Lipid characterization with time-of-flight secondary ion mass spectrometry (TOF-SIMS).

摘要

The normal function of a cell and tissue depends upon an elaborate series of interconnected biochemical interactions and reactions. Lipids, the main component of cell membranes, not only provide structural support, but also participate directly in complex cellular chemistry. As a result, secondary ion mass spectrometry (SIMS), an analytical technique capable of providing information on the chemical composition and spatial distribution of these molecules, will be a powerful tool for elucidating complex biochemical processes.;In this thesis, cluster SIMS is used to map lipid distributions in a cellular and a tissue model system. SIMS is an established technique in the field of lipid imaging. In Chapter 1, the successful applications of SIMS in lipid-based investigation are reviewed and the challenges associated with the technique are discussed. The basic principles of SIMS and design of the QSTAR mass spectrometer are discussed in Chapter 2. Also, recent instrument developments to improve the analytical power of the SIMS technique are discussed. The C60-QSTAR instrument combines the advantages associated with cluster ion sources, continuous ion sources and tandem MS capabilities. This ability of this instrument to analyze lipids is examined in Chapter 3. Specifically, the ability to assist with in situ lipid identification and issues plaguing quantification efforts are discussed. In Chapter 4 and 5 the lipid profiles and distribution of lipids across the surface of normal functioning tissues and cells are characterized. In addition, the chemical composition and distribution of lipids in a diseased brain tissue after a traumatic brain injury are discussed in Chapter 5. The future direction of the technique in the analysis of lipids is discussed in Chapter 6. The development of additional protocols aimed toward improving lipid-related molecular ion sensitivity, such as cryogenic sample preparation techniques and molecular depth profiling are illustrated with preliminary data.