EVALUATION OF THE EFFECT OF 3 SURFACE TREATMENTS ON THE BIOCOMPATIBILITY OF 316L STAINLESS-STEEL USING HUMAN DIFFERENTIATED CELLS

AISI 316L stainless steel (SS) is widely used in orthopaedic implantol ogy, although biological complications may result from its insufficien t mechanical and tribological properties. In order to improve the wear and corrosion resistance as well as the hardness of 316L SS, three su rface treatments, derived from those applied in mechanical engineering industries, were investigated: (1) glow discharge nitrogen implantati on, (2) carbon-doped stainless steel coating sputtering and (3) low te mperature plasma nitriding. Surface characterization according to the different heat treatments showed that corrosion and wear resistance we re strongly improved, especially by ion implantation or carbon-doped S S coating sputtering. In the same way, microhardness was significantly increased after the three treatments. The effect of such treatments o n the biocompatibility of 316L SS was studied with human osteoblast an d fibroblast cultures. Basic and specific features of the cells showed that ion-implanted and carbon-doped stainless steels were biocompatib le, whereas dramatic cellular reactions were noted when contacted with nitrided stainless steel. A hypothesis is given to explain this obser vation but further experiments are needed to optimize the nitriding pr ocess. Nitrogen implantation and carbon-doped layer deposition could b e efficient means for improving the physical properties of stainless s teel without affecting its biocompatibility. Such surface treatments m ay have relevance for increasing the life time of 316L SS biomedical d evices.