COMPARISON OF THE PHOTOPHYSICS OF AN AGGREGATING AND NON-AGGREGATING ALUMINUM PHTHALOCYANINE SYSTEM INCORPORATED INTO UNILAMELLAR VESICLES

The hydrophobic sensitizer, aluminium phthalocyanine chloride (AlPcCl) , and the amphiphilic sensitizer, cis-disulphonated aluminium phthaloc yanine (cis-AlPcS(2)), were incorporated into small unilamellar vesicl es (SUVs) and large unilamellar vesicles (LUVs). AlPcCl exhibits aggre gation, which increases with increasing sensitizer concentration, wher eas cis-AlPcS(2) is monomeric at all concentrations studied. Complex f luorescence decays are observed, showing decay time distributions whic h broaden with increasing phthalocyanine concentration. The phthalocya nine aggregate, although non-fluorescent, influences the overall photo physical behaviour of the phthalocyanine-vesicle system. The effect of aggregation on the resulting photophysics of phthalocyanines was inve stigated by comparing aggregated and non-aggregated phthalocyanine sys tems. The implications for photodynamic therapy (PDT) are briefly disc ussed.