A method of preparing an antibody- or antibody fragment-targeted cationic immunoliposome or polymer complex comprises the steps of (a) preparing an antibody or antibody fragment； (b) mixing said antibody or antibody fragment with a cationic liposome to form a cationic immunoliposome or with a cationic polymer to form a polyplex； and (c) mixing said cationic immunoliposome or said polyplex with a therapeutic or diagnostic agent to form said antibody- or antibody fragment-targeted cationic immunoliposome or polymer complex.
