<title>Dynamic fluorescence changes of hydrophilic and lipophilic phthalocyanines during PDT in vivo and in vitro</title>

Abstract

The fluorescence emission of hydrophilic tetrasulphonated aluminum phthalocyanine (AlPcS4) and hydrophobic zinc phthalocyanine (ZnPc), bound to the membrane of liposomes were investigated in vivo in an appropriate tumor model of the rat bladder and in addition in RR 1022 epithelial cells of the rat. The sensitizers were administered systemically to the rats and PDT was performed 24 h later. During PDT treatment the fluorescence was measured every 15 s. Fluorescence was excited with the 633 nm light of a HeNe laser and the fluorescence spectra were recorded with an optical multichannel analyzer system. PDT was performed in the case of both sensitizers with 672 nm light from an Ar+-Dye laser. Fluorescence changes during PDT were significantly different for the two phthalocyanines. In the case of AlPcS4 an initial fluorescence intensity increase followed by subsequent photobleaching could be observed. In contrast, ZnPc fluorescence showed an exponential decrease and no increase in the beginning of the treatment. Tumor necrosis 24 h after PDT was significant only for ZnPc. RR 1022 cells incubated 24 h with AlPcS4 revealed a granular fluorescence pattern, whereas ZnPc was localized diffusely in the cytoplasm of the cells. In correlation to the measurements in vivo subcellular relocalization and fluorescence intensity increase could be detected exclusively in the case of AlPcS4.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.