Haemocompatibility of amorphous hydrogenated carbon thin films, optical properties and adsorption mechanisms of blood plasma proteins.

Haemocompatibility is one of the most important properties, together with the tissue compatibility and corrosion and wear resistance that determine the biocompatibility of the artificial implants. Carbon-based thin films, such as amorphous carbon (a-C) and amorphous hydrogenated diamond-like carbon (a-C:H or DLC) are considered as excellent candidates for use as biocompatible coatings on biomedical implants. The aim of this work is the comparative study of the haemocompatibility of the a-C:H thin films developed by magnetron sputtering under various deposition conditions, the development of a methodology in order to study the haemocompatibility of thin films, the optical properties of the adsorbed proteins (human serum albumin and fibrinogen) and their adsorption mechanisms. Haemocompatibility and the optical properties of a-C:H thin films and the adsorbed proteins were studied by spectroscopic ellipsometry (SE). The films grown under floating conditions performed better haemocompatibility compared with those deposited under application of bias voltage. In the range of vis-UV, proteins are transparent, while they present an absorption peak at higher energies, but except these characteristics, their optical functions are rather featureless. Adsorption mechanisms were studied through AFM technique too. AFM results are in accordance with those derived by SE. Combination of the two techniques gives us a more accurate description of protein adsorption mechanisms.