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Proceedings Paper

Spectroscopic investigation of light-induced intracellular reactions of hydrophilic meso-tetraphenylporphyrins
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Paper Abstract

Light-induced reactions of different hydrophilic meso-tetraphenyl porphyrins (TPPS4, TPPC4, T4MPyP) were investigated during PDT treatment. These measurements were carried out in vitro using micro-spectrofluorometry and were correlated with measurements in buffer solutions. In the case of the anionic TPPS4, before light exposure, a neutral free base and a protonated species could be detected simultaneously in the cells. During irradiation, the protonated species first disappeared. Due to the fact that a coexistence of a protonated and unprotonated species requires a pH value around 5, TPPS4 was at first located in the lysosomes (pH 5) and was released into the cytoplasm during irradiation as a result of lysosomal rupture. Further light exposure led to a drastic fluorescence formation in the nuclei, in particular the nucleoli of the cells, which was concomitant with a renewed observation of a fluorescence emission spectrum similar to that of the protonated species. In the case of the anionic TPPC4, a similar fluorescence increase was observed during irradiation. However, the formation of a protonated species played a less important role. The cationic T4MPyP again showed fluorescence increase during irradiation. Two Soret-bands separated by about 20 nm could be detected. The red-shifted band may be due to a special intercalation of T4MPyP in nucleic acids.

Paper Details

Date Published: 1 June 1992
PDF: 7 pages
Proc. SPIE 1645, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy, (1 June 1992); doi: 10.1117/12.60950
Show Author Affiliations
Angelika C. Rueck, Univ. Ulm (Germany)
Wolfgang S. L. Strauss, Univ. Ulm (Germany)
Herbert Schneckenburger, Univ. Ulm (Germany)
Rudolf W. Steiner, Univ. Ulm (Germany)

Published in SPIE Proceedings Vol. 1645:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy
Thomas J. Dougherty, Editor(s)

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