Bacterial adhesion reduction on a biocompatible Si+ ion implanted austenitic stainless steel

The colonization of an implant surface by bacteria is an extremely important medical problem, which often leads to the failure of medical devices. Modern surface modification techniques, such as ion implantation, can confer to the surfaces very different properties from those of the bulk underlying material. In this work, austenitic stainless steel 316 LVM has been superficially modified by Si+ ion implantation. The effect of surface modification on the biocompatibility and bacterial adhesion to 316 LVM stainless steel has been investigated. To this aim, human mesenchymal stem cells (hMSCs), as precursor of osteoblastic cells, and bacterial strains relevant in infections related to orthopedic implants, i.e., Staphylococcus aureus and Staphylococcus epidermidis, have been assayed. For the understanding of changes in the biological response associated to ion implantation, variations in the chemical surface composition, topography, surface Gibbs energy, isoelectric point and in vitro corrosion behavior have been evaluated. hMSCs adhesion, viability and differentiation to the osteoblastic lineage were unaffected by Si+ ion implantation. On the other hand, Si+ ion implantation diminished the number of attached bacteria in static conditions and led to smaller adhesion rates and retention strength. The ability of implanted surfaces to reduce the bacterial adhesion was higher for Staphylococcus epidermidis than for Staphylococcus aureus. This study proposes Si+ ion implantation as an effective way of reducing bacterial adhesion on 316 LVM stainless steel surfaces without compromising its good biocompatibility. (C) 2011 Elsevier B.V. All rights reserved.