Covalent surface modification of a titanium alloy with a phosphorylcholine-containing copolymer for reduced thrombogenicity in cardiovascular devices
✍ Scribed by Sang-Ho Ye; Carl A. Johnson Jr.; Joshua R. Woolley; Trevor A. Snyder; Lara J. Gamble; William R. Wagner
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 810 KB
- Volume
- 91A
- Category
- Article
- ISSN
- 1549-3296
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✦ Synopsis
Abstract
Our objective was to develop a surface modification strategy for a titanium alloy (TiAl~6~V~4~) to provide thromboresistance for surfaces in rigorous blood‐contacting cardiovascular applications, such as that found in ventricular assist devices. We hypothesized that this could be accomplished by the covalent attachment of a phospholipid polymer, poly(2‐methacryloyloxyethylphosphorylcholine (MPC)‐co‐methacryl acid) (PMA). TiAl~6~V~4~ was H~2~O plasma treated by radio frequency glow discharge, silanated with 3‐aminopropyltriethoxysilane (APS), and ammonia plasma treated to increase surface reactivity. The TiAl~6~V~4~ surface was then modified with PMA via a condensation reaction between the amino groups on the TiAl~6~V~4~ surface and the carboxyl groups on PMA. The surface composition was verified by X‐ray photoelectron spectroscopy, confirming successful modification of the TiAl~6~V~4~ surfaces with APS and PMA as evidenced by increased Si and P. Plasma treatments with H~2~O and ammonia were effective at further increasing the surface reactivity of TiAl~6~V~4~ as evidenced by increased surface PMA. The adsorption of ovine fibrinogen onto PMA‐modified surfaces was reduced relative to unmodified surfaces, and in vitro ovine blood contact through a rocking test revealed marked reductions in platelet deposition and bulk phase platelet activation relative to unmodified TiAl~6~V~4~ and polystyrene controls. The results indicate that the PMA‐modification scheme for TiAl~6~V~4~ surfaces offers a potential pathway to improve the thromboresistance of the blood‐contacting surfaces of cardiovascular devices. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009