Osteoblasts attachment on amorphous carbon films

In this work we studied the osteoblasts response to amorphous carbon (a-C) films deposited on stainless steel substrates with different surface textures. For osteoblasts cells, attachment to the substrate is the first step in the process of cell/surface interactions which affects subsequent cellular and tissue response. Amorphous carbon films are characterized by very smooth surfaces that imaged the surface roughness of the substrate and many of their applications rely on this property. However, in the biomedical field the cell response is strongly influenced by the topography and particularly, for osteoblasts cells it has been shown that rough surfaces enhances cellular attachment and differentiation. Therefore, in this work we modified the surface roughness of the substrate in order to obtain carbon films with different values of average surface roughness. The substrates were abraded or fine-polished to obtain four different average roughness: 0.01, 1.5, 2.1 and 3.5 μm. Surface topography before and after deposition of the a-C films was evaluated by profilometry and scanning electron microscopy (SEM), while chemical composition was determined by X-ray photoelectron spectroscopy. Human osteoblasts cells were used to evaluate the effect of the different surface finishes on the adhesion. The number of attached cells was determined by a colorimetric technique after 24 h of incubation, while morphological and cytoskeletal changes were monitored using SEM. The cellular attachment on a-C surfaces increases monotonically with the roughness attaining up to 160% more cells than the positive control.