Development of mass spectrometry techniques for analysis of biomedical systems
Date
2020
Authors
Tapia, Jesus B., author
Reynolds, Melissa M., advisor
Henry, Charles S., committee member
Farmer, Delphine K., committee member
Kipper, Matthew J., committee member
Zadrozny, Joseph M., committee member
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Abstract
The advances of modern mass spectrometry (MS) have allowed MS to become one of the essential analytical tools for biological and biomedical research. Mass spectrometry's ability to provide rapid and sensitive analysis of many types of analytes made it an excellent candidate to study the polysaccharide dextran, biodegradable poly(organophosphazene) and polyester derived polymers, as well as interfering species in commonly used cell viability studies. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS) was used to analyze the polysaccharide dextran. Polysaccharides, including dextran, are difficult to ionize due to their inherent neutrality. Ionization efficiency is poor in negative polarity ESI because they lack acidic groups typically needed for proton abstraction, and ionization efficiency in positive polarity ESI is poor because polysaccharides have low proton affinity. In efforts to circumvent the issue of low ionization efficiency, dextran was derivatized to try mimicking protein-like ionization. Dextran was derivatized using a one-pot derivatization procedure with ethylenediamine, thus, giving dextran free terminal amine groups. The derivatization procedure attached up to four ethylenediamine groups and allowed dextran to have up to four protonations (or positive charges). The ability to carry up to four charges shifted the molecular weight of dextran to a lower m/z, similar to protein supercharging ionization. Mass spectrometric analysis was successfully applied to identify potential degradation products during the catalytic release of nitric oxide (NO) from S-nitrosoglutathione (GSNO) when it was exposed to metal-organic frameworks (MOFs) embedded onto chitosan polymer support systems. Oxidized glutathione (GSSG) was confirmed to be the reaction byproduct of the release of NO from GSNO, and glucosamine and N-acetylglucosamine were identified as the degradation products from the chitosan polymer support system. In a similar use of MS, potential interferences in the commonly used CellTiter Blue and MTT cell viability assays were studied. When the UV-vis spectroscopic assays suggested interferences or produced inconclusive results, mass spectrometric analyses accurately determined whether selected small molecules were responsible for conversion of resazurin to resorufin, MTT to formazan, or if they were responsible for severe signal suppression on the UV-vis spectroscopic assays. MS was also successfully used to study the biodegradable poly(phosphazene), polyester polymers and their nitrosated analogues. The purpose of the studies was to investigate the potential degradation products from the degradation of these polymers. In-depth understanding of the degradation products from these polymers may aid in determining potential unwanted side effects that may render the polymeric devices unusable. A combination of direct flow injection MS, liquid chromatography mass spectrometry (LC-MS), and tandem mass spectrometry (LC-MS/MS) were successfully applied to identify the degradation products from each polymer system investigated. Identification of each degradation product from these polymers strongly suggests the implementation of LC-MS/MS when biodegradable polymers are developed for biomedical applications. Particularly because these methods can be used when a device intended for medical use undergoes the ISO 10993 series Biological Evaluation of Medical Devices. Additionally, in a highly collaborative effort, a chiral metal-organic framework (MOF) was used as a chiral stationary phase (CSP) for chiral resolution. The chiral-MOF (TAMOF-1) was packed in-house into an empty HPLC column and successfully used to resolve chiral compounds efficiently using normal and reversed phase solvent systems, highlighting the versatility of the chiral-MOF.
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Subject
dextran
mass spectrometry
polymers
LC-MS
chiral chromatography
metal-organic frameworks