In recent years,
photodynamic therapy (
PDT) with a
photosensitizer and
laser has been given attention, especially for the treatment of superficial
cancers, such as lung, gastric, bladder and
cervical cancer. In this study, in order to enhance the efficacy of
PDT,
photofrin liposome (PF-Lip) was prepared with
dimyristoylphosphatidylcholine,
dimyristoylphosphatidylglycerol and
cholesterol. Polyethyleneglycol modified
photofrin liposome (PF-PEG-Lip) was prepared by modification of PF-Lip with monomethoxypolyethyleneglycol-2.3-dimyristoylglycerol. PF-Lip and PF-PEG-Lip entrapped with
photofrin with 81.0+/-5.9 and 81.2+/-9.2%, respectively. The particle size of each
liposome was 114.3+/-5.7nm (PF-Lip) and 118+/-3.5nm (PF-PEG-Lip), respectively. It was suggested that PEGylated
liposomes has no effect on the trapping ratio of PF and particle size.
Phototoxicity was enhanced by liposomalization, especially PEG-modification. However, PF-PEG-Lip inhibited the uptake of
photofrin into
tumor cells. The amount of
singlet oxygen from
photofrin solution (PF-
sol) and each
liposome was PF-PEG-Lip=PF-Lip>PF-
sol. The
photofrin release revel of PF-PEG-Lip was lower than that of PF-Lip. In conclusion, the
phototoxicity of PF-PEG-Lip was significantly higher than that of PF-
sol or PF-Lip. It is expected that formation of a fixed aqueous layer on the
liposome membrane by PEGylation physically changed it into the stable state of PF-PEG-Lip.