Coupling Paternò-Büchi Reaction with Surface-Coated Probe Nanoelectrospray Ionization Mass Spectrometry for In Vivo and Microscale Profiling of Lipid C═C Location Isomers in Complex Biological Tissues

Abstract

Lipids are important structural components of biological systems, and lipid CC locations play important roles in their biophysical and biochemical properties. Rapid, in vivo, in situ, and microscale lipidomics investigation (including precise identification of lipid CC locations and isomers) of biological specimen has great potential for clinical diagnosis, biological studies, and biomarker discovery. Here we report a novel lipidomics methodology by coupling Paternò-Büchi (PB) reaction with surface-coated probe nanoelectrospray ionization mass spectrometry (SCP-nanoESI-MS) for in vivo, in situ, and microscale analysis of lipid species and CC location isomers in complex biological tissues. The proposed SCP-PB-nanoESI-MS method was performed by application of a biocompatible solid-phase microextraction (SPME) probe for in vivo, in situ, and microscale sampling and extraction of lipids from biological tissues, and then some spray solvent containing PB reagent was applied to desorb lipid species enriched on SPME probe within a nanospray tip. Subsequently, ultraviolet irradiation was employed to initiate PB reaction for unsaturated lipids within the nanospray tip. After that, a high voltage was applied on the SPME probe to induce nanoESI for MS analysis under ambient and open-air conditions, and collision-induced dissociation was performed to the PB reaction product ions for determination of lipid CC locations and isomers. By using our proposed SCP-BP-nanoESI-MS method, microscale investigation of lipid compositions and CC location isomers for lipid droplet of Perilla seed and human intestinal tissue were successfully achieved, and in vivo analysis of lipid species and CC locations for zebrafish was accomplished.

Mass Spectrometry Imaging of Lipids with Isomer Resolution Using High-Pressure Ozone-Induced Dissociation

“…For PB and epoxidation, reaction times are typically on the order of several minutes, with conversion efficiencies up to 40%. 33 One disadvantage, however, is that derivatization increases signal degeneracy—particularly for polyunsaturated lipids—dividing ion populations into derivatized, underivatized, and fragmented product ions.…”

Review of Recent Advances in Lipid Analysis of Biological Samples via Ambient Ionization Mass Spectrometry

“…For instance, a polymer coating transfer enrichment (PCTE) method coupled with the PB reaction was developed for a nanoelectrospray ionization mass spectrometry (PCTE-PB-nanoESI-MS) analysis of unsaturated lipids in human biofluid samples [48]. Similarly, the in vivo and microscale profiling of lipid C=C location isomers in biological tissues has been realized by combining the PB reaction with surfacecoated probe nanoESI-MS (SCP-PB-nanoESI-MS) [47]. In SCP-PB-nanoESI-MS analysis (Figure 2C), a biocompatible SPEM probe with a nanospray tip was used for the extraction and ionization of lipids from a biological tissue sample, and then the solvent containing the PB regents was used to desorb lipids enriched on the SPEM probe.…”

Recent Advances in In Vivo SPME Sampling

“…Deng and coworkers [21,70] have used biocompatible surface-coated probe nanoelectrospray-high resolution mass spectrometry (BSCP-nanoESI-HRMS) for in vivo lipidomics study of widely used model organisms in ecotoxicology like Daphnia magna, zebrafish (Danio rerio), zebrafish eggs and eukaryotic cells. The main advantage of this approach relies on the rapid, microscale and in situ analysis of complex biological samples.…”

“…In addition, isomers could not be differentiated due to the lack of a chromatographic separation. To solve the discrimination of C=C lipid isomers, online Paternò-Büchi (PB) reaction has been proposed [70]. Benzophenone was used as reagent to obtain high reaction efficiency with the methanol/chloroform solvent mixtures.…”