Current challenges in medical diagnostics, e.g., determination of tumor margins in cancer, and the development of new pharmaceuticals require information on molecular distributions in biological tissues. The ability to detect and spatially map biomolecules such as proteins, peptides, lipids and metabolites in biological tissue sections has resulted in the widespread adoption of mass spectrometry imaging (MSI). Matrix-assisted laser desorption ionization (MALDI), the current method-of-choice for MSI applications, has distinguished itself with its broad molecular coverage. However, MALDI has continually suffered in its ability to sufficiently ionize classes of neutral lipids such as triglycerides (TGs) and hexosylceramides (HexCers), due to ion suppression by phospholipids, such as phosphatidylcholines (PCs).
To help circumvent this limitation, we have implemented silicon nanopost arrays (NAPA), a matrix-free laser desorption ionization (LDI) platform previously developed by our lab, to test its ability to selectively ionize the aforementioned lipid classes. Through performing MSI analysis of various biological tissues in tandem with MALDI, NAPA demonstrated the ability to offer enhanced ionization efficiency for lipid classes such as phosphatidylethanolamines (PEs), HexCers, and TGs relative to MALDI. These results help establish NAPA as a complementary MSI platform with respect to MALDI, creating the opportunity to potentially expand the coverage of lipids in future MSI studies when both MSI platforms are used in conjunction.
Jarod Fincher received his B.S. in chemistry from Winthrop University, located in Rock Hill, SC. His graduate school research projects, directed by Dr. Akos Vertes, have focused on the development and applications of MSI.