(229az) Perfluoro-Treated Bioresorbable Polylactic Acid for Coronary Artery Stents

The permanent presence of rigid metallic coronary stents in the vessel wall can cause stent failure over long times. This failure may be in part related to hyperplasia stimulated by the stent and mechanical inhibition of physiologic vasomotion around it. Bioresorbable stents, in which their composition allows gradual breakdown, are an emerging and novel treatment for improving stent long-term outcomes. Poly(lactic acid) (PLA) has been the predominant polymer used for making bioresorbable stents. This polymer is fully resorbable and it degrades through a bulk erosion process through hydrolysis of ester bonds, with resulting lactic acid and oligomers being metabolized into CO₂ and water.

Although bioresorbable vascular scaffolds have various advantages over the long term, they are associated with higher thrombosis than permanent metallic stents. To address this issue, we modify the surface of PLA with a perfluoro compound facilitated by surface activation using RF plasma. Fluoropolymers have been extensively used in blood contacting materials, such as blood vessel replacements due to their lower thrombogenicity. In addition, our previous studies with fluoropolymers have shown low platelet reactivity.

Here, we will discuss the synthesis and blood compatibility of our perfluoro-treated PLA substrates. The compositions of plasma-treated surfaces determined by electron spectroscopy for chemical analysis (ESCA) will be studied. Also, contact angle measurements, cell cytotoxicity and the degradation profile of our treated polymers will be presented. Finally, relevant blood compatibility parameters, including plasma protein adsorption, platelet adhesion and morphology, will be evaluated. A hypothesis will be presented where tight binding of adsorbed albumin by fluoropolymers accounts for its success in blood-contacting applications.