Mg ²⁺ , Sr ²⁺ , Ag ⁺ , and Cu ²⁺ co‐doped β‐tricalcium phosphate: Improved thermal stability and mechanical and biological properties

Abstract β‐tricalcium phosphate (β‐TCP, β‐Ca 3 (PO 4 ) 2 ) is an attractive biomaterial for bone repair applications. However, its sintering and mechanical properties are limited by a problematic phase transition to α‐TCP. Cationic doping of β‐TCP is able to postpone the formation of α‐TCP allowing higher sintering temperatures and better mechanical properties. The co‐doping of β‐TCP with Mg 2+ and Sr 2+ has already been studied in detail, but the addition of antibacterial cations (Ag + and Cu 2+ ) on the Mg–Sr β‐TCP co‐doped composition remains unexplored. Thus, two co‐doped β‐TCP compositions were realized by aqueous precipitation technique without any secondary phase and compared with undoped β‐TCP: Mg–Sr (2.0–2.0 mol%) and Mg–Sr–Ag–Cu (2.0–2.0–0.1–0.1 mol%). Differential thermal analysis and dilatometry analyses showed a slight decrease of the β‐TCP → α‐TCP phase transition temperature for the Mg–Sr–Ag–Cu (2.0–2.0–0.1–0.1% mol) composition as compared to the Mg–Sr (2.0–2.0 mol%). However, both exhibited much higher transition temperatures than undoped β‐TCP. The addition of Ag + and Cu 2+ slightly reduces the grain size after sintering compared to the Mg–Sr (2.0–2.0 mol%) and the undoped compositions. The co‐doped compositions also exhibited improved mechanical properties, specifically a higher Vickers hardness and elastic modulus. Finally, cell proliferation assays showed that the presence of dopants, even Ag + and Cu 2+ , does not affect the survival and proliferation of cells. Thus, the use of Mg 2+ , Sr 2+ , Ag + , and Cu 2+ co‐doped β‐TCP could be very promising for biomedical applications due to the improvements of these dopants on the thermal stability and mechanical and biological properties.