Tribological assessments of bilayer titanium nanocomposite hydrogels for cartilage replacement in articular joints

Polymeric hydrogels are gaining recognition as cartilage implants for articular joints. Formulating and synthesizing hydrogels mimicking the native cartilage with respect to tribological properties have proven to be a challenging task. We hypothesized that a bilayer nanocomposite hydrogel (NCH) with an optimum amount of titania nanoparticles (NPs) could enhance tribological properties and be considered as a cartilage implant. In this work, a series of titania NPs loaded acrylamide-alginate bilayer hydrogels were synthesized via modulated polymerization process and tribological assessments of the hydrogels were conducted. Multi-factor sliding wear tests were conducted on hydrogel samples using a linear reciprocating tribometer, with a steel ball counterface. Tribological test results showed a low mean coefficient of friction values of 0.007 and 0.014 for non-reinforced hydrogels and NCHs, respectively, and wear resistance of NCHs improved significantly. SEM images showed that wear mechanisms are a combination of adhesive wear and fatigue wear.