Time-resolved detection of singlet oxygen luminescence in red cell ghosts generated by photosensitizers via excitation in the far red

Stefan Oelckers; Thomas Hanke; Joerg G. Moser; Beate Roeder

doi:10.1117/12.199134

12 January 1995 Time-resolved detection of singlet oxygen luminescence in red cell ghosts generated by photosensitizers via excitation in the far red

Stefan Oelckers, Thomas Hanke, Joerg G. Moser, Beate Roeder

Author Affiliations +

Proceedings Volume 2325, Photodynamic Therapy of Cancer II; (1995) https://doi.org/10.1117/12.199134
Event: International Symposium on Biomedical Optics Europe '94, 1994, Lille, France

Abstract

In recent years a lot of new far red absorbing sensitizers for photodynamic therapy (PDT) were synthesized, like derivatives of bacteriopheophorbide. The possibility of increasing the accumulation in tumor tissue by coupling these dyes to carrier molecules is investigated. The photophysical properties of these dyes can be dramatically changed as a result of covalent binding to carrier molecules, different solvents, or biological surroundings. In heterogeneous systems ¹O₂ is strongly quenched. Therefore, its luminescence is difficult to detect. Another difficulty is the fact that especially far red absorbing sensitizers show fluorescence at the wavelength of ¹O₂-luminescence at 1270 nm, which can be several magnitudes higher than the luminescence of ¹O₂. The efficiency of singlet oxygen (¹O₂) generation is of major interest because ¹O₂ seems to play an important role in PDT. Time resolved luminescence measurements of ¹O₂ generated by dyes in micelles and liposomes in D₂O were already made in our group. In order to investigate more complex systems and to avoid unwanted photochemistry we changed the excitation wavelength from UV (337 nm) to VIS/NIR(ND:YAG/OPO). The excitation power was increased and the detection limit was decreased. First measurements in red cell ghosts are presented.

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Stefan Oelckers, Thomas Hanke, Joerg G. Moser, and Beate Roeder "Time-resolved detection of singlet oxygen luminescence in red cell ghosts generated by photosensitizers via excitation in the far red", Proc. SPIE 2325, Photodynamic Therapy of Cancer II, (12 January 1995); https://doi.org/10.1117/12.199134

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