A novel strategy affords high-yield coupling of antibody to extremities ofliposomal surface-grafted PEG chains

Several methodologies for the preparation of polyethylene glycol-grafted im munoliposomes have been developed by attaching antibodies to the terminus o f the polymer. Unilamellar liposomes were prepared containing a combination of a functionalized polyethylene glycol(3400) and an inert polyethylene gl ycol(2000) phosphatidylethanolamine derivate up to 5 mol%. The greater leng th of the functionalized polyethylene glycol derivate did not alter the lip osomal sterical stability or the remote loading of doxorubicin. Anti-CD34 i mmunoliposomes were prepared by the reaction of maleimide-derivatized My10 antibody with generated thiol groups at the periphery of the liposomes and efficiencies of nearly 100% were obtained. The greater accessibility of the reactive group makes this strategy more efficient than others described. T he immunoliposomes prepared bound specifically to CD34+ cells, (C) 1999 Els evier Science B.V, All rights reserved.