Improved biotribological performance of Ti6Al4V alloy through the synergetic effects of porous TiO2 layer and zwitterionic hydrogel coating

To improve the biotribological properties of Ti6Al4V alloy for artificial joints, motivated by the composite structure of ‘natural articular cartilage - subchondral bone’ and the hydration lubrication mechanism of articular cartilage, a soft/hard bilayer coating composed of a porous TiO 2 layer and a zwitterionic hydrogel coating was designed and fabricated on Ti6Al4V alloy through micro-arc oxidation (MAO) combined with ultraviolet (UV) radiation technology. Characterization results revealed that the bio-inspired bilayer coating could be successfully constructed on Ti6Al4V alloy, and such a coating displayed good hydrophilicity (WCA: 32°). Notably, by ball - on - disk friction test, this biomimetic bilayer coating exhibited an ultra-low friction coefficient (∼0.038) in PBS solution, which was reduced by an order of magnitude compared with that of the Ti6Al4V alloy substrate. This was due to the synergistic effects of soft/hard composite structure and the hydration lubrication of zwitterionic MPC polymer. This work provides a novel and effective strategy for surface modification of Ti6Al4V alloy for artificial joints.