While ultraviolet (UV) radiation is essential for sustaining life, it can also be destructive for biological systems. In humans, for example, UV radiation initiates production of vitamin D, while also being the primary external source of skin cancer. Despite the skin's melanin providing natural protection against radiative stress, and despite the wide range of commercially available photoprotective lotions, i.e. sunscreens, skin cancer incidence has risen in recent years. The urgent need for more effective sunscreens is, therefore, obvious. However, the sunscreen industry is currently challenged with limited availability of suitable and photostable sunscreen active ingredients. The work presented in this thesis aims to address these challenges by presenting an innovative approach to sunscreen molecular design based on the unique insight provided by laser femtochemistry. The ideal sunscreen should dissipate excess energy via fast, efficient and safe relaxation mechanisms, which typically occur on ultrafast timescales. The studies presented in this thesis focus on two categories of sunscreens, the cinnamates and the anthranilates, and employ ultrafast laser spectroscopy techniques to map and understand the photoprotection mechanisms that afford these sunscreens their photoprotective capabilities. As such, this thesis constitutes a significant contribution to the field of research whose primary concern is to unveil the mechanisms of action of photoprotection in sun screen molecules: the results reported have identified key photophysical photoprotective mechanisms and raised important questions regarding the effects of a sunscreen molecule's environment on its photodynamics. Based on the insight provided by the research herein presented, a rationale for sun screen molecular design may be developed for which the molecular structure of sunscreen active ingredients can be manipulated in order to either enhance the desired energy redistribution mechanisms or hinder any relaxation pathways that may lead to harmful side photochemistry. In reaching its full potential, this innovative approach to sunscreen development has the potential to create a new generation of high-performance sunscreens to be incorporated in commercial sunscreen formulations, in an attempt to disrupt the rise in skin cancer incidence.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:767140 |
| Date | January 2018 |
| Creators | Rodrigues, NateĢrcia das Neves |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/114335/ |
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