Large-Scale Metabolite Analysis of Standards and Human Serum by Laser Desorption Ionization Mass Spectrometry from Silicon Nanopost Arrays

The
unique challenges presented by metabolomics have driven the
development of new mass spectrometry (MS)-based techniques for small
molecule analysis. We have previously demonstrated silicon nanopost
arrays (NAPA) to be an effective substrate for laser desorption ionization
(LDI) of small molecules for MS. However, the utility of NAPA-LDI-MS
for a wide range of metabolite classes has not been investigated.
Here we apply NAPA-LDI-MS to the large-scale acquisition of high-resolution
mass spectra and tandem mass spectra from a collection of metabolite
standards covering a range of compound classes including amino acids,
nucleotides, carbohydrates, xenobiotics, lipids, and other classes.
In untargeted analysis of metabolite standard mixtures, detection
was achieved for 374 compounds and useful MS/MS spectra were obtained
for 287 compounds, without individual optimization of ionization or
fragmentation conditions. Metabolite detection was evaluated in the
context of 31 metabolic pathways, and NAPA-LDI-MS was found to provide
detection for 63% of investigated pathway metabolites. Individual,
targeted analysis of the 20 common amino acids provided detection
of 100% of the investigated compounds, demonstrating that improved
coverage is possible through optimization and targeting of individual
analytes or analyte classes. In direct analysis of aqueous and organic
extracts from human serum samples, spectral features were assigned
to a total of 108 small metabolites and lipids. Glucose and amino
acids were quantitated within their physiological concentration ranges.
The broad coverage demonstrated by this large-scale screening experiment
opens the door for use of NAPA-LDI-MS in numerous metabolite analysis
applications.

代谢组学所提出的独特挑战推动了基于质谱（MS）的小分子分析新技术的开发。我们先前已证明硅纳米阵列（NAPA）是激光解吸电离（LDI）小分子进行MS分析的有效基底。然而，NAPA-LDI-MS在广泛代谢物类别中的应用潜力尚未得到研究。本研究中，我们应用NAPA-LDI-MS对覆盖氨基酸、核苷酸、碳水化合物、异生物、脂质和其他化合物类别的代谢物标准库进行了大规模的高分辨率质谱和串联质谱的采集。在针对代谢物标准混合物的非靶向分析中，检测到374种化合物，并获得了287种化合物的有价值的MS/MS谱，无需对电离或裂解条件进行个别优化。在31个代谢途径的背景下评估了代谢物检测，发现NAPA-LDI-MS为63%的调查途径代谢物提供了检测。对20种常见氨基酸的个体靶向分析检测到了所研究化合物的100%，这表明通过优化和针对单个分析物或分析物类别，可以实现更广泛的覆盖。在直接分析人类血清样本的水相和有机提取物时，将光谱特征分配给了总共108种小代谢物和脂质。葡萄糖和氨基酸在其生理浓度范围内进行了定量。这种大规模筛选实验所展现的广泛覆盖范围，为NAPA-LDI-MS在众多代谢物分析应用中的使用开辟了道路。