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Proceedings Paper

Direct phosphorescent detection of primary event of photodynamic action
Author(s): Anatoly P. Losev; Valentin N. Knukshto; Ivan N. Zhuravkin
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Paper Abstract

Highly phosphorescent photosensitizer Pd-tetra (o-methoxy-p-sulfo)phenyl porphyrin (Pd- MSPP) was used to follow primary events of photodynamic therapy (PDT). The sensitizer forms complexes with proteins in solutions and biosystems showing remarkable hypsochromic shifts of band and an increase of the quantum yield and life time of phosphorescence at the binding to proteins. It was found the life time of phosphorescence depends mostly on the energy of the lower triplet state of the sensitizer. Therefore photo-chemical quenching of the triplets by cell components is negligible. The quenching of the sensitizer triplets is observed in the presence of free oxygen in biosystems. The degree of quenching varies in dependence on the kind and state of the system and is governed by oxygen concentration and viscosity of the media. It was concluded that the singlet oxygen mechanism of photosensitization is operative only at the primary step of the process.

Paper Details

Date Published: 1 March 1994
PDF: 5 pages
Proc. SPIE 2078, Photodynamic Therapy of Cancer, (1 March 1994); doi: 10.1117/12.168658
Show Author Affiliations
Anatoly P. Losev, Institute of Molecular and Atomic Physics (Belarus)
Valentin N. Knukshto, Institute of Molecular and Atomic Physics (Belarus)
Ivan N. Zhuravkin, Research Institute of Oncology and Medical Radiology (Belarus)

Published in SPIE Proceedings Vol. 2078:
Photodynamic Therapy of Cancer
Giulio Jori; Johan Moan; Willem M. Star, Editor(s)

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