Biocompatible Surface-Coated Probe for in Vivo, in Situ, and Microscale Lipidomics of Small Biological Organisms and Cells Using Mass Spectrometry

Lipidomics is a significant way to understand the structural and functional roles that lipids play in biological systems. Although many mass spectrometry (MS)-based lipidomics strategies have recently achieve remarkable results, in vivo, in situ, and microscale lipidomics for small biological organisms and cells have not yet been obtained. In this article, we report a novel lipidomics methodology for in vivo, in situ, and microscale investigation of small biological organisms and cells using biocompatible surface-coated probe nanoelectrospray ionization mass spectrometry (BSCP-nanoESI-MS). A novel biocompatible surface-coated solid-phase microextration (SPME) probe is prepared, which possesses a probe-end diameter of less than 5 μm and shows excellent enrichment capacity toward lipid species. In vivo extraction of living biological organisms (e.g., zebrafishes), in situ sampling a precise position of small organisms (e.g., Daphnia magna), and even microscale analysis of single eukaryotic cells (e.g., HepG2) are easily achieved by the SPME probe. After extraction, the loaded SPME probe is directly applied for nanoESI-MS analysis, and a high-resolution mass spectrometer is employed for recording spectra and identifying lipid species. Compared with the conventional direct infusion shotgun MS lipidomics, our proposed methodology shows a similar result of lipid profiles but with simpler sample pretreatment, less sample consumption, and shorter analytical times. Lipidomics of zebrafish, Daphnia magna, and HepG2 cell populations were investigated by our proposed BSCP-nanoESI-MS methodology, and abundant lipid compositions were detected and identified and biomarkers were obtained via multivariate statistical analysis.