Metabolomic Profiling of Adherent Mammalian Cells In Situ by LAESI-MS with Ion Mobility Separation.

Ambient ionization-based mass spectrometry (MS) methods coupled with ion mobility separation (IMS) have emerged as promising approaches for high-throughput in situ analysis for biomedical to environmental applications. These methods are capable of direct profiling and molecular imaging of metabolites, lipids, peptides, and xenobiotics from biological tissues with minimal sample preparation. Furthermore, employing IMS within the workflow improves the molecular coverage, resolves isobaric species, and improves biomolecule identifications through accurate collision cross section measurements. Laser ablation electrospray ionization (LAESI)-MS coupled with IMS has been successful in profiling and molecular imaging of small biomolecules directly from biological tissues and single cells. Herein, we describe a protocol for the direct analysis of adherent mammalian cells with limited perturbations by LAESI-IMS-MS. A benefit of IMS is that within the same LAESI acquisition, the spectral features related to the ESI background, washing buffer, and cell signal can be extracted and isolated separately.