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kinetic and mechanistic studies of fading of fluorescent dyes and application in vital fields

Al-Wattar, Eman 2020. kinetic and mechanistic studies of fading of fluorescent dyes and application in vital fields. PhD Thesis, Cardiff University.
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Abstract

This thesis is divided into six Chapters. Chapter 1 introduces general information about forensic chemistry, dyes and pigments, light, and its effect in chemistry. The second chapter describes the development of a LED device, with support from Dr. Joe Beames, that allows us to generate reproducible kinetic data on photofading reactions by irradiating a sample with high intensity white light. The third chapter shows that thiazole orange (TO) shows increased fading with increased intensity of light. Additionally, we investigated the effect of oxygen within the solution. Many other factors may also play a role in the fading process, for example, temperature, type of buffer, buffer concentration, pH, and the presence of additives. We examine each of these in turn and show that this provides new kinetic insights into the mechanism of fading of thiazole orange. Mass spectroscopy suggests that the product may be formed following reaction of the photoexcited species with a molecule of oxygen. The fading of dyes such as thiazole range (which is a known DNA binder) may have implications for typical studies of DNA binders. The fourth chapter present analyses of the kinetics of the fading process of 3,3'- diethyloxadicarbocyanine iodide (DODC) when exposed to light, determining that it is irradiation itself that drives the colour change. Another factor is the presence of O2 with limiting oxygen concentrations limiting the observed reaction rate constant. Many other factors may also play a role in the fading process, for example, temperature, type of buffer, buffer concentration, pH and the presence of additives. We examined each of these in turn. Mass spectroscopy suggests that the product may be formed following reaction of the photoexcited species with a molecule of oxygen. Finally, the fifth Chapter describes the effects of biomacromolecules and serum on fading of TO and DODC. DNA is found to have little effect of fading of TO but to retard fading of DODC. Serum is found to strongly retard fading of TO and DODC. Similarly, added ethanol and DMSO also strongly retard the kinetics of fading. Overall conclusions, future outlooks, remarks and suggestions can be found in Chapter 6.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Chemistry
Date of First Compliant Deposit: 21 July 2021
Last Modified: 21 Jul 2021 09:57
URI: http://orca.cardiff.ac.uk/id/eprint/142735

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