THE USE OF LIQUID MICROJUNCTIONS AS AN ANALYTICAL TOOL IN BIOLOGICAL SURFACE ANALYSIS
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Authors
McEwen, Rory
Date
Type
thesis
Language
eng
Keyword
microfluidics , analytical chemistry , strawberries , tissue imaging , mass spectrometry , ambient soft ionization , LMJ-SSP , MALDI , ESI , electrospray ionization , Imaging Mass Spectrometry
Alternative Title
Abstract
Imaging mass spectrometry (IMS) typically requires extensive sample preparation involving formalin fixation, staining, matrix deposition and embedding (e.g. optimum cutting temperature polymer, OCT) to enable microtomy. The sample preparation steps add considerable time to the analysis and risk altering analyte distribution. Herein we investigate the use of liquid microjunctions as a tool in imaging mass spectrometry to mitigate sample handling steps. First, we describe a new liquid tissue stamping method, Poly-Synchronous Surface Extraction (PSSE), that utilizes an omniphobic substrate patterned with hydrophilic surface energy traps, which when wetted with solvent, form a dense microdroplet array. When contacted with a tissue sample, each droplet locally extracts analytes from the tissue surface, which subsequentially can be analyzed with MALDI-MS or ambient ionization-MS techniques (LMJ-SSP). Optimization of the patterned surface (droplet size and spacing) and its comparison to established imaging techniques is examined. The PSSE method showed good alignment with direct analysis and demonstrated potential to increase the speed of ambient MS tissue imaging techniques. Secondly, the different properties associated with liquid microjunction surface sampling probe imaging mass spectrometry were investigated to determine their effect on the overall image quality. Extraction tests examined the extraction efficiencies of eight different solvents/mixtures. Four of the solvents from the extraction test and one additional mixture were then used as the LMJ-SSP solvent to directly image 10μm thick strawberry slices. After concluding the best imaging solvent (50/50 Water/Methanol), the dependency of sample thickness on signal intensity was investigated. In addition, an absolute quantitative imaging run was conducted using a pseudo internal standard and at external calibration curve. The use of liquid microjunction methods for direct and indirect analysis showed great potential for increasing sensitivity and versatility, while also decreasing sample handing steps.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.