WETTING BEHAVIOUR AND PROTEIN ADSORPTION TESTS ON ULTRANANOCRYSTALLINE DIAMOND AND AMORPHOUS HYDROGENATED CARBON THIN FILMS

Hydrogenated amorphous carbon (a-C:H) and ultra-nanocrystalline diamond/amorphous carbon (UNCD/a-C:H) composite films are considered as excellent candidates for use as biocompatible coatings on biomedical implants. The aim of this work is a comparative study of the wetting beha- viour and protein adsorption on a-C:H and UNCD/a-C:H films prepared by microwave plasma chemical vapour deposition (MWCVD) under different process conditions. All films were characterized by a variety of methods: their morphology by scanning electron microscopy (SEM), the topography by atomic force microscopy (AFM), the chemical bonding structure by Raman spectroscopy. SEM revealed that the a-C:H films possess a column- like morphology, while the UNCD/a-C:H surfaces are composed of struc- tures with diameters of several hundreds nanometers, which themselves have a sub-structure. All films under investigation were rather smooth with rms roughnesses down to 2 nm for a-C:H and to 12 nm for UNCD/a-C:H, as shown by AFM topography analyses. The wettability of the coatings was investigated by contact angle measurements, from which the surface energy was determined. An inverted Enzyme-Linked ImmunoSorbent Assay (ELISA) was performed in order to investigate the protein adsorption on the surfaces of the materials. The proteins studied were albumin and fibrinogen which