Assessing the potential of sputtered gold nanolayers in mass spectrometry imaging for metabolomics applications.

Pere Ràfols,Esteban Del Castillo,Noelia Ramírez,Liam A Mcdonnell,Jesús Brezmes,Xavier Correig,Bram Heijs,Raul Calavia,Oscar Yanes,Sònia Torres,Dídac Vilalta,Konradin Metze

doi:10.1371/journal.pone.0208908

Abstract

Mass spectrometry imaging (MSI) is a molecular imaging technique that maps the distribution of molecules in biological tissues with high spatial resolution. The most widely used MSI modality is matrix-assisted laser desorption/ionization (MALDI), mainly due to the large variety of analyte classes amenable for MALDI analysis. However, the organic matrices used in classical MALDI may impact the quality of the molecular images due to limited lateral resolution and strong background noise in the low mass range, hindering its use in metabolomics. Here we present a matrix-free laser desorption/ionization (LDI) technique based on the deposition of gold nanolayers on tissue sections by means of sputter-coating. This gold coating method is quick, fully automated, reproducible, and allows growing highly controlled gold nanolayers, necessary for high quality and high resolution MS image acquisition. The performance of the developed method has been tested through the acquisition of MS images of brain tissues. The obtained spectra showed a high number of MS peaks in the low mass region (m/z below 1000 Da) with few background peaks, demonstrating the ability of the sputtered gold nanolayers of promoting the desorption/ionization of a wide range of metabolites. These results, together with the reliable MS spectrum calibration using gold peaks, make the developed method a valuable alternative for MSI applications.

Highlights

IntroductionIn which the visual inspection of stained tissue sections is used for the identification of specific morphological regions and minute structures in the tissue, is one of the essential tools in medical diagnosis
Classic histopathological analysis, in which the visual inspection of stained tissue sections is used for the identification of specific morphological regions and minute structures in the tissue, is one of the essential tools in medical diagnosis
The viability of the optimized gold nanolayers for metabolomics Mass spectrometry imaging (MSI) applications by laser desorption/ionization (LDI)-Mass Spectrometry (MS) was checked by acquiring MSI data of different animal organ tissue sections

Summary

Introduction

In which the visual inspection of stained tissue sections is used for the identification of specific morphological regions and minute structures in the tissue, is one of the essential tools in medical diagnosis. In ambiguous cases the pathologist is not always capable of determining the correct diagnosis using histopathological methods alone. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Conclusion