Matrix‐assisted laser desorption/ionization‐Fourier‐transform ion cyclotron resonance‐mass spectrometry analysis of exosomal lipids from human serum

• Published in: Rapid communications in mass spectrometry 2023-01, Vol.37 (2), p.e9427-n/a
• Main Authors: Jalaludin, Iqbal, Nguyen, Huu‐Quang, Jang, Kyoung‐Soon, Lee, Jaebeom, Lubman, David M., Kim, Jeongkwon
• Format: Article
• Language: English
• Subjects: Biomarkers; Cyclotron resonance; Desorption; Dihydroxybenzoic acid; Graphene; Humans; Hydroxycinnamic acid; Ionization; Ions; Lasers; Lipids; Lipids - analysis; Mass spectrometry; Phosphatidylcholine; Positive ions; Proteins; Scientific imaging; Sinapic acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Spectroscopy
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.9427

Rationale Exosomes contain biomarkers such as proteins and lipids that help in understanding normal physiology and diseases. Lipids, in particular, are infrequently studied using matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry (MS) for biomarker discovery. In this study, MALDI was equipped with a high‐resolution MS to investigate exosomal lipids from human serum. Methods Exosomal lipids were profiled using MALDI with Fourier‐transform ion cyclotron resonance (FTICR)‐MS. Four matrices (i.e., α‐cyano‐4‐hydroxycinnamic acid [CHCA], 2,5‐dihydroxybenzoic acid, sinapinic acid, and graphene oxide [GO]) and three sample preparation methods (i.e., dried droplet, thin layer, and two layer) were compared for the number of lipid species detected and the relative abundance of each lipid from human serum and human serum exosomes. Results In sum, 172 and 89 lipid species were identified from human serum and human serum exosomes, respectively, using all the methods. The highest number of exosome lipid species, 69, was detected using the CHCA matrix, whereas only 8 exosome lipid species were identified using the GO matrix. Among the identified lipid species, phosphatidylcholine was identified most frequently, probably due to the use of a positive ion mode. Conclusions Exosomes and human serum showed comparable lipid profiles as determined using MALDI‐FTICR‐MS. These findings provide a new perspective on exosomal lipidomics analysis and may serve as a foundation for future lipidomics‐based biomarker research using MALDI‐FTICR‐MS.