PREPARATION OF PURIFIED ATACTIC POLYPROPYLENE AND POLYVINYL METHYL-ETHER SURFACES FOR THROMBOGENICITY STUDIES

Commercial samples of atactic polypropylene (aPP) and polyvinyl methyl ether (PVME) were purified and spin-cast onto glass coverslips with a view to using these as model surfaces in thrombogenicity studies. The se materials differ from polyvinyl alcohol (PVA) in a single functiona l group and are similarly amorphous: with the same backbone they have a hydroxyl, a methoxy, or a methyl group. The objective was to underst and the role of the hydroxyl group in the platelet reactivity of PVA. Surface characterization showed that they were chemically pure (as det ermined by X-ray photoelectron spectroscopy) but not smooth (as determ ined by scanning electron microscopy or interferometry), presumably du e to the difficulties of spin-casting optically clear films from hot s olutions (aPP or polyethylene [PE]) or because of imperfect adhesion t o the saline-treated substrate (PVME). PVME was also gamma-irradiated to insolubilize it. Fewer platelets adhered to PVA than to PVME or to aPP and PE, but roughness effects and limited data preclude definitive conclusions regarding the effect of functional groups. Less protein w as found on PVA than on the hydrophobic surfaces, but the significance of this observation is unclear. Further studies with more sensitive p rotocols are called for to examine the extent of platelet activation a nd its relationship to surface chemistry. (C) 1996 John Wiley & Sons, Inc.