Single-Cell\nLipidomics: An Automated and Accessible\nMicrofluidic Workflow Validated by Capillary Sampling

We report the first demonstration of a microfluidics-based\napproach\nto measure lipids in single living cells using widely available liquid\nchromatography mass spectrometry (LC-MS) instrumentation. The method\nenables the rapid sorting of live cells into liquid chambers formed\non standard Petri dishes and their subsequent dispensing into vials\nfor analysis using LC-MS. This approach facilitates automated sampling,\ndata acquisition, and analysis and carries the additional advantage\nof chromatographic separation, aimed at reducing matrix effects present\nin shotgun lipidomics approaches. We demonstrate that our method detects\ncomparable numbers of features at around 200 lipids in populations\nof single cells versus established live single-cell capillary sampling\nmethods and with greater throughput, albeit with the loss of spatial\nresolution. We also show the importance of optimization steps in addressing\nchallenges from lipid contamination, especially in blanks, and demonstrate\na 75% increase in the number of lipids identified. This work opens\nup a novel, accessible, and high-throughput way to obtain single-cell\nlipid profiles and also serves as an important validation of single-cell\nlipidomics through the use of different sampling methods.