Fibrinogen absorption on plasma modified polypropylene films

Thin films from acrylic acid (AAc) and Ar mixtures were deposited on polypropylene (PP) substrates by RF plasma polymerization. Different deposition conditions were investigated, varying the RF power input and keeping constant the other relevant operating parameters (total pressure, acrylic acid and Ar flow rate, treatment time). The films were characterized by water contact angle measurements, Attenuated Total Reflectance Fourier Transformed Infrared (ATR/FT-IR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscope (AFM). Thin films deposited at lower power input shows high-COOH concentration and hydrophilicity. On the other hand, the strong interaction with water molecules and the low cross-linked structure gave rise to total or partial dissolution of the coating when the plasma treated substrates were immersed in water. By increasing the power input, a decreased retention of-COOH groups and a lower coating hydrophilicity were observed. However, such coatings show high stability in water. Finally, fibrinogen adsorption on stable thin films and on untreated PP substrates was evaluated by means of confocal fluorescence microscopy and the results correlated with the substrate and coating properties.