Lipid Mass Tags via Aziridination for Probing Unsaturated Lipid Isomers and Accurate Relative Quantification**

Abstract

Knowing concentrations of lipids is essential for understanding their physiological functions and discovering new disease biomarkers. However, it is highly challenging to accurately quantify lipids due to structural diversity and multiple isomeric forms of lipids. To address these critical gaps, we have developed a novel aziridine‐based isobaric tag labelling strategy that allows (i) determination of lipid double‐bond positional isomers, (ii) accurate relative quantification of unsaturated lipids, and (iii) improvement of ionization efficiencies of nonpolar lipids. The power of this method is demonstrated in characterization and quantification of various categories of lipids such as fatty acids, phosphoglycerol lipids, cholesteryl esters (CE), and glycerides. 17 CE lipid isomers were identified and quantified simultaneously from Alzheimer's disease (AD) mouse serum without using lipid standards. Among them, 6 CE isomers showed significant changes in concentrations in AD serum.

Rapid Characterization of Phospholipids from Biological Matrix Enabled by Indium Tin Oxide (ITO) Coated Slide Assisted Enrichment MALDI Mass Spectrometry

“…[15,16] By characterizing and quantifying the composition of lipid species in blood samples, the health status of individuals can be better understood. [17][18][19] Besides lipid profiling of human blood samples, there has been a notable increase in the interest surrounding the examination of cellular lipid composition. This approach to analyzing phospholipids within individual cells offers the ability to distinguish between cell types and explore overall organismal balance.…”