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Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings
Author(s) -
Eric Jones John,
Chen Meng,
Yu Qingsong
Publication year - 2014
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.33115
Subject(s) - materials science , corrosion , trimethylsilane , x ray photoelectron spectroscopy , dielectric spectroscopy , plasma electrolytic oxidation , nanoindenter , scanning electron microscope , polarization (electrochemistry) , plasma , metallurgy , composite material , chemical engineering , electrochemistry , electrolyte , nanoindentation , electrode , chemistry , physics , quantum mechanics , medicinal chemistry , engineering
ABSTRACT To improve their corrosion resistance and thus long‐term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20–25 nm in thickness. Both direct current (DC) and radio‐frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH 3 /O 2 plasma treatment to tailor the surface properties. X‐ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si‐ and C‐rich composition, and the O‐ and N‐contents on the surfaces were substantially increased after NH 3 /O 2 plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH 3 /O 2 plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1363–1374, 2014.