Properties of carbon films and their biocompatibility using in-vitro tests

Abstract

In this paper we report the results of a comparative study of the biological response of amorphous carbon coated stainless steel. Films of amorphous carbon (a-C), amorphous carbon nitride (a-CN) and hydrogenated amorphous carbon (a-C:H) were deposited on stainless steel substrates (AISI 316L) using a dc magnetron sputtering system. In-vitro studies were carried out on the coated samples using human osteoblasts cell culture lines and fibroblasts. Preliminary biocompatibility was assessed by cell adhesion and proliferation, as determined by a spectroscopic technique. Comparison of the optical absorbance results between control uncoated disks and the test cultures provided a semi-quantitative analysis of the cytotoxic effect of the different carbon compounds. Osteoblasts cells were grown on uncoated steel, a-C, a-CN and Ti coated steel samples. The degree of fibroblast adhesion measured at 24 h is very similar for all the test samples, however, osteoblasts adhesion was higher for a-C films. Similarly, cellular proliferation at 7 days showed an outstanding increase of osteoblasts cells for a-C and Ti in contrast with uncoated steel. The physical film properties, such as, roughness measured by atomic force microscopy, surface composition determined by both Rutherford Backscattering and Auger Spectroscopy and the electro-optic properties of the films were also determined. The relation between film properties and cellular response is discussed.