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Proceedings Paper

Photoproducts and new spectral bands during PDT probed by cw and time-gated microscopy and spectroscopy
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Paper Abstract

Intracellular modifications of sensitizers during PDT were observed with combined measurements of cw and time-gated microscopy and spectroscopy. Protoporphyrin when stimulated with 5-aminolevulinic acid (ALA) showed photobleaching after irradiation with blue light (1 - 10 J/cm2) in competition with the formation of photoproducts (i.e., photoprotoporphyrins). The anionic meso-tetra(4-sulfonatophenyl)porphyrin (TPPS4) was incubated in cells seeded at low cell density (isolated cells; 25 cells/mm2) or high cell density (confluent growing cells; 500 cells/mm2), respectively. A similar granular fluorescence pattern, cw and time-gated fluorescence spectra could be observed before light exposure in both cases. With increasing irradiation a redistribution from the cytoplasm to the nucleus in addition with a pronounced formation of a fluorescent band around 615 nm was dependent on the growth phase of the cells and could be detected mainly for isolated cells. This species was correlated with a short fluorescence decay time and detected with an `early' time gate between 0 - 5 ns, whereas the neutral TPPS4 molecule was detected within a `late' time-gate between 10 - 15 ns.

Paper Details

Date Published: 17 August 1994
PDF: 7 pages
Proc. SPIE 2134, Laser-Tissue Interaction V; and Ultraviolet Radiation Hazards, (17 August 1994); doi: 10.1117/12.182937
Show Author Affiliations
Angelika C. Rueck, Institut fuer Lasertechnologien in der Medizin/Univ. Ulm (Germany)
Wolfgang S. L. Strauss, Institut fuer Lasertechnologien in der Medizin/Univ. Ulm (Germany)
Michael H. Gschwend, Institut fuer Lasertechnologien in der Medizin/Univ. Ulm (Germany)
Karsten Koenig, Institut fuer Lasertechnologien in der Medizin/Univ. Ulm (Germany)
Reinhard Sailer, Institut fuer Lasertechnologien in der Medizin/Univ. Ulm (Germany)
Rudolf W. Steiner, IInstitut fuer Lasertechnologien in der Medizin/Univ. Ulm (Germany)
Herbert Schneckenburger, Institut fuer Lasertechnologien in der Medizin/Univ. Ulm and Fachhochschule Aalen (Germany)


Published in SPIE Proceedings Vol. 2134:
Laser-Tissue Interaction V; and Ultraviolet Radiation Hazards
Steven L. Jacques; David H. Sliney; Michael Belkin, Editor(s)

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