Antibody-conjugated magnetoliposomes for targeting cancer cells and their application in hyperthermia

Magnetoliposomes for hyperthermia treatment of cancer were prepared by coating phospholipid on to magnetite particles. The optimum phospholipid composition for dispersibility was a phosphatidylcholine/phosphatidylethanolamine ratio of 2:1. The average size of the magnetoliposomes, which were aggregates of 10 nm core magnetite particles, was about 80 nm. The magnetoliposomes were coated with hydrazide pullulan to stabilize the phospholipid capsules and provide an anchor for the immobilization of antibodies. By this method, 90-180 molecules of a monoclonal antibody were immobilized on to a magnetoliposome particle. When the antibody-conjugated magnetoliposomes were incubated with cancer cells, they were adsorbed on to the cell surface and incorporated by the cells about 12 times more effectively than the control after 4 h. The amount of incorporated magnetite was 0.61-3.6 pg/cell, depending on the antigen-antibody system. The heating properties of the magnetoliposomes were also measured and found to vary with the size of the core magnetite.