Imaging of Neurotransmitters and Small Molecules in Brain Tissues Using Laser Desorption/Ionization Mass Spectrometry Assisted with Zinc Oxide Nanoparticles.

Authors

Chaochao Chen
Steven R Laviolette
Shawn N Whitehead
Justin B Renaud
Ken K-C Yeung

Document Type

Article

Publication Date

3-30-2021

Journal

Journal of the American Society for Mass Spectrometry

Volume

32

Issue

4

First Page

1065

Last Page

1079

URL with Digital Object Identifier

https://doi.org/10.1021/jasms.1c00021

Abstract

Inorganic nanostructured materials such as silicon, carbon, metals, and metal oxides have been explored as matrices of low-background signals to assist the laser desorption/ionization (LDI) mass spectrometric (MS) analysis of small molecules, but their applications for imaging of small molecules in biological tissues remain limited in the literature. Titanium dioxide is one of the known nanoparticles (NP) that can effectively assist LDI MS imaging of low molecular weight molecules (LMWM). TiO₂ NP is commercially available as dispersions, which can be applied using a chemical solution sprayer. However, aggregation of NP can occur in the dispersions and the aggregated NP can slowly clog the sprayer nozzle. In this work, the use of zinc oxide (ZnO) NP for LDI MS imaging is investigated as a superior alternative due to its dissolution in acidic pH. ZnO NP was found to deliver similar or better results in the imaging of LMWM in comparison to TiO₂ NP. The regular acid washes were effective in minimizing clogging and maintaining high reproducibility. High-quality images of mouse sagittal and rat coronal tissue sections were obtained. Ions were detected predominately as Na⁺ or K⁺ adducts in the positive ion mode. The number of LMWM detected with ZnO NP was similar to that obtained with TiO₂ NP, and only a small degree of specificity was observed.

Notes

J. Am. Soc. Mass Spectrom. 2021, 32, 4, 1065–1079 Publication Date:March 30, 2021 https://doi.org/10.1021/jasms.1c00021

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jasms.1c00021.

• MS images, additional experimental conditions, a figure showing effects on signal intensities due to additional salt ions, and a comparison of our data with those in the literature (PDF)

• MALDI mass spectra and tandem mass spectra (PDF)