Long circulating, cationic liposomes containing amino‐PEG‐phosphatidylethanolamine

Ligand attachment to polyethylene glycol (PEG) grafted, long circulating liposomes at the polymer terminus is of interest for targeting but the effect of positively charged groups is unknown. Amino-polyethylene glycol-phosphatidylethanolamine (AminoPEG-PE), prepared in four steps from alpha-amino-omega-hydroxy-PEG, was tested for influence on liposome interactions in vivo: blood circulation and biodistribution. Despite surface amines on each liposome conferring cationic behavior, in vivo properties are comparable to those obtained with methoxy-PEG-PE. The consequences are profound for targeting and possibly systemic delivery of cationic lipidic-polynucleotide complexes.