MS<sup>3</sup> Imaging Enables the Simultaneous Analysis of Phospholipid C═C and <i>sn</i>-Position Isomers in Tissues
X. Guo, Wenbo Cao, Xiaomin Fan, Qinhua Chen, Lun Wu, Xiaoxiao Ma, Zheng Ouyang, Wenpeng Zhang
Abstract
Mass spectrometry (MS) imaging of lipids in tissues with high structure specificity is challenging in the effective fragmentation of position-selective structures and the sensitive detection of multiple lipid isomers. Herein, we develop an MS 3 imaging method for the simultaneous analysis of phospholipid C═C and sn -position isomers by on-tissue photochemical derivatization, nanospray desorption electrospray ionization (nano-DESI), and a dual-linear ion trap MS system. A novel laser-based sensing probe is developed for the real-time adjustment of the probe-to-surface distance for nano-DESI. This method is validated in mouse brain and kidney sections, showing its capability of sensitive resolving and imaging of the fatty acyl chain composition, the sn -position, and the C═C location of phospholipids in an MS 3 scan. MS 3 imaging of phospholipids has shown the capability of differentiation of cancerous, fibrosis, and adjacent normal regions in liver cancer tissues.