Combined tribological and bactericidal effect of nanodiamonds as potential lubricant for artificial joints.

The artificial joints, e.g., knee and hip implants, are widely used for the treatment of degenerative joint diseases and trauma. Current most common material choice for clinically used implants is the combination of polymer-on-metal structures. Unfortunately, these joints often suffer from high friction and wear, leading to associated inflammation and infection and ultimate failure of the artificial joints. Here, we propose an alternative solution to this tribologically-induced failure of the joint materials. We demonstrate that friction and wear behavior of ultra-high-molecular-weight polyethylene (UHMWPE) and titanium tribopair, used to mimic the artificial joint interface, can be improved by introducing nanodiamond (ND) particles in the sliding contact. Characterization of the wear track using energy dispersive spectroscopy (EDS) and Raman spectroscopy revealed that the tribofilm formed from embedded NDs during sliding significantly suppressed the wear of the UHMWPE surface. In addition to the improved lubrication characteristics, NDs exhibit high biocompatibility with the bone cells and promising antibacterial properties against S. aureus, the most common strain associated with artificial joint infection. These results indicate that NDs can be used as a promising nontoxic human-body lubricant with anti-wear and antibacterial features, thus demonstrating their great potential to treat artificial joint complications through intra-articular injection.