High affinity polyethylene oxide for improved biocompatibility

Albumin passivation methods are based on the premise that a confluent layer of conformationally intact albumin will provide a biocompatible surface. However, albumin in contact with foreign surfaces tends to denature, and other proteins will adsorb to the surface, making the albumin passivation theory difficult to test. To overcome these two limitations, it was necessary to have a nondenaturing ligand specific for albumin attached to the surface by a long chain polyethylene oxide (PEO), which is known to have low protein binding. Clinical reports suggest no denaturation of albumin upon binding with warfarin, a drug known to have high albumin affinity. Thus, we tethered warfarin to glass lead surfaces previously coated with poly(methyl-co-amiopropyl)siloxane (PMAS) by means of a 4.6 kilodalton PEO chain. This would provide a surface that may come close to satisfying the conditions of the albumin passivation theory. Platelet adhesion and activation on warfarin treated surfaces was reduced compared to several controls, including: PEO PMAS, and a ligand containing mercury, which also is tethered to PMAS by PEO. We conclude that the warfarin ligand, when tethered to surfaces by PEO, demonstrates improved biocompatibility. This treatment is promising for implant applications.