Patent ID: 7863470

Claim:
A method comprising reacting a linear polyethylenimine having an average molecular weight of about 423 to about 50,000 and comprising a terminal hydroxyl group with a chloroformate ester of a sterol comprising a 3-ol group, thereby resulting in a linear polyethylenimine sterol conjugate comprising the sterol covalently bonded to the terminal hydroxyl group wherein the linear polyethylene sterol conjugate has a formula represented by H 3 Câ€”NHâ€”(CH 2 â€”CH 2 â€”NH) x â€”CH 2 â€”Xâ€”Y wherein x is an integer of about 8 to about 1,200, X is â€”Oâ€”COâ€”, and Y is a residue of the sterol comprising a 3-ol group.