Biomimetic Coatings for Small Diameter Vascular Grafts

Wang, Shuwu

Abstract

Cardiovascular biomaterials suffer from well-known problems associated with thrombosis and infection. The surface of a biomaterial is one of the most important factors that determine its blood compatibility. The proposed studies focus on evaluating new biomimetic coating materials specifically designed to improve the blood compatibility of small diameter poly(tetrafluoroethylene) (PTFE) vascular prostheses. The objectives are to develop new biomimetic coatings, based on an interface design that mimics a cell surface glycocalyx, which will promote improved blood compatibility that is stable under dynamic flow conditions. The proposed biomimetic materials are designed to undergo surface-induced self-assembly on the vascular graft biomaterials, and consist of surfactant comb polymers with pendant oligosaccharides, and perfluorocarbons. Multiple surface interactions of perfluorocarbon branches are designed to provide polymer adhesion stability under physiologic shear stress conditions. Glycocalyx-like function will be achieved by quantitative inclusion of a high surface density of oligosaccharides. Specifically, we propose to: 1) prepare and characterize prototype biomimetic materials that assemble on PTFE; 2) evaluate the adhesion stability of biomimetic coatings under dynamic flow conditions; and 3) evaluate in vitro blood compatibility of the biomimetic coatings. Surface modifications will be characterized by sensitive spectroscopic and physical methods, and the shear-stability of modified surfaces will be evaluated in vitro using a rotating disk system (0-60 dyn/cm2). Preliminary In vitro blood compatibility evaluations will include assessment of non-specific protein adsorption and blood platelet-surface interactions. From these studies, we shall determine the optimum formulations by which alteration in interracial properties of the surfactant polymer improves blood compatibility. We anticipate that this project will lead to highly effective biomimetic materials that facilitate shear stable modification of small diameter vascular prostheses that demonstrate improved blood compatibility.