Surfaces engineering of polymeric films for biomedical applications

The present study deals with the deposition of acrylic acid thin films by RF plasma assisted chemical vapour deposition. In situ diagnostics (Mass Spectrometry and Optical Emission Spectroscopy) have been used in order to control the deposition processes and analyse the fragmentation steps. The films have been characterised with X-ray Photoemission Spectroscopy (XPS) and Fourier Transformed Infrared Spectroscopy (FTIR). Surface energy of the coatings has been determined by contact angle measurements. The protein adsorption kinetics has been evaluated with the Quartz Crystal Microbalance (QCM) with Human Serum Albumin. The results demonstrate a strong link between monomer fragmentation in the plasma and functional groups retention in the films. By increasing the RF power, the COOH concentration in the films (XPS and FTIR) as well as hydrophylicity, hydrogen bondings and acid-base character decrease while the CO concentration in the plasma phase (MS and OES) increases. At the same time, the dispersive and the polar components of the surface-free energy increase. These surface properties have a strong influence on the protein attachment kinetics, as determined by QCM measurements.