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Journal of Biomedical Optics

Time-resolved singlet oxygen luminescence detection under photodynamic therapy relevant conditions: comparison of ex vivo application of two photosensitizer formulations
Author(s): Jan C. Schlothauer; Steffen Hackbarth; Lutz Jäger; Kai Drobniewski; Hemantbhai Patel; Sergiu M. Gorun; Beate Röder
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Paper Abstract

Singlet oxygen plays a crucial role in photo-dermatology and photodynamic therapy (PDT) of cancer. Its direct observation by measuring the phosphorescence at 1270 nm, however, is still challenging due to the very low emission probability. It is especially challenging for the time-resolved detection of singlet oxygen kinetics in vivo which is of special interest for biomedical applications. Photosensitized generation of singlet oxygen, in pig ear skin as model for human skin, is investigated here. Two photosensitizers (PS) were topically applied to the pig ear skin and examined in a comparative study, which include the amphiphilic pheophorbide-a and the highly hydrophobic perfluoroalkylated zinc phthalocyanine (F64PcZn). Fluorescence microscopy indicates the exclusive accumulation of pheophorbide-a in the stratum corneum, while F64PcZn can also accumulate in deeper layers of the epidermis of the pig ear skin. The kinetics obtained with phosphorescence measurements show the singlet oxygen interaction with the PS microenvironment. Different generation sites of singlet oxygen correlate with the luminescence kinetics. The results show that singlet oxygen luminescence detection can be used as a diagnostic tool, not only for research, but also during treatment. The detection methodology is suitable for the monitoring of chemical quenchers' oxidation as well as O2 saturation at singlet oxygen concentration levels relevant to PDT treatment protocols.

Paper Details

Date Published: 8 November 2012
PDF: 11 pages
J. Biomed. Opt. 17(11) 115005 doi: 10.1117/1.JBO.17.11.115005
Published in: Journal of Biomedical Optics Volume 17, Issue 11
Show Author Affiliations
Jan C. Schlothauer, Humboldt-Univ. zu Berlin (Germany)
Steffen Hackbarth, Humboldt-Univ. zu Berlin (Germany)
Lutz Jäger, Humboldt-Univ. zu Berlin (Germany)
Kai Drobniewski, Humboldt-Univ. zu Berlin (Germany)
Hemantbhai Patel, Seton Hall Univ. (United States)
Sergiu M. Gorun, Seton Hall Univ. (United States)
Beate Röder, Humboldt-Univ. zu Berlin (Germany)

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