Triboelectric Nanogenerator-Driven Laser Ablation Electrospray Ionization Enables Neutral Lipid Ionization and in...

Ambient ionization mass spectrometry includes numerous techniques, many of which are useful for analyzing lipids in biological samples. We report the development of a triboelectric nanogenerator (TENG)-driven laser ablation electrospray ionization (LAESI) platform, a novel ambient ionization method for the direct analysis of lipid mixtures. Detailed structural lipid annotation remains challenging due to the structural diversity of lipids. Previous research has shown that a TENG-driven dual nanoelectrospray ionization (nESI) and atmospheric pressure chemical ionization (APCI) mechanism helps localize lipid double bonds. In this study, we integrated infrared (IR) laser ablation with TENG nESI (TENG-LAESI). This novel ionization platform can ablate and ionize neutral lipids, including cholesterol and its derivatives, unsaturated fatty acids, and complex lipid mixtures. Rapid MS analysis reveals distinct ionization regimes within each TENG pulse and provides temporal resolution for various sterol species. Critically, the APCI stage drives epoxidation of fatty acid double bonds, generating diagnostic fragmentation patterns that enable reagent-free double-bond position assignment through tandem MS experiments, without chemical derivatization. Lastly, a novel TENG device was created and compared to existing designs, showing increased epoxidation efficiency and ionization potential. These experiments demonstrate the analytical potential of TENG-LAESI for structural lipid annotation and establish a foundation for its future development as a spatially resolved ambient MS imaging platform.