In vivo fluorescence of phthalocyanines during light exposure

Nude mice were given AlPcS2a (aluminum phthalocyanine disulfonate) and AlPcS4 (aluminum phthalocyanine tetrasulfonate) by intraperitoneal injections. After time intervals of 1-48 hours the mice were exposed to 150 mW cm-2 light at 670 nm and the phthalocyanine fluorescence was measured during light exposure. During the first few minutes of light exposure the phthalocyanine fluorescence of the skin of the mice increased by up to a factor of two, indicating lysosomal localization of the dye and permeabilization of the lysosomes. The process did not occur in the skin of dead mice, indicating that the process was dependent on oxygen.