Fabrication of a phospholipid membrane-mimetic film on the luminal surface of an ePTFE vascular graft.

ABSTRACT

A stabilized, membrane-mimetic film was produced on the luminal surface of an ePTFE vascular graft by in situ photopolymerization of an acrylate functonalized phospholipid using a fiber optic diffusing probe. The phospholipid monomer was synthesized, prepared as unilamellar vesicles, and fused onto close-packed octadecyl chains that were components of an amphiphilic terpolymer anchored onto the polyelectrolyte multilayer (PEM) by electrostatic interactions. Scanning electron microscopy (SEM) confirmed that gelatin impregnation of the graft followed by the subsequent biomimetic film coating filled in the fibril and node structure of the luminal surface of the ePTFE graft and was smooth. The lipid film displayed an initial advancing contact angle of 44 degrees , which increased to 55 degrees after being subjected to a wall shear rate of 500s(-1) for 24h at 37 degrees C in phosphate buffered saline (PBS). Fourier transform (FT-IR) spectroscopy was used to characterize the stages of biomimetic film assembly and confirmed the stability of the film under shear flow conditions. In vivo assessment using a baboon femoral arteriovenous shunt model demonstrated minimal platelet and fibrinogen deposition over a 1-h blood-contacting period. The results of this study confirm the versatility of a biomimetic film coating system by successfully transferring the methodology previously developed for planar substrates to the luminal surface of an ePTFE vascular graft.