Ge(IV) phthalocyanine (GePc) with two axially ligated cholesterol moieties was prepared by chemical synthesis and incorporated in a monomeric state into small unilamellar liposomes (CGP 55398). Upon photoexcitation with light wavelengths around its intense absorption peak at 680 nm, GePc shows an efficient photosensitising activity towards biological substrates through a mechanism which largely involves the intermediacy of singlet oxygen. GePc injected systemically into mice bearing an intramuscularly implanted MS-2 fibrosarcoma is quantitatively transferred to serum lipoproteins and localises in the tumour tissue with good efficiency: at 24 h post injection the GePc content in the tumour is 0.74 and 1.87 micrograms per g of tissue with a tumour/peritumoral ratio of 4.35 and 5.67 for injected doses of 0.76 and 1.52 mg kg-1 respectively. At this time the red-light irradiation of the GePc-loaded fibrosarcoma causes a fast and massive tumour necrosis involving both malignant cells and blood vessels.
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Liposomes were prepared containing zinc-phthalocyanine (ZnPc). The composition was ZnPc/POPC/OOPS (1 :90:1 0 w/w 1w). The phospholipids (PL) were dissolved in t-butanol at 50°C under magnetic stirring and mixed with ZnPc, dissolved in NMP for two hours in an ultrasonic bath at 80 °C. This mixture (50°C) was diluted with lactose-NaCI solution (9.475 % lactose, 0.027% NaCl) at 4°C using a dynamic mixer. The collected liposomal suspension was concentrated first, to 20 mg PLiml suspension and then the organic solvents were removed by tangential flow filtration (CentrasetteR) against a ten fold volume of lactose-NaCl solution . After sterile filtration the liposomal suspension was freeze-dried for 24 hours. For preparation of the liposomal suspension, water for injection was added to the lyophilisate and shaken by hand after hydration for 60 5.
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