Ti6Al4V-Bioglass-Copper Composites for Load-Bearing Implants

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) utilize cobalt-chromium-molybdenum alloys; however, the release of cobalt ions is a significant clinical concern. Ceramic-based alternative systems also have concerns regarding long-term mechanical stability. Ti6Al4V (Ti64) is a better alternative; however, it is unsuitable for articulating surfaces due to its low wear resistance. We have designed and manufactured a novel Ti64-based composite by adding 45S5 bioglass (BG) and copper (Cu). Adding BG on titanium improves wear resistance and biocompatibility, whereas Cu addition improves mechanical strength while providing inherent lifelong bacterial resistance. Ti64, Ti64-1 wt% BG (Ti64-1BG), Ti64-3 wt% BG (Ti64-3BG), and Ti64-3 wt.% BG-3 wt.% (Ti64-3BG-3Cu) compositions were processed using the laser-directed energy deposition (L-DED) additive manufacturing (AM) technique. Microstructural characterisation and phase analysis were done to evaluate the influence of BG and Cu addition on Ti64. While BG was preferentially located along the melt pool boundaries, Cu was uniformly distributed throughout the sample. Uniaxial compression tests were conducted, and the addition of BG and Cu increased the strength. Biotribological analysis using flat-on-disc fixtures under fully immersed conditions in DMEM revealed that wear resistance improved due to the addition of BG and Cu to Ti64. Tribological testing revealed the formation of a protective nanoscale tribofilm on BG-containing samples, as indicated by increased contact resistance and reduced wear rates at higher loads. In vitro biocompatibility studies were done with human osteoblast (OB) cells for 3 and 7 days. Cell attachment and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays were performed to understand the influence of BG and Cu on biocompatibility, with Ti64 serving as a control. An antibacterial test was performed for 24 and 72 h using Staphylococcus aureus to evaluate the influence of Cu addition on the sample's antibacterial properties. Overall, the results demonstrated a superior implant material with enhanced biocompatibility, inherent antibacterial properties, and improved wear resistance through the innovative formation of a protective nanoscale tribofilm.