A novel hydroxyapatite modified MXene-based hydrogel coating on Ti6Al4V alloy with improved biotribological properties and corrosion resistance

As a commonly used bone implant, the Ti6Al4V alloy is prone to wear in the human environment because of its corrosion resistance and poor wear resistance, resulting in aseptic loosening and even implantation failure. Here, inspired by mussel adhesion chemistry, a novel hydrogel coating based on hydroxyapatite-modified MXene (polyvinyl alcohol (PVA)/polyacrylic acid (PAA)/polydopamine (PDA)/hydroxyapatite (HA)-MXene) was created via a sol‒gel method involving cyclic freezing and thawing, as well as chemical self-assembly techniques, on the surface of a titanium alloy. The corrosion resistance and biotribological behaviors of the hydrogel coating on cortical bone were studied in simulated body fluid (SBF). The results demonstrated that the HA-MXene-based hydrogel coating exhibited outstanding biotribological and anti-corrosion properties. The novel HA-MXene-based hydrogel coatings can validly reduce the wear rate of cortical bone by 88.0% because of the lubrication film formed on the surface of hydrogel and the sliding and rolling friction mechanisms. Moreover, the enhanced anticorrosion properties of hydrogel coatings, which were optimal when the quantity of MXene reached 0.05 wt%, were attributed to the blocking effect of MXene-based hydrogel. This study provides an innovative idea of surface modification design for the application of titanium alloy implants in the field of orthopedics.