Novel Ambient Ionization Mass Spectrometry For Cellular Analysis

Mass-spectrometric analysis is a process that the targets are firstly introduced into ionization source, ionized and transferred into detector where they are differentiated from each other based on mass-to-charge ratios. In the process, the ionization modes is the heart of mass spectrometers because they decide the introduction pattern of the samples, and influence the final presentation of targets such as the fragments and the electric charges.There are a variety of classic ionizations including matrix-assisted laser desorption ionization (MALDI), electrospray ionization (ESI) and desorption electrospray ionization (DESI). The aforementioned methods perform the ionization effectively and have been widely used in commercial instruments. However, they have their respective limitations. Specifically, MALDI must be performed under vacuum. ESI can analyze liquid samples only limiting the scope of detection. And enhancing ionization efficiency of DESI is still needed. In this thesis, we developed two mass spectrometry ionization methods for cell analysis, including surface desorption atmospheric pressure chemical ionization and nano-electrospray ionization.In the first work, surface desorption atmospheric pressure chemical ionization (SDAPCI) was set up for the analysis of living cells.20μL/min and 1.5MPa were optimized as the flow rate of assisted solvent and the gage pressure of sheath gas. Under this condition, we have successfully realized simultaneous detection of intracellular fluorescein and surface phospholipids. To enhance the potential gradient and the ionization efficiency, grounded micro probe was placed under the glass slide. The enhancement was investigated in both theory and practice.In the second work, we reported the analysis of cytosol at single cells using improved nano-electrospray (nano-ESI) ionization. In this ionization source, a small volume of sample solution with salts is loaded into the emitter tip and the ionizing solution is added in the capillary. A metal wire is inserted in the capillary to form a strong electric field. Typically, sample is ionized under high voltage and analyzed by the mass analyzer. For single cell analysis, we use micromanipulator system to achieve single cell sampling and analyze the cell contents analysis with the improved nano-ESI-MS method. To elucidate the PKC pathway inside the cell, PKC substrate is loaded into the cell and detected using our strategy. This nano-ESI-MS method could give comprehensive information in one cell, which should have potential in biological or clinic studies.The third part was an assessment report of Hexin atmospheric pressure ionization time-of-flight mass spectrometry (API-TOFMS) L-01 and Agilent quadrupole time-of-flight (Q-TOF) 6530. Contrastive analysis was performed to evaluate the function of API-TOFMS L-01, including sensitivity, mass accuracy, ionization source compatibility, etc.