The recently synthesized photosensitizer 9-acetoxy-tetra-npropylporphycene (ATPPn), a compound of the group of porphycenes,
was tested for photodynamic therapy on a human bladder carcinoma cell line. Because of the hydrophobic character of the molecules, ATPPn was incorporated into soya phosphatidylcholine liposomes for administration. Bladder carcinoma cells were incubated for 60 mm at 37°C with the liposomes containing 0.5-μg ATPPn ad 1.5-ml medium. Using these concentrations, no dark toxicity and no phospholipid cytotoxicity were evident. Fluorescence measurements were made to show intracellular uptake of the photosensitizer. For the irradiation treatment, cells were exposed to coherent light delivered by a dye laser at a power density of 30 mW/cm2. Irradiation with 1, 3, 6, 12, 24, and 48 J/cm2 resulted in an increasing photokilling effect in correspondence to a decreasing survival rate of 93.0, 75.9, 60.1, 43.5, 28.3, and 11.3%, respectively. The results do encourage further investigations that include in vivo studies.