Quantifying Interactions Between Lipids And Surfaces

Sample preparation techniques remain one of the most prominent bottlenecks in the field of lipidomics, where the extremely skewed distribution of lipids by their class prevents the discovery and characterization of new lipid species in the lipidome. In this chapter, we study the interactions of phospholipids with surfaces made of metal oxides. Knowledge of such interactions are key to the fabrication of efficient solid phase extraction resins which can resolve the conundrum in sample preparation strategies. We present comparisons between various metal oxides with respect to their phospholipid enrichment capacities in 3 formats, first by modifying MALDI plates, second by fabricating mu columns packed with metal oxide powder and finally third by employing a batch sample processing technique incorporating metal oxide powder. Thereafter, owing to the scatter in acquisition of data in all the former approaches, we demonstrate an extremely sensitive technique based on surface plasmon resonance to quantify phospholipid adhesion to metal oxide surfaces with sub-nanogram level accuracy. We also show the effect of the headgroup in determining the affinity to metal oxide surfaces. Finally, we demonstrate a new technique based on thin planar TiO2 columns deposited on MALDI target plates to perform on-target enrichment on phospholipid species, in a format easily integrated into existing commercial MALDI-MS systems.