Oxygen plasma functionalization of parylene C coating for implants surface: Nanotopography and active sites for drug anchoring

The effect of oxygen plasma treatment (t = 0.1-60 min, p(O2) = 0.2 mbar, P = 50 W) of parylene C implant surface coating was investigated in order to check its influence on morphology (SEM, AFM observations), chemical composition (XPS analysis), hydrophilicity (contact angle measurements) and biocompatibility (MG-63 cell line and Staphylococcus aureus 24167 DSM adhesion screening). The modification procedure leads to oxygen insertion (up to 20 at.%) into the polymer matrix and together with surface topography changes has a dramatic impact on wettability (change of contact angle from theta = 78 +/- 2 to (theta = 33 +/- 1.9 for unmodified and 60 min treated sample, respectively). As a result, the hydrophilic surface of modified parylene C promotes MG-63 cells growth and at the same time does not influence S. aureus adhesion. The obtained results clearly show that the plasma treatment of parylene C surface provides suitable polar groups (C=O, C-O, O-C=O, C-O-O and O-C(O)-O) for further development of the coating functionality. (C) 2013 Elsevier B.V. All rights reserved.