The photophysical properties of porphyrin and phthalocyanine photosensitisers for the photodynamic therapy of cancer (PDT), sterically hindered porphyrins and a novel chemotherapeutic agent (Mitoxantrone), have been investigated using the time resolved techniques of laser flash photolysis, pulse radiolysis, fluorescence and near infrared luminescence. Current topics of interest in PDT and phototherapy of neonatal jaundice are the use. of 5-aminolaevulinic acid to stimulate the formation of protoporphyrin IX for treatment of tumour and skin lesion, and the formation of the potentially cytotoxic species, lumirubin, by green light irradiation of infants with hyperbilirubinemia. Continuous irradiation, and steady state techniques have been used to study the photoproduct, and singlet oxygen formation, by these systems. The effect of environment on the photophysical properties of haematoporphyrin has been studied. It was found that under certain conditions the triplet state lifetime and relative quantum yield are enhanced. The results of this have been used to suggest an explanation for enhanced singlet oxygen yields in such environments. A novel water soluble phthalocyanine with no peripheral substitution, but the axial ligands conferring the desired property, has been studied and found to have a triplet state lifetime in aqueous solution of approximately O.7J.1s, and a singlet oxygen yield of zero. Yet this phthalocyanine has been reported to be efficient sensitizer for the photodynamic therapy of cancer. This supports current discussions that mechanisms other than type II (singlet oxygen) could be of significance in the destruction of tumours.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:358499 |
| Date | January 1993 |
| Creators | Charlesworth, Paul |
| Publisher | Keele University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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