Surface analysis of lipids by mass spectrometry: more than just imaging

Abstract

Mass spectrometry is now an indispensable tool for lipid analysis and is arguably the driving force in the renaissance of lipid research. In its various forms, mass spectrometry is uniquely capable of resolving the extensive compositional and structural diversity of lipids in biological systems. Furthermore, it provides the ability to accurately quantify molecular-level changes in lipid populations associated with changes in metabolism and environment; bringing lipid science to the "omics" age. The recent explosion of mass spectrometry-based surface analysis techniques is fuelling further expansion of the lipidomics field. This is evidenced by the numerous papers published on the subject of mass spectrometric imaging of lipids in recent years. While imaging mass spectrometry provides new and exciting possibilities, it is but one of the many opportunities direct surface analysis offers the lipid researcher. In this review we describe the current state-of-the-art in the direct surface analysis of lipids with a focus on tissue sections, intact cells and thin-layer chromatography substrates. The suitability of these different approaches towards analysis of the major lipid classes along with their current and potential applications in the field of lipid analysis are evaluated.

Keywords: 1,5-diaminonapthalene; 1,8-bis(dimethylamino)naphthalene; 2,4,6-trihydroxyacetophenone; 2,5-dihydroxybenzoic acid; 2,6-dihydroxyacetphenone; 2-AEP; 2-aminophosphonolipid; 2-mercaptobenzothiazole; 7,7,8,8-tetracyanoquinodimethane; 9-AA; 9-aminoacridine; AP-MALDI; APCI; ASAP; Ambient ionization; CHCA; CID; Cer; Cer1P; DAG; DAN; DAPPI; DART; DESI; DHA; DHB; DIOS; DMAN; EASI; ELDI; ESI; FAEE; FAME; FFA; GALDI; GL; GSL; GalCer; IR; IR-MALDI; LAESI; LDI; LESA; LIAD; LPE; LPS; LTP; LacCer; Lipidomics; MALDESI; MALDI; MBT; ME-SIMS; MS/MS; MTPFPP; Mass spectrometry imaging; Met-SIMS; NALDI; NIMS; PA; PC; PCA; PE; PESI; PG; PI; PL; PMMA; PNA; PS; PSI; PTFE; PVDF; REIMS; SIMS; SM; SSSP; ST; TAG; TCNQ; THAP; TLC; Thin-layer chromatography; V-EASI; atmospheric pressure chemical ionization; atmospheric pressure matrix-assisted laser desorption ionization; atmospheric pressure solids analysis probe; ceramide; ceramide-1-phosphate; collision-induced dissociation; desorption atmospheric pressure photoionization; desorption electrospray ionization; desorption/ionisation from porous silicon; diacylglyceride; direct analysis in real time; easy ambient sonic spray ionization; electrospray ionization; electrospray laser desorption ionization; fatty acid ethyl ester; fatty acid methyl ester; free fatty acid; galactosylceramide; ganglioside; glycosphingolipid; graphite-assisted laser desorption ionization; infrared; infrared matrix-assisted laser desorption ionization; lactosylceramide; laser ablation electrospray ionization; laser desorption ionization; laser-induced acoustic desorption; liquid extraction surface analysis; low temperature plasma; lyso phosphatidylethanolamine; lyso phosphatidylserine; matrix-assisted laser desorption electrospray ionization; matrix-assisted laser desorption ionization; matrix-enhanced secondary ion mass spectrometry; meso-tetrakis (pentaflurophenyl) porphyrin; metal-assisted secondary ion mass spectrometry; nanostructure-initiator mass spectrometry; nanowire-assisted laser desorption ionization; p-nitroaniline; paper spray ionization; phosphatidic acid; phosphatidylcholine; phosphatidylethanolamine; phosphatidylglycerol; phosphatidylinositol; phosphatidylserine; phospholipid; poly(methyl methacrylate); polytetrafluoroethylene; polyvinylidene difluoride; principal component analysis; probe electrospray ionization; rapid evaporative ionization mass spectrometry; sealing surface sampling probe; secondary ion mass spectrometry; sphingomyelin; sulfatide; tandem mass spectrometry; thin-layer chromatography; triacylglycerides; venturi-easy ambient sonic spray ionization; α-cyano-4-hydroxycinnamic acid.