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Proceedings Paper

Detection of free oxygen in tissues and testing of primary step of photodynamics action by time-resolved phosphorescence of photosensitizer
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 the primary events of photodynamic action -- quenching of triplet states by free oxygen in different systems: water solutions of proteins, cells and tissues in vivo and in vitro. The photosensitizer forms complexes with proteins in solutions and biosystems showing remarkable hypsochromic shifts of band and an increase of the quantum yield and lifetime of phosphorescence at the binding to proteins. In absence of oxygen the lifetime of phosphorescence is almost single exponential, depends on the energy of the lowest triplet state of the sensitizer. The photochemical quenching of the triplets by cell components is negligible. In the presence of free oxygen the quenching of the sensitizer triplets takes place. The emission spectrum of singlet oxygen with maximum 1271 nm was recorded in water protein solutions and quantum yield of sensitized luminescence was measured. In the systems studied oxygen consumption was detected and oxygen concentration was estimated in the course of photodynamics by an increase in photosensitizer phosphorescence lifetime, using laser flash photolysis technique. At least two exponential kinetic of the phosphorescence decay shows that the distribution of the free oxygen is not uniform in tissues. The unexpected effect of photoinduced hyperoxia was observed just after the several minutes of tumor exposition with following slow development of a hyposia in a course of continual light exposition.

Paper Details

Date Published: 2 January 1995
PDF: 9 pages
Proc. SPIE 2370, 5th International Conference on Laser Applications in Life Sciences, (2 January 1995); doi: 10.1117/12.197410
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. 2370:
5th International Conference on Laser Applications in Life Sciences
Pavel A. Apanasevich; Nikolai I. Koroteev; Sergei G. Kruglik; Victor N. Zadkov, Editor(s)

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