Novel Multi-Doped Apatite-Related Calcium Phosphates and Composites With SiO₂ for Medical Application

This study presents the synthesis and comprehensive characterization of the structural, mechanical, and biological properties of multi-doped with cations (Na⁺, Mg²⁺, Zn²⁺) and anions (SiO₄ ^4-, CO₃ ^2-, BO₃ ^3-, BO₂ ^-) hydroxyapatites, as well as their composites containing 25 wt% SiO₂. XRD analysis confirmed the formation of a hexagonal apatite structure (space group P6₃/m) with crystallite sizes range from 17 nm to 23 nm. FTIR spectroscopy verified the successful incorporation of anionic groups into the calcium phosphate lattice via A-type and B-type substitution mechanisms. It was established that the introduction of silicate anions in structure or silica in composite allows for the precise tailoring of material surface reactivity in a model solution (pH elevation to 8.2-9.4) without significant degradation of mechanical performance (microhardness ∼0.32-0.33 GPa). The composite of (Na⁺, Mg²⁺, Zn²⁺, CO₃ ^2-)-doped HAP with 25 wt% SiO₂ exhibited the highest antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa, alongside superior nucleic acid sorption efficiency, outperforming borate-containing analogues by 1.36-1.89 times. These findings highlight the potential of the developed composites as multifunctional bioactive materials for bone tissue regeneration and nucleic acid extraction systems.