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In vitro Fluence Rate Effects in Photodynamic Reactions with AIPcS 4 as Sensitizer
Author(s) -
Moor Anne C. E.,
Lagerberg Johan W. M.,
Tijssen Karmi,
Foley Sarah,
Truscott T. George,
Kochevar Irene E.,
Brand Anneke,
Dubbelman Tom M. A. R.,
VanSteveninck John
Publication year - 1997
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 - 10.1111/j.1751-1097.1997.tb03238.x
Subject(s) - fluence , photochemistry , chemistry , biophysics , in vitro , in vivo , oxygen , photodynamic therapy , reaction rate , biochemistry , biology , organic chemistry , ion , microbiology and biotechnology , catalysis
— It has been shown previously that the efficiency of photodynamic therapy (PDT) both in vivo and in vitro is dependent on fluence rate. In this study, different in vitro experiments showed that tetrasulfonated aluminum phthalocyanine (AlPcS 4 ) is more efficient in photosensi‐tization if the light is delivered at low fluence rate. Erythrocyte damage, virus inactivation and photooxidation of reduced glutathione (GSH) and histidine were all enhanced if light was delivered at 100 W/m 2 as compared to 500 W/m 2 . Bleaching did not occur under these conditions. Oxygen depletion, shown to be important in fluence rate effects observed in vivo , does not seem to be involved. On theoretical grounds saturation of the triplet state is not likely under these conditions. A possible explanation for the observed fluence rate effects might be found in different reaction pathways, that are favored under high or low fluence rate illuminations. These reactions might involve uni‐ or bimolecular reactions of intermediate products, resulting in less efficiency at higher fluence rate. It proves to be important, under all circumstances, to monitor fluence rate, because a change in fluence rate, even with similar total fluences, might influence photobiological results in an unexpected way.