The Development of a Novel Series of Cationic Porphyrins as Disinfectants for Use in Public Health Public Deposited

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  • March 22, 2019
Creator
  • Young, Aaron Jamal
    • Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
Abstract
  • In the United States, alone, an estimated 4 million to 33 million cases of gastrointestinal illness resulting from contaminated water supplies occur annually. There is a need for the exploration of new types of disinfectants for water treatment with different mechanisms of action that can be used along with or in place of currently used disinfectants to further improve modern drinking water treatment. Photodynamic inactivation (PDI) of pathogens is a unique approach to water treatment. In general, PDI consists of a chromophore that absorbs energy from light, and ultimately uses that energy to inactivate pathogens via singlet oxygen. Cationic porphyrins are one group of chromophores that have proven to be effective in the inactivation of viral, bacterial, fungal and parasitic pathogens. It is believed that the positive charge on cationic photosensitizers (PS) help them to better associate with the predominantly negatively charged surfaces on pathogens most resistant to chemical disinfection. The cationic porphyrins used in previous tests have carried fixed positive charges on the periphery of the tetrapyrrole macrocycle. Porphyrins that carry positive charges connected farther from the ring through an aliphatic carbon chain have been synthesized and characterized using proton nuclear magnetic resonance (1 H NMR), mass spectrometry (MS), and UV-Visible spectrometry (UV/Vis). The hypothesis was that this would allow for the positive charge to move more freely and possibly better adapt to the shape and negative charge distribution on the surface of target microorganisms. Using literature-based isolation techniques and the double layer enumeration method, the new cation location was observed to increase the porphyrins' binding to, and subsequent inactivation of E. coli and Salmonella. Viral binding was not as well correlated to inactivation as that of bacteria. This novel group of porphyrins is also marked by a decrease in the compound's stability as well as its toxicity in the absence of light. This method of increasing cation flexibility, in theory, could be used to increase the efficiency of PDI of bacteria for other synthetic chromophores.
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  • In Copyright
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  • "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Environmental Sciences and Engineering."
Advisor
  • Ball, Louise
Degree
  • Doctor of Philosophy
Graduation year
  • 2011
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