Antibacterial Effect of the Controlled Nanoscale Precipitates Obtained by Different Heat Treatment Schemes with a Ti-Based Nanomaterial, Ti-7.5Mo-5Cu Alloy.

It is well known that copper is an excellent option for a Ti-based alloy component as a β-stabilizer that provides improved biocompatibility and antibacterial ability. The development of a Ti-based nanomaterial containing Cu is a promising strategy for addressing implant-associated infections (OII). However, the antibacterial mechanism of copper-related alloys is still unknown. There are two popular hypotheses: copper ion release sterilization and alloy contact sterilization. The main mechanism of contact sterilization may be Cu-related phase (Ti2Cu) precipitation. Because excess copper can lead to cytotoxicity and reduce the β-Ti phase content, molybdenum needs to be added to the alloy given its well-known and widely researched β-stabilizer characteristics, which can provide satisfactory mechanical properties, wear resistance, and biocompatibility. Our study created a Ti-based nanomaterial, Ti-7.5Mo-5Cu, and performed two kinds of heat treatment schemes at different solution temperatures: 750 and 900 °C. The above schemes resulted in homogeneous and heterogeneous nucleation on the precipitation behavior of the Ti2Cu crystal phase, which controlled its amount, distribution, and size. Finally, our results showed that Ti-7.5Mo-5Cu, especially at 900 °C, possessed excellent antibacterial ability, corrosion resistance, cytocompatibility, and induced osteogenic differentiation, indicating its potential for use as a biomedical antibacterial alloy in the future.