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Novel spectroscopic probes of sunscreens, initial excited-state structural dynamics and DNA photodamage Open Access

Descriptions

Other title
Subject/Keyword
Spectroscopic probes
Sunscreens
DNA damage
Smart probes
Excited-state structural dynamics
Molecular beacons
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Oladepo, Sulayman
Supervisor and department
Loppnow, Glen (Chemistry)
Examining committee member and department
Choi, Phillip (Chemical and Materials Engineering)
Klassen, John (Chemistry)
Lucy, Charles (Chemistry)
McDermott, Mark (Chemistry)
Aroca, Ricardo (Chemistry and Biochemistry) University of Windsor
Department
Department of Chemistry
Specialization

Date accepted
2010-03-26T14:48:31Z
Graduation date
2010-06
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
This thesis discusses developing new tools to probe DNA damage resulting from photoinduced chemical processes and probing the initial excited-state structural dynamics of nucleic acids and sunscreen agents. The results of this thesis show that UV resonance Raman spectroscopy (UVRRS) is an information-rich probe of chemical compositions in in situ analysis of sunscreen formulations. The results indicate that 244-nm excited UV resonance Raman spectra can provide a limit of detection of 0.23% w/w of sunscreen active ingredients (AIs), far below typical active ingredient (AI) concentrations in sunscreen formulations. UVRRS was used to probe the photostability of sunscreens, by determining the initial excited-state structural dynamics of Benzophenone-3 (BZ3), a common sunscreen active ingredient. Only minor excited-state structural distortions were obtained, based on the low displacement values, suggesting an inherently stable molecule. The largest structural change occurs along the carbonyl stretch, suggesting a strong interaction with the methanol solvent and a dissipative decay path for the molecule. Similarly, to gain an insight into how the structure of nucleic acids determine their photochemistry, UVRRS was used to probe the initial excited-state structural dynamics of 9-methyladenine (9-MeA). As for BZ3, the initial excited-state structural dynamics obtained for 9-MeA, are low, and much lower than for pyrimidine bases, providing a strong evidence for the photochemical stability of this purine base analog, compared to pyrimidines. Since DNA does not exist in isolation in cells, the role of a UV-absorbing amino acid, tryptophan, in UV-induced DNA photodamage was explored using molecular beacons (MBs) to detect the damage. The results indicate that tryptophan protective effects on DNA far outweighs their photodamage potential. However, MBs are expensive and they have some technical limitations, despite their exquisite sensitivity. Therefore, a new DNA damage detection method was developed based on smart probes (SPs). These probes are shown to be sensitive and sequence specific for detecting DNA photodamage.
Language
English
DOI
doi:10.7939/R3DD5M
Rights
License granted by Sulayman Oladepo (soladepo@ualberta.ca) on 2010-03-25T20:28:41Z (GMT): Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of the above terms. The author reserves all other publication and other rights in association with the copyright in the thesis, and except as herein provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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