Selenite-Doped β‑TCP Powders with Improved Biological Properties: Microwave-Assisted Synthesis and Detailed...

β-Tricalcium phosphate (β-TCP, Ca₃(PO₄)₂) is a widely used bioresorbable ceramic in orthopedic applications, particularly as a bone graft material and as a coating on bioinert metallic implants. Its bioactivity, resorption kinetics, and biocompatibility account for its extensive clinical use, motivating efforts to further enhance its performance. The incorporation of various ions into the β-TCP lattice has been widely explored to tailor its structural, physicochemical, and biological properties. Among these, selenium (Se) is an essential trace element that enhances osteoblast activity and supports bone regeneration. To achieve this, microwave-assisted synthesis was employed for its advantages, including rapid reaction kinetics, homogeneous heating, limited grain growth, and efficient ion incorporation. In this study, submicron-sized selenite (SeO₃ ^2-)-doped β-TCP (Se-β-TCP) powders were successfully synthesized using this technique and characterized in detail. Structural analyses confirmed the incorporation of SeO₃ ^2- into the β-TCP lattice, as evidenced by a reduction in the c parameter from 37.372 Å to 37.242 Å and the emergence of a Se-O vibration band at 904-806 cm^-1, in the infrared spectra. In vitro results showed that MC3T3-E1 preosteoblasts cultured with Se-β-TCP proliferated for up to 5 days, while the powders inhibited colony growth of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli. These findings demonstrate that Se-β-TCP synthesized via microwave-assisted processing is both cytocompatible and antibacterial, highlighting its potential for orthopedic applications.