EFFECT OF PHOSPHATYDYLCHOLINE ON SPECTRAL PROPERTIES AND PHOTOSTABILITY OF 3,3'-DIETHYLOXADICARBOCYANINE IODIDE (DODCI) - A POTENT ANTITUMOR PHOTOSENSITIZER

The potential anti-tumor photosensitizer 3,3'-diethyloxadicarbocyanine iodide (DODCI) has been immobilized in dimyristoyl phosphatidylcholin e (DMPC) vesicles. Binding of the dicarbocyanine to the lipid vesicles induces several changes in the electronic absorption, emission and ex citation spectra of the dye. The monomeric dye molecules exist in at l east two forms when immobilized in the DMPC liposomes and the non-lumi nescing H-aggregates of:he dye show efficient excitation energy transf er to the DODCI monomers. Entrapment of the dye in the liposomes gener ally decreases the photostability of DODCI. While emission from single t oxygen (O-1(2)) has not been recorded, indirect results suggest that this reactive molecule is formed upon irradiation of the dye. (C) 199 8 Elsevier Science B.V.