Detection of oxygen-based radicals using electron spin resonance under PDT conditions

Bernd Algermissen; Basil Jamil; Kurt Osterloh; Hans-Peter Berlien

doi:10.1117/12.297808

29 December 1997 Detection of oxygen-based radicals using electron spin resonance under PDT conditions

Bernd Algermissen, Basil Jamil, Kurt Osterloh, Hans-Peter Berlien

Proceedings Volume 3191, Photochemotherapy: Photodynamic Therapy and Other Modalities III; (1997) https://doi.org/10.1117/12.297808
Event: BiOS Europe '97, 1997, San Remo, Italy

Abstract

The standard theories about the mechanisms involved in PDT concern themselves primarily with oxygen-centered species, above all singlet oxygen (¹O₂) and the hydroxyl radical (OH). The efficacy of the therapy depends very much not only on the photosensitizer used, but also to a great extent on the choice of irradiation parameters, the light source, and the tissue's degree of oxygenation. Both clinical and experimental studies point to the fact that the treatment of hypoxic areas generally results in a disappointing response, and the effects of the changes in perfusion and oxygenation induced by the PDT itself certainly complicate any analysis. The radical nature both of the secondary products generated from singlet oxygen reactions and of the other hypothesized primary products themselves mean that the physical method of choice for research on PDT is electron spin resonance (ESR). The aim of our investigations was the gathering of the particular information that this method could yield in order to make a comparison of the degrees to which various photosensitizers produce both singlet oxygen and hydroxide radicals in vitro. We also dedicated part of our efforts to an investigation into the effects of a simple variation in the partial pressure of the dissolved molecular oxygen.

Citation Download Citation

Bernd Algermissen, Basil Jamil, Kurt Osterloh, and Hans-Peter Berlien "Detection of oxygen-based radicals using electron spin resonance under PDT conditions", Proc. SPIE 3191, Photochemotherapy: Photodynamic Therapy and Other Modalities III, (29 December 1997); https://doi.org/10.1117/12.297808

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