抄録
As liposomes containing ferromagnetic particles may be applicable for hyperthermia therapy against cancer, a convenient method for their preparation was studied; factors affecting the characteristics of liposomes were also examined. The procedures are as follows: Phosphatidylcholine (PC), cholesterol and hematoporphyrin were dissolved in a mixture of chloroform and methanol (9: 1) . The resultant solution was evaporated by a decompression rotary evaporator so that lipid film was formed on the inner wall of the round-bottom flask. Distilled water was added to the flask and the lipid film was suspended. After adding ferromagnetic Fe3O4 particles to the suspension, the preparation was ultrasonicated under a N2 atmosphere. After centrifugation of the liposomal suspension, the supernatant was concentrated to 30% of the initial volume by ultrafiltration. Thereafter, the concentrated suspension of liposomes containing the ferromagnetic particles was filtered through a Millipore filter with 0.65μm pore size of make the particle size of the liposomes homogeneous. Results of the temperature rise of liposomes when heated with a high frequency induction heater indicated the following: as a main component of liposomes, egg-yolk PC was more preferable than dipalmitoyl Phosphatidylcholine, 30min was sufficient ultrasonication time, addition of rich cholesterol improved the liposomal stability, 15 nm diameter of the ferromagnetic magnetite was more preferable than 150 nm. This liposomal suspension was stable for about two months when kept at 4°C. Based on these findings, these liposomes can be considered beneficial for the study of cancer therapy.
