Chitosan/phospholipid coated polyethylene terephthalate (PET) polymer surfaces activated by air plasma

In our studies the hybrid chitosan/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (Ch/DPPC) films on the air plasma treated polyethylene terephthalate (PET) plates were prepared using a few methods: spreading (S), Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS). Wetting properties of the prepared layers were determined measuring the contact angles of water, formamide and diiodomethane. Moreover, the theoretical model proposed by van Oss et al. was used to study the surface thermodynamics, i.e. surface free energy and its components. The surface topography was analyzed based on the images from atomic force microscope (AFM), optical and mechanical profilometers. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used for surface chemical analysis. It was found that the way of layers preparation had a significant effect on wetting properties and surface free energy of the PET/Ch/DPPC films. Both topographic features and surface chemistry influenced the material characteristics. Moreover, the study gives information on the film polarity strongly affected by the molecular organization and packing. It is believed that the DPPC molecules, modifying the chitosan coating, can improve its hemostatic properties to obtain a positive assessment of athrombogenicity. Therefore the developed surfaces seem to be promising for the enhanced PET biocompatibility suitable for cardiovascular devices.