Patent ID: 7408014

Claim:
A process for preparing a modified polyurethane comprising a lipid substituent pendant from at least one urethane nitrogen and/or at least one carbon atom of the modified polyurethane, the process comprising: providing a polyurethane comprising a urethane amino moiety and at least one carbon; providing a multifunctional linker reagent of a formula: LG-R L -(FG) n wherein n is an integer from 1 to 3, FG is a functional group selected from the group consisting of a halogen, a carboxyl group, a sulfonate ester, and an epoxy group, LG is a leaving group selected from the group consisting of a halogen, a carboxyl group, a sulfonate ester, and an epoxy group, and R L is an (n+1)-valent organic radical comprising at least one carbon atom; providing a lipid comprising the lipid substituent; reacting the multifunctional linker reagent with the urethane amino moiety to form a polyurethane substituted with at least one substituent group of a formula —R L -(FG) n ; and reacting the lipid and the polyurethane substituted with the at least one substituent group to form the modified polyurethane; wherein the lipid comprises a steroid lipid and the lipid substituent comprises a steroid lipid substituent; wherein the steroid lipid comprises modified cholesterol and the steroid lipid substituent is a thiol-modified cholesterol substituent; wherein the modified cholesterol is prepared by contacting a cholesterol with at least one reactant to provide at least one substituent group on the modified cholesterol, wherein the substituent group is a thiol group; and wherein the modified cholesterol is a thiol modified cholesterol and wherein the step of treating the cholesterol with at least one reactant comprises treating the cholesterol with epihalohydrin to yield a glycidyl modified cholesterol and treating the glycidyl modified cholesterol with a thiolating agent.