Patent ID: 7390780

Claim:
A composition for transfecting a host cell with a gene, comprising: a complex comprised of (i) liposomes comprised of a cationic lipid and a vesicle-forming lipid derivatized with a hydrophilic polymer and (ii) a nucleic acid having a selected gene for transfection, wherein said lipid-derivatized polymer has the general structure: wherein R 1 is the hydrophilic polymer comprising a linkage for attachment to the dithiobenzyl moiety; R 2 and R 5 are independently selected from the group consisting of H, alkyl and aryl; R 3 is selected from the group consisting of O(C═O) R 4 , S(C═O) R 4 , and O(C═S) R 4 ; where R 4 is the vesicle-forming lipid; and where orientation of CH 2 —R 3 is selected from the ortho position and the para position.