Comparative photophysical study of disulfonated aluminum phthalocyanine in unilamellar vesicles and leukemic K562 cells.

The photophysical properties of cis-disulfonated aluminum phthalocyanine (AlPcS2) in unilamellar vesicles (liposomes) of DL-alpha-dipalmitoyl-phosphatidylcholine have been measured. Both the fluorescence and triplet quantum yields decreased with increasing sensitizer concentration. The time-resolved fluorescence decays, analyzed by both the sum of exponentials and decay time distribution analyses, are compared with those reported for AlPcS2 in leukemic K562 cells. Information on the photodynamic transport and localization mechanism has been obtained by drawing correlations between the two systems, indicating active transport of the phthalocyanine into tumor cells involving lysosomal accumulation.