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Proceedings Paper

Phthalocyanines And Their Sulfonated Derivatives As Photosensitizers In Photodynamic Therapy.
Author(s): Peter Riesz; C. Murali Krishna
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Paper Abstract

Photodynamic therapy (PDT) of human tumors with hematoporphyrin derivative (HpD) has achieved encouraging results. However, HpD is a complex mixture whose composition varies in different preparations and with time of storage. The future promise of PDT for cancer treatment depends on the development of new chemically defined sensitizers which absorb more strongly than HpD in the 600-800 nm region. A shift to higher wavelengths is desirable since it allows increased light penetration in human tissues. In vivo, these sensitizers should be non-toxic, localize selectively in tumors and generate cytotoxic species upon illumination with a high quantum yield. These damaging species may be singlet oxygen (1O2) produced by the transfer of energy from the triplet state of the sensitizer to oxygen (Type II) or superoxide anion radicals formed by electron transfer to oxygen or substrate radicals generated by electron or hydrogen transfer directly from the sensitizer (Type I). The recent work of several groups indicating that phthalocyanines and their water soluble derivatives are promising candidates for PDT is reviewed. The photophysics, photochemistry, photosensitized killing of cultured mammalian cells and the use for in vivo photodynamic therapy of phthalocyanines is outlined. Our studies of the post-illumination photohemolysis of human red blood cells as a model system for membrane photomodification sensitized by phthalocyanine sulfonates are consistent with the predominant role of 1O2 as the damaging species.

Paper Details

Date Published: 19 February 1988
PDF: 14 pages
Proc. SPIE 0847, New Directions in Photodynamic Therapy, (19 February 1988); doi: 10.1117/12.942685
Show Author Affiliations
Peter Riesz, National Institutes of Health (United States)
C. Murali Krishna, National Institutes of Health (United States)

Published in SPIE Proceedings Vol. 0847:
New Directions in Photodynamic Therapy
Douglas C. Neckers, Editor(s)

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