Triple-Doped (Mg, Zn, Sr) β-Tricalcium Phosphate Ceramics: Biomimetic Synthesis, Femtosecond Laser-Induced Microstructure Formation and Biological Assessment

Triple-doped substitution and femtosecond laser surface microstructuring represent synergistic strategies for tailoring the physicochemical, structural, and biological properties of β-tricalcium phosphate (β-TCP) ceramics for bone tissue engineering. In this study, β-TCP ceramic materials were synthesized, substituted with Mg (8–9 mol%), Zn (3 mol%), and Sr (1 mol% or 5 mol%), and possessed a (Ca + Mg + Zn + Sr)/P molar ratio of 1.51 or 1.55. The synthesis was carried out by biomimetic precipitation in simulated body fluid at pH 8.0–8.2, followed by tableting and calcination up to 1000 °C. The effect of femtosecond laser texturing was investigated by applying scanning patterns consisting of parallel lines, as well as intersecting lines at angles of 90° and 45°. The materials were characterized using scanning electron microscopy (SEM), optical profilometry, and water contact angle measurements. The results indicate that laser irradiation forms hierarchical microchannels and porous-granular structures without thermal cracking. The intersecting-line pattern (at a 45° angle) yields the highest surface roughness (Sa = 4.95 μm)—particularly for the composition containing 5 mol% Sr—compared to Sa value of 2.45 μm for the untreated control sample. Water contact angle measurements demonstrate a significant increase in hydrophilicity. Contact angles for samples with 1 mol% Sr decreased from 83.05° to 34.19°, whereas all laser-treated surfaces with 5 mol% Sr exhibited immediate droplet spreading, indicating hydrophilic wetting behavior. Preliminary biological tests revealed no significant reduction in HaCaT cell viability or marked adverse changes in cell morphology under the tested conditions. Bacterial adhesion of E. coli varied according to surface configuration; samples textured with parallel lines showed a lower degree of colonization compared to the other variants tested. These results demonstrate that femtosecond laser processing of β-TCP ceramics modified with Mg (8–9 mol%), Zn (3 mol%), and Sr (1 mol% or 5 mol%) can generate specific surface structures characterized by measurable differences in roughness, wettability, and initial biological responses. Further research employing appropriate osteogenesis cell models and systematic control of composition and surface structure is required to establish the biological significance of these findings.