. MSI was adapted for analysis of metabolites in foods and was successfully used for visualization using soft ionization techniques, such as matrix-assisted laser desorption/ionization (MALDI) [9,10,11,12,13,14,15,16,17] or desorption ESI [18,19]. These techniques generally require preparation of thin sections (usually 10–20 μm) of the samples using a cryomicrotome

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