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Plasma Membrane Properties Involved in the Photodynamic Efficacy of Merocyanine 540 and Tetrasulfonated Aluminum Phthalocyanine
Author(s) -
Lagerberg Johan W. M.,
Überriegler Karl P.,
Krammer Barbara,
VanSteveninck John,
Dubbelman Tom M. A. R.
Publication year - 2000
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(2000)0710341pmpiit2.0.co2
Subject(s) - photosensitizer , singlet oxygen , chemistry , photodynamic therapy , photochemistry , phthalocyanine , phototoxicity , membrane , hyperpolarization (physics) , biophysics , reactive oxygen species , liposome , oxygen , in vitro , biochemistry , stereochemistry , organic chemistry , biology , nuclear magnetic resonance spectroscopy
Merocyanine 540 (MC540)‐mediated photodynamic damage to erythrocytes was strongly reduced when illumination was performed at pH 8.5 as compared to pH 7.4. This could be explained by high pH‐mediated hyperpolarization of the erythrocyte membrane, resulting in decreased MC540 binding at pH 8.5. In accordance, the MC540‐mediated photooxidation of open ghosts was not inhibited at pH 8.5. Photoinactivation of vesicular stomatitis virus (VSV) was not inhibited at pH 8.5. This suggests that illumination at increased pH could be an approach to protect red blood cells selectively against MC540‐mediated virucidal phototreatment. With tetrasulfonated aluminum phthalocyanine (AlPcS 4 ) as photosensitizer, damage to erythrocytes, open ghosts and VSV was decreased when illuminated at pH 8.5. A decreased singlet oxygen yield at high pH could be excluded. The AlPcS 4 ‐mediated photooxidation of fixed erythrocytes was strongly dependent on the cation concentration in the buffer, indicating that the surface potential may affect the efficacy of this photosensitizer. This study showed that altering the environment of the target could increase both the efficacy and the specificity of a photodynamic treatment.