Method for Simultaneous Imaging of Endogenous Low Molecular Weight Metabolites in Mouse Brain Using TiO2 Nanoparticles in Nanoparticle-Assisted Laser Desorption/Ionization-Imaging Mass Spectrometry

We report the detection of a group of endogenous low molecular weight metabolites (LMWM) in mouse brain (80-500 Da) using TiO2 nanoparticles (NPs) in nanoparticle-assisted laser desorption/ionization-imaging mass spectrometry (Nano-PALDI-IMS) without any washing and separation step prior to MS analysis. The identification of metabolites using TiO2 NPs was compared with a conventional organic matrix 2,5-dihydroxybenzoic acid (DHB) where signals of 179 molecules were specific to TiO2 NPs, 4 were specific to DHB, and 21 were common to both TiO2 NPs and DHB. The use of TiO2 NPs enabled the detection of a higher number of LMWM as compared to DHB and gold NPs as a matrix. This approach is a simple, inexpensive, washing, and separation free for imaging and identification of LMWM in mouse brain. We believe that the biochemical information from distinct regions of the brain using a Nano-PALDI-IMS will be helpful in elucidating the imbalances linked with diseases in biomedical samples.