Optimizing and Evaluating Zinc Oxide Nanoparticles as a Matrix for Matrix-Assited Laser/ Desorption Ionization Mass Spectrometry for Small Molecule Detection in Rodent Brain Tissue
Abstract
Matrix-assisted laser/desorption ionization (MALDI) is the preferred method for mass spectrometry imaging (MSI) due to its high spatial resolution. Detecting small molecules like γ-aminobutyric acid (GABA) and glutamate, which are the main inhibitory and excitatory neurotransmitters respectively, proves challenging as their low masses conflict with background signals from most matrices.
This work optimizes zinc oxide nanoparticles (ZnO NP) as a matrix, focusing on GABA and Glutamate detection. Its absence of background signal makes ZnO suitable for small molecule detection. Its shortcomings, especially batch-to-batch variability, were mitigated through filtration and sonication before deposition, achieving high-resolution imaging of rat brain tissue sections.
To assess ZnO NP viability, MALDI MSI was employed to relatively quantify glutamate, glutamine, and GABA in brain tissue sections from adolescent rat brains exposed to Δ-9-tetrahydrocannabinol (Δ-9-THC) through edibles in the nucleus accumbens (NAc) subregions. ZnO NP consistently detected all, revealing a downregulation in each molecule in both subregions.