Screening Assay of Very Long Chain Fatty Acids in Human Plasma with Multiwalled Carbon Nanotube-Based Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

摘要

Peroxisomal disorders are characterized biochemically bynelevated levels of very long chain fatty acids (VLCFAs) innserum. Herein, we describe a novel approach for quantificationnof VLCFAs in serum, namely, eicosanoic acidn(C20:0), docosanoic acid (C22:0), tetracosanoic acidn(C24:0), and hexacosanoic acid (C26:0). The methodologynis based on (i) enrichment of VLCFA derivatives usingnmultiwalled carbon nanotubes (MWCNTs); (ii) quantificationnusing stable isotope-labeled internal standards; andn(iii) direct detection using MWCNT-based surface-assistednlaser desorption/ionization-time-of-flight mass spectrometryn(SALDI-TOFMS). Four kinds of MWCNTs (Aldrichn636843, 636495, 636509, and 636819) of differentnlengths and diameters were tested using the developedntechnique. The data show that 636843, the MWCNT withnthe largest outer diameter (o.d.), the widest wall thickness,nand shortest length, had the best limit of detectionn(0.5-1 μg/mL) We also found that there was no significantndifference in enrichment efficiency of VLCFAs betweennthe four MWCNTs, which suggests that the size ofnthe MWCNT may contribute to desorption/ionizationnefficiency. To our knowledge, this is the first study to testnthe enrichment of VLCFAs using MWCNTs of differentnsizes. We have shown that the VLCFAs adsorbed bynMWCNTs can be analyzed by SALDI-TOFMS. In addition,nthis method does not require liquid/gas chromatographynseparation, thereby allowing for high-throughput screeningnof VLCFAs in peroxisomal disorders.