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Proceedings Paper

Mechanism of photosensitization in photodynamic therapy of tumor: interaction of metal phthalocyanine-excited states with molecular oxygen
Author(s): Huijun Xu; Xian-Fu Zhang; J. X. Ran; J. H. Song; Q. Yu; Q. F. Zhou; Jinshi Ma; D. W. Chen
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Paper Abstract

The ability of photosensitized generation of singlet oxygen by phthalocyanines has been evaluated using diphenylisobenzofuran as a chemical trap and arranged in the following decreasing order: ZnDSPC > ClGaTSPC > H2TSPC > ClAlTSPC. The efficiency of photogeneration of superoxide anion radical has also been estimated using 5,5-dimethyl-1-pyrroline-1-oxide DMPO as a spin trap and identified by ESR. The ability of photochemical generation of O2- is arranged in the decreasing order: ClGaTSPC > ClAlTSPC > CuDSPC > ZnDSPC. The interaction of phthalocyanines with amino acids has been studied by laser flash photolysis. The results show that the excited states of phthalocyanines interact with tyrosine and tryptophan via electron transfer but not with cysteine. It is thus concluded that photo-oxidation of cysteine sensitized by phthalocyanines is mediated solely by Type II (O2- involving) mechanism while photo-oxidation of tyrosine and tryptophan proceeds via Type I (electron transfer) and Type II mechanism depending on the structure of the sensitizer and substrate as well as the environment.

Paper Details

Date Published: 5 March 1993
PDF: 7 pages
Proc. SPIE 1616, International Conference on Photodynamic Therapy and Laser Medicine, (5 March 1993);
Show Author Affiliations
Huijun Xu, Institute of Photographic Chemistry (China)
Xian-Fu Zhang, Institute of Photographic Chemistry (China)
J. X. Ran, Institute of Photographic Chemistry (China)
J. H. Song, Institute of Photographic Chemistry (China)
Q. Yu, Institute of Photographic Chemistry (China)
Q. F. Zhou, Institute of Photographic Chemistry (China)
Jinshi Ma, Institute of Photographic Chemistry (China)
D. W. Chen, National Lab. for Structural Chemistry of Unstable and Stable Species (China)

Published in SPIE Proceedings Vol. 1616:
International Conference on Photodynamic Therapy and Laser Medicine
Junheng Li M.D., Editor(s)

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