Instantaneous Lipid Profiling in Rat Cerebrospinal Fluid via a Nanoconfined Sampling Extraction and Grouping Separation Integrated System: Overcoming Ex Vivo Degradation.

Monitoring lipid dynamics in cerebrospinal fluid (CSF) is critical for understanding central nervous system disorders. However, rapid ex vivo lipid degradation under the effect of enzymes in CSF during in vitro analysis compromises accuracy. To address this, we developed an integrated nanoconfined sampling extraction and grouping separation system using carbon nanofibers (CNFs) and tandem carbon fibers (TCFs). The system achieves rapid in situ sampling and extraction of various lipids in rat CSF within 80 s through nanoconfinement of methyl tert-butyl ether on the surface of CNFs, concurrently separating enzymes (including other proteins) and salts. Coupled with an activated carbon fiber/carbon fiber tandem system, it achieves online grouping and separation of multiple polar lipids within 5 min. Integrated with mass spectrometry, the platform enables the determination and identification of 176 lipids that cover a broad polarity spectrum of lipid metabolites in CSF, offering a sensitive and efficient strategy for authentic lipid analysis in vivo. Notably, the detected lipids include four key classes, namely, fatty acyls, glycerophospholipids, sphingolipids, and sterols, which have been closely associated with Alzheimer's disease pathology. This advancement enhances early diagnosis accuracy and mechanistic insights into brain disorders.