Titanate biomaterials with enhanced antiinflammatory properties.

While titanium implants are generally recognized as having excellent biocompatibility, the mechanistic basis for this has yet to be established. We previously demonstrated that TiO2, found on surfaces of titanium, has antioxidant properties that degrade the reactive oxygen species (ROS) which mediate the inflammatory response. We hypothesized that the antioxidant mechanism was similar to that known to mediate photocatalysis by titanium oxides. Specifically, we investigated whether the electronic or valence state of the surface titanium atoms mediates the catalytic degradation of ROS. Surface Ti(IV) atoms in TiO2 and SrTiO3 single crystal substrates were converted into Ti(III) while maintaining the bulk crystalline structure by vacuum annealing or Niobium doping. The degradation of both chemically-induced and neutrophil-derived ROS were significantly increased by changing the valence state of surface titanium. These results suggest that titanium-mediated degradation of ROS is through a catalytic mechanism. Furthermore, we describe a series of novel biomaterials that have antioxidant properties superior to those of titanium. Copyright 2006 Wiley Periodicals, Inc.