Premium
In Vitro Investigation on the pH Dependence of the Absorption and Fluorescence Properties of the Photosensitizer mTHPC ¶
Author(s) -
Zimmermann Andreas,
RitschMarte Monika,
Kostron Herwig
Publication year - 2002
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2002)0750335iviotp2.0.co2
Subject(s) - photosensitizer , fluorescence , photochemistry , chemistry , absorption (acoustics) , in vitro , materials science , optics , biochemistry , physics , composite material
Fluorescence excitation efficiency is of great importance for photodynamic diagnosis. Because usually a difference in the interstitial pH between normal and tumor tissue occurs, it is necessary to assess the impact of pH on the fluorescence emission intensity of the photosensitizer meta ‐tetrahydroxyphenylchlorin (mTHPC) in this context. The results obtained by in vitro fluorescence measurements clearly indicate that pH values below 6 lead to a significant decrease in the fluorescence intensity. In the physiological range of pH 6.5–7.2, however, no pH dependence was found. Besides the decrease in the fluorescence intensity of mTHPC for pH < 6, changes in the spectral shape of the absorption were found. These changes can be utilized for “dual‐wavelength ratio imaging,” using mTHPC as a pH‐sensitive indicator with the excitation pair 405 nm/436 nm in the range of pH 3.5–6.