Developing and Utilizing Gas-phase Laser Spectroscopy Techniques to Study the Effect of Desolvation on Molecules

Mass spectrometry is a valuable analytical technique that has applications in diverse fields. One requirement of employing mass spectrometry (MS) as a technique is that analysis occurs in the gas phase. Many samples, however, are found in solution and therefore desolvation is required for the analytes to be introduced into the mass spectrometer. This process, and the gas phase environment may fundamentally change the properties of the analyte due to the removal of intermolecular interactions. On the other hand, gas-phase analysis can present opportunities to reveal the effects of these interactions on the analyte. In this dissertation, the effect of desolvation on the structure of biomolecules and the photophysics of chromophores is explored. Specifically, gas-phase laser spectroscopic techniques were developed and utilized to perform spectroscopic measurement of mass-selected gaseous ions to explore these effects. In Chapter 2, specific changes in the simple rhodamine scaffold, starting with rhodamine 123 are shown to induce changes in the dyes’ fluorescence excitation and emission spectral profiles in the gas phase. The possibility of these changes being indicative of the effect of solvent interactions on excited state relaxation pathway is discussed. Chapters 3 and 4 showcase the development in the use of Förster resonance energy transfer (FRET) as a tool for structural analysis of gas-phase proteins, focusing on ubiquitin ions as a model system. FRET efficiencies of the ions suggest that their conformation can remain similar to what is known in solution. However, caution needs to be taken in order not to disrupt the structure. The photophysics of gaseous thioflavin T (ThT) in isolation and with select binding partners is examined in Chapters 5 and 6. The fluorescence enhancement (“turn-on”) response of ThT after binding, which is important in the effectiveness of ThT as a probe for amyloid fibrils in vitro, is investigated in the gas phase. Intermolecular interactions needed for the preservation of the turn-on response and the prevention of non-radiative relaxation pathways are postulated. Ultimately, this work demonstrates the power of gas-phase laser spectroscopy as a tool to study molecular behaviour of chromophores and macrobiomolecules in the gas phase.

Department dc:contributor.department

Chemistry

Year dc:date.issued

2019

Author dc:creator

• Kung, Chun Kui Jocky

Advisor dc:contributor.advisor

• Jockusch, Rebecca A

• desolvation
• gas phase
• laser spectroscopy
• mass spectrometry

Handle dc:identifier.uri

http://hdl.handle.net/1807/108186

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/108186