Degree
Doctor of Philosophy (PhD)
Department
Chemistry
Document Type
Dissertation
Abstract
Localized biomolecular identification, quantification, and characterization are important for understanding molecular processes in cells and tissue. A method was developed with a deep ultraviolet (DUV) optical parametric oscillator (OPO) laser to sample biomolecules from surfaces for biological mass spectrometry (MS). The DUV OPO laser ablation electrospray (LA-ESI) source was coupled to an ion mobility mass spectrometer (IM-MS). The DUV laser ablated biomolecules from a surface and the resulting material was merged with an electrospray for post-ionization. The ionized analytes were then analyzed with a quadrupole time-of-flight (q-ToF) ion mobility mass spectrometer (IM-MS) for molecular identification and structural analysis. Mass spectra and ion mobility data were compared between DUV LA-ESI and direct ESI samples. The DUV LA-ESI system was first demonstrated under denaturing conditions with a conventional electrospray solvent. Mass spectra and ion mobility drift-time vs m/z plots of DUV LA-ESI and direct ESI were similar. The transfer efficiency of the DUV LA-ESI source was found to be approximately 1%. The DUV laser system was then demonstrated for native surface mass spectrometry in which the ablated particles were merged with an electrospray consisting of a volatile pH neutral solution. Plots of mass spectra, average charge state, drift-scope plots, and collision induced unfolding (CIU) were compared between DUV LA-ESI and direct ESI. Carbonic anhydrase (CA), a protein that does not refold after denaturation, was used as a probe to determine the effect of DUV LA-ESI on protein conformation. The mass spectra showed no indication of conformational changes of CA and CIU plots revealed similar conformational transitions between DUV LA-ESI and direct ESI. These results suggest that material is ejected as solvated protein or nm size particles. Overall, these results show that DUV LA-ESI can be used as a sampling method for structural biological MS, particularly for native surface mass spectrometry (NSMS).
Date
11-3-2025
Recommended Citation
Hines, Kelcey B., "Deep Ultraviolet Laser Ablation Electrospray Ionization Ion Mobility Mass Spectrometry" (2025). LSU Doctoral Dissertations. 6956.
https://repository.lsu.edu/gradschool_dissertations/6956
Committee Chair
Murray, Kermit K.