Photomodifications of photodrugs in tumors

Petras Juzenas; Janina Didziapetriene; Laima Staciokiene; V. Gudelis; J. Slavenas; Ricardas Rotomskis

doi:10.1117/12.231004

31 January 1996 Photomodifications of photodrugs in tumors

Petras Juzenas, Janina Didziapetriene, Laima Staciokiene, V. Gudelis, J. Slavenas, Ricardas Rotomskis

Proceedings Volume 2625, Photochemotherapy: Photodynamic Therapy and Other Modalities; (1996) https://doi.org/10.1117/12.231004
Event: BiOS Europe '95, 1995, Barcelona, Spain

Abstract

The phototransformation of photodrugs during irradiation can influence the photosensitization reactions: (1) the photobleaching has been proposed to be taken advantage of to enhance the therapeutic ratio and to protect a normal tissue during photosensitized tumor therapy (PTT), (2) the formation of a photoproduct with absorption in the red spectral region can introduce new sensitization pathways. Therefore, the spectroscopic characteristics of the photodrugs in tumors and photostability under the irradiation by visible light were investigated. A few photoprocesses were studied under the irradiation of tumors ex vivo. Efficient photobleaching of porphyrin emission bands at 630 and 690 was detected in all cases. This process was accompanied by the formation of a broad emission band in the spectral region 660 - 680 nm. Careful examination of the emission spectra of tumors ex vivo (excitation at 488 nm) shows that the emission around 660 nm was related with photoproduct formation. The increase of emission intensity at around 680 nm and the observed redistribution of emission intensity after prolonged irradiation can be caused by photoinduced relocalization of the sensitizers in the tumor.

Citation Download Citation

Petras Juzenas, Janina Didziapetriene, Laima Staciokiene, V. Gudelis, J. Slavenas, and Ricardas Rotomskis "Photomodifications of photodrugs in tumors", Proc. SPIE 2625, Photochemotherapy: Photodynamic Therapy and Other Modalities, (31 January 1996); https://doi.org/10.1117/12.231004

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