Multimodal Mass Spectrometry Methods for the Analysis of Biochemical Systems and Tissues
Mass spectrometers come in a variety of unique types and flavors, each capable of analyzing different types of molecules and chemical systems. Matrix-assisted laser desorption ionization (MALDI) is widely used in biochemical research for qualitative analysis of lipids, peptides, proteins, and oligomers. Recent advancements in MALDI mass spectrometry (MS) allow for the visualization of these species directly on histological tissue sections. However, the identification of the species by MS/MS often requires an instrument of higher mass resolution than possible with current time-of-flight instruments, so coupling MALDI-TOF to electrospray ionization (ESI) orbitap is a multimodal format both visualize and characters peptides and proteins on tissue. For quantitation, triple quadrupoles (QQQs) coupled with liquid chromatography (LC) are unparalleled. All of these instrument types are used in this thesis to answer four biochemical questions. 1) Can MALDI mass spectrometry imaging (MSI) visualize and track enamel forming proteins in mouse hemi-mandibles? 2) Can we increase the instrument defined spatial resolution limit by expanding tissue? 3) Can we develop a method to quantify polyunsaturated fatty acids (PUFAs) which link to chronic pain? And 4) Can we utilize metal salts and MALDI MSI to improve the signal of and visualize neurodegenerative species in Alzheimer's disease tissue? We prove the answer to all these questions is yes utilizing novel methodology in mass spectrometric analysis.